ADHD exists in all cultures and countries worldwide. The frequency of occurrence is called prevalence.
Prevalence can define different terms:
Diagnosis prevalence: Frequency of existing medical diagnoses of a disease in the total population (e.g. within the last 12 months). Dependent on the diagnostic scale and expertise of the person making the diagnosis.
True prevalence / field prevalence / epidemiological prevalence: Frequency of a disease in a thorough examination of a representative group by experts, extrapolated to the total population. This value also depends on the instruments used (for ADHD, for example, higher in DSM 5 than in DSM III).
Treatment prevalence: Prevalence determined on the basis of treatment/prevention contacts. Dependent on the treatment commitment of those affected.
Administrative prevalence: Prevalence determined from routine statistics (e.g. cancer register). Hardly possible for ADHD.
Point prevalence: Number of existing cases at a point in time.
Period prevalence: All cases occurring in a period.
Incidence: Frequency of new diagnoses of a disease in the overall population (e.g. within the last 12 months).
The diagnostic prevalence of ADHD, i.e. the frequency with which practicing doctors and psychologists diagnose ADHD, has risen sharply in recent years as ADHD has become better understood and doctors and psychologists are now better trained. However, the true prevalence, i.e. the frequency with which ADHD actually exists, has not changed. In test studies in which representative groups are examined by specialists, the true prevalence of ADHD remains unchanged.
If we use the term prevalence without further explanation, this should in future refer to diagnosis prevalence. As of April 2021, this differentiation has not yet been consistently verified, which is made more difficult by the fact that a number of studies do not formulate this transparently.
1. Population prevalence¶
1.1. Worldwide¶
An overall average prevalence of 5.29% was determined in 2007 from studies conducted between 1978 and 2005. Few differences were found between North America and Europe, while the figures for Africa and the Middle East differed.
A meta-study determined an ADHD prevalence of 3.10 % in adults. ADHD-I was more common than ADHD-HI, ADHD-C was the least common.
Children and young people:
A comprehensive study of 13 meta-studies (588 primary studies with 3,277,590 test subjects) determined a worldwide ADHD prevalence of 8% in children and adolescents (boys: 10%, girls: 5%). The most common ADHD subtype was ADHD-I, followed by ADHD-HI and ADHD-C.
in 2018, a study found a prevalence of around 5% in children and adolescents and a further 5% just below the cut-off for a diagnosis. in 2015, a meta-analysis of 175 studies according to DSM III to DSM IV found a worldwide pooled overall prevalence of ADHD in children and adolescents of 7.2 % (6.7 % to 7.8 %). in 2012, a meta-analysis of 86 studies with n = 163,688 children and adolescents determined a prevalence of 5.9 % to 7.1 % according to DSM IV
Adults
in 2012, a meta-analysis of 11 studies with n = 14,112 adults determined a prevalence of around 5% according to DSM IV
A study conducted worldwide using the same standardized methods on adults aged 18 to 44 according to the DSM-IV criteria (aimed at children) found an ADHD prevalence of 2.8% and was higher in high (3.6%) and upper middle (3.0%) income countries than in low/lower middle income countries (1.4%). We are critical of the design of the study because a pre-selection of subjects was made in a preliminary study. We consider it questionable that adult ADHD should be more common than ADHD in children above the threshold, especially as DSM IV was used as a diagnostic tool tailored to ADHD in children and adolescents.
Country |
Prevalence in children (Treshold) |
Prevalence in children (Subtreshold) |
Prevalence in adults |
Belgium |
2.9 % |
8.6 % |
4.1 % |
France |
4.7 % |
8.9 % |
7.3 % |
Germany |
1.8 % |
5.6 % |
3.1 % |
Italy |
0.9 % |
3.7 % |
2.8 % |
Netherlands |
2.9 % |
9.2 % |
5.0 % |
Northern Ireland |
3.2 % |
4.5 % |
6.0 % |
Poland |
0.3 % |
0.8 % |
0.8 % |
Portugal |
1.5 % |
4.0 % |
3.0 % |
Spain |
1.8 % |
1.9 % |
1.2 % |
Spain (Murcia) |
2.0 % |
4.2 % |
3.3 % |
USA |
8.1 % |
6.6 % |
5.2 % |
Brazil (Sao Paulo) |
2.5 % |
7.0 % |
5.9 % |
Colombia (Medellin) |
2.5 % |
3.0 % |
3.0 % |
Lebanon |
1.5 % |
3.3 % |
1.8 % |
Mexico |
3.0 % |
3.7 % |
1.9 % |
Romania |
0.4 % |
0.7 % |
0.6 % |
Colombia |
1.2 % |
2.9 % |
2.5 % |
Iraq |
0.1 % |
1.0 % |
0.6 % |
Peru |
0.8 % |
2.5 % |
1.4 % |
China (Shenzen) |
0.7 % |
3.0 % |
1.8 % |
The following differences in (diagnostic) prevalence in different regions of the world are likely to represent differences in diagnostic methodology rather than differences in the true prevalence of ADHD.
1.2. Europe¶
1.2.1. Germany¶
The first KiGGS study in 2006 found that just under 5% of children and young people in Germany aged between 3 and 17 had already received a medical diagnosis of ADHD (diagnosis prevalence). In addition, a further 5% can be classified as suspected cases
The second KiGGS study from 2017 speaks of 4.4% of children and adolescents who have already received a medical diagnosis. These are reports from parents or guardians. The statement that an ADHD diagnosis has been made once does not mean that this diagnosis still has to exist at the time of the study survey.
The overall prevalence of ADHD in children and adolescents was found to be 2.2% in the 2007 Bella study (which we consider to be too low). A Bella sub-study with n= 2500 subjects between the ages of 7 and 17 puts the prevalence in the parents’ assessment at around 5%. Both studies confirm a strong divergence in prevalence according to social class. According to the Bella Study 2007, the middle class has the average prevalence, while the lower social class has a prevalence of 3.9%, which is four times higher than the upper class. The Bella sub-study reports a prevalence of ADHD in the lower social class (at 7.2%) that is approx. 2.3 times higher than in the upper class at 2.8% (with 3 strata).
In older adults, one study found an ADHD field prevalence of:
- 40-59-year-olds: 3.1 %
- 60-80 year olds: 2.1 %
With regard to current ADHD symptoms, 92.1% of the results of the self-assessment instrument used matched those of the external observation instrument.
Another study found a field prevalence (epidemiological prevalence) in adults of 4.7%.
In Germany, 20% of psychiatric and psychotherapeutic patients are said to be affected by ADHD.
33.3% of all Germans and 38.8% of all EU citizens suffer from a mental disorder (within 12 months). Men and women are affected in roughly equal numbers, but with different types of disorder. The 18 to 34 age group is most frequently affected.
Of these 33.3%, 1/3 (i.e. a total of 11.1% of all Germans) suffer from more than one disorder. In these cases, there is an overt comorbidity of several disorders from different diagnostic groups. The comorbidity with regard to different individual diagnoses from the same group is significantly higher again.
Comorbidities increase with age.
The lifetime prevalence of ADHD in Germany is roughly equivalent to that of diabetes.
Further information on the prevalence distribution of ADHD: http://www.adhs.info/fuer-paedagogen/allgemein-stoerungsbild/praevalenzraten.html
1.2.2. Denmark¶
A cohort study in Denmark found a prevalence of 5.9% in boys under 18 years of age according to ICD 10. Another study of all children born between 1990 and 199 found a prevalence of 3.68%.
1.2.3. Finland¶
In Finland, a national cohort study observed an increase in the use of ADHD medication in children from 1.26% in 2008 to 4.42% in 2018 and in adolescents from 0.93% in 2008 to 4.21% in 2018. At the same time, the proportion of women on medication increased.
1.2.4. France¶
The prevalence of ADHD in children aged 6 to 12 was reported to be between 3.5% and 5.6%. Another study gives a value of 0.3%, which seems too low.
1.2.5. Czech Republic¶
In a representative cross-section of the population, the diagnostic prevalence in 2019 was 3% and the field prevalence (according to the very simple ASRS) was 7.84%.
1.2.6. Ireland¶
7,6 %
1.3. North America¶
1.3.1. USA¶
In the USA, the frequency of diagnoses of all developmental disorders, including ADHD, increased significantly between 2009 and 2018:
- Children aged 3 to 17 with a diagnosis of ADHD (diagnosis prevalence)
- 2010: 8 %
- 2017: 8.5 % to 9.5 %
- 2018: 9,8 %
- Boys
- 2010: 11 %
- 2018: 13 %
- 1997 to 2018: 12.93 %
- Girls
- 2010: 6 %
- 2018: 6,6 %
- 1997 to 2018: 5.61 %
- Black girls aged 7 to 17: 6.4% to 9.2%; the inattentive subtype was most common
- White girls aged 7 to 17: 2.3% to 6.4%; the inattentive subtype was most common
- By age
- 3-4: Learning disability 3.2%, ADHD 1.2% (2018)
- 5-9: ADHS 6.57 % (1997-2018)
- 5-11: Learning disability 6.7 %, ADHD 9 % (2018)
- 12-17: Learning disability 9.4%, ADHD 13.6% (2018)
- 10-17: ADHS 11.09 % (1997-2018)
- Children aged 4 to 17 in a nationwide telephone survey (diagnosis prevalence)
- 2003: 7,8 %
- 2007: 9.5 %; 4.8 % taking ADHD medication
- 2019/2020: 8,5 %
- Children aged 5 to 11 in California (diagnosis prevalence)
By ethnicity:
-
Hispanic children (2010: 4 %; 2018: 6.9 %)
-
non-Hispanic white children (2010: 10 %; 2018: 10.9 %)
-
non-Hispanic black children (2010: 11 %; 2018: 13.1 %) Children
-
Children of couples with one white and one Native American parent (American Indian / Alaska Native) 2018: 26.4 %
-
People who identify as two or more races: ADHS 12.36 % (1997-2018)
-
Whites: ADHD 9.83 % (1997-2018)
-
Blacks/African Americans: ADHD 10.09% (1997-2018)
-
Hispanic/Latino: ADHD 5.36% (1997-2018)
-
Non-Hispanic/Latino: ADHD 10.64% (1997-2018)
-
Below the poverty line: ADHS 11.41 % (1997-2018)
-
Income from 100 to 199 % of the poverty line: ADHS 10.6 % (1997-2018)
-
Income from 200 to 399 % of the poverty line: ADHS 8.6 % (1997-2018)
-
Income of 400% or more of the poverty line: ADHS 8.39% (1997-2018)
-
Medicaid recipients: ADHD 12.57% (1997-2018)
-
Privately insured: ADHD 9.65% (1997-2018)
-
Insured persons: ADHD 8.11 % (1997-2018)
-
Uninsured: ADHD 5.83 % (1997-2018)
Children of single mothers were around twice as likely to have learning difficulties (2010: 12%; 2018: 11.3%) or ADHD (2010: 13%; 2018: 12.6%) as children in families with two parents (learning difficulties 2010: 6%, 2018: 5.9%; ADHD 2010: 7%, 2018: 8.8%). In 2018, only 5% of children of single fathers had learning difficulties and 6.7% had ADHD.
Children with average or poor health were around five times as likely to have a learning disability (2010: 28% to 6%; 2018: 32.3% to 5.9%) and around twice as likely to have ADHD (2010: 18% to 7%; 2018: 16.2% to 8.8%) as children with excellent or very good health. At 15.4%, ADHD was hardly more common among children in good health in 2018 than among those in average or poor health.
In 2018, children in cities with over 1 million inhabitants were less likely to be diagnosed with ADHD (8.2%) than children in cities with less than 1 million inhabitants (12%) or outside of large cities (11.6%).
Between 2009 and 2016, an increase in the annual prevalence of ADHD of around 250% from 0.23% to 0.84% was observed in war veterans.
Friedmann reports that the lifetime prevalence of ADHD in the USA has risen from 7.8% in 2003 to 11% in 2011. This is not due to an increase in ADHD (true prevalence), but to the fact that ADHD is now better recognized and more reliably diagnosed (diagnostic prevalence).
A 20-year study from 1997 to 2016 in the USA found diagnosis prevalence in children and adolescents:
- 6.1 % in 1997/1998
- 10.2 % in 2015/2016, of which
- Boys 14.0 %
- Girls 6.3 %
- hispanic 6.1 %
- non-Hispanic white 12.0 %
- non-Hispanic black 12.8 %
The increase in the prevalence of diagnosis can probably be explained by the improved diagnosis of ADHD. The true prevalence of ADHD in children in the USA did not change between 2003 and 2007.
One study found very different ADHD prevalence rates by county. The data was collected through parental reports, which severely impairs its validity:
USA national: 12.9 % (11.5 % to 14.4 %)
Areas with a high prevalence of ADHD:
- West South Central: 55.1% of counties had a prevalence of 16% or more
- East South Central: 53.6% of counties had a prevalence of 16% or more
- New England: 49.3% of counties had a prevalence of 16% or more
- South Atlantic: 46.2% of counties had a prevalence of 16% or more
Areas with a low prevalence of ADHD:
- East North Central: 11.7% of counties had a prevalence of 16% or more
- Pacific: 6.9% of counties had a prevalence of 16% or more
- West North Central: 5.8% of counties had a prevalence of 16% or more
- Mid Atlantic: 4% of counties had a prevalence of 16% or more
- Mountain: 2.1% of counties had a prevalence of 16% or more
1.3.2. Canada¶
Canadian children diagnosed with ADHD were
In contrast, the calculated true prevalence was
- 4 - 17 years
- 2008: 6,92 %
- 2015: 8,57 %
- Girls: 6.5 %
- Boys: 10.1 %
- 18 - 34 years
- 2008: 5,73 %
- 2015: 7,33 %
- 35 - 64 years
- 2008: 5,20 %
- 2015: 5,54 %
1.4. South America¶
1.4.1. Colombia¶
One study found an ADHD prevalence of 16.4% among Paisa children in Colombia (boys 19.8%, girls 12.3%).
1.5. Asia¶
1.5.1. China¶
In China, a prevalence of 6.26% was found in children and adolescents (63 studies from 1983 to 2015, 70% of which were conducted between 2005 and 2015), with significant regional differences.
1.5.2. Japan¶
The prevalence of ADHD among Japanese adults is said to be 1.7%.
Among Japanese female students (∅ 19.2 years), ADHD-HI was found in 27.2% and ADHD-I in 1.1%. Another study reported 27% ADHD in Japanese students (29.7% males, 25.3% females).
One study reports 31.1% ADHD according to the parent report (n = 7,566) and 4.3% ADHD according to the teacher report (n = 9,9 56) with an overall prevalence of 7.2 to 7.9% among Japanese preschool children. It is possible that parental reports in Japan are not reliable for cultural reasons. Another study also found evidence of excessive parental ratings for young children in Japan. While the parents of 4 to 12-year-olds identified an ADHD rate of 7.7%, the children’s teacher ratings revealed ADHD (according to DSM III) in only 3.19%.
1.5.3. Taiwan¶
A large study found an increase in new ADHD diagnoses according to ICD 9 from 7.92/10000 person-years in 2000 to 13.92/10000 person-years in 2011. The ratio of males to females decreased from 3.61 to 2.90. The largest increase was found in young adults (19-30 years), followed by preschool children (0-6 years).
1.5.4. India¶
A large study put the prevalence of ADHD in India at 0.3% in 2017. The prevalence of ASD was put at 3.2%.
In a rural area of northern India, a prevalence of AD
1.6. Africa¶
A meta-study of 63 studies with n = 849,902 participants found an average prevalence of 10.3% for the Middle East and North Africa.
1.6.1. Ethiopia¶
In Ethiopia in 2022, a study of children and adolescents aged 6 to 17 years found a field prevalence of 13%. in 2015, a study of 6 to 17-year-olds found a prevalence of 7.3%. It affected 80% more boys than girls, children of single parents were 5 times more likely to be affected and children from families with a low socio-economic status were 2.4 times more likely to be affected. Another study found a field prevalence of 9.9%
1.6.2. Ghana¶
A study in Ghana in 2016 found a prevalence of 1.64% among children aged 7 to 15.
1.6.3. Somalia¶
A study in Somalia found a prevalence of 2.8% in children aged 7 to 15.
1.6.4. Mozambique¶
An ADHD prevalence of 13.4% was found among primary school pupils in Mozambique. Using stricter standards, the prevalence was 6.7%.
1.7. Middle East¶
A meta-study of 63 studies with n = 849,902 participants found an average prevalence of 10.3% for the Middle East and North Africa. The prevalence in children and adolescents (59 studies) was 10.1 %, the prevalence in adults (4 studies) was 13.5 %.
1.7.1. Iran¶
A meta-study of 19 studies found an average prevalence of 14.8% in Iran.
In Iran, a study published in 2019 found a prevalence of 4% (5.2% in boys, 2.7% in girls) between the ages of 6 and 18.
1.7.2. Saudi Arabia¶
A meta-analysis of 14 studies with n = 455,334 affected persons found an ADHD prevalence of 12.4% in the Saudi population as a whole
A meta-study of 8 studies found an average prevalence of 13.5% for Saudi Arabia.
A study of 2280 students from 11 colleges at King Abdulaziz University, one of the largest universities in Saudi Arabia, were personally assessed with a validated Arabic version of the Adult ADHD Self-Report Scale. Of the 2059 students (90 %) who completed the questionnaire (average age: 21.2 years), 11.9 % met the criteria for adult ADHD. Only 6.5% had been diagnosed with ADHD in childhood and only 0.8% had taken medication for it.
This is one of the few studies on the true prevalence (field prevalence) of ADHD.
The risk of ADHD correlated with
- high family income
- poor grades in the last semester
- Divorce of the parents
-
ADHD diagnosis in childhood
- previous diagnosis of depression
- higher severity of current depression and anxiety
- Smoking cigarettes.
A study of adults aged 21 to 30 (77 women) reported ADHD symptoms in 48%
A study of young adults reported an ADHD prevalence of 34.7% based on the ASRS.
1.7.3. Egypt¶
A meta-study of 9 studies found an average prevalence of 13.3% for Egypt.
The prevalence of ADHD in preschool children (3 to 6 years) was 10.5%. ADHD-I was the most common (5.3 %), followed by the hyperactivity form (3.4 %).
The risk of ADHD correlated with
- positive family history of psychological and neurological symptoms (17.9% positive vs. 9.7% negative)
- Family history of ADHD symptoms (24.5% positive vs. 9.4% negative)
- active smoking of the mother (21.1 % positive vs. 5.3 % negative)
- Delivery by caesarean section (66.4 % positive vs. 53.9 % negative)
- increased blood pressure during pregnancy (19.1 % positive vs. 12.4 % negative)
- Drug use during pregnancy (43.6% positive vs. 31.7% negative)
Significant risk factors for children were:
- Lead exposure (25.5% positive compared to 12.3% negative)
- Children with heart problems (38.2% positive compared to 16.6% negative)
- Hours a child spent in front of the TV or cell phone (any screen) per day (60.0% of children who tested positive spent more than 2 hours per day compared to 45.7% negative).
The prevalence among medical students was 11.0%.
1.7.4. Jordan¶
A meta-study of 2 studies found an average prevalence of 23.4 % for Jordan (one study with 40.6 %, one study 6.2 %).
2. Differences in different ethnic groups¶
A meta-study found the following ADHD prevalence rates by ethnicity in children and adolescents:
Whites: 16.8 %, n = 835,505, k = 25
Blacks: 15.9 % n = 218,445, k = 26
Asians: 12.4 %, n = 66,413, k = 7
Latin Americans: 10.1 %, n = 493,417, k = 24
N represents the number of test subjects, K the number of studies analyzed. There were no significant differences in prevalence by ethnicity.
A study of 5.2 million patients came to the conclusion that the incidence of ADHD depends on the population:
- Whites: 102.8 %
- Indigenous people: 0.56 %-1.14 %
- Hispanic or Latino: 0.25 %-0.65 %
- Colored: 0.22 %-0.69 %
- Asian-American persons: 0.11 %-0.35 %
- Pacific Islanders: 0.11 %-0.39 %
- Individuals of other ethnicities: 0.29 %-0.71 %
This is not the lifetime prevalence of the population as a whole, but the frequency of diagnoses given within a year to patients who use a specific medical record system.
As ADHD is largely genetic, a different prevalence between different ethnic groups would not be surprising.
A cohort study of Scottish schoolchildren found the following relative prevalence distribution by ethnicity. 100% would be an even distribution. Asians and blacks therefore had ADHD considerably less frequently than would have been expected based on the proportion of test subjects
Whites: 102.8 %
Asians: 8.3 %
Blacks: 33.3 %
Mixed: 55.6 %
Other: 100 %
Notes on the terms population and race:
- The term race characterizes humanity as a whole. There are no different human races.
- The English term race does not refer to a genetic definition, but to a social construct.
- The genetic differences between continents are gradual. For example, there are groups of people in Africa (e.g. the San) who have lighter skin than groups of people in Europe (e.g. in Andalusia). The light skin color of Europeans only developed a few thousand years ago. Before that, all people were more or less “black”.
- Over a family tree of 4000 years, every human being is related to every other human being by blood.
3. Prevalence according to life circumstances¶
3.1. Prison inmates¶
One study found an ADHD field prevalence (“true prevalence”) of 25% among adult prison inmates in the UK. In France (11%) and Canada (17%), the field prevalence was determined in prisons with stricter diagnostic criteria.
Field prevalence is determined by examinations of a representative group of test persons by specialists and is to be distinguished from treatment prevalence (diagnosis prevalence), which measures the frequency of existing diagnoses by the normal medical profession.
Among Spanish prison inmates, the lifetime prevalence of ADHD was found to be 54.4%, with an acute prevalence of 16.4%. The lifetime prevalence of an Axis 1 disorder was 81.4%.
3.2. Refugees and asylum seekers under the age of 18¶
Among refugees and asylum seekers under the age of 18, a meta-study of 8 studies found an ADHD prevalence of 8.6% (1 to 16%), with PTSD (22.71%), anxiety disorders (15.77%), depression (13.81%) and ODD (1.77%) also being identified. In our opinion, the high levels of PTSD, anxiety disorders and depression may have masked the actual prevalence of ADHD in the target group studied.
4. Prevalence in psychiatric clinics¶
In adult inpatients at a German psychiatric clinic, 59% were diagnosed with ADHD (12-month prevalence).
The prevalence of ADHD in adult patients at outpatient treatment centers ranged from 14.7% to 26.1%.