Grey matter loss across deteriorating cognitive stages in Parkinson’s disease

The purpose of the present study was to depict the pattern of grey matter (GM) abnormalities in patients with Parkinson's disease (PD) and various stages of cognitive decline. GM changes were investigated with the use of voxel-based morphometry in three age-matched groups consisted of PD patients with normal cognition (PD-NC, n = 20), mild cognitive impairment (PD-MCI, n = 20) and dementia (PDD, n = 21). The Parkinson's disease-cognitive rating scale (PD-CRS) was used for the neuropsychological assessment of the subjects and to define patient groups. GM atrophy was observed in the PD-MCI group in right middle and inferior temporal gyri and in the PDD group in right thalamus and hippocampus both compared to PD-NC group. Regression analyses retrieved significant associations among total, cortical, and subcortical PD-CRS scores and GM volume in multiple areas, with an exceptionally stable finding being the correlation of striatal atrophy with deteriorating cognitive function. Significant associations were also observed between GM volume in specific regions and the performance of patients in particular PD-CRS items. The study findings reveal a central role of striatal atrophy in the PD-related cognitive decline. Degenerative changes in temporal regions could contribute to MCI, while hippocampal and thalamic atrophy are proposed to accompany the transition to dementia.