title: Attention-deficit/hyperactivity disorder symptom expression: a comparison of individual age at onset using item response theory.
abstract: BACKGROUND
  The DSM-IV age at onset criterion for attention-deficit/hyperactivity disorder (ADHD) has been a subject of debate. In DSM-5, the required age at onset (ie, the age by which impairing symptoms must have been present) has increased from 7 years to 12 years. The present study examined measurement properties of ADHD symptoms according to age at onset.
  
  
  METHODS
  Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions, which included 34,653 US participants. Among participants with a lifetime DSM-IV diagnosis of ADHD (assessed using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV), we compared the psychometric properties of the 18 ADHD symptoms according to 3 categories of age at onset (≤ 7 years, > 7 and ≤ 12 years, and > 12 and ≤ 18 years). A 2-parameter item response model was used to estimate differential item functioning (DIF) between these groups.
  
  
  RESULTS
  364 participants with a lifetime DSM-IV diagnosis of ADHD had an age at onset ≤ 7 years, 252 had an age at onset > 7 and ≤ 12 years, and 148 had an age at onset > 12 and ≤ 18 years. In both dimensions of ADHD (ie, inattention and hyperactivity-impulsivity), there was no significant DIF between age at onset groups.
  
  
  CONCLUSIONS
  Expression of DSM-IVADHD symptoms was not affected by age at onset in the 3 groups considered. This study provides psychometric support to the change in the age criterion introduced by DSM-5 and further suggests that the age at onset criterion could be extended to 18 years without changing the psychometric properties of the ADHD symptoms.
authors.affiliation: Laboratoire de Sciences Cognitives et Psycholinguistique, Département d'Etudes Cognitives, Ecole Normale Supérieure, 29 rue d'Ulm, 75005 Paris, France peyrehugo@yahoo.fr.
authors.forename: Hugo
authors.initials: H
authors.lastname: Peyre
authors.forename: Nicolas
authors.initials: N
authors.lastname: Hoertel
authors.forename: Samuele
authors.initials: S
authors.lastname: Cortese
authors.forename: Eric
authors.initials: E
authors.lastname: Acquaviva
authors.forename: Pierre
authors.initials: P
authors.lastname: De Maricourt
authors.forename: Frédéric
authors.initials: F
authors.lastname: Limosin
authors.forename: Richard
authors.initials: R
authors.lastname: Delorme
mesh_terms: D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000523:psychology; D002648:Child; D005163:Factor Analysis, Statistical; D006801:Humans; D007406:Interview, Psychological; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics