Psychiatric comorbidities in ADHD

Author: Ulrich Brennecke
Review 10/2024: Dipl.-Psych. Waldemar Zdero

In persons with ADHD, the following psychiatric disorders often occur in addition (comorbid), sorted in descending order of frequency with ADHD (in % of people with ADHD) compared to the frequency in non-affected persons.

Adults with the highest 10% of ADHD symptom severity according to ADHD-E were 6.99 times more likely to experience psychological distress than non-affected adults.¹

One study found 51.8% of people with ADHD had one or more comorbid mental illnesses.²
Another study in Japan in 2019 found comorbid ASD in 54.4% of children and adolescents with ADHD and affective disorders (depression, etc.) in 60.9% of adults.³

The percentages in the headings should indicate the frequency of comorbidity in ADHD. Example: 70 to 80 % of children with ADHD suffer from sleep disorders, compared to 35 to 40 % of children without ADHD. Unfortunately, the figures are currently mixed up and need to be corrected.

• 1. Learning disorders - up to 92
  • 1.1. Learning disorders in children - 10 to 92 %
  • 1.2. Learning disorder in adults - 2 % (vs. 1.6 %)
• 2. Autism Spectrum Disorders (ASD) - 3.6% to 85% (vs. 0.40% for girls to 1.85% for boys)
• 3. Sleep disorders - up to 80
  • 3.1. Sleep disorders in children with ADHD - 70 to 80 % (vs. 35 to 40 % = + 100 %)
  • 3.2. Sleep disorders in adults with ADHD - 11.3% (vs. 2.3%)
  • 3.3. Consequences of sleep disorders (sleep disorders: children 47.1 %; adults: 0.6 to 7.8 %)
• 4. Body-related repetitive behavior disorders (BFRDB, BFRB)
  • 4.1. Trichotillomania
  • 4.2. Chew nails
• 5. Affective disorders (depression / dysphoria / dysthymia / mania / bipolar) - 30 to 61 % (vs. 4.7 to 8.9 % = + 550 %)
  • 5.1. Depression
  • 5.2. Dysthymia 6.3 % (vs. 3.4 %)
  • 5.3. Bipolar Disorders - 4.7% to 33.5% (vs. 3.1% to 14.3%)
• 6. Motor clumsiness up to 60
  • 6.1. Developmental motor coordination disorder, dyspraxia, DCD - 29 % to 47 %
  • 6.2. Gross motorist
  • 6.3. Impaired fine motor skills, poor handwriting - 60 %
• 7. Behavioral disorders / social disorders (aggression, antisocial behavior, oppositional defiant behavior) - up to 55 %
  • 7.1 Severe behavioral disorder (disruptive behavior disorders) - 30 to 50 %
  • 7.2. Deficient Emotional Self Regulation (DESR) - 44 to 55 %
  • 7.3. Oppositional Defiant Disorder (ODD) - 26 to 53 % (vs. 3.9 % = + 560 % to + 1,260 %)
  • 7.4. Disorders of social behavior / Conduct Disorder (CD) - up to 20.2 % (vs. 4.3 %)
  • 7.5. Aggressive behavior - over 50
• 8. Anxiety disorders - up to 47 % (vs. 19.5 %)
  • 8.1. Anxiety disorders in children - 25 to 38 % (vs. 7 to 10 % = up to + 400 %)
  • 8.2. Anxiety disorders in adults - 44 % (vs. 4.9 %)
    • 8.2.1. Generalized anxiety disorder - 5.9 to 25 % (vs. 2 %)
    • 8.2.2. Social phobia - 5 to 29.3 % (vs. 3.5 to 10 %)
    • 8.2.3. Panic disorder - 1.9 to 4.3 % (vs. 2.9 %)
    • 8.2.4. Specific phobias
• 9. Substance abuse and addiction - up to 45
  • 9.1. Substance-related addictions / substance abuse
    • 9.1.1. Substance abuse - 21.9 % to 35 % (vs. 2.9 % to 3.6 %)
    • 9.1.2. Smoking - 40 to 45 % (vs. 22 to 25 %)
    • 9.1.3. Alcohol dependence (30 to 39 % vs. 5 to 15 %) / alcohol abuse
    • 9.1.4. Substance-related addictions in general - 7.8 %
    • 9.1.5. Drug addiction
  • 9.2. Behavioral addiction / gambling 5.3 % (vs. 2.4 %)
  • 9.3. Substance abuse (illegal drugs: 10 %, nicotine: 16.6 to 25.5 %)
  • 9.4. Addiction / dependency (alcohol: 5%, gambling: 0.31%)
• 10. Restless legs (RLS, akathisia) - 11 to 44 % (vs. 2.6 to 15.3 %)
• 11. Partial performance disorders - up to 40
  • 11.1. Reading difficulties, dyslexia, dyslexia - 8 to 40 % (vs. 5.6 %)
  • 11.2. Spelling difficulties (agraphia, dysgraphia) - 12 to 40 %
  • 11.3. Dyscalculia 12 - 27 %
  • 11.4. Weakness in facial recognition (prosopagnosia)
  • 11.5. Name recall weakness
  • 11.6. Speech disorders
  • 11.7. Right-left weakness
• 12. Developmental disorder - up to 37.4
  • 12.1. Specific developmental disorders - 37.4 % (vs. 13.4 %)
  • 12.2. Specific developmental disorders of school skills - 23% (vs. 2.8%)
• 13. Bipolar Disorders - 4.5 to 35.5% (vs. 0.2 to 3.6%)
• 14. Personality disorders (in adults) - 11.5 % to 33.2 % (vs. 0.9 % to 1.4 %)
  • 14.1. Antisocial PS - 18 % (vs. 2 to 3.5 %)
  • 14.2. Borderline PS / emotionally unstable PS - 18 to 33 % (vs. 1 to 5 %)
  • 14.3. Anxious PS - 10.6 % (vs. 2.1 %)
  • 14.4. Self-insecure PS
  • 14.5. Compulsive PS - 19.3 (vs. 7.8 %)
  • 14.6. Combined PS
  • 14.7. Paranoid PS - 14.8 % (vs. 4.1 %)
  • 14.8. Dependent PS - 3.1 % (vs. 0.4 %)
  • 14.9. Narcissistic PS
  • 14.10. Histrionic PS - 10.7 % (vs. 1.6 %)
  • 14.11. Schizotypal PS - 22.4 % (vs. 3.5 %)
  • 14.12. Schizoid PS - 9.2 % (vs. 2.9 %)
• 15. Premenstrual dysphoric disorder (PMDD) - 31.4 % (vs. 9.8 %)
• 16. Tic disorders 30 % (vs. 5 %)
• 17. Post-traumatic stress disorder (PTSD) - 11.9% to 28% (vs. up to 3.3% to 6%)
• 18. Impulse control disorder, impulse control disorder (ICD) - 19.6 % (vs. 6.1 %)
• 19. Adjustment disorders - 18.9 % (vs. 3 %)
• 20. Mental disability - 13 %
• 21. Eating disorders - Loss of Control Eating Syndrome (LOC-ES) - 7.5 to 11.4 % (vs. 1.4 %)
• 22. Psychoses - 8.8 % (vs. 3 %)
• 23. Epilepsy - 3.4 % (vs. 0.5 to 1 %)
• 24. Schizophrenia - 3.4 % (vs. 0.8 %)
• 25. Obsessive-compulsive disorder - 1.9 to 2.4 %
• 26. Intellectual disability - 1.4 %
• 27. Migraine
• 28. Obesity
• 29. Socialization disorder
• 30. Disorder of sexual development
• 31. Narcolepsy
• 32. Messi syndrome / Hoarding
• 33. Attachment disorders
• 34. Enuresis (enuresis)
• 35. Encopresis (defecation)
• 36. Suicidal tendencies - 2.4 to 6.7-fold
• 37. Fibromyalgia - 4-fold
• 38. Dopamine transporter deficiency syndrome (DTDS)
• 39. Stuttering
• 40. Mental disorders in relatives of people with ADHD - 6.8-fold

1. Learning disorders - up to 92¶

1.1. Learning disorders in children - 10 to 92 %¶

10 - 92 % Frequency of comorbidity in children with ADHD⁴/ general learning disability (approx. 20 %)⁵⁶

1.2. Learning disorder in adults - 2 % (vs. 1.6 %)¶

Total adults 1.6 %; women 1.4 %, men 2.4 %; ADHD-I 1.5 %, ADHD-C 2.5 %, ADHD-HI 2.5 %⁷

2. Autism Spectrum Disorders (ASD) - 3.6% to 85% (vs. 0.40% for girls to 1.85% for boys)¶

People with ADHD have a high risk of comorbid ASD.

• 15- to 21-fold risk (based on an ASA population prevalence of 1%)(meta-analysis)⁸
  • 15% to 21% of children and adolescents with ADHD have an autism spectrum disorder
  • Children with ADHD with ASD show stronger ADHD symptoms than children without ADHD
• 24% of children with ADHD met the criteria for ASD⁹
• 31% to 37% increased risk of ASA¹⁰

Children with ADHD without an ASD diagnosis showed increased ASD traits¹¹, which was associated with negative interpersonal, academic and cognitive outcomes¹².
The degree of autistic characteristics in children without ASD can be measured using the CBCL-AT scale.¹³¹⁴ The CBCL-AT scale is positive if the sum of the T-scores for the withdrawal, social problems and thinking problems subscales of the Child Behavior Checklist (CBCL) is 195 or greater. According to this criterion, 18.18% of children with ADHD without autism showed autistic traits, compared to 0.87% of children without ADHD (20.9-fold risk, + 1,990%).¹⁴

• 60% of children with ADHD showed ASD traits.¹⁵¹⁶

People with ADHD also have an increased risk of ADHD^{617 18 19} It has been named with:

• 85 %²⁰
• 78 % (among n = 83 children with ASD, Asperger’s and permanent developmental disorder)²¹
• 26 % (study of n = 103 children, 85 % of whom were boys with ADHD without intellectual impairment - 27 cases were found to have previously undiagnosed ASD)²²
• 21.6% of people with ADHD had comorbid ADHD²³
• 3.6 % over the entire age range (cohort study)²⁴

DSM-IV still stipulated that ADHD and autism spectrum disorders should not be diagnosed as comorbid. This was changed in DSM 5.

Girls with autism who also had ADHD showed significantly stronger symptoms of ADHD, learning disabilities and ODD than boys with ASD and ADHD in a large study.²⁵

In the overall population, ASD occurs in 1 in 54 boys (1.85%) and 1 in 252 girls (0.40%).²⁶

There is evidence that ADHD and autism have common genetic roots.²⁷¹⁰ ADHD and ASD share two genes known as risk genes.¹⁷ There are suggestions that ADHD and autism may have further common genetic roots.²⁷ Disorders of dopaminergic neurotransmission are suspected in ASD, among other things,²⁸ while such disorders are documented in ADHD.

Around 28%²⁹ to 50% of people with ADHD have ADHD as a comorbidity.
The fact that ADHD could not be diagnosed in autism according to DSM IV speaks against empirical experience and is therefore omitted in DSM 5.¹⁸

3. Sleep disorders - up to 80¶

3.1. Sleep disorders in children with ADHD - 70 to 80 % (vs. 35 to 40 % = + 100 %)¶

70 - 80 %³⁰; 73.3 % (28.5 % mild plus 44.8 % moderate and severe),³¹⁶ twice as common as in children not affected by the disease³²³³
For the treatment of sleep disorders ⇒ Sleep problems with ADHD.

A meta-analysis found that around 33% of people with narcolepsy also have ADHD.³⁴
Narcolepsy is associated with a reduced level of dopamine in the cerebrospinal fluid. This is consistent with the dopamine deficiency found in ADHD. In dogs with narcolepsy, on the other hand, increased dopamine levels were found in the amygdala and increased noradrenaline levels in the oral pontine reticular nucleus. Nevertheless, the dogs respond to stimulants that increase dopamine and noradrenaline.³⁵
Kooij sees sleep disorders (difficulty falling asleep or sleeping through the night) in 43% of people with ADHD.³⁶

3.2. Sleep disorders in adults with ADHD - 11.3% (vs. 2.3%)¶

Sleep problems that last longer than a month are called sleep disorders.

• In adult people with ADHD: 11.3%³⁷ to 29%³⁸
• For non-affected persons: 2.3 %³⁷
  = 5 to 12 times the risk

The annual prevalence of sleep disorders in Germany in 2008 was 0.6 % (15 to 19 years) to 6.6 % (60 years and over) for men and 0.8 % (15 to 19 years) to 7.8 % (60 years and over) for women.³⁹
Sleep problems with ADHD are extremely common:

• 70 - 80 % of people with ADHD suffer from sleep problems
• 20 - 30 % of adults with ADHD suffer from sleep problems
  Of the 670 adult persons with ADHD (with a medical diagnosis) who took the ADxS.org online symptom test, 69% reported sleep disorders, compared to 39% of the 159 people with ADHD who said they were certainly not affected (as of March 1, 2022).

A meta-analysis found that around 33% of people with narcolepsy also had ADHD.³⁴

3.3. Consequences of sleep disorders (sleep disorders: children 47.1 %; adults: 0.6 to 7.8 %)¶

A Chinese study of 23,791 schoolchildren found that 68.7% of children with ADHD had poor sleep quality, compared to 47.1% of children without ADHD⁴⁰

See also: ⇒ ADHD - comorbidity, there on sleep problems

When it comes to sleep problems and ADHD, it is difficult to separate cause and effect. ADHD very often causes sleep disorders and sleep disorders often cause ADHD-like symptoms.

In the case of an ADHD diagnosis, comorbid sleep disorders should always be treated with special priority. In addition, when taking medication for sleep problems, their possible negative effect on ADHD symptoms must be taken into account, just as medication for ADHD must be checked to ensure that it does not exacerbate sleep problems. More on the treatment of sleep problems with ADHD: ⇒ Treatment of sleep problems with ADHD

• Vigilance disorders with impaired sleep-wake regulation⁴¹⁴²
• Consequences of sleep apnea syndrome⁴³
  “Obstructive sleep apnoea syndrome (OSAS) is the most common sleep-related breathing disorder. The prevalence is around 4% in men and around 2% in women.
  Obstructive sleep apnea (OSA) is even more common and reaches strikingly high figures, particularly when subgroups are considered. For example, there is a prevalence of around 36% in patients with diabetes mellitus or arterial hypertension, a prevalence of 50% in obese patients and a prevalence of 83% in patients with refractory arterial hypertension. It is estimated that 80 % of male and 90 % of female patients with sleep apnoea syndrome are undiagnosed and therefore untreated.”⁴⁴
  Breathing interruptions in children’s sleep can trigger cognitive stress, causing symptoms that resemble ADHD.⁴⁵
• Chronic lack of sleep⁴¹
• Disorders of the dream sleep phases occur within a few days:
  • Increased irritability⁴⁶
  • Increased impulsivity⁴⁶
  • Reduced concentration⁴⁷
  • Reduced attention⁴⁷
  • Disorders of the working memory⁴⁸

Common symptoms of sleep problems and ADHD:⁴⁹

• Motor hyperactivity, physical restlessness
• Concentration problems
• Attention problems

ADHD symptoms that are atypical of sleep problems:

• Inner restlessness (typical in atypical depression, less so in melancholic depression)
• Impulsiveness
• High flow of speech (logorrhea, polyphrasia)
• Chasing thoughts, circling thoughts
• Rapid mood swings
• Dysphoria with inactivity

Symptoms of sleep problems that are atypical for ADHD:

• Drowsiness
• (Day) tiredness

4. Body-related repetitive behavior disorders (BFRDB, BFRB)¶

Body-focused repetitive behavior disorders (BFRDB) are related to impulse control disorder. Some of them are sometimes considered impulse control disorders, but the distinction is difficult to make.
BFRBDs show an irresistible urge, often associated with tension, that is relieved by the act, which has similarities to ICDs. While ICDs are traditionally disorders in their own right, in ICD-11 BFRBDs are now classified within the spectrum of obsessive-compulsive and related disorders, albeit in their own subcategory, emphasizing their complex nature.

BFRDB includes, among other things:

• Bruxism (teeth grinding)
• Crepitus (cracking of the finger joints)
• Dermatophagia (skin biting)
• Thumb sucking
• Lip keratosis (lip biting)
• Morsicatio buccarum (cheek biting)
• Onychophagia (nail biting)
• Onychotillomania (nail biting)
• Rhinotillexomania (nose picking)
• Trichophagia (hair eating)
• Trichotillomania (pulling out hair)

4.1. Trichotillomania¶

Trichotillomania (compulsive hair plucking) showed a 5.34-fold risk of ADHD as well as increased risks of⁵⁰

• Obsessive-compulsive disorder: 18.3-fold
• Borderline personality disorder: 15-fold
• Anxiety disorders: 10.2-fold
• Alcohol abuse: 6.13 times
• Depression: 5.89 times
• Vitamin D deficiency: 4.2-fold

4.2. Chew nails¶

A study examined 450 children. 14% of them bit their nails. Among these were found:⁵¹

• ADHD at 74.6 %
• Oppositional defiant behavior at 36
• Separation anxiety at 20.6 %
• Enuresis at 15.6 %
• Tic disorders at 12.7 %
• Obsessive-compulsive disorder at 11.1
• mental retardation at 9.5 %
• major depressive disorders at 6.7 %
• profound developmental disorders at 3.2 %

5. Affective disorders (depression / dysphoria / dysthymia / mania / bipolar) - 30 to 61 % (vs. 4.7 to 8.9 % = + 550 %)¶

Dysphoria with inactivity is an original ADHD symptom and not a symptom of depression. Antidepressant treatment of dysphoria with inactivity would be malpractice.
⇒ Depression and dysphoria in ADHD
Of 70 adults with ADHD, 60.7% had had an affective disorder in their lifetime, compared to 25.7% of those not affected ⁵²

5.1. Depression¶

Depression found

• according to a large Swedish cohort study in 42.28% (men: 35.60%; women: 40.27%) of adult people with ADHD compared to 4.69% (men: 3.55%; women: 5.87%) of those without.⁵³
• according to another cohort study at 29.9% (across the age range) and 55.7% vs. 24.3% in a small study of adults with ADHD^{52
  24}
• a Norwegian cohort study found major depression in 24.5 % (men: 20.3 % women: 28.8 %) of adult people with ADHD compared to 5.8 % (men: 4 %; women: 7.6 %) of those not affected.⁵⁴

• In children with people with ADHD:
  • 37 %⁵⁵⁵⁶
  • 37.34 % (vs. 7.42 % for people not affected by ADHD) = 5-fold risk of depression or anxiety disorder⁵⁷
• For children not affected: 8.9 %⁵⁶ to 14 % ⁵⁵
  = 4 times the risk
• Mood swings (15 - 75 %)⁵⁸
• Depressive disorders⁶
• A simple survey by www.adhs-chaoten.net, in which 73 people with ADHD took part, revealed that a majority suffer from seasonal fall-winter depression.⁵⁹ This is quite regularly the result of a vitamin D3 deficiency.
  ⇒ Vitamin D3
• In adult people with ADHD: 61.8 %³⁷;
  • Depression (40 to 60 %)⁶⁰; 25 %³⁸
• Severe depression (MDD
  • 32 %⁶¹
  • At least once in the lifetime of 26.4% of adult persons with ADHD compared to 16.2% of people without ADHD⁶²
  • Major depression (6 %)⁶¹
    = 4 to 5 times the risk
• Depression (adults with ADHD overall: 21.4 %; women 32.1 %, men 19.8 %; ADHD-I 22.3 %, ADHD-C 17.6 %, ADHD-HI 32.5 %)⁶³

• The population prevalence of major depression is 7.8%. People with ADHD have a prevalence of 18.6%, which is 2.4 times higher.⁶⁴

• Adults with the highest 10% of ADHD symptom severity according to ADHD-E are 6.68 times more likely to experience depression than non-affected adults.¹

• A meta-analysis found depression in people with ADHD and those without:⁶⁵

  • in the total population at
    • 8.6 % to 55 % of persons with ADHD vs. 1.2 % to 12.5 % of people without ADHD
  • in clinical cases with
    • 15.4 % to 39.7 % of persons with ADHD vs. 5.8 % to 39.6 % of people without ADHD

• Predictors of comorbid depressive symptoms in adults with ADHD are

  • female gender
    • Women with ADHD had a 3.69-fold risk of depression. Women with ADHD who used hormonal contraception (“pill”) had a 5.19-fold risk of depression.⁶⁶
  • Cyclothymic affective temperament and coping strategies with little positive attitude⁶⁷
  • emotional dysregulation and dysthymic temperament⁶⁸

5.2. Dysthymia 6.3 % (vs. 3.4 %)¶

Dysthymia was found in:

• Adults with ADHD overall: 7.3 %; women 9.4 %, men 5.4 %; ADHD-I 6.3 %, ADHD-C 7.6 %, ADHD-HI 15 %)⁶³

• In 6.1% of adult persons with ADHD compared to 3.4% of people without ADHD at least once in their lives⁶²

• The population prevalence of dysthymia is 1.9%. People with ADHD have a prevalence of 12.8%, which is 6.7 times higher.⁶⁴

• Dysthymia 5.7 % vs. 1.4 %⁵²

5.3. Bipolar Disorders - 4.7% to 33.5% (vs. 3.1% to 14.3%)¶

Bipolar Disorders (“manic/depressive”):

• 33.5% of adults with ADHD compared to 6.2% of people without ADHD at least once in their lives⁶²

• 19.4 % in persons with ADHD, 3.1 % population prevalence, i.e. 6.3 times higher.⁶⁴
• 6.4 % Adults with ADHD overall (women 8.3 %, men 4.7 %; ADHD-I 5.1 %, ADHD-C 8.0 %, ADHD-HI 10.0 %)⁶³
• 6 %³⁸
• 4.7 % (over the entire age range)²⁴

• In adult psychiatric hospital patients with ADHD: 92.2 %⁶⁹

• For those not affected: 14.3 %³⁷

• Mania 0.15 % (for ADHD over the entire age range)²

• 57 to 86% of children and adolescents with bipolar Disorder also have ADHD⁷⁰

One (experimentally unvalidated) hypothesis regards bipolar as an extreme form of ADHD-C. The hypothesis sees ADHD and bipolar as a disorder of the self-regulation of extracellular dopamine levels⁷¹
ADHD - like bipolar - suffers from a disorder of self-regulation of the extracellular dopamine level, so that the DAT works partially or completely in the mode of an inappropriately high dopamine efflux, whereby either the range between the lower and upper control limit (at which other influences intervene to stabilize the dopamine level) or the DAT homeostasis feedback is different. Bipolar has a much narrower range of functional extracellular dopamine levels than ADHD. Whereas ADHD-HI remains emotionally balanced with an excessive extracellular dopamine level and ADHD-I with a reduced extracellular dopamine level, so that regulation can be achieved by D2 autoreceptor regulation alone.
without, however, utilizing the appropriate autoregulation of extracellular dopamine levels, is in ADHD-C
A high extracellular dopamine level results from a certain number of DAT working in efflux mode. The D2 autoreceptor can regulate this level to varying degrees, resulting in a state with a high extracellular dopamine level (ADHD-HI) or a low extracellular dopamine level (ADHD-I). In ADHD-C, on the other hand, extracellular dopamine levels fluctuate between too high and too low. Bipolar differs from ADHD-C in that extracellular dopamine levels are even higher than in ADHD-HI and the upper limit of ADHD-C and even lower than in ADHD-I and the lower limit of ADHD-C. An extremely high extracellular dopamine level in bipolarity correlates with a manic phase, an extremely low one with a depressive phase.
In our view, this model is subject to criticism:

• In ADHD-C, inattentive and hyperactive-impulsive symptoms occur simultaneously, while bipolar clearly alternates between manic and depressive phases.
• The model of the hypothesis does not differentiate between different brain regions.
• In our view, it is more conceivable that the extracellular dopamine levels in ADHD-C in different regions of the brain are in different states at the same time.
• Not all people with ADHD also have bipolar, but this would have to be the case if bipolar were merely a more intense variant of ADHD-C
• Amfetamine medication works better than methylphenidate in adults with ADHD. Amfetamine causes a DAT efflux - certainly in higher (drug) doses, but it is unclear whether this is also the case in medication doses. If amfetamine also causes DAT efflux in drug doses, amfetamine would have to increase ADHD symptoms according to the hypothesis.

Cyclothymia is another form of affective disorder in which the bipolar mood swings occur at shorter intervals and to a lesser extent than in bipolar.
In our view, cyclothymia would therefore be a more obvious candidate for “attenuated” bipolar than ADHD.

6. Motor clumsiness up to 60¶

Source⁶

6.1. Developmental motor coordination disorder, dyspraxia, DCD - 29 % to 47 %¶

• 47 % Developmental coordination disorder (DCD, dyspraxia) in persons with ADHD⁷²⁷³
• over 50 %. An online survey of German parents (n = 149) found a significantly higher prevalence of DCD (over 50%), even if the parents had never heard of DCD⁷⁴
• 34% of boys and 29% of girls with ADHD (n = 755)⁷⁵

Children with DCD were more likely to show ADHD symptoms.⁷⁶
In an online survey of university students (up to the age of 29) in Japan, 7.4% of participants were found to have dyspraxia (≥ 32 points in the AAC-Q, average 36.2). 17.6% achieved a score ≥ 27. Participants without DCD achieved an average of 19.5 points. ADHD was found in 3.2%. The AAC-Q scores correlated strongly with the results of the ADHD Developmental Disorder Difficulty Scales short (r = 0.65), moderately to strongly with the ASD Developmental Disorder Difficulty Scales short (r = 0.55) and moderately with mental health problems according to the UPI (r = 0.41). The result is in line with other studies that found DCD in 7 to 9% of all young adults⁷⁷

A combination of ADHD and DCD usually represents a more severe phenotype. Despite some shared neuronal features, ADHD and DCD appear to have a separate etiology.⁷³

Diagnostic criteria according to DSM 5:

1. The learning and execution of coordinated motor skills (if the opportunity to learn the skills is given) is below the level expected for the age.
2. The motor difficulties significantly impair the activities of daily life and have an impact on school performance, pre-professional and professional activities as well as leisure and play.
3. The beginning is in the early development phase.
4. A doctor cannot better explain motor difficulties by intellectual delay, visual impairment or other neurological conditions that affect movement.

The delay is usually in the acquisition of motor skills. Motor milestones are often not delayed.

6.2. Gross motorist¶

Frequent accidents, bumping into things, bruises. See also under Symptoms of ADHD.

6.3. Impaired fine motor skills, poor handwriting - 60 %¶

Up to 60% of people with ADHD suffer from impaired fine motor skills, such as poor handwriting.⁷⁸

7. Behavioral disorders / social disorders (aggression, antisocial behavior, oppositional defiant behavior) - up to 55 %¶

• 30 to 50% of people with ADHD have comorbid ODD or CD.⁷⁹
• 30% of adults with ADHD showed some form of social behavior disorder⁸⁰

7.1 Severe behavioral disorder (disruptive behavior disorders) - 30 to 50 %¶

Frequency of DBD in children with ADHD:

• 50 %⁸¹
• 30 to 50% of people with ADHD have comorbid ODD or CD.⁷⁹
• 31% in Iran for children between 6 and 18 years of age.⁸²

Newer definition models of externalizing aggressive disorders are

• Disruptive Mood Dysregulation Disorder (DMDD)⁸³ and
• Intermittent Explosive Disorder (IED)⁷⁹

7.2. Deficient Emotional Self Regulation (DESR) - 44 to 55 %¶

DESR is described as

1. Self-regulation deficits of physiological arousal caused by strong emotions
2. Difficulty inhibiting inappropriate behavior in response to positive or negative emotions
3. Problems with refocusing attention when emotions are strong
4. Disorganization of behavioral coordination in response to emotional activation

• DESR is distinct from the persistent and severe aggressive irritability that is common in (rarely occurring) pediatric bipolar Disorder⁸⁴
• The abnormal moods of bipolar Disorder are not due to poor self-control and include other DSM-IV mood criteria. DESR is not associated with an increased risk of bipolar Disorder.⁸⁵

Among people with ADHD, DESR was found in

• 55 %⁸⁶

• 44 %⁸⁵

• In 2 % of the non-ADHD people with ADHD.⁸⁵

DESR is diagnosed if the person with ADHD scores between 180 and 210 points on the 3 scales of anxiety/depression (intense emotions), aggression and attention (impulsivity) of the Child Behavioral Check List (CBCL) (on average between 60 and 70 per scale). Scores above 210 points are no longer referred to as DESR, but as more severe forms of affective disorders (mood and behavioral dysregulation disorders). Due to the defined diagnostic criteria of DESR, which cannot be achieved without a high score on the aggression scale, the diagnosis of DESR is likely to be limited to the ADHD-HI subtype, which is phenotypically more likely to react to perceived stress with aggression
The CBCL scale for aggressive behavior:⁸⁷
1. Argues or disagrees a lot
2. Specifies, cuts to
3. Is crude or mean to others, intimidates them
4. Requires a lot of attention
5. Breaks his own things
6. Breaks things that belong to parents, siblings or others
7. Does not obey at home
8. Does not obey at school
9. Is easily jealous
10. Easily gets into fights, arguments
11. Physically attacks others
12. Screams a lot
13. Likes to produce or clown around
14. Is stubborn, grumpy or irritable, is easily annoyed by others
15. Shows sudden changes in mood and emotion
16. Talks too much
17. Likes to tease others
18. Has outbursts of anger or a hot temper
19. Threatens, bullies or intimidates others
20. Is unusually loud

Consequently, significantly more than 44 to 55% of all people with ADHD are likely to suffer from emotional dysregulation, although the forms of expression can vary greatly
Here, too, studies would be desirable that take into account the subtypes and the phenotypic expression of intense emotions (ADHD-HI: externalization / ADHD-I: internalization).

7.3. Oppositional Defiant Disorder (ODD) - 26 to 53 % (vs. 3.9 % = + 560 % to + 1,260 %)¶

• 60% ODD prevalence in children with ADHD⁸⁰ We consider this to be a translation. In our opinion, this could be true at best when considering only boys with severe ADHD-HI. In addition, * the prevalence figures by gender do not match the overall prevalence stated:
  • 55 % for boys
  • 30 % for girls
  • 30% in adults for the entirety of social behavior disorders in ADHD⁸⁰
• 53 % in children and adolescents with ADHD-C⁸⁹
  • 63 % with ADHD-C and ASD⁸⁹, with 80 % of people with ADHD-C also showing ASD
  • 28 % for ADHD-I and ASD⁸⁹
  • 24 % for ASA⁸⁹
  • 14 % for ADHD-I⁸⁹
• 39.3 % in children with ADHD⁹⁰
• 35 % ODD in children with ADHD⁹¹
• 26.1 % in Iranian children with ADHD between 6 and 18 years of age⁸²
• 0.7 % ODD in adults with ADHD (women 0.0 %, men 1.7 %; ADHD-I 0.0 %, ADHD-C 1.5 %, ADHD-HI 5.0 %)⁶³

ODD in non-affected people: 3.9%³⁷
= 8 to 15 times the risk

• ODD refers primarily to people with ADHD-HI (with hyperactivity) and less to people with ADHD-I (without hyperactivity), as hyperactivity is an outgrowth of an externalizing stress response pattern, while ADHD-I is an outgrowth of an inwardly directed stress (playing dead, fleeing). ⇒ The subtypes of ADHD: ADHD-HI, ADHD-I, SCT and others
• We understand ODD (Oppositonal Defiant Disorder) as a pure comorbidity to ADHD, i.e. not as ADHD symptoms.
  • Steinhausen describes disorders of social behavior on the one hand as the most common comorbidity of ADHD,⁹² describes the comorbidity on the other hand on page 174 as a subtype of ADHD.
  • Apart from the fact that sleep disorders are likely to be significantly more common, we do not consider ODD to be a subtype due to the delimitability of the genetic basis.
    • A specific polymorphism of the MAO-A gene is cited as a genetic contributory cause of both social behavior disorders and ADHD (in each case as one of several interacting specific genes). However, this gene polymorphism seems to play a much greater role with regard to social behavior disorders, as it is mentioned much more frequently there and ADHD can also manifest itself without the involvement of this gene (through the interaction of other genes). In the case of ADHD, the MAO-A gene is always mentioned in a subset of people with ADHD who also suffer from behavioral disorders.
    • A further argument in favor of pure comorbidity is that non-specific ADHD medications such as risperidone only reduce aggressiveness but not ADHD symptoms, while MPH (methylphenidate) can alleviate the symptoms of ADHD and ODD equally.⁹³
• ODD does not correlate with any of the symptom circuits of the dual / triple pathway model, so at least in this respect it has a different neurological basis.⁹⁴

Symptoms of Oppositional Defiant Disorder (ODD):

• Frequent and persistent defiance or disobedience towards authority figures
• Quarrelsome and easily irritated or annoyed
• Deliberate attempts to annoy others or behave vindictively
• Difficulty following rules and displaying a pattern of negative, hostile and defiant behavior

7.4. Disorders of social behavior / Conduct Disorder (CD) - up to 20.2 % (vs. 4.3 %)¶

Conduct Disorder (CD) is more common in ADHD.⁶

• 20.2% of adult persons with ADHD compared to 4.3% of people without ADHD at least once in their lives⁶²

• 16 % in children with ADHD (boys 18 %, girls 8 %)⁸⁰

• 1.2 % in adults with ADHD overall: 1.2 %; women 0.7 %, men 1.7 %; ADHD-I 0.3 %, ADHD-C 1.0 %, ADHD-HI 10.0 %⁶³

Persons with Disorder of Social Behavior have 21 times the risk (compared to people with ADHD) of also suffering from ADHD.⁹⁵
Disorders of social behavior and aggression disorders have their own genetic disposition in a specific polymorphism of the MAO-A gene. ⇒ How ADHD develops: genes or genes + environment

The population prevalence of conduct disorder in children and adolescents was determined by an Iranian study:⁹⁶

• 0.58 % for children aged 6 to 9 years
• 0.57 % for adolescents aged 10 to 14 years
• 1.22 % for young people aged 15 to 18

32% also met the criteria for ADHD, 55% the criteria for ODD.

Symptoms of conduct disorder (CD):

• Aggressive or violent behavior
  • Frequent physical altercations
  • Harm to humans or animals
  • Bullying or cruelty
• Antisocial behavior
  • Frequent disregard for the rights of others
• Recurring and persistent patterns of difficulties in accepting norms
  • Destruction of property
  • Participation in thefts
  • Fraudulent behavior
  • Lies
• Lack of remorse or feelings of guilt for one’s own actions
  • Lack of empathy

7.5. Aggressive behavior - over 50¶

Slightly more than 50 %⁹⁷

Aggressive behavior is not an original symptom of ADHD-HI. Aggressiveness can be an expression of stress, but not everyone reacts to stress with aggression, nor does everyone externalize stress.
One of the arguments in favor of pure comorbidity is that non-ADHD-specific drugs such as risperidone only reduce aggressiveness but not ADHD symptoms, while MPH (methylphenidate) can alleviate the symptoms of ADHD and ODD in equal measure.⁹³

Reduced cortisol levels have been reported in ADHD in conjunction with aggression disorders.⁹⁸
Externalizing stress reactions are associated with lower basal cortisol levels and a reduced cortisol response to acute stress.
Disorders of stress hormone levels, especially cortisol, are extremely common in ADHD.
⇒ Cortisol in ADHD

See also ⇒ Neurophysiological correlates of aggression

8. Anxiety disorders - up to 47 % (vs. 19.5 %)¶

47.1 % among people with ADHD, i.e. around 2.4 times higher⁶⁴

The population prevalence of anxiety disorders is 19.5%.⁹⁹
Generalized anxiety disorder (a form of anxiety disorder) affects up to 5% of children and adolescents and between 3 and 6% of adults.¹⁰⁰

There was no genetic overlap between ADHD and anxiety disorders. Genes that correlated with high intelligence showed a protective factor against ADHD, but not against anxiety disorders.¹⁰¹

8.1. Anxiety disorders in children - 25 to 38 % (vs. 7 to 10 % = up to + 400 %)¶

The prevalence of anxiety disorders in children with ADHD was:

• 37.9% in Iranian children with ADHD between the ages of 6 and 18.⁸²
• 37.34 % (vs. 7.42 % for people not affected by ADHD) = 5-fold risk of depression or anxiety disorder⁵⁷
• 37 % over the entire age range²⁴
• 34 %¹⁰²,
• 25 %¹⁰³
• 25 % ⁹¹,
• Increased (without % indication)¹⁰⁴

The population prevalence of anxiety disorders is

• Around 10 %¹⁰⁵
• 7,42 %⁵⁷
  = 3 to 5 times the risk
• Anxiety disorders and ADHD seem to reinforce each other. Treating anxiety or AD(HS also reduces the symptoms of the other Disorder.¹⁰⁶
• Generalized anxiety disorder tripled and a half the risk of ADHD, while ADHD quadrupled the risk of generalized anxiety disorder.¹⁰⁷
• 40 to 85% of children with an anxiety disorder also had ADHD¹⁰⁸

8.2. Anxiety disorders in adults - 44 % (vs. 4.9 %)¶

According to a large Swedish cohort study, an anxiety disorder was found in

• 4.3 % to 47.1 % of persons with ADHD vs. 0.5 % to 9.5 % of people without ADHD (meta-analysis)⁶⁵
• 44.65% (men: 37.02%; women: 55.74%) of adult people with ADHD compared to 4.89% (men: 3.64%; women: 6.19%) of people without ADHD⁵³
• 42 % or 20 to 60 % in adults with ADHD⁶⁰
• 34.3% of adults with ADHD at least once in their lives, compared to 25.7% of those not affected⁵²
• 34.5 % (19 % anxiety disorders and 15.5 % phobic disorders)³⁸
• 22.2 % (men: 18.2 % women: 26.3 %) among adult persons with ADHD compared to 5 % (men: 3.3 %; women: 6.7 %) of people without ADHD (Norwegian register study)¹⁰⁹

Among adult psychiatric inpatients with ADHD

• 3.9 % to 84 % for inpatients with ADHD vs. 5.4 % to 40 % for psychiatric inpatients without ADHD (meta-analysis)⁶⁵
• 28,6 %⁶⁹
• 25 %¹⁰³

Anxiety disorders and ADHD seem to reinforce each other. Treating anxiety or AD(HS also reduces the symptoms of the other Disorder.¹⁰⁶

8.2.1. Generalized anxiety disorder - 5.9 to 25 % (vs. 2 %)¶

• 8 % among people with ADHD, vs. 2.6 % population prevalence, i.e. around 3 times higher.⁶⁴

• In adult people with ADHD:
  • 25 %⁶¹
  • 5.9 % among adults with ADHD (women 7.6 %, men 4.4 %; ADHD-I 7.1 %, ADHD-C 3.5 %, ADHD-HI 7.5 %)⁶³
  • 2.9% of adults with ADHD at least once in their lives compared to 1.4% of those not affected⁵²

Population prevalence: 2 %⁶¹

8.2.2. Social phobia - 5 to 29.3 % (vs. 3.5 to 10 %)¶

• 29.3 % among people with ADHD, vs. 7.8 % population prevalence, i.e. almost 3.8 times higher.⁶⁴
• 22.8% social anxiety disorder among adult persons with ADHD compared to 6.6% among non-affected people at least once in their lifetime.⁶²
• 18.6% of adults with ADHD at least once in their lives, compared to 10% among those not affected⁵²
• 3.5 % among adults with ADHD (women 2.5 %, men 4.4 %; ADHD-I 3.3 %, ADHD-C 3.0 %, ADHD-HI 7.5 %)⁶³

8.2.3. Panic disorder - 1.9 to 4.3 % (vs. 2.9 %)¶

• 22% of adults with ADHD compared to 7% of people without ADHD at least once in their lives⁶²
• 8.9 % among people with ADHD, population prevalence 3.1 %, i.e. almost 3 times higher.⁶⁴
• 4.3% of adults with ADHD at least once in their lives, compared to 2.9% of those not affected⁵²
• 1.9 % among adults with ADHD (women 2.9 %, men 2.4 %; ADHD-I 2.1 %, ADHD-C 2.5 %, ADHD-HI 7.5 %)⁶³

8.2.4. Specific phobias¶

• 35.8% of adult persons with ADHD at least once in their lives compared to 14.6% of non-affected people ⁶²

• 22.7 % among people with ADHD, population prevalence 9.5 %, i.e. almost 2.4 times higher.⁶⁴

• Agoraphobia:

  • 4.0 % among people with ADHD, population prevalence 0.7 %, i.e. around 5.7 times higher.⁶⁴

9. Substance abuse and addiction - up to 45¶

A meta-analysis found addictive disorders:¹¹⁰

• in the total population at
  • 2.3 % to 41.2 % of persons with ADHD vs. 0 % to 16.6 % of people without ADHD
• in clinical cases with
  • 10 % to 82.9 % of persons with ADHD vs. 2 % to 72.2 % of people without ADHD

Among patients of addiction centers, ADHD serial studies found 21 to 23% of people with ADHD¹¹¹, which corresponds to 4.6 to 9.2 times the adult ADHD population prevalence of 2.5 to 5%. One study found 45% of people with ADHD¹¹², which corresponds to 10 to 20 times this figure

9.1. Substance-related addictions / substance abuse¶

Of n = 873 patients in a psychiatric emergency department in an emerging urban county in North Carolina (USA) with ICD10 diagnoses of anxiety, depression, schizophrenia, ADHD, bipolar disorder, alcohol abuse, or schizoaffective disorder showed:¹¹³

• 58% of patients with a psychiatric history have a positive urine drug test
• ADHD (n = 135)
  • 34.7 % alcohol
  • 20.2 % THC
  • 15.3 % Cocaine
  • 14.9 % Paracetamol
  • 12.9 % Benzodiazepines
  • 12.1 % Opiates
  • 8.1 % Amfetamine drugs
  • 1.6 % barbiturates
• Depression (n = 225)
  • 40.8 % Paracetamol
  • 25.6 % THC
  • 20.9 % alcohol
  • 15.0 % Opiates
  • 13.7 % Benzodiazepines
  • 12.6 % Cocaine
  • 7.4 % Amfetamine drugs
  • 2.1 % barbiturates
• States of anxiety
  • 30.8 % THC
  • 10.3 % alcohol
  • 5.1 % Opiates
  • 5.1 % Cocaine
  • 4.7 % paracetamol
• bipolar disorders
  • 29.4 % THC
  • 27.3 % alcohol
  • 16.9 % Opiates
  • 13.0 % Cocaine
  • 10.4 % Benzodiazepines
  • 9.2 % Paracetamol
  • 8.2 % Amfetamine drugs
• Schizoaffective Disorder (n = 245)
  • 26.1 % THC
  • 25.6 % alcohol
  • 24.4 % Paracetamol
  • 20.8 % Cocaine
  • 12.1 % Benzodiazepines
  • 8.7 % Opiates
  • 5.1 % Amfetamine drugs
  • 2.5 % barbiturates
• Schizophrenia (n = 45)
  • 32.6 % THC
  • 14.4 % alcohol
  • 10.9 % Cocaine
  • 5.5 % paracetamol
  • 8.7 % Benzodiazepines
  • 2.2 % opiates

Overall, there was no significant correlation between the psychiatric diagnosis and positive drug screening.¹¹³

9.1.1. Substance abuse - 21.9 % to 35 % (vs. 2.9 % to 3.6 %)¶

• 35.12% (men: 39.44%; women: 30.88%) of adult persons with ADHD compared to 3.61% (men: 4.40%; women: 2.79%) of people without ADHD (large Swedish cohort study)⁵³
• 21.9 % (men: 27.5 %; women: 16.2 %) of adult persons with ADHD compared to 2.9 % (men: 3.6 %; women: 2.1 %) of people without ADHD (large Norwegian cohort study)¹¹⁴

Among adult SUD patients in three drug rehabilitation centers in urban Malaysia, ADHD prevalence was 47.2%. SUD affected persons with ADHD were less likely to have medical comorbidities (84.9% vs. 93.3%), more likely to have a history of incarceration (80.8% vs. 65.6%) and more likely to have a first incarceration before the age of 18 years (24.6% vs. 16.8%) compared to SUD affected persons.¹¹⁵

Substance abuse is a common comorbidity of ADHD.⁶ One possible connection could be that dopamine deficiency leads to an increased expression of CB1 cannabinoid receptors.^116117118 THC binds to CB1 receptors.

Of 70 adults with ADHD, 17.1% had experienced substance misuse in their lifetime, compared to 2.9% of those without⁵²
People with ADHD showed an ADHD prevalence of 21% (meta-analysis).¹¹⁹
Among 153 addicts (98.7% males) at a clinic in India, 33% were found to have ADHD. The prevalence of ADHD was different for certain addictions:¹²⁰

• 47.6 % of people with cannabis addiction
• 38.8 % of people who use tobacco/smoke
• 33% of people with cocaine addiction and
• 21.5 % of people with alcohol dependence.

• The prevalence of ADHD among opioid addicts was around 50%. ADHD symptoms, especially impulsivity, increase the risk of opioid addiction. ¹²¹
• For people with ADHD, substance abuse begins on average 3 years earlier¹²²
• Appropriate medication (especially methylphenidate) reduces the likelihood of addiction or substance abuse in ADHD.
• People with ADHD with comorbid cocaine addiction showed a significant reduction in addictive behavior when treated with stimulants, corresponding to a decrease in ADHD symptoms.¹²³

A small Norwegian cohort study found no association between ADHD and alcohol or drug abuse,¹²⁴ as well as an earlier study,¹²⁵ which found increased alcohol and drug abuse in people with ADHD only in the presence of additional externalizing disorders.
However, these studies clearly contradict the vast majority of specialist literature, which reports a significant risk increase in ADHD.

9.1.2. Smoking - 40 to 45 % (vs. 22 to 25 %)¶

Among adult people with ADHD who smoked

• 44,8 %⁶²

• 42 %¹²⁶¹²⁷

• 40 % ¹²⁸

• 51% of adult psychiatric inpatients with ADHD are addicted to nicotine⁶⁹

Among people with ADHD who did not smoke

• 27% of women and 32% of men in the total population aged 18 and over¹²⁹
• 26 % (2005)¹³⁰
• 22.6 %⁶²

The risk of smoking is therefore almost doubled with ADHD (regardless of medication).
Among adult people with ADHD-HI/ADHD-C, the risk of smoking is doubled.¹³¹

ADHD medication, nicotine (smoking) and zinc block the dopamine transporters (DAT) (which are elevated in ADHD) and thus reduce their overactivity¹³²

9.1.3. Alcohol dependence (30 to 39 % vs. 5 to 15 %) / alcohol abuse¶

The German guidelines now stipulate an ADHD examination as a standard procedure for alcohol addiction.

Alcohol dependence is drastically increased with ADHD¹³³

• In adult people with ADHD
  • 38,9 %⁶²
  • 30 %⁶¹, 25 to 44 %¹³¹
  • 8.6% of adults with ADHD at least once in their lives, compared to 2.9% of those not affected⁵²
  • 4.1 % in adult psychiatric inpatients with ADHD⁶⁹
• For non-affected persons
  • 5 %⁶¹ up to 14.6⁶²

= 6 to 8 times the risk

Conversely, among n = 153 alcoholics, 43% were found to have childhood ADHD and 22% were found to have persistent ADHD.¹³⁴ Another study found an ADHD diagnosis in 19% of 100 adult alcoholics in India.¹³⁵

Alcohol / substance abuse:

• 1.6% of adults with ADHD showed alcohol or substance misuse (women 1.1%, men 2.0%; ADHD-I 0.9%, ADHD-C 2.5%, ADHD-HI 2.5%)⁶³

• 18.1 % to 22.6 %⁶² compared to 19.3 % for those not affected⁶²

• A small Norwegian cohort study found no association between ADHD and alcohol or drug abuse,¹²⁴ as well as an earlier study,¹³⁶ which found increased alcohol and drug abuse in people with ADHD only in the presence of additional externalizing disorders.

For alcohol dependence, 6 parameters predicted the presence of comorbid ADHD with an AUC of 0.926:.¹³³

• reduced self-control
• increased novelty seeking
• Self-transcendence
• Damage prevention
• Craving
• early first consumption of alcohol

Self-steering and novelty seeking together achieved an accuracy of 85%.¹³³

9.1.4. Substance-related addictions in general - 7.8 %¶

• In adult persons with ADHD: 7.8 %³⁷, 20 %⁶¹ to 50 to 60 %¹³⁷¹³⁸
• For those not affected: 1.9 %³⁷ to 5 %⁶¹¹³⁸
  = 4 to 12 times the risk
• According to another source, the lifetime prevalence of psychoactive substance use in people with ADHD is 52%, compared with 24% in people without the disorder.¹³⁹
• Of 70 adults with ADHD, 11.4% had a substance dependence in their lifetime, compared to 0% of the 70 unaffected⁵²

9.1.5. Drug addiction¶

• The population prevalence of drug addiction is 0.6%. People with ADHD have a prevalence of 4.4%, which is around 7.3 times higher.⁶⁴
• Among adult psychiatric clinical patients with ADHD, 7.1% have comorbid drug dependence.⁶⁹
• Drug addicts are 4 to 5 times more likely to have ADHD¹⁴⁰
• 15.5%¹⁴¹ to 25% of all addicts have ADHD¹⁴²
• ADHD was found in 11.2% of all adult addiction patients who used intravenous opiods or intravenous/intranasal benzodiazepines. The ADHD rate was higher among women (15.3 %) than among men (10.3 %).¹⁴³
• With ADHD, the risk of substance dependence (addiction) is 2 to 3 times higher than for those not affected.¹⁴⁴
• The risk of nicotine dependence is up to 9 times higher in those with ADHD than in those without.¹⁴⁴
• Persons with ADHD are about as likely to be addicted as relatives who are not affected by ADHD.
  • Cannabis: 67 vs. 72 %¹³⁸
  • Cocaine: 23 vs. 21 %¹³⁸
  • Stimulants: 18 vs. 10 %¹³⁸
  • Hallucinogens: 18 vs. 7 %¹³⁸
  • Opioids: 16 vs. 3 %¹³⁸
  • Sedatives: 14 vs. 10 %¹³⁸
• According to one study, 12% of cocaine users had ADHD in childhood and 10% still had it as adults.¹⁴⁵

9.2. Behavioral addiction / gambling 5.3 % (vs. 2.4 %)¶

People with ADHD have more than double the risk of developing a gambling addiction (5.3% compared to 2.4%). Problem gambling behavior is 4 times more common among persons with ADHD (2.4%) than among people without ADHD (0.6%).¹⁴⁶
Another study found gambling addiction in 1.54% of adult persons with ADHD compared to 0.39% of non-affected people at least once in their lifetime.⁶²

A study of n = 97 gambling addicts found an ADHD rate of 26.0 % and an ASD rate of 29.8 %.¹⁴⁷
One study found that gene variants that correlate with substance use can causally increase the risk of ADHD.¹⁴⁸

9.3. Substance abuse (illegal drugs: 10 %, nicotine: 16.6 to 25.5 %)¶

Among adults with ADHD, the prevalence of substance abuse is 33.5%.¹⁴⁹ The risk of substance abuse among adults with ADHD in the USA is 1.7 to 7.9 times higher.¹⁵⁰

If aggressive and oppositional defiant behavior and low self-esteem are present in addition to ADHD, the probability of substance abuse is significantly increased, while no more frequent substance abuse was found in adolescent people with ADHD without these additional symptoms.¹⁵⁵¹⁵⁶

In our opinion, substance abuse is much more likely to be a consequence of ADHD than the cause of a full ADHD symptom picture. In rarer cases, it is comorbid. Treatment with stimulants very often eliminates the addictive tendency in ADHD. Modern dosage forms of stimulant medications are barely suitable for abuse as a drug (e.g. Vyvanse: prodrug of amphetamine bound to lysine, which is only very slowly converted to the active ingredient in the intestine).

In the Continuous Performance Test, people with ADHD showed more responses to correct timing compared to those with substance abuse.¹⁵⁷

9.4. Addiction / dependency (alcohol: 5%, gambling: 0.31%)¶

Prevalence: Present in 24.9% of adults with people with ADHD.¹⁵⁸

Alcohol:¹⁵³

• Dependence
  • Men 4.8 %
  • Women 2 %
• Abuse
  • Men 4.6 %
  • Women 1.5 %

In Berlin, 5.0% of 15- to 64-year-old respondents met the criteria for alcohol dependence according to DSM-IV (men: 6.4%, women: 3.5%).¹⁵⁹

In Germany, the prevalence of gambling addiction is 0.31% and the prevalence of problematic gambling behavior is 0.56%.¹⁶⁰
A study of n = 97 gambling addicts found an ADHD rate of 26.0 % and an ASD rate of 29.8 %.¹⁴⁷

In the case of comorbidity of ADHD and addiction, there is an increased probability that ADHD is the causal cause of the addiction and not addiction the cause of ADHD. This was shown at least for smoking, cannabis and probably also alcohol.¹⁶¹

One study found that increased polygenic risk scores (PRS) for ADHD also increased the likelihood of addiction by 20%. There were no differences with regard to the intensity of the addiction (use, abuse, dependence) or the type of addictive substance (alcohol, cannabis, other illegal drugs). Conversely, the ADHD-PRS explained only 0.2% of the probability of addiction compared to other risk factors.¹⁶²

One study showed an ADHD prevalence of 16.7% in severe addicts compared to 2.5% in the control group.¹⁶³
Even more significant was the fact that 53% of severe addicts had socially disturbed behavior in childhood or adolescence (up to 15 years), as measured by the SKID-II (control subjects with 2.5%).¹⁶⁴ An earlier Disorder of Social Behavior (OR = 35.1) compared to childhood hyperkinetic behavior (OR = 5.7) is by far the greater risk factor for severe addiction.¹⁶⁵
This indicates to us that addiction plays a role predominantly in ADHD-HI and less in ADHD-I.
The preference for addictive substances indicates a more frequent use of cannabis products among people with (former) hyperkinetic behavior. There appears to be no significant difference for opiates, cocaine, amphetamines, sedatives and hallucinogens.¹⁶⁶
Although a joint occurrence of hyperkinetic and socially disturbed behavior is associated with an early first use of illegal drugs, statistically only an earlier and increased use of nicotine could be proven.¹⁶⁶
Adults with ADHD and addiction had a lower age of onset of substance use and used as an addictive substance:¹⁶⁷

• more frequently: alcohol, cannabis, methamphetamine, tramadol
• less frequently: methylphenidate, methadone, ecstasy, morphine, hypnotics

Long-term abuse of dopaminergic drugs (cocaine, amphetamines) leads to prolonged downregulation of dopamine levels. Withdrawal symptoms then correspond to ADHD symptoms. ¹⁶⁸ Against this background, the question arises as to whether ADHD medications (stimulants), which are known to have no intoxicating effect, could be helpful in the withdrawal of dopaminergic drugs.
People with ADHD with comorbid cocaine addiction showed a significant reduction in addictive behavior when treated with stimulants.¹²³

Common symptoms of addiction / substance abuse and ADHD:⁴⁹

• Impulsiveness
• (Inner) restlessness, motor hyperactivity
• Concentration problems
• High flow of speech (logorrhea, polyphrasia)

ADHD symptoms that are atypical for addiction / substance abuse:

• Chasing thoughts, circling thoughts
• Attention problems
• Dysphoria with inactivity
• Mood swings

Symptoms of addiction / substance abuse that are atypical for ADHD:

• Substance abuse:
  • Excessive consumption of a substance, even if there are serious Consequences
• Addiction / dependence:
  • Excessive consumption to the point of dependence on the drug
  • Very difficult to stop

10. Restless legs (RLS, akathisia) - 11 to 44 % (vs. 2.6 to 15.3 %)¶

A meta-analysis found RLS in 11 to 42.9 % of children with ADHD and in 20 - 33.0 % of adults with ADHD. In the general population, RLS was found in 2.6 to 15.3%.¹⁶⁹
A study of children with ADHD (aged 6 to 16) found RLS in 33.3%.¹⁷⁰ Other sources speak of 44%.¹⁷¹ A smaller study of adults with ADHD found RLS in 20%, with comorbid RLS aggravating ADHD symptoms.¹⁷²
Kooij sees RLS in 30 % to 40 % of people with ADHD.³⁶
One study found 10% of people with ADHD had a disorder of periodic limb movements (PLMS) (more than 5/h).¹⁷³ Another study found 66% of children with ADHD had a PLM index greater than 5/h, which is a marker for RLS, while no ADHD non-affected individuals had an elevated PLM index.¹⁷⁴ A meta-analysis found no evidence of more frequent PLMS in ADHD.¹⁷⁵
In adult psychiatric clinical patients with ADHD, 25.5% showed RLS⁶⁹
A large cohort study found a strong correlation between restless legs and ADHD.¹⁷⁶

ADHD is found in up to 26% of people with ADHD.¹⁷¹

Irrespective of ADHD, RLS occurs in around 2% of all children and adolescents, and in 0.5 to 1% in moderate to severe form. In adults, it affects 5 to 10 %. In 25% of people with ADHD, the disorder begins between the ages of 10 and 20.¹⁷⁷ Other sources cite a prevalence of RLS of up to 8%.¹⁷⁸
In 70% of people with ADHD, one parent is also affected.

A genetic link between RLS and ADHD has not yet been established. It is conceivable that the BTBD9 gene, which is associated with iron stores, could be involved.
69.4% of children and adolescents with RLS have sleep disorders (vs. 39.6% of those not affected), 80.6% have a history of “growing pains” (vs. vs. 63.2% of those not affected).¹⁷⁸

11. Partial performance disorders - up to 40¶

Source⁶

One study found that 6.6% of children between the ages of 7 and 11 had learning-specific partial performance disorders. Reading difficulties were found in 4%, dyscalculia in 3.6% and a weakness in written expression in 1.8%. Approximately 63% of children with learning-specific partial performance disorders had one or more comorbid diagnoses, with ADHD being the most common comorbidity at 54.9%. Boys were more frequently affected.¹⁹⁴

11.1. Reading difficulties, dyslexia, dyslexia - 8 to 40 % (vs. 5.6 %)¶

A distinction must be made:

• Reading and spelling difficulties (LRS): acquired temporary weakness, usually caused by external circumstances
• Dyslexia: genetically caused disorder in the area of reading and writing that cannot be overcome through normal practice
• Dyslexia (reading difficulty): Limited ability to read and understand words or texts, despite normal vision and hearing. Tool disorder.
• Alexia: complete loss of reading ability

8 - 39 %¹⁹⁵¹⁹⁶ , 25 - 40 %⁸⁴, 40 %¹⁰²

Dyslexia and ADHD have a relevant genetic correspondence.¹⁹⁷¹⁹⁸ There is no evidence of mutual causality.¹⁹⁸
One study found only weak evidence of concordant neurophysiological changes in ADHD and dyslexia.¹⁹⁹

6-year-old children with reading difficulties are around 4 times more likely to have ADHD in the teacher assessment (21.0% instead of 5.6%) and around twice as likely to have ADHD in the parent assessment (30.5% instead of 17.8%) than children without reading difficulties.²⁰⁰
There is evidence that reading impairment with ADHD shows different connectivity in the brain than reading impairment without ADHD.²⁰¹

65 to 70 % of all children with dyslexia are said to have functional binocular disorders:²⁰²

• Oculomotor dysfunctions (OMD) (9 %)
  • Fixation impaired
  • Subsequent movements impaired
  • Horizontal eye saccades impaired
• Dysfunctional binocular vision (DBS) (16%)
  • Heterophoria
  • Suppression
  • Convergence insufficiency
  • Accommodative dysfunction
  • Fusion insufficiency
  • Stereopsis insufficient
• DBS and OMD (51 %)
• Neither DMS nor OMD (24 %)

A study of 1260 children in Pakistan found dyslexia in 21.2% and ADHD in 7.6%:²⁰³

• for 192 dyslexia (15.2 %)
• for 76 Dyslexia and ADHD (6.0 %)
• with 20 ADHD (1.6 %)

11.2. Spelling difficulties (agraphia, dysgraphia) - 12 to 40 %¶

12 - 27 %⁵, 25 - 40 %⁸⁴, 40 %¹⁰²
Also for adults with ADHD.²⁰⁴

11.3. Dyscalculia 12 - 27 %¶

12 - 27 %⁵
A meta-analysis found that reading problems correlate more strongly with math problems than with ADHD.²⁰⁵
Also for adults with ADHD.²⁰⁴
ADHD and dyscalculia appear to have common genetic causes. No evidence of mutual causality was found¹⁹⁸

Math performance is said to correlate less with ADHD than with executive function problems in ADHD.²⁰⁶ Math problems correlated with working memory problems in ADHD, but not with anxiety.²⁰⁷

11.4. Weakness in facial recognition (prosopagnosia)¶

It is unclear whether facial recognition deficits are more common in ADHD. There are sources for this²⁰⁸ and against it²⁰⁹.

11.5. Name recall weakness¶

A weakness in remembering names is said to occur more frequently with ADHD.²⁰⁸

11.6. Speech disorders¶

Speech disorders are said to occur more frequently with ADHD.⁶

11.7. Right-left weakness¶

Right-left weakness correlates with ADHD.²¹⁰
The overall prevalence of right-left weakness among medical students was 14.7%.

12. Developmental disorder - up to 37.4¶

Developmental disability (adults with ADHD overall: 24.7 %; women 25.6 %, men 23.8 %; ADHD-I 22.6 %, ADHD-C 25.6 %, ADHD-HI 37.5 %)⁶³

12.1. Specific developmental disorders - 37.4 % (vs. 13.4 %)¶

• In children with people with ADHD: 37.4%³⁷
• For those not affected: 13.4 %³⁷
  = 3 times the risk

12.2. Specific developmental disorders of school skills - 23% (vs. 2.8%)¶

• In children with people with ADHD: 23.0%³⁷
• For those not affected: 2.8%³⁷
  = 8 times the risk

13. Bipolar Disorders - 4.5 to 35.5% (vs. 0.2 to 3.6%)¶

Bipolar Disorder was found in

• 14.29% (men: 9.95%; women: 18.95%) of adult persons with ADHD compared to 0.72% (men: 0.53%; women 0.91%) of people without ADHD (large Swedish cohort study)⁵³
• 10.9 % (men: 8.9 % women: 12.9 %) of adult people with ADHD compared to 1.3 % (men: 1.1 %; women: 1.6 %) of those not affected.⁵⁴
• 6 %³⁸; (adults with ADHD overall: 6.4 %; women 8.3 %, men 4.7 %; ADHD-I 5.1 %, ADHD-C 8.0 %, ADHD-HI 10.0 %)⁶³
• 5.1% of adult psychiatric clinical patients with ADHD⁶⁹
• 4.7 % (over the entire age range)²⁴

In 2.4 million people examined, 9250 bipolar disorders were observed. If an ADHD disorder was already present, the risk of bipolar disorder increased 12-fold over a lifetime; if ADHD and an anxiety disorder were previously present, the risk increased 30-fold compared to people without ADHD and without an anxiety disorder.²¹¹

People with ADHD have an ADHD prevalence of:

• 60 % (meta-analysis of twenty studies with n = 2,722 PBD patients (average age = 12.2 years)²¹²
• 27 % in euthymic people with ADHD²¹³
• 25% (n = 703 adult people with ADHD), with males and BP type I more likely to have ADHD comorbidity²¹⁴
• 3.06-fold increase²¹⁵

A meta-analysis found Bipolar Disorder in people with ADHD and non-affected people:⁶⁵

• in the total population at
  • 4.48 % to 35.5 % of persons with ADHD vs. 0.2 % to 3.6 % of people without ADHD
• in clinical cases with
  • 7.4 % to 80 % of persons with ADHD vs. 2 % to 19.5 % of people without ADHD

One study found evidence of overlap between the genetic causes of bipolar and ADHD, particularly in early-onset bipolar (under the age of 21),²¹⁶ another study also found genetic overlap between bipolar and ADHD.²¹⁷

14. Personality disorders (in adults) - 11.5 % to 33.2 % (vs. 0.9 % to 1.4 %)¶

Personality disorders are generally not yet diagnosed in children.

The following prevalence rates were found in adults:

• 11.5 % (men: 9.1 % women: 13.6 %) of adult people with ADHD compared to 1.4 % (men: 1.1 %; women: 1.7 %) of those not affected.⁵⁴
• 33.2 % in adult persons with ADHD³⁷ to 80.3 % in adult outpatients with ADHD²¹⁸
• For non-affected persons: 0.6 %³⁷
  = 50 times the risk

A meta-analysis found personality disorders:¹¹⁰

• in the total population at
  • 0.31 % to 33.8 % of persons with ADHD vs. 0 % to 3.9 % of people without ADHD
• in clinical cases with
  • 21.9 % to 65.95 % of persons with ADHD vs. 6.6 % to 34.4 % of people without ADHD

14.1. Antisocial PS - 18 % (vs. 2 to 3.5 %)¶

One study found antisocial personality disorder in 18% of people with ADHD-HI with hyperactivity compared to 2% of those without.²¹⁹.
Other sources cite 37.1 %²²⁰⁸⁷ .
One study found Antisocial PS in 18.9% of adult persons with ADHD compared to 3.5% of non-affected people at least once in their lifetime.⁶²

Of 30 prison inmates with ADHD-HI, 96% also had antisocial personality disorder.
In contrast, 20 non-prison ADHD-HI affected people and 18 non-affected people (without ADHD) were not found to have Antisocial Personality Disorder.Interestingly, amphetamines are the drugs most commonly used by prison inmates affected by ADHD-HI.¹²⁹ Amphetamines are known to be a highly effective medication for ADHD.

For domestic violence offenders who had ADHD, ADHD treatment reduced domestic violence far more significantly than domestic violence interventions.²²¹

14.2. Borderline PS / emotionally unstable PS - 18 to 33 % (vs. 1 to 5 %)¶

Adults with ADHD are said to have BPD in 18.3% of cases²²²
A population study found that 33.7% of people with ADHD also had borderline personality disorder (BPD) (vs. 5.2% in the general population).⁶²
A Swedish cohort study found a 19.4-fold risk of comorbid borderline personality disorder in people with ADHD.²²³ 3.9% of the more than 2 million people studied had an ADHD diagnosis (women 3.0%, men 4.8%), 0.5% had BPD (women 0.8%, men 0.1%). People who had relatives with an ADHD diagnosis also had an increased risk of BPD:

• Identical twins: n = 9,130, OR = 11.2 (Among 9,130 twins, the risk of BPD was 11.2 times higher if the other twin had ADHD)
• Fraternal twins: N = 17,350, OR = 1.0
• Full siblings: n = 2,211,396, OR = 2.4
• Maternal half-siblings: n = 332,486, OR = 1.4
• Half-siblings on the paternal side: n = 331,080; OR = 1.5
• Cousins Parents Full siblings:n = 6,456,848; OR = 1.5
• Cousins Maternal parents Half-siblings: n = 472,212; OR = 1.3
• Cousins Paternal parents Half-siblings: n = 466,836; OR = 1.2

The risk of a BPD diagnosis if the person with ADHD had ADHD themselves or a full sibling was:²²³

• 19.1 times higher in women (OR = 19.1)
• 21.8 times higher in men (OR = 21.8)

People with ADHD in childhood were 14% more likely to be diagnosed with BPD later in life.²²⁴

BPD in people with ADHD: 35.7%²²⁰⁸⁷

In adult psychiatric clinical patients with ADHD: 30.6 %⁶⁹

People with ADHD have an ADHD prevalence of 30 to 60 %.^225226227228

For the differential diagnosis of ADHD / Borderline, see ⇒ Emotionally unstable personality / Borderline In the article ⇒ Differential diagnostics for ADHD in the chapter ⇒ Diagnostics.

14.3. Anxious PS - 10.6 % (vs. 2.1 %)¶

One study found avoidant PS in 10.6% of adult persons with ADHD compared to 2.1% of non-affected people at least once in their lifetime.⁶²
In adult psychiatric clinical patients with ADHD: 31.6 %⁶⁹

14.4. Self-insecure PS¶

27,1 %²²⁰⁸⁷

14.5. Compulsive PS - 19.3 (vs. 7.8 %)¶

One study found compulsive PS in 19.3% of adult persons with ADHD compared to 7.8% of non-affected people at least once in their lifetime.⁶²
40,7 %²²⁰⁸⁷

In adult psychiatric clinical patients with ADHD: 10.2 %⁶⁹

14.6. Combined PS¶

In adult psychiatric clinical patients with ADHD: 25.5 %⁶⁹

14.7. Paranoid PS - 14.8 % (vs. 4.1 %)¶

20,0 %²²⁰⁸⁷
One study found Paranoid PS in 14.8% of adult persons with ADHD compared to 4.1% of non-affected people at least once in their lifetime.⁶²

14.8. Dependent PS - 3.1 % (vs. 0.4 %)¶

15,7 %²²⁰⁸⁷
One study found Dependency PS in 3.1% of adult persons with ADHD compared to 0.4% of non-affected people at least once in their lifetime.⁶²

In adult psychiatric clinical patients with ADHD: 18.4 %⁶⁹

14.9. Narcissistic PS¶

15.7 %²²⁰⁸⁷
One study found Narcissistic PS in 25.2% of adult persons with ADHD compared to 5.7% of non-affected people at least once in their lifetime.⁶²

14.10. Histrionic PS - 10.7 % (vs. 1.6 %)¶

14,3 %²²⁰⁸⁷
One study found Histrionic PS in 10.7% of adult persons with ADHD compared to 1.6% of non-affected people at least once in their lifetime.⁶²

14.11. Schizotypal PS - 22.4 % (vs. 3.5 %)¶

8,6 %⁸⁷
One study found Schizotypal PS in 22.4% of adult persons with ADHD compared to 3.5% of non-affected people at least once in their lifetime.⁶²

Former names: Borderline schizophrenia, latent schizophrenic reaction, pseudoneurotic schizophrenia

14.12. Schizoid PS - 9.2 % (vs. 2.9 %)¶

6.4 %⁸⁷
One study found schizoid PS in 9.2% of adult persons with ADHD compared to 2.9% of non-affected people at least once in their lifetime.⁶²

15. Premenstrual dysphoric disorder (PMDD) - 31.4 % (vs. 9.8 %)¶

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS). It occurs in the days before menstruation and subsides after it begins. Symptoms are

• Mood swings
• Irritability
• Feelings of anxiety
• Concentration difficulties
• depressive moods.

PMDD was reported by 31.4% of women with a self-reported ADHD diagnosis and by 41.1% of women with a positive ADHD screening according to ASRS, compared to 9.8% of women without ADHD.²²⁹

16. Tic disorders 30 % (vs. 5 %)¶

Source⁶¹⁸

About 30% of all patients with ADHD have tics or Tourette syndrome, while about half of all patients with a tic disorder or TS also have ADHD.²³⁰
The population prevalence of tic disorders is around 5%²³¹

17. Post-traumatic stress disorder (PTSD) - 11.9% to 28% (vs. up to 3.3% to 6%)¶

• The population prevalence of PTSD is
  • 3,3 %⁶⁴
  • 6 % Lifetime prevalence⁶²

The following prevalence values of comorbid PTSD were found in people with ADHD:

METASTUDY:

• 28 to 36 % in adults with ADHD (meta-analysis, k = 21)²³²

Studies:

• 0.7 % Adults with ADHD in total⁶³
  • 0.7 % Women
  • 0.7 % Men
  • 0.9 % ADHD-I
  • 0.0 % ADHD-C
  • 2.5 % ADHD-HI
• 11.9 %, i.e. around 3.6 times higher.⁶⁴
• 22% of adult people with ADHD⁶²
• 26.5 % In adult psychiatric clinical patients with ADHD⁶⁹
• Comorbidity of ADHD and PTSD occurred 32% more frequently in women than in men, but only in adults (meta-analysis, k = 13, n = 13,585²³³

PTSD is associated with a greatly increased risk of ADHD (up to + 153 %)

• 2.53-fold risk of ADHD (+153%) in war veterans with previous PTSD²³⁴
• 2.19-fold ADHD risk (+ 119%) in war veterans with existing PTSD²³⁴

18. Impulse control disorder, impulse control disorder (ICD) - 19.6 % (vs. 6.1 %)¶

• The population prevalence of impulse control disorder (ICD) is 6.1%. People with ADHD have a prevalence of 19.6%, which is around 3.2 times higher.⁶⁴
• Total adults 2.6 %; women 2.9 %, men 3.7 %; ADHD-I 1.2 %, ADHD-C 5.0 %, ADHD-HI 12.5 %⁶³

Impulse control disorders are characterized by a recurring, irresistible urge to perform certain actions that harm the person with ADHD or others and are often associated with feelings of guilt or shame, although they provide short-term relief.

• Pathological gambling (gambling addiction)
• Kleptomania (stealing)
• Pyromania (arson)

19. Adjustment disorders - 18.9 % (vs. 3 %)¶

Adjustment disorders are described as reactions to a one-off or ongoing stressful life event.
Types of adjustment disorders are:

• Short depressive reaction
• Prolonged depressive reaction (up to 2 years)
• Mixed anxiety and depressive reaction
• With predominant impairment of other feelings
• With predominant Disorder of social behavior
• With mixed disorders of emotions and social behavior
• With other predominantly mentioned symptoms

Prevalence in the presence of ADHD:

• In adult people with ADHD: 18.9%³⁷
• For non-affected persons: 3.0 %³⁷
  = 6 times the risk

20. Mental disability - 13 %¶

13 %¹⁰²

21. Eating disorders - Loss of Control Eating Syndrome (LOC-ES) - 7.5 to 11.4 % (vs. 1.4 %)¶

12-fold increased risk in people with ADHD-HI.²³⁵²³⁶

A cohort study of Iranian children and adolescents found an increased prevalence of ADHD of 7.5% among people with ADHD.²³⁷

A very large study found the risk of bulimia or anorexia increased 18.3-fold with ADHD.²³⁸

Appetite disorders in adults with ADHD: 21 %

Disordered eating was 40% more common in adolescents with ADHD.²³⁹

22. Psychoses - 8.8 % (vs. 3 %)¶

One study found psychosis in 8.8% of adult persons with ADHD compared to 3% of non-affected people at least once in their lifetime.⁶²

23. Epilepsy - 3.4 % (vs. 0.5 to 1 %)¶

A meta-analysis of 63 studies with N = 1,073,188 people from 17 countries found:²⁴⁰
People with ADHD had an ADHD prevalence of 22.3% (12.7% for the ADHD-I subtype).
People with ADHD had an epilepsy prevalence of 3.4%.
The prevalence of ADHD is greatly increased in drug-resistant epilepsy.²⁴¹

One study found that 35% of adult people with ADHD also had ADHD.²⁴²
Epilepsy and ADHD have a genetic correlation (rg=0.18), which was even stronger for focal epilepsy (rg=0.23).²⁴³

In adults with psychogenic non-epileptic seizures (PNES), ADHD was found in 63.6%, while in adults with epileptic seizures (ES), ADHD was found in 27.8%.²⁴⁴

Some anti-seizure medications can cause or worsen ADHD symptoms as a side effect, while some ADHD medications can increase the risk of seizures.²⁴⁵

The prevalence of epilepsy in the general population is 0.5 to 1 %.
44.1% of people with ADHD have at least one other mental health diagnosis in their lifetime.²⁴³

24. Schizophrenia - 3.4 % (vs. 0.8 %)¶

Frequency of schizophrenia in ADHD:

• 4.59-fold risk of schizophrenia with ADHD (meta-analysis, k = 12, n = 1.85 million)²⁴⁶
  • 5.09 times the risk of a psychotic Disorder
• 4.74-fold risk of schizophrenia with ADHD diagnosed in childhood²⁴⁷
  • 3.5% of the people with ADHD who were examined also had ADHD F 90.0, i.e. ADHD with hyperactivity, without ADHD-I (which, however, does not seem to fit in any way with the other figures mentioned in this section)
• A Norwegian cohort study found schizophrenia in 3.4 % (men: 4.2 % women: 2.5 %) of adult people with ADHD compared to 0.8 % (men: 0.9 %; women: 0.6 %) of those not affected.⁵⁴
• Another study found a schizophrenia prevalence in ADHD of 0.9% across the age range²⁴
• People with ADHD with an additional comorbidity had a 2.14-fold risk of schizophrenia compared to people with ADHD without an additional comorbidity²⁴⁸ The risk of schizophrenia increased further with the number of comorbidities. In particular, ASD, mental retardation, tic disorder, depression and bipolar disorder showed the strongest correlation. 73.8% of persons with ADHD who initially had no psychiatric comorbidities had other psychiatric disorders prior to the onset of schizophrenia.

The incidence of ADHD is significantly increased in schizophrenia.

• Children and adolescents with schizophrenia
  • 17% to 57% have ADHD at the same time (meta-analysis, k = 5)²⁴⁹
• Adults with schizophrenia
  • 10% to 47% have ADHD at the same time (meta-analysis, k = 5)²⁴⁹
• 47% reported ADHD in childhood or adulthood²⁵⁰
• 23% reported ADHD in childhood and adulthood²⁵⁰

25. Obsessive-compulsive disorder - 1.9 to 2.4 %¶

Obsessive-compulsive disorders are more common in adults with ADHD.⁶

• Adults with ADHD overall: 1.9 %; women 1.4 %, men 2.4 %; ADHD-I 0.9 %, ADHD-C 1.5 %, ADHD-HI 12.5 %⁶³
• 2.4 % over the entire age range²⁴

• In a large study, the prevalence of ADHD was found to be 2.19 times higher in family members of people with ADHD.²⁵¹
• Of 70 adults with ADHD, 8.7% had OCD in their lifetime, compared to 5.7% of the 70 unaffected⁵²

26. Intellectual disability - 1.4 %¶

Total adults 1.4 %; women 1.8 %, men 1.0 %; ADHD-I 1.2 %, ADHD-C 1.0 %, ADHD-HI 5.0 %⁶³

27. Migraine¶

Source¹⁸

28. Obesity¶

2.1-fold risk for people with ADHD.²⁵²

ne study found that gene variants that correlate with obesity can causally increase the risk of ADHD.¹⁴⁸
For treatment options, see below under 4.5.

29. Socialization disorder¶

Source⁶

30. Disorder of sexual development¶

Source⁶

• Earlier onset of sexual activity
  • For children with people with ADHD: 15 years²⁵³
  • For non-affected persons: 16 years²⁵³
• More sexual partners
  • For people with ADHD: 18.6²⁵³
  • For non-affected persons: 6.5²⁵³
• Less time with a partner²⁵³
• Higher rate of contraception²⁵³
• High rate of unwanted pregnancies
  • In children with ADHD: 38 %²⁵³
  • For non-affected persons: 4 %²⁵³
    = 19.5 times the risk
• Teenage pregnancies 5.5 times²⁵⁴
  • Teenage pregnancies of mothers with ADHD: 15.3%
  • Teenage pregnancies of mothers without ADHD: 2.8%
• Birth rate increased (42:1)²⁵³
  = 42 times the risk
• Higher risk of sexually transmitted diseases
  • For people with ADHD: 16 %²⁵³
  • For non-affected persons: 4 %²⁵³
    = 4 times the risk

31. Narcolepsy¶

A meta-analysis found that around 33% of people with narcolepsy also have ADHD.³⁴

32. Messi syndrome / Hoarding¶

Messi syndrome is characterized by a strong urge to collect useless objects with a tendency to litter the living environment. A strong coincidence with ADHD is discussed.²⁵⁵ An overview of the literature can be found in Kuwano et al.²⁵⁶ They found a comorbidity of ADHD in 26.7% of people with ADHD.

In 71.6% of ADHD sufferers with comorbid hoarding, MPH improved the hoarding.²⁵⁷ In 5% it remained unchanged, 23.4% showed a slight worsening.

33. Attachment disorders¶

Source⁶

One study found that gene variants that correlate with increased social interaction are a protective factor against ADHD.¹⁴⁸

34. Enuresis (enuresis)¶

Source⁶
Enuresis in children increased the risk of comorbid ADHD by 2.15-fold (OR 3.15).²⁵⁸

35. Encopresis (defecation)¶

Source⁶

36. Suicidal tendencies - 2.4 to 6.7-fold¶

A meta-analysis of 57 studies found a correlation between ADHD and²⁵⁹

• Suicide attempts (OR 2.37)
• Suicidal thoughts (OR 3.53)
• Suicide plans (OR 4.54)
• Suicide (OR 6.69).

According to the study, suicide is between 2.37 and 6.69 times more common in people with ADHD than in those without the disorder.

Another study found increased suicidality in children and adolescents with ADHD (OR 1.1), but this was mediated by comorbid depression, irritability and anxiety, not ADHD itself.²⁶⁰

37. Fibromyalgia - 4-fold¶

One study found a fourfold frequency of ADHD in people with fibromyalgia, without quantifying the frequency of fibromyalgia in people with ADHD.²⁶¹

38. Dopamine transporter deficiency syndrome (DTDS)¶

Dopamine transporter deficiency syndrome (DTDS) is also known as infantile parkinsonism-dystonia.
Prevalence: very rare. To date, 60 people with ADHD are known.²⁶²

DTDS is a hereditary genetic disorder with a dysfunctional dopamine transporter.
The classic early-onset DTDS occurs within the first 6 months of life. Rarely, there is late-onset DTDS, which only becomes apparent in adolescence or adulthood.²⁶²²⁶³

In one study, all people with ADHD from early (infantile or juvenile) parkinsonism showed severely reduced DAT function (homozygous dysfunctional or two heterozygous dysfunctional DAT variants). The more severe the DAT deficiency, the earlier the onset of parkinsonism. Most of the people with ADHD showed previously unknown de novo variants. The dysfunctions were multifaceted: reduced dopamine binding affinity, reduced cell surface transporter, loss of post-translational dopamine transporter glycosylation and failure of amphetamine-mediated dopamine efflux.²⁶³ DTDS-DAT variants have been reported:

• Homozygous
  • C.941C>T –> Ala314Val (3 of 8 persons with ADHD)
  • C.1269 + 1G>A –> unknown (2 of 8 persons with ADHD) another study also reported this variant²⁶⁴
  • C.1408_1409delinsAG –> Tyr470Ser (1 of 8 people with ADHD)
• Combination of two dysfunctional DAT variants:
  • 1 out of 8 people with ADHD:
    • C.287-5_287-2delinsAAC –> unknown
    • C.1156G>A –> Gly386Arg
  • 1 out of 8 people with ADHD:
    • C.254G>T –> Arg85Leu
    • C.1333C>T –> Arg445Cys

Classic early-onset DTDS:²⁶²

• Onset in the first 6 months (infants)
• unspecific symptoms
  • Irritability
  • Difficulties with breastfeeding
  • axial hypotension
  • delayed motor development
• consequences of a hyperkinetic movement disorder
  • with characteristics of
    • Chorea
    • Dystonia
    • Ballism
    • orolingual dyskinesia
• In the course of time
  • Parkinsonism-dystonia complex
    • Bradykinesia, progressing to akinesia
    • dystonic posture
    • distal tremor
  • Rigidity
  • diminished facial expressions
  • severe motor delay due to restriction of voluntary movements
  • Episodic status dystonicus
  • Exacerbations of dystonia
  • secondary orthopaedic, gastrointestinal and respiratory complications
• usually relative preservation of intelligence with good cognitive development

Atypical late-onset DTDS²⁶²

• Onset in childhood to adulthood (4th decade of life)
  • in 5 of the 60 known people with ADHD
• Infancy and toddlerhood:
  • Normal psychomotor development
• Childhood
  • ADHD or individual ADHD symptoms
• late onset
  • Parkinsonism dystonia with
    • Tremor
    • progressive bradykinesia
    • variable tone
    • dystonic posture

Diagnostics:²⁶²

Cerebrospinal fluid (CSF) almost always shows

• HVA:5-HIAA ratio in SLC6A3-related DTDS is >4.0 (5.0-13.0) (normal range 1.0-4.0).
  • increased homovanillic acid levels (HVA, a metabolite derived from dopamine)
  • normal 5-hydroxyindoleacetic acid level (5-HIAA, a metabolite derived from serotonin)
• Pterin normal
• SPECT imaging using the ligand Ioflupane (DaTSCAN):
  • very abnormal results with absent/reduced tracer uptake in the basal ganglia
• Genetic analysis
  • Presence of a heterozygous dominant-negative SLC6A3 pathogenic variant known to cause autosomal dominant DTDS
    • e.g. p.Lys619Asn

39. Stuttering¶

One study reports an ADHD prevalence of 50% in children and adolescents who stutter.²⁶⁵

40. Mental disorders in relatives of people with ADHD - 6.8-fold¶

An analysis of the entire Taiwanese population in 2010 examined 220,966 parents of children with ADHD-HI (according to ICD-9, which did not recognize ADHD-I), 174,460 siblings of children with ADHD-HI, and 5,875 children of parents with ADHD-HI. Among these relatives of people with ADHD-HI, the risk of severe psychiatric disorders was significantly increased compared to matched control subjects without relatives with ADHD-HI:²⁶⁶

• ADHD-HI: 6.87-fold risk
• Autism spectrum disorder: 4.14 times the risk
• Bipolar disorders: 2.21 times the risk
• Major depressive disorders: 2.08 times the risk
• Schizophrenia: 1.69 times the risk

This can be understood as an indication of common genetic causes. However, it is also theoretically conceivable that this could be explained by the immunological consequences of (primarily viral) infections (which are more frequently transmitted between close relatives). See the chapter ⇒ Immune system and behavior.
Similarly, similar external life circumstances and similar dysfunctional behavior patterns and stressful experiences are likely to be shared more frequently among close people. These mechanisms can complement each other.