title: Further evidence for co-segregation between pediatric obsessive compulsive disorder and attention deficit hyperactivity disorder: a familial risk analysis.
abstract: BACKGROUND
  To examine the relationship between obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) in children and adolescents using familial risk analysis.
  
  
  METHODS
  We assessed for ADHD and OCD in the 1057 first-degree relatives of three groups of index children: those with OCD and ADHD, those with OCD but no ADHD and matched controls with neither disorder.
  
  
  RESULTS
  The age-corrected risk for OCD was similarly elevated in families of OCD youth with (14.8%) and without ADHD (17.5%) (p=.78), and both groups had significantly higher rates of OCD compared with controls (.5%) (p<.001). In contrast, the risk for ADHD was significantly elevated only among relatives of youth who had ADHD (15.3%) compared with controls (4.6%) (p<.001). Relatives affected with ADHD also had a significantly elevated risk for OCD compared to relatives unaffected by ADHD (20% vs. 4.9%, hazard ratio 4.8) (p<.001) and the two disorders occurred together with higher than expected frequency in affected relatives of OCD+ADHD probands (p<. 001) suggesting co-segregation between these two disorders. There was no evidence of nonrandom mating between OCD- and ADHD-affected spouses.
  
  
  CONCLUSIONS
  These results extend previous findings regarding the familiality of both OCD and ADHD and provide further evidence of a familial relationship between ADHD and pediatric OCD which best fit the hypothesis of a unique familial subtype.
authors.affiliation: Pediatric Psychopharmacology Program, Department of Psychiatry, Psychiatric and Neurodevelopmental Genetics Unit, Center for Human Genetics, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. dageller@partners.org
authors.forename: Daniel
authors.initials: D
authors.lastname: Geller
authors.forename: Carter
authors.initials: C
authors.lastname: Petty
authors.forename: Fe
authors.initials: F
authors.lastname: Vivas
authors.forename: Jessica
authors.initials: J
authors.lastname: Johnson
authors.forename: David
authors.initials: D
authors.lastname: Pauls
authors.forename: Joseph
authors.initials: J
authors.lastname: Biederman
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D002648:Child; D016241:Child of Impaired Parents / Q000706:statistics & numerical data; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires