title: Comorbidity in ADHD: implications for research, practice, and DSM-V.
abstract: OBJECTIVE
  Since the introduction of DSM-III/III-R, clinicians and investigators have shown increasing interest in the study of conditions comorbid with attention-deficit hyperactivity disorder (ADHD). Better understanding ADHD comorbidity patterns is needed to guide treatment, research and future classification approaches.
  
  
  METHODS
  The ADHD literature from the past 15 years was reviewed to (1) explore the most prevalent patterns of ADHD comorbidity; (2) examine the correlates and longitudinal predictors of comorbidity; and (3) determine the extent to which comorbid patterns convey unique information concerning ADHD etiology, treatment and outcomes. To identify potential new syndromes, the authors examined comorbid patterns based on eight validational criteria.
  
  
  RESULTS
  The largest available body of literature concerned the comorbidity with ADHD and conduct disorder/aggression, with a substantially smaller amount of data concerning other comorbid conditions. In many areas the literature was sparse, and pertinent questions concerning comorbidity patterns remain unexplored. Nonetheless available data warrant the delineation of two new subclassifications of ADHD: (1) ADHD aggressive subtype, and (2) ADHD, anxious subtype.
  
  
  CONCLUSIONS
  Additional studies of the frequency of comorbidity and associated factors are greatly needed to include studies of differential effects of treatment of children with various comorbid ADHD disorders, as well as of ADHD children who differ on etiological factors.
authors.affiliation: Child and Adolescent Disorders Research Branch, NIMH, Rockville, MD 20857, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Jensen
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.forename: D P
authors.initials: DP
authors.lastname: Cantwell
mesh_terms: D000374:Aggression; D001007:Anxiety / Q000453:epidemiology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000145:classification / Q000453:epidemiology; D002648:Child; D002653:Child Behavior Disorders / Q000453:epidemiology; D015897:Comorbidity; D006801:Humans; D007859:Learning Disabilities / Q000453:epidemiology; D008370:Manuals as Topic / Q000592:standards*; D015995:Prevalence; D009626:Terminology as Topic