Epidemiology

The mean worldwide prevalence of ADHD is between 5.29% and 7.1% in children and adolescents (<18 years).1,2 The prevalence of ADHD in Europe was estimated at just under 5%, however, there are still few global or European data on rates of incidence, prevalence or epidemiology of ADHD.1 Estimation of the prevalence of ADHD may be complicated by a range of factors such as methodological and cultural differences, and variability in identification and medical classification systems used for diagnosis.1

Prevalence factors

ADHD prevalence rates may vary depending on several factors:

  • Age – ADHD can affect children from pre-school age2-4 and increasing recognition is now given to the fact that ADHD can extend beyond childhood and adolescence into adulthood.2,5-8
  • Gender – a higher prevalence is often reported in males.2,9,10
  • Subtype of ADHD – combined-type ADHD is generally considered most prevalent in all age-groups.11,12

ADHD is often present alongside comorbidities such as oppositional defiant disorder (ODD) and anxiety disorder,5,12-15 which may further complicate understanding of true prevalence rates.

Geographical factors

ADHD affects individuals across regions worldwide and prevalence rates vary depending on geographical location, although these variations may reflect the fewer number of contributory studies in certain geographical regions.1 Cultural differences and differences in study methodology are also likely to play a role in prevalence variations.1 For example, prevalence rates may vary depending on the source of information on a patient’s condition (e.g. parent, patients, teacher or specialist)1,16 and the origin of the population sample (e.g. community versus school samples).1 Global variations in diagnostic criteria or rating scales used to assess symptoms may also contribute to variations in prevalence rates.1,17-19

The two main guidelines used for the diagnosis of ADHD are DSM-IV18 and ICD-10.17

  • ICD-10 uses narrower diagnostic criteria, which requires evidence of inattention, hyperactivity and impulsivity,17 whereas DSM-IV requires evidence of inattention and/or hyperactivity-impulsivity (combined-symptoms).18

As expected, the more restrictive ICD-10 criteria result in fewer diagnoses than the broader DSM-IV criteria.19


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  1. 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.
  2. Willcutt EG. The prevalence of DSM-IV attention-deficit/hyperactivity disorder: a meta-analytic review. Neurotherapeutics. 2012; 9(3):490-9.
  3. Wichstrøm L, Berg-Nielsen TS, Angold A, et al. Prevalence of psychiatric disorders in preschoolers. J Child Psychol Psychiatry 2012; 53: 695-705.
  4. 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.
  5. 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.
  6. Faraone SV, Biederman J, Mick E. The age-dependent decline of attention deficit hyperactivity disorder: a meta-analysis of follow-up studies. Psychol Med 2006; 36: 159-165.
  7. Lara C, Fayyad J, de Graaf R, et al. Childhood predictors of adult attention-deficit/hyperactivity disorder: results from the World Health Organization World Mental Health Survey Initiative. Biol Psychiatry 2009; 65: 46-54.
  8. Barkley RA, Fischer M, Smallish L, et al. The persistence of attention-deficit/hyperactivity disorder into young adulthood as a function of reporting source and definition of disorder. J Abnorm Psychol 2002; 111: 279-289.
  9. Biederman J, Faraone SV, Monuteaux MC, et al. Gender effects on attention-deficit/hyperactivity disorder in adults, revisited. Biol Psychiatry 2004; 55: 692-700.
  10. 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: I15-I24.
  11. Faraone SV, Biederman J, Weber W, et al. Psychiatric, neuropsychological, and psychosocial features of DSM-IV subtypes of attention-deficit/hyperactivity disorder: results from a clinically referred sample. J Am Acad Child Adolesc Psychiatry 1998; 37: 185-193.
  12. Wilens TE, Biederman J, Faraone SV, et al. Presenting ADHD symptoms, subtypes, and comorbid disorders in clinically referred adults with ADHD. J Clin Psychiatry 2009; 70: 1557-1562.
  13. Steinhausen HC, Novik TS. ADORE Study Group. Co-existing psychiatric problems in ADHD in the ADORE cohort. Eur Child Adolesc Psychiatry 2006; 15: i25-i29.
  14. Yoshimasu K, Barbaresi WJ, Colligan RC, et al. Childhood ADHD is strongly associated with a broad range of psychiatric disorders during adolescence: a population-based birth cohort study. J Child Psychol Psychiatry 2012; 53: 1036-1043.
  15. Jensen PS, Hinshaw SP, Kraemer HC, et al. ADHD comorbidity findings from the MTA study: comparing comorbid subgroups. J Am Acad Child Adolesc Psychiatry 2001; 40: 147-158.
  16. Skounti M, Philalithis A, Galanakis E. Variations in prevalence of attention deficit hyperactivity disorder worldwide. Eur J Pediatr 2007; 166: 117-123.
  17. 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 27 Feb 2013.
  18. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC: American Psychiatric Association, 2004.
  19. National Collaborating Centre for Mental Health. The NICE guideline on diagnosis and management of ADHD in children, young people and adults – National Clinical Practice Guideline Number 72. The British Psychological Society and The Royal College of Psychiatrists, 2009.

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