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

Abstract

Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.