Resting-State Network Connectivity in Newly Diagnosed Drug-Naïve Parkinson’s Disease Patients With Mild Cognitive Impairment

Background: Cognitive impairment (CI) is one of the most frequent non-motor features in Parkinson's disease (PD). The frequency of mild cognitive impairment (MCI) was reported to exceed 40% in a large cohort of newly diagnosed PD patients. Method: Resting-state functional MRI (rs-fMRI) data was collected in 47 newly diagnosed drug-naïve PD patients (including 28 PD patients with MCI (PD-MCI subgroup) and 19 PD patients with cognitively unimpaired (PD-CU subgroup)) and 28 age- and sex-matched healthy controls (HCs). Independent component analysis (ICA) can decompose rs-fMRI data into resting state networks (RSNs). Brain intra- and inter-network alterations were investigated in RSNs among PD-MCI, PD-CU, and HCs groups. Results: Seven large-scale brain networks were extracted. The default mode network (DMN), visual network (VN) and sensorimotor network (SMN) were selectively vulnerable in the PD-MCI subgroup relative to the HC group. In PD-MCI patients, the reduced functional connectivity (FC) within the DMN was positively correlated with brief visuospatial memory test-revised (BVMT-R) scores (memory function); the reduced FC within the VN was positively correlated with clock copying test (CCT) scores (visuospatial function). In whole PD patients, the reduced FC within the SMN was negatively correlated with the Unified PD Rating Scale (UPDRS) part III scores. Moreover, FC between the SMN and limbic network, and between the ventral attention network (VAN) and VN were more prone to be damaged in PD patients. Conclusions: The DMN, VN and SMN were disrupted in PD-MCI patients. FC between the SMN and limbic network, and between the VAN and VN were also impaired in PD patients. The impaired intra- and inter-connectivity could provide further insights into the pathophysiological alterations of brain connectivity in newly diagnosed drug-naïve PD.