LATENT CLASS AND FACTOR-ANALYSIS OF DSM-IV ADHD - A TWIN STUDY OF FEMALE ADOLESCENTS

Objective: In an attempt to validate the current DSM-IV criteria for a ttention-deficit/hyperactivity disorder (ADHD) in females and to deter mine whether symptoms are continuously distributed or categorically di screte, the authors performed factor and latent class analysis on ADHD symptom data from a large general population of adolescent female twi ns (1,629 pairs). Method: A structured diagnostic assessment of DSM-IV ADHD was completed with at least one parent of 1,629 pairs by telepho ne. ADHD symptoms from 1,549 pairs were subjected to latent class and factor analysis. Results: Latent class and factor analyses were consis tent with the presence of separate continuous domains of inattention ( ATT), hyperactivity-impulsivity (H-I), and combined ATT with H-I probl ems. Severe latent classes corresponding to the predominantly inattent ive, predominantly hyperactive-impulsive, and combined types were iden tified with lifetime prevalence estimates of 4.0%, 2.2%, and 3.7%, res pectively. Membership in the severe ATT class predicted academic probl ems, family problems, and referral to health care providers. Membershi p in the H-I and combined classes also predicted impaired social relat ionships. Conclusions: These results suggest that DSM-IV ADHD subtypes can be thought of as existing on separate continua of inattention, hy peractivity-impulsivity. and combined type problems. Membership in any of the three severe ADHD latent classes did not preclude academic exc ellence, but ii, was associated with different types of impairment and health care-seeking behavior. These data have implications in the are as of diagnosis, classification, treatment, and research.