Gray matter structural and functional brain abnormalities in Parkinson's disease: a meta-analysis of VBM and ALFF data.

Background: Previous studies based on resting-state functional imaging and voxel-based morphometry (VBM) have revealed structural and functional alterations in several brain regions in patients with Parkinson's disease (PD), but their results have been inconsistent. Furthermore, no studies have investigated specific and common functional and structural alterations in PD.

Methods: The whole-brain voxel-wise meta-analyses on the VBM and amplitude of low-frequency fluctuation (ALFF) studies were conducted using the Seed-based d Mapping with Permutation of Subject Images (SDM-PSI) software, respectively, with multimodal overlapping to comprehensively identify the gray matter volume (GMV) and spontaneous functional activity changes in patients with PD.

Results: A total of 30 independent studies for ALFF (1413 PD and 1424 HCs) and 27 independent studies for VBM (1236 PD and 1185 HCs) were included. Compared with HCs, patients with PD displayed significantly decreased spontaneous functional activity in the left striatum. For the VBM meta-analysis, patients with PD showed significantly decreased GMV in the right temporal pole: superior temporal gyrus (extending to the right hippocampus, parahippocampal gyrus, and amygdala), the left superior temporal gyrus (extending to the left insula, and temporal pole: superior temporal gyrus), and the left striatum. Furthermore, after overlapping functional and structural differences, patients with PD displayed a conjoint decrease of spontaneous functional activity and GMV in the left striatum.

Conclusions: The multimodal meta-analysis revealed that PD showed similar pattern of aberrant brain functional activity and structure in the striatum. In addition, some brain regions within the within the temporal lobe and limbic system displayed only structural deficits. These findings provide useful insights for understanding the underlying pathophysiology of PD.