Attention-deficit hyperactivity disorder (ADHD) or hyperkinetic disorder (HKD) affects people of all ages, and ADHD prevalence rates are known to vary between children, adolescents and adults.1-5
Although there is no global consensus, meta-regression analyses have estimated the worldwide ADHD/HKD prevalence at between 5.29%2 and 7.1%5 in children and adolescents, and at 3.4% (range 1.2–7.3%) in adults.1 The prevalence of ADHD in very young children (aged <6 years) or later in adult life (aged >44 years) is less well studied.1
ADHD prevalence rates may vary depending on several factors:
- Age – ADHD can affect people of all ages, and ADHD prevalence rates are known to vary between children, adolescents and adults1-5
- Gender – a higher prevalence of ADHD is often reported in males5-7
- Presentation of ADHD – the predominantly inattentive presentation of ADHD is considered most prevalent in school-age children, adolescents and adults5
- ADHD is often present alongside psychiatric comorbidities such as oppositional defiant disorder, conduct disorder, anxiety disorder, personality disorders and depression,6,8-14 which may further complicate understanding of true prevalence rates.
Reported ADHD prevalence rates vary worldwide, mainly due to methodological differences between studies.2
The Diagnostic and Statistical Manual of Mental Disorders – 5th Edition (DSM-5™) also suggests that cultural attitudes towards the interpretation of behaviour may contribute to differences in prevalence estimates across studies.15
A meta-analysis of studies (n=102) of children and adolescents diagnosed with ADHD found that the prevalence of ADHD in individuals aged ≤18 years varied between countries worldwide; the prevalence estimate for Europe specifically was just under 5% (Figure).2
Prevalence of ADHD in children and adolescents by geographical location (n=102 studies). Reproduced with kind permission.2*
Geographical location was associated with significant variability between the prevalence estimates from North America and both the Middle East (p=0.01) and Africa (p=0.03), while no significant differences were reported for prevalence rates between North America and Europe (p=0.40), South America (p=0.83), Asia (p=0.85) or Oceania (p=0.45). This finding was confirmed in a meta-regression model using Europe as the comparator: significant differences in prevalence were found between Europe and both Africa (p=0.05) and the Middle East (p=0.03).2*
Estimates from individual studies have indicated that the global prevalence of ADHD in adults ranges from 1.1% in Australia to 7.3% in France (Figure).1,16-18
Prevalence of ADHD in adults by country1, 16-18
Methodological features of prevalence studies
Review papers have concluded that ADHD prevalence data may vary widely between studies due to various factors such as: population characteristics; methodological, environmental and cultural differences; and variability in identification and diagnostic guideline tools employed in studies, rather than geographical location per se.2,5,19*
A worldwide meta-analysis of 86 studies in children and adolescents, and 11 studies in adults, found no significant prevalence differences between countries, after controlling for differences in the diagnostic algorithms used to define ADHD.5* An update to this meta-analysis combined with results of another systematic review of 102 worldwide studies similarly found that country was not significantly associated with the heterogeneity of prevalence estimates in children and adolescents.2,20* Researchers therefore argue that ADHD is not a cultural construct associated with a particular geographical location.5,20*
The differences in diagnostic criteria applied to define whether ADHD is present or not may affect prevalence estimates. The DSM-5TM and the International Classification of Mental and Behavioural Disorders 10th revision (ICD-10) have different diagnostic criteria.15,21
Additionally, different versions of each of the diagnostic criteria used may affect prevalence rates; for example, an update of two systematic literature reviews and meta-regression analyses of the prevalence of ADHD in children and adolescents found that prevalence rates based on the Diagnostic and Statistical Manual of Mental Disorders – 3rd Edition – Text Revision (DSM-III-TR) and ICD-10 were 2.42% and 4.09% lower, respectively, than rates based on the DSM-IV (p=0.044 and p=0.009, respectively).20*
Finally, the source of the symptom report (e.g. parent report vs teacher report), and the setting that the population comes from (e.g. community vs school) may affect whether ADHD is deemed to be present or not.2,5
*These studies were conducted prior to publication of the DSM-5TM
- Fayyad J, De Graaf R, Kessler R, et al. Cross-national prevalence and correlates of adult attention-deficit hyperactivity disorder. Br J Psychiatry 2007; 190: 402-409.
- Polanczyk G, de Lima MS, Horta BL, et al. The worldwide prevalence of ADHD: a systematic review and metaregression analysis. Am J Psychiatry 2007; 164: 942-948.
- Schlack R, Holling H, Kurth BM, et al. The prevalence of attention-deficit/hyperactivity disorder (ADHD) among children and adolescents in Germany. Initial results from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2007; 50: 827-835.
- Wichstrøm L, Berg-Nielsen TS, Angold A, et al. Prevalence of psychiatric disorders in preschoolers. J Child Psychol Psychiatry 2012; 53: 695-705.
- Willcutt EG. The prevalence of DSM-IV attention-deficit/hyperactivity disorder: a meta-analytic review. Neurotherapeutics 2012; 9: 490-499.
- Novik TS, Hervas A, Ralston SJ, et al. Influence of gender on attention-deficit/hyperactivity disorder in Europe–ADORE. Eur Child Adolesc Psychiatry 2006; 15(Suppl 1): I/15-I/24.
- Biederman J, Faraone SV, Monuteaux MC, et al. Gender effects on attention-deficit/hyperactivity disorder in adults, revisited. Biol Psychiatry 2004; 55: 692-700.
- Steinhausen HC, Novik TS. ADORE Study Group. Co-existing psychiatric problems in ADHD in the ADORE cohort. Eur Child Adolesc Psychiatry 2006; 15: I/25-I/29.
- Preuss U, Ralston SJ, Baldursson G, et al. Study design, baseline patient characteristics and intervention in a cross-cultural framework: results from the ADORE study. Eur Child Adolesc Psychiatry 2006; 15(Suppl 1): I/4-I/14.
- Jensen CM, Steinhausen HC. Comorbid mental disorders in children and adolescents with attention-deficit/hyperactivity disorder in a large nationwide study. Atten Defic Hyperact Disord 2015; 7: 27-38.
- Cuffe SP, Visser SN, Holbrook JR, et al. ADHD and psychiatric comorbidity: functional outcomes in a school-based sample of children. J Atten Disord 2015; Epub ahead of print.
- Kessler RC, Adler L, Barkley R, et al. The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication. Am J Psychiatry 2006; 163: 716-723.
- Friedrichs B, Igl W, Larsson H, et al. Coexisting psychiatric problems and stressful life events in adults with symptoms of ADHD–a large Swedish population-based study of twins. J Atten Disord 2012; 16: 13-22.
- Piñeiro-Dieguez B, Balanzá-Martinez V, García-García P, et al. Psychiatric comorbidity at the time of diagnosis in adults with ADHD: the CAT study. J Atten Disord 2016; 20: 1066-1075.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. 2013.
- Ebejer JL, Medland SE, van der WJ, et al. Attention deficit hyperactivity disorder in Australian adults: prevalence, persistence, conduct problems and disadvantage. PLoS One 2012; 7: e47404.
- de Zwaan M, Gruss B, Muller A, et al. The estimated prevalence and correlates of adult ADHD in a German community sample. Eur Arch Psychiatry Clin Neurosci 2012; 262: 79-86.
- Polanczyk G, Laranjeira R, Zaleski M, et al. ADHD in a representative sample of the Brazilian population: estimated prevalence and comparative adequacy of criteria between adolescents and adults according to the item response theory. Int J Methods Psychiatr Res 2010; 19: 177-184.
- Skounti M, Philalithis A, Galanakis E. Variations in prevalence of attention deficit hyperactivity disorder worldwide. Eur J Pediatr 2007; 166: 117-123.
- Polanczyk GV, Willcutt EG, Salum GA, et al. ADHD prevalence estimates across three decades: an updated systematic review and meta-regression analysis. Int J Epidemiol 2014; 43: 434-442.
- World Health Organization. The ICD-10 Classification of Mental and Behavioural Disorders. Available at: www.who.int/entity/classifications/icd/en/bluebook.pdf. Last updated 1993; 1: 1-263. Accessed 04 January 2017.