Comprehensive Summary
This study investigates the role of the human cerebellum in multiple dimensions of impulsivity, particularly in individuals with cerebellar ataxia (CA). Using a large, cross-sectional study, trait impulsivity was assessed via the Barratt Impulsiveness Scale (BIS-11), and behavioral impulsivity through a delay discounting (DD) task. This study compared individuals with CA to matched neurotypical healthy (NH) controls. The results showed that CA participants demonstrated significantly lower discounting rates across all reward magnitudes, indicating greater future-oriented decision-making. Machine learning models using impulsivity features alone were able to classify CA vs. NH participants with high accuracy (up to 83%), supporting the robustness of impulsivity differences as a distinguishing feature of CA. Additionally, longer disease duration was associated with reduced decision-making impulsivity, but neither impulsivity measure correlated with cognitive status or ataxia severity. These findings suggest that impulsivity in CA is not globally elevated, but selectively altered. The cerebellum’s involvement in non-motor functions, like planning and decision-making, supports its emerging role in broader neurocognitive networks.
Outcomes and Implications
This research is important because it challenges the traditional view that cerebellar ataxia is solely a motor disorder by identifying impulsivity as a distinct and measurable non-motor feature. Clinically, these findings highlight the need for comprehensive neuropsychological assessments in patients with CA, beyond motor symptoms, to detect subtle cognitive-affective changes that may affect daily functioning. The high classification accuracy of impulsivity profiles also suggests the potential utility in diagnostic support or disease monitoring tools. While the immediate clinical implementation is limited, this work lays a foundation for future interventions targeting cognitive compensation and behavioral adaptation in cerebellar disorders.