title: Implications of extending the ADHD age-of-onset criterion to age 12: results from a prospectively studied birth cohort.
abstract: OBJECTIVE
  To evaluate whether including children with onset of symptoms between ages 7 and 12 years in the ADHD diagnostic category would: (a) increase the prevalence of the disorder at age 12, and (b) change the clinical and cognitive features, impairment profile, and risk factors for ADHD compared with findings in the literature based on the DSM-IV definition of the disorder.
  
  
  METHODS
  A birth cohort of 2,232 British children was prospectively evaluated at ages 7 and 12 years for ADHD using information from mothers and teachers. The prevalence of diagnosed ADHD at age 12 was evaluated with and without the inclusion of individuals who met DSM-IV age-of-onset criterion through mothers' or teachers' reports of symptoms at age 7. Children with onset of ADHD symptoms before versus after age 7 were compared on their clinical and cognitive features, impairment profile, and risk factors for ADHD.
  
  
  RESULTS
  Extending the age-of-onset criterion to age 12 resulted in a negligible increase in ADHD prevalence by age 12 years of 0.1%. Children who first manifested ADHD symptoms between ages 7 and 12 did not present correlates or risk factors that were significantly different from children who manifested symptoms before age 7.
  
  
  CONCLUSIONS
  Results from this prospective birth cohort might suggest that adults who are able to report symptom onset by age 12 also had symptoms by age 7, even if they are not able to report them. The data suggest that the prevalence estimate, correlates and risk factors of ADHD will not be affected if the new diagnostic scheme extends the age-of-onset criterion to age 12.
authors.affiliation: Duke University, USA.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Polanczyk
authors.forename: Avshalom
authors.initials: A
authors.lastname: Caspi
authors.forename: Renate
authors.initials: R
authors.lastname: Houts
authors.forename: Scott H
authors.initials: SH
authors.lastname: Kollins
authors.forename: Luis Augusto
authors.initials: LA
authors.lastname: Rohde
authors.forename: Terrie E
authors.initials: TE
authors.lastname: Moffitt
mesh_terms: D000328:Adult; D017668:Age of Onset; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics / Q000523:psychology; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004200:Diseases in Twins / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D010552:Personality Assessment; D011446:Prospective Studies; D012307:Risk Factors; D006113:United Kingdom