Differentiation of attention-deficit/hyperactivity disorder subtypes: application of a neuropsychological model of...

This study represents a neuropsychological attempt to differentiate subtypes of Attention Deficit/Hyperactivity Disorder (ADHD). Participants (N = 80) were grouped by gender and ADHD subtype-Predominantly Inattentive (ADHD-I) versus Combined (ADHD-C)-resulting in four age-matched groups. Statistical analysis revealed significant differences in performance on selective attention tasks for those with ADHD-I and those with ADHD-C. Relative to their counterparts without hyperactivity, participants with ADHD-C earned disproportionately lower scores on tasks associated with executive control. Both subgroups with ADHD-I and ADHD-C demonstrated significant difficulty on some tasks assessing complex mental operations relative to age-standardized normative data. Discriminant analysis revealed that a combination of five neuropsychological measures discriminated between the ADHD-I and ADHD-C subgroups with 80% accuracy. Results provide support for the notion of the Predominantly Inattentive and Combined subtype classifications as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (American Psychiatric Association, 1994). Further, findings from this study lend preliminary support for the utility of a neurophysiologically sensitive model of attention in the differentiation of these subtypes.