Disrupted Resting-state Functional Connectivity of the Nucleus Basalis of Meynert in Parkinson's Disease with Mild Cognitive Impairment.

The basal nucleus of Meynert (BNM) shows structural abnormalities in Parkinson's disease with mild cognitive impairment (PD-MCI). However, it is yet unknown whether functional connectivity (FC) in the BNM (BNM-FC) is altered in patients with PD-MCI. Therefore, in this study, we compared the BNM-FC of patients with PD-MCI and PD patients with normal cognition (PD-NC), to evaluate the relationship between the observed differences of BNM-FC and neuropsychological test scores. Three patient groups, namely PD-MCI, PD-NC, and healthy controls (HCs) (n = 22 each) including were recruited for functional magnetic resonance imaging (fMRI) scanning and neuropsychological assessment. Analysis of covariance was used to assess the inter-group differences. The relationships between BNM-FC and results of cognitive tests were evaluated by partial correlation analysis. Multivariate pattern analysis was used to test whether PD-MCI can be distinguished from PD-NC based on the BNM-FC. Classifier performance was assessed through permutation testing. Compared to PD-NC and HCs, PD-MCI showed reduced BNM-FC in the right superior parietal lobe (SPL) and the right postcentral gyrus. Furthermore, a positive correlation was observed between BNM-FC and the clock copying test (CLOX)/auditory verbal learning test (AVLT) immediate recall scores. We found that 86.36% subjects were correctly classified based on the BNM-FC using the leave-one-out cross-validation (LOOCV) method, with a sensitivity of 90.91% and specificity of 81.82%. Our study provides new insights into the neural basis of cognitive dysfunction in PD patients. We also found that BNM-FC can be an effective feature to distinguish PD-MCI from PD-NC.