title: Is the diagnosis of ADHD influenced by time of entry to school? An examination of clinical, familial, and functional correlates in children at early and late entry points.
abstract: OBJECTIVE
  The authors examined the proposed immaturity hypothesis, which suggests that younger children may have developmental immaturity and not ADHD, using data from a large, clinically referred population of individuals with and without ADHD.
  
  
  METHODS
  The sample consisted of individuals with and without an ADHD diagnosis, ascertained from ongoing studies in our laboratory, born in August (Younger Cohort N = 562) and born in September (Older Cohort N = 529). The authors compared studywide diagnosis rates of ADHD, ADHD familiality patterns, ADHD symptoms, psychiatric comorbidity, and functional impairments between the two cohorts.
  
  
  RESULTS
  Studywide rates of ADHD diagnosis, ADHD-associated symptoms, ADHD-associated impairments, ADHD-associated comorbid disorders, and familiality were similar in the two age cohorts.
  
  
  CONCLUSIONS
  Results showed that ADHD-associated familial, clinical, and functional correlates are similar irrespective of age at entry to school, indicating that when ADHD symptoms are present, a diagnosis of ADHD should be considered rather than attributing these symptoms to developmental immaturity.
authors.affiliation: 1Massachusetts General Hospital, Boston, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Biederman
authors.forename: Carter R
authors.initials: CR
authors.lastname: Petty
authors.forename: Ronna
authors.initials: R
authors.lastname: Fried
authors.forename: K Yvonne
authors.initials: KY
authors.lastname: Woodworth
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Faraone
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D002648:Child; D015331:Cohort Studies; D015897:Comorbidity; D003937:Diagnosis, Differential; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D012574:Schools / Q000706:statistics & numerical data*; D012923:Social Class; D013997:Time Factors