Currently diagnosis and assessment of ADHD relies on clinical interview and subjective ratings. Standardized objective cognitive tests can provide additional information about ADHD and help distinguish symptom profiles.
Objective: To assess the cognition of adolescent ADHD subtypes using a standardized cognitive test battery.
Study group: Seventy-two ADHD combined subtype, 58 ADHD predominantly inattentive subtype and 130 age- and sex-matched healthy controls.
Methods: Cognitive differences between ADHD subtypes were examined according to 1. symptom dimensions (inattentive versus hyperactivity/impulsivity scores) and 2. category (ADHDcom vs. ADHDin). We examined whether cognitive performance would discriminate symptom profiles (from each other and from healthy controls), and whether these profiles could predict test performance. All subjects completed the standardized and fully computerized IntegNeuro test battery using a touch-screen protocol. These tests span the domains of sensori-motor, attention, executive function, language and memory, and have robust construct validity compared to traditional paper-and-pencil tests. The results highlighted the consistency with which performance varied across symptom profiles, irrespective of categorical or dimensional definitions. ADHDcom was primarily distinguished from ADHDin by increased errors and response variability in response inhibition and (to a lesser extent) selective attention tasks. Inattentive symptoms were more likely to predict cognitive performance and there is an indication that despite the same criteria, these symptoms may be more severe in the ADHDcom subtype.
Conclusions: These findings highlight the specificity of cognitive deficits, which differentiate ADHD subtypes in adolescence. This study provides consistent evidence that accuracy and response variability in an executive function (response inhibition) task may best distinguish the common ADHD subtypes.