We aimed to perform a combined analysis of cortical thickness and functional connectivity to explore their association with cognitive impairment in Parkinson's disease (PD). A total of 53 PD and 15 healthy control subjects were enrolled. PD patients were divided into PD with normal cognition (PD-NC, n = 25), PD with mild cognitive impairment (PD-MCI, n = 11), and PD with dementia (PDD, n = 17). Cognitive status was assessed with the Mini-Mental State Examination (MMSE). Anatomical magnetic resonance imaging and resting-state functional connectivity analysis were performed in all subjects. First, surface-based morphometry measurements of cortical thickness and voxels with cortical thickness reduction were detected. Then, regions showing reduced thickness were analyzed for changes in resting-state functional connectivity in PD involving cognitive impairment (PD-MCI and PDD groups together). Our results showed that, compared with PD-NC, patients with cognitive impairment showed decreased cortical thickness in the left superior temporal, left lingual, right insula, and right fusiform regions. PD-MCI patients showed these alterations in the right lingual region. Widespread cortical thinning was detected in PDD subjects, including the left superior temporal, left fusiform, right insula, and right fusiform areas. We found that cortical thinning in the left superior temporal, left fusiform, and right temporal pole regions positively correlated with MMSE score. In the resting-state functional connectivity analysis, we found a decrease in functional connectivity between the cortical atrophic brain areas mentioned above and cognition-related brain networks, as well as an increase in functional connectivity between those region and the cerebellum. Alterations in cortical thickness may result in a dysfunction of resting-state functional connectivity, contributing to cognitive decline in patients with PD.voxel-based morphometry for the identi cation of regional cortical thinning associated with PD (Pereira et al., 2012). Previous work found regional thinning in left temporal-occipital and right parietal-frontal areas in PD patients with cognitive disorder compared to patients without it (Pagonabarraga et al., 2013), while another study did not nd this difference (Pereira et al., 2014).Recently, several studies have examined so-called 'resting state' networks (Schindlbeck & Eidelberg, 2018;Wu & Hallett, 2013). Resting state networks are characterized by organized basal activity during rest or passive visual xation and by low-frequency signal uctuations. Analysis of these resting state networks suggest the existence of an underlying structural core of functional connectivity (FC) networks in the human brain (van den Heuvel & Hulshoff Pol, 2010).
