Cognitive heterogeneity in Attention Deficit Hyperactivity Disorder: Implications for maths.

This study investigated whether cognitive function better predicted maths test performance than a clinical diagnosis of attention deficit hyperactivity disorder (ADHD). Forty-four drug naïve children (M age  = 101.34 months, SD = 19.39; 30% girls) were recruited from clinical ADHD referral waiting lists. Children underwent assessment of Executive Functions (EF), lower-level cognitive processes, and maths performance. Children were grouped using a categorical approach comprising (1) children with a clinical ADHD diagnosis and (2) children without a diagnosis (i.e., subthreshold ADHD). Secondly, hierarchical cluster analysis generated subgroups of children using EF scores. Children were compared on cognition, maths, and parent-rated symptoms of ADHD and co-occurring difficulties. Children's diagnostic outcomes did not differentiate maths performance. By contrast, EF subgroups generated meaningful cognitive clusters which differentiated maths test scores. This suggests that cognitive patterns of performance, rather than children's diagnostic outcomes, are more informative for identifying meaningful groups with variable maths performance which has implications for remedial support.