Interrelationships of inattention, hyperactivity, and impulsivity in children
Two related questions were examined in this study. First, is the factor structure of ADHD unidimensional? Second, is there evidence of a developmental subtype progression in ADHD? The favored unidimensional conceptualization of the disorder advocated discontinued use of the subtypes and continuous measurement of the core symptoms (inattention, hyperactivity, impulsivity). The unidimensional conceptualization was theoretically driven by Barkley's Inhibitory Deficit Hypothesis which posits that ADHD is the result of a unitary deficit of inhibition (thoughts, actions, impulses) stemming from frontal lobe dysfunction. Two archival data sets, the MTA Study (MTA Cooperative Group, 1999) and DSM-IV Field Trials (Lahey et al. 1994) were separately assessed in order to examine the questions of interest. For the first question it was predicted that structural equation models comparing bi-dimensional models of core symptoms against unidimensional models would favor the latter. The reasoning was that if unidimensional models provided a viable fit and hyperactivity was included in each model, it could be surmised that the core symptoms are interrelated and therefore appropriate for a unidimensional conceptualization. Inattention/Hyperactivity, Hyperactivity/Impulsivity, and Inattention/Hyperactivity/Impulsivity (all symptoms) models were assessed. Initially, Aggregated Models utilizing both parent and teacher informants were utilized but only one of the models was acceptable which suggested that separate exploration of model fit for each informant was worth exploring. Parent and Teacher Models were assessed for each data set. In summary it was found that parent and teacher perspectives may differ. It was found that parents are more likely to favor a unidimensional model of the disorder and may view the core symptoms as more interrelated than teachers do. Significant correlations between the core symptoms were also a consistent finding. For the second question the DSM-IV Field Trials data set was used to assess the impact that a Preschool status variable and an Inattention variable has on the diagnosis of the Hyperactive/Impulsive subtype of ADHD in a regression model. A Parent and Teacher Model were assessed separately. It was found that, all other things being equal being a preschool had a significant impact on attaining this diagnosis. ^
"Interrelationships of inattention, hyperactivity, and impulsivity in children"
(January 1, 2007).
ETD Collection for Fordham University.