Supplementary Material for: Precuneal Thickness and Depression in Parkinson Disease

Background: Depression-related gray matter changes in Parkinson disease (PD) patients have been reported, although studies investigating cortical thickness in early-stage disease are lacking. Objective: We aimed to evaluate cortical changes related to depression in early-stage PD patients with an extensive neuropsychological evaluation. Methods: 17 PD patients and 22 healthy controls underwent a 1.5-T brain MR protocol, and voxel-wise differences in cortical thickness among patients with (n = 6) and without (n = 11) depression and controls were evaluated using FreeSurfer software. Results: Cortical thickness was increased in the precuneus bilaterally in PD patients with depression compared to the other groups (number of vertices >100; p < 0.001, uncorrected) with a direct correlation with the Beck Depression Inventory score (p < 0.001, uncorrected). Conclusion: Precuneal cortical thickening is evident in PD patients with mild-moderate depression even in the early stages of the disease. This finding may reflect the early involvement of this region in the development of PD-related depression.