Alterations in cortical sulcal morphology in Parkinson's disease patients with impulse control disorders

Impulse control disorders, debilitating non-motor complications of Parkinson's disease, are linked to dopaminergic therapy and mesocorticolimbic dysfunction. This study aimed to characterize cortical sulcal depth, a sensitive morphometric index of cortical folding, and cortical thickness and subcortical volumetric alterations in Parkinson's disease patients with impulse control disorders. Sixty-eight Parkinson's disease patients (30 with impulse control disorders, 38 without impulse control disorders) and 32 healthy controls were enrolled. Regional sulcal depth, cortical thickness, and subcortical volumes were computed using FreeSurfer. Group differences were assessed, along with their associations with symptom severity and diagnostic utility. Patients with impulse control disorders exhibited significantly reduced sulcal depth in the right frontal pole and left middle temporal gyrus compared to those without impulse control disorders and healthy controls, while no significant differences in cortical thickness and subcortical volumes were observed among the groups. Within the impulse control disorders group, reduced sulcal depth in the right frontal pole correlated negatively with symptom severity. Receiver operating characteristic analysis demonstrated that sulcal depth in the right frontal pole and left middle temporal gyrus effectively discriminated Parkinson's disease patients with impulse control disorders from those without, with the combined model achieving superior discrimination. This study identifies distinct cortical sulcal morphology alterations, specifically reduced sulcal depth in the right frontal pole and left middle temporal gyrus, in Parkinson's disease patients with impulse control disorders. Sulcal depth metrics show promise as structural biomarkers for impulse control disorders in Parkinson's disease.