title: Is season of birth a risk factor for attention-deficit hyperactivity disorder?
abstract: OBJECTIVE
  To investigate seasonal variations in the birth patterns of children with attention-deficit hyperactivity disorder (ADHD) in reference to a group of normal control children, attending to issues of comorbidity, familiality, and learning disability.
  
  
  METHODS
  Subjects were boys with DSM-III-R ADHD (n = 140) and normal controls (n = 120). The ADHD children were stratified by the presence of comorbid psychiatric disorders, learning disability, and family history of ADHD, and logistic regression was used to estimate relative risks.
  
  
  RESULTS
  No statistically major effect for season of birth was observed in the comparison of ADHD and control children. However, significant effects were found for September births for ADHD children with learning disability (odds ratio = 5.4) and for ADHD children without psychiatric comorbidity (odds ratio = 4.5). A trend was also noted for winter births in ADHD children with learning disabilities, no psychiatric comorbidity, and positive family history for ADHD.
  
  
  CONCLUSIONS
  These preliminary results suggest that there may be a seasonal pattern of birth for subtypes of ADHD. If season of birth serves as a proxy for the timing of seasonally mediated viral infections, it may lead to a greater understanding of the etiology and pathophysiology of ADHD.
authors.affiliation: Pediatric Psychopharmacology Unit, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: E
authors.initials: E
authors.lastname: Mick
authors.forename: J
authors.initials: J
authors.lastname: Biederman
authors.forename: S V
authors.initials: SV
authors.lastname: Faraone
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D001900:Boston / Q000453:epidemiology; D002648:Child; D015897:Comorbidity; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000235:genetics; D008297:Male; D016017:Odds Ratio; D012044:Regression Analysis; D012306:Risk; D012621:Seasons