Supplementary Material for: Precuneal Thickness and Depression in Parkinson Disease

<b><i>Background:</i></b> Depression-related gray matter changes in Parkinson disease (PD) patients have been reported, although studies investigating cortical thickness in early-stage disease are lacking. <b><i>Objective:</i></b> We aimed to evaluate cortical changes related to depression in early-stage PD patients with an extensive neuropsychological evaluation. <b><i>Methods:</i></b> 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 (<i>n</i> = 6) and without (<i>n</i> = 11) depression and controls were evaluated using FreeSurfer software. <b><i>Results:</i></b> Cortical thickness was increased in the precuneus bilaterally in PD patients with depression compared to the other groups (number of vertices &gt;100; <i>p</i> &lt; 0.001, uncorrected) with a direct correlation with the Beck Depression Inventory score (<i>p</i> &lt; 0.001, uncorrected). <b><i>Conclusion:</i></b> 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.