Objective: This study examines one-, two-, and three-factor models of attention-deficit/hyperactivity disorder (ADHD) using the existing 18 Diagnostic and Statistical Manual of Mental Disorder, 4th edition (DSM-IV) symptoms in a sample of symptomatic preschoolers.
Methods: Parent and/or teacher ratings of DSM-IV symptoms were obtained for 532 children (aged 3–5.5) who were screened for the Preschool ADHD Treatment Study (PATS). Confirmatory factor analysis (CFA) using symptoms identified on the Conners' Parent and Teacher Rating Scales was conducted to assess a two-factor model representing the DSM-IV dimensions of inattention (IN) and hyperactivity/impulsivity (H/I), a three-factor model reflecting inattention, hyperactivity, and impulsivity, and a single-factor model of all ADHD symptoms. Exploratory factor analysis (EFA) was subsequently used to examine the latent structure of the data.
Results: For parent ratings, the two-factor and three-factor models were marginally acceptable according to several widely used fit indices, whereas the one-factor model failed to meet minimum thresholds for goodness-of-fit. For teachers, none of the models was a solid fit for the data. Maximum likelihood EFAs resulted in satisfactory two- and three-factor models for both parents and teachers, although all models contained several moderate cross loadings. Factor both parents and teachers, although all models contained several moderate cross loadings. Factor loadings were generally concordant with those published for older children and community-based samples.
Conclusion: ADHD subtypes according to current DSM-IV specifications may not be the best descriptors of the disorder in the preschool age group.
