Cognitive impairment and resting-state network connectivity in Parkinson's disease

Abstract

Previous functional MRI studies have revealed changes in the default-mode network (DMN) in Parkinson's disease (PD). The purpose of this work was to evaluate changes in the connectivity patterns of a set of cognitively relevant, dynamically interrelated brain networks in association with cognitive deficits in PD using resting-state functional MRI. Sixty-five non-demented PD patients and 36 matched healthy controls (HC) were included. Thirty-four percent of PD patients were classified as having mild cognitive impairment (MCI) based on performance in the three mainly-affected cognitive domains in Parkinson's disease (attention/executive, visuospatial/visuoperceptual and declarative memory). Data-driven analyses through independent-component analysis (ICA) was used to identify the DMN, the dorsal attention network (DAN) and the bilateral frontoparietal networks (FPN), which were compared between groups using a dual-regression approach. Additional seed-based analyses using a-priori defined regions of interest were used to characterize local changes in intra and inter-network connectivity. ICA results revealed reduced connectivity between the DAN and right frontoinsular cortical regions in MCI patients, which correlated with worse performance in attention/executive functions. The DMN, on the other hand, displayed increased connectivity with medial and lateral occipito-parietal regions in MCI patients; these increases correlated with worse visuospatial/visuoperceptual performance. In line with data-driven results, seed-based analyses mainly revealed reduced within-DAN, within-DMN and DAN-FPN connectivity, as well as increased DAN-DMN coupling in MCI patients. Our findings demonstrate differential connectivity changes affecting the networks evaluated, which we hypothesize to be related to the pathophysiological bases of different types of cognitive impairment in PD.