ADHD in adults

ADHD does not, as was assumed until the end of the last millennium,¹ automatically end with adulthood.

• 1. Prevalence of ADHD persistence into adulthood
• 2. Possible reasons for persistence of ADHD into adulthood
• 3. Late Onset ADHD: first onset in adulthood
  • 3.1. Late-Onset ADHD: late-onset or late-diagnosed ADHD?
• 4. ADHD symptoms changed in adults
• 5. Adult treatment
• 6. Remission in adulthood

1. Prevalence of ADHD persistence into adulthood¶

According to the updated European consensus on the diagnosis and treatment of ADHD in adults, ADHD persists - with altered symptoms - throughout life in about 66%.²³ A follow-up of the MTA study after 2 to 16 years found complete remission in about 30% of affected children at at least one of the follow-up time points. Of these children (with at least one complete remission time point), nearly one-third showed no recurrence of ADHD, a good third showed partial recurrence, and a good third showed complete recurrence of ADHD. Full ADHD was found in 10.8% of the children studied during all study time points. 63.8% of those studied had fluctuating periods of remission and recurrence during childhood and young adulthood. 90% showed at least residual symptoms into young adulthood. ⁴ A follow-up study of 110 affected boys and 105 controls found complete persistence of ADHD in 35% and partial remission in another 43% of affected individuals at the 10-year test time. Thus, ADHD persisted at least partially in 78% of those affected at this time. About 30% of children with ADHD experienced complete remission at some point during the follow-up period. In most (60%), ADHD recurred after an initial period of remission. Only 9.1% showed durable remission by the end of the study, and 10.8% showed durable ADHD at all study time points. Most participants with ADHD (63.8%) had fluctuating remission and relapse phases over time.⁵⁶
Barkley reported in his follow-up to the MTA study that even those affected who were no longer diagnosed with ADHD in adulthood continued to have significant limitations in terms of educational and occupational achievement compared to unaffected individuals, although these problems were not as great as those who continued to be diagnosed with ADHD.⁷
Of 55 participants in our ADxS.org online symptom test (as of 2020) who reported having had ADHD-HI (predominant hyperactivity) as a child, the test found evidence of persistent ADHD in 49 (89%). Among the 34 participants who reported having had ADHD-I (predominant inattention) as a child, the test found evidence of persistent ADHD in 31 (91%). It should be noted that voluntary participation in the online test requires some acute interest in the question, which is likely to bias toward an excessively high rate of persistent ADHD.
65% of all children with ADHD continue to have at least some ADHD symptoms as adults.⁸ These figures were also cited by the updated 2019 European Consensus on the Treatment and Diagnosis of ADHD in Adults.⁹
In another study, nearly 22% still fully met DSM 5 criteria (aimed at children) at age 18.¹⁰
5% of all children have ADHD (another 5% are suspected of having ADHD). According to other sources, 30 to 80% of these remain affected into adulthood, with symptoms changing from childhood. In the USA, about 4.4% of all adults are affected by ADHD.¹¹¹² Further research can be found in Krause.¹³

One study observed in adults whose previous ADHD remitted that only the symptom groups

• Executive problems
• Behavioral problems

were remitted, while

• Hyperactivity/restless behavior
• Planning/organization deficits

persisted.¹⁴

Another large international study even found a higher prevalence of ADHD in adults (2.8%) than in children (2.2%).¹⁵ This could be consistent with the fact that the heritability of ADHD may be lower in adults than in children, i.e., that the proportion of environmental influences on ADHD development may be higher in adults than in children.¹⁶

2. Possible reasons for persistence of ADHD into adulthood¶

It is not possible to predict which ADHD sufferers will lose their ADHD in adulthood. Whether ADHD sufferers lose their ADHD by the age of 27 is independent of

• The severity of the disorder¹⁷
• The age at first onset of ADHD¹⁷
• The IQ of childhood¹⁷
• Childhood behavior problems¹⁷
• The severity of ADHD-HI, ODD, or CD¹⁷
• The duration of stimulant treatment after adolescence¹⁷

There are several theories as to why childhood ADHD disappears in some adults and persists in others.

• It was reported that children with ADHD from a low socioeconomic background benefited from special school support, while children from higher strata did so less.¹⁸ In our view, this suggests that families with low socioeconomic status are less able to compensate for their children’s deficits.
• A study of stress levels in children with ADHD found that severe stress levels in childhood and adolescence were associated with severe ADHD-HI or ADHD-I progression into adulthood, whereas children with mild stress levels often showed remitting ADHD (all subtypes).¹⁹ A large cohort study in Sweden confirms this²⁰
  • Puberty is associated with greatly altered dopaminergic innervation in the PFC. The PFC is particularly vulnerable to dopaminergic stimulation during this period. This explains the behavior of adolescents that fluctuates between the poles of novelty seeking and strong withdrawal. The strong dopaminergic vulnerability in this developmental phase further explains the dangers of alcohol and drug abuse or excessive media consumption. These can cause permanent dysfunction of the dopamine system, increasing the risk of impulsivity, addiction, or psychosis.²¹
    Prolonged cortical maturation in the frontoparietal network has a favorable effect on the final performance of the brain, whereas acceleration, e.g., by too much dopaminergic stimulation, has an unfavorable effect.²² In ADHD as in giftedness, the maturation of the brain is slowed down.
    See ⇒ Giftedness and ADHD In the section ⇒ Differential diagnostics in ADHD in the section ⇒ Diagnostics
• Anxiety symptoms at age 15 make mental disorders much more likely in early adulthood²³
  • Anxiety disorder: 4.9 times
  • Depression: 4.8 times
  • ADHD, ASD, or developmental disability: 3.4 times
    This may be another indication that middle adolescence represents a second particularly vulnerable developmental window in addition to early childhood.
• One theory assumes a post-maturation of brain functions. However, not every delay in brain maturation is also a sign of ADHD. In giftedness, there is a delay in the development of the cortex that corresponds exactly to the delay until the emergence of the first cortex thickness maximum in ADHD.
  ⇒ ADHD and giftedness.
• Another theory is that certain brain regions take on compensatory tasks so that the child’s ADHD deficits can be corrected through this.²⁴
• Another model assumes that certain childhood ADHD deficits persist throughout life.²⁴
• A study of adults in whom ADHD persisted found an imbalance between connections in the brain within the default mode network, on the one hand, and those between the default mode network and those areas that support attention and cognitive control, on the other. These differences did not exist in adults whose ADHD had remitted.²⁵²⁶
• Another study found up to an 11.8-fold increase in trauma in late-onset ADHD. Neurophysiologically, late-onset ADHD was no different from ADHD in sufferers who had had it since childhood. However, the effects were significantly more severe. At the same time, 1/3 of late-onset ADHD sufferers were no longer diagnosed with ADHD after one year.²⁷
• A comparison of partially remitted versus unremitted adolescents found significantly less activation of the vlPFC in partial remission. This improvement in vlPFC efficiency correlated with performance on a Go/No-Go task and was intermediate between ADHD diagnosis and normal controls.²⁸
• A gene analysis study found four genome-wide significant loci for childhood ADHD and one for late onset ADHD. Persistent ADHD was found to have elevated polygenic risk scores for ADHD (ADHD-PRS). Childhood ADHD showed greater genetic overlap with hyperactivity and autism and the highest burden of rare protein truncating variants in evolutionarily restricted genes. Late onset ADHD, in contrast, showed greater genetic overlap with depression and no increased burden of rare protein-cutting variants.³

3. Late Onset ADHD: first onset in adulthood¶

New research results from several long-term studies also show that ADHD can be diagnosed for the first time in adulthood. Depending on the study, this occurs in 0.4 to 10% of ADHD cases. For example, one study of young adults with ADHD found that only 12.6% had already been diagnosed with ADHD in childhood.²⁹ Accordingly, ADHD could be diagnosed for the first time much more frequently than previously assumed, even after the age of 6 or 12.
We are skeptical whether ADHD actually appears for the first time in adulthood (late onset). We assume that it was rather overplayed by intensive coping until then. Such coping costs a lot of energy and cannot always be sustained. If the strength is then used up, the coping facade collapses, the ADHD becomes visible. In adults, the gender ratio of ADHD sufferers is (almost) balanced.³⁰
In particular, women with late diagnosis suffer from the most severe symptoms and often comorbidities such as anxiety disorders or depression, which are a typical consequence of a long untreated ADHD.
On the other hand, women are more prone to develop emotional disorders that start later (on average in adolescence), such as depression, dysthymia, various anxiety disorders, or eating disorders. Sex hormones are often discussed as possible reasons.³¹

3.1. Late-Onset ADHD: late-onset or late-diagnosed ADHD?¶

Until DSM IV, the criteria for the diagnosis of ADHD stipulated that the first symptoms must have appeared by the age of 7. With DSM 5, this was increased to an age of 12 years.

Recent findings from population-based longitudinal studies suggest that in a subset of ADHD sufferers, ADHD symptoms only increase after childhood and they first meet criteria for ADHD in later adolescence or early adulthood.^{323334353610293738}

The updated 2018 European Consensus on the Treatment and Diagnosis of ADHD in Adults³⁹ notes that many ADHD sufferers have poor memory, making it very difficult to recall events and details of their childhood, and that there are reports of adults documenting an initial onset of symptoms after age 12.⁴⁰⁴¹

If the age by which the first symptoms must have appeared is set at 16, 99% of ADHD sufferers are covered, according to one study.⁴²

Accordingly, every hundredth case of ADHD still has a time of onset of the first symptoms after the age of 16. Assuming a prevalence for ADHD of 8%, this would mean 64,000 people in Germany; at 5%, 40,000 people would have late-onset ADHD after the age of 16.
In most cases, it is found that at least one symptom was highly prominent in adolescence, which could indicate faulty diagnosis in adolescence.⁴³

Another study found in a survey of young adults with ADHD that only 12.6% already had ADHD in childhood.⁴⁴ Accordingly, ADHD could “appear” for the first time much more frequently than previously assumed, even after the age of 6 or 12 (late onset). In the meantime, there are clear indications from extensive cohort studies in various countries that ADHD can also “appear” for the first time in adulthood.⁴⁵ One study showed that in children with ADHD, symptoms disappeared in up to 95% of those affected in adulthood, while a significant proportion of adults with ADHD did not “have” ADHD as children.⁴⁶ Several long-term studies over 20 to 40 years show that ADHD in children and ADHD in adults often affect separate groups of people. In adults, moreover, gender participation was balanced, whereas in children there was still a male predominance. This may also suggest a separation of the groups of individuals.^4748495030
However, we assume that ADHD usually already existed earlier and was just not diagnosed - be it due to ignorance of the doctors or therapists or due to intensive coping. Nevertheless, some questions about this remain unanswered.⁵¹

One publication reports that in later-onset ADHD, the expression should be milder.³⁵ This is in contrast to reports that especially late diagnosed women tend to have more severe symptoms with strong comorbidity (depression, anxiety).⁵⁰
The risk of being (diagnosed with) ADHD for the first time in adulthood also seems to be related to comorbidities. Childhood (ADHD)-typical comorbidities seem to increase the risk of developing ADHD in old age - just as (what has been known for some time), conversely, childhood ADHD increases the risk of developing typical comorbidities in adulthood.⁵²⁵³

A long-term study found that of 318 children with birth problems, at age 40, those who had developed ADHD as a child had only 21% ADHD, but had poorer educational attainment, more ADHD symptoms, and executive problems. Those who had attention problems as a child but not full-blown ADHD had 6.6% ADHD at age 40; those who did not show attention problems as a child had 6% ADHD. Controls without birth problems had ADHD at 40 at 1.6%.⁵⁴ Accordingly, approximately 6 to 6.6% of those children with birth problems and 1.6% of those without birth problems could receive an ADHD diagnosis for the first time at age 40.

A study of 488 consecutively admitted patients to a special dementia outpatient clinic found ADHD in 7 patients initially suspected of having an early form of ADHD. These 7 of a “very late onset ADHD” or “senile onset ADHD” affected had four features in common:⁵⁵

• significantly younger (< 65 years) than the overall study population
• predominantly inattention-related symptoms
• latent manifestation
• stressful life event before manifestation (stress experience)

4. ADHD symptoms changed in adults¶

The DSM IV criteria for ADHD describe the symptoms of children and not specifically those of adults.⁵⁶
The symptoms of ADHD in adults change considerably from those of ADHD in children.⁵⁷⁵⁸ Above all, hyperactivity decreases considerably. Symptoms such as inner restlessness, inability to relax and “having to be active all the time” come to the fore.

One study reported a linear decline in hyperactivity from 6 to 2.9 points from age 8 to 16.⁵⁹ Inattention decreased only from 5.8 to 4.9 points in the same period.
However, another study shows that hyperactivity - here measured by infrared motion sensors during the performance of attention tests - is still a better discriminator to non-affected persons than attention problems, even in adults. Even in affected individuals of the predominantly inattentive ADHD-I subtype, hyperactivity/motion agitation was found to be significantly higher than in unaffected individuals.⁶⁰

Barkley has created a list of typical symptoms of ADHD in adults and verified it through research. Physical hyperactivity decreases sharply, inner restlessness becomes more visible. Likewise, inattention decreases significantly.

In adults, the following symptoms predominate:

• Inattention (reduced by up to 40% compared to children)
  Attention problems decrease by up to 40% in adults compared to children and adolescents (the decrease is thus smaller than that of the other main symptoms).⁶² The data are taken from the publication by Biedermann. We cannot understand why the literature interprets them differently. However, the decrease of attention problems in adults, which can be read from the data, is in line with our perception (at least for some affected persons). One study reports a linear decrease in inattention from 5.8 to 4.9 points between the ages of 8 and 16.⁵⁹
  In contrast, other sources report an increase in inattention at age⁶³ and consistent attention problems and executive problems from working memory between ages 60 and 94, some of which stemmed from depression.⁶⁴
• Hyperactivity (reduced by up to 60% compared to children)
  Hyperactivity transforms to Inner Restlessness (Barkley) in adulthood and decreases by up to 60% compared to children / adolescents⁶²⁵⁹ We suspect that this is not so much a transformation but that after the hyperactivity subsides, the symptoms of inner tension become more apparent.
• Impulsivity (reduced by up to 60% compared to children)
  Impulsivity is said to decrease by up to 60% compared to children / adolescents, according to various sources⁶²⁶⁵⁵⁹
  Another study found no change in impulsivity with age.⁶³
• Emotional overreactivity (increased in adults)⁶⁶
• Affect lability⁶⁷
• Disorganization⁶⁷

Some changes can also be measured neurophysiologically.

The problems and quality-of-life limitations of older adults with ADHD are similar to those of younger adults with ADHD, according to one study. This suggests that there is no long-term improvement from continued aging during adulthood.⁷³

5. Adult treatment¶

In adults, much lower amounts of stimulants are usually required to correct the dopamine and noradrenaline deficit in the reinforcement system and dlPFC, which may be related to the fact that the preponderance of dopamine transporters appears to partially regress compared with children.
A (starting) dosage of stimulants as in children would therefore be medical malpractice. Regardless of this, stimulant treatment should always be initiated with dosages below the smallest package dosage sizes.

6. Remission in adulthood¶

One study examined adults three times, each 7 years apart, from age 34 to age 47, showing a remission rate of 5.7%.⁷⁴