Neuropsychological performance in DSM-IV ADHD subtypes: An exploratory study with untreated adolescents

Objective: To explore neuropsychological performance in untreated Brazilian adolescents suffering from attention-deficit hyperactivity disorder (ADHD). Method: We assessed 30 untreated adolescents with ADHD and 60 healthy control subjects, aged 12 to 16 years, using a neuropsychological battery including the Wisconsin Card-Sorting Test (WCST), the Stroop Test (ST), the Digit Span, and the Word Span. Results: We found neuropsychological differences among the DSM-IV ADHD subtypes. Adolescents with the predominantly inattentive subtype (ADHD-I) performed more poorly than did control subjects on both the Digit Span and the ST. On both the Digit Span and the WCST, adolescents with the combined subtype (ADHD-C) presented significantly more impairments than did control subjects. Adolescents with the predominantly hyperactive-impulsive type (ADHD-HI) did not differ significantly from the control subjects in any measure assessed, but had a better performance than did those with ADHD-C on both the Digit Span and the WCST. In addition, adolescents with ADHD-HI performed better on the ST than did adolescents with ADHD-I. Conclusions: These findings suggest cognitive differences among ADHD subtypes, supporting the diagnostic distinction among them. Adolescents with ADHD-HI do not seem to have significant cognitive deficits.