Psychostimulant effects on motor and cognitive function in adults attention deficit hyperactivity disorder

This study aims to compare the performance on motor and cognitive functions of adult patients with attention deficit hyperactivity disorder (ADHD) with or without psychostimulant medication and controls. A secondary objective is to investigate differences on test performance across varying levels of disorder severity.

We included patients with unmedicated ADHD (U-ADHD) (n = 52), patients with ADHD treated with psychostimulants (n = 40), and controls (n = 80). A multimodal set of motor and cognitive tests was administered to evaluate cerebellar and motor functions, attention and processing speed, executive functions, visuospatial perception, and visuospatial abilities.

Both patient groups performed significantly worse than controls across all functions. No significant performance differences were observed between the medicated and U-ADHD groups when disorder severity was not considered. However, some differences emerged when stratified by disorder severity. Patients with moderate to severe U-ADHD showed more impairments in sensorimotor functions compared to the medicated ADHD (M-ADHD), while those with mild U-ADHD displayed lower scores on visuospatial perception compared to M-ADHD. Regression analysis indicated that education, anxiety, and sleep disturbances minimally affect test performance.

In summary, psychostimulant medication did not show consistent overall differences in motor and cognitive performance among adults with ADHD. Importantly, when stratifying by disorder severity, some group-level differences emerged, underscoring the need to account for disorder severity in future research and clinical assessment.