title: Intellectual disability in children with attention deficit hyperactivity disorder.
abstract: OBJECTIVE
  To determine whether children with attention deficit hyperactivity disorder (ADHD) and mild intellectual disability (ID) are a clinically distinct ADHD subgroup.
  
  
  METHODS
  This was a cross-sectional study comparing clinical characteristics (ADHD subtypes, total number of symptoms, and rates of common comorbidities) between children with ADHD and mild ID and those with ADHD and IQ test scores >70, and also between children with ADHD and ID and a general population sample of children with ID alone. The sample comprised a clinical sample of children with ADHD with ID (n = 97) and without ID (n = 874) and a general population sample of children with ID and without ADHD (n = 58).
  
  
  RESULTS
  After correcting for multiple statistical tests, no differences were found between the 2 ADHD groups on any measure except the presence of conduct disorder (CD) symptoms and diagnoses. Children with ADHD and ID had higher rates of both (OR, 2.38; 95% CI, 1.71-3.32 and OR, 2.69; 95% CI, 1.69-4.28, respectively). Furthermore, children with ADHD and ID had significantly higher rates of oppositional defiant disorder (OR, 5.54; 95% CI, 2.86-10.75) and CD (OR, 13.66; 95% CI, 3.25-57.42) symptoms and a higher incidence of oppositional defiant disorder diagnoses (OR, 30.99; 95% CI, 6.38-150.39) compared with children with ID without ADHD.
  
  
  CONCLUSIONS
  Children with ADHD and mild ID appear to be clinically typical of children with ADHD except for more conduct problems. This finding has implications for clinicians treating these children in terms of acknowledging the presence and impact of ADHD symptoms above and beyond ID and dealing with a comorbid CD.
authors.affiliation: Ty Bryn Unit, St Cadocs Hospital, Newport, United Kingdom.
authors.forename: Alka
authors.initials: A
authors.lastname: Ahuja
authors.forename: Joanna
authors.initials: J
authors.lastname: Martin
authors.forename: Kate
authors.initials: K
authors.lastname: Langley
authors.forename: Anita
authors.initials: A
authors.lastname: Thapar
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications* / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000150:complications* / Q000175:diagnosis; D007361:Intelligence Tests; D008137:Longitudinal Studies; D008297:Male; D012044:Regression Analysis
keywords: ADHD; ALSPAC; ASD; Attention deficit hyperactivity disorder; Autism spectrum disorder; Avon Longitudinal Study of Parents and Children; CAPA; CD; CNV; Child and Adolescent Psychiatry Assessment; Conduct disorder; Copy number variant; DSM-III-R; DSM-IV; Diagnostic and Statistical Manual of Mental Disorders, 3rd edition revised; Diagnostic and Statistical Manual of Mental Disorders, 4th edition; ID; Intellectual disability; ODD; Oppositional defiant disorder