MCI-LB brain networks reorganization in relation to specific cognitive domains deficits

To tackle the disease-related process in early pre-dementia Lewy Body Dementia, we investigated the changes of functional brain networks and their cognitive relevance. A cohort of 38 Mild Cognitive Impairment with Lewy Bodies (MCI-LB) subjects and one of 24 healthy controls (HC) underwent neuropsychological assessment and resting state (RS) functional and structural MRI. Functional connectivity (FC) between ROIs belonging to a set of RS networks, including the Salience Network (SN), Fronto-Parietal (FPN), Default Mode (DMN), Dorsal and Ventral Attention (DAN and VAN), Somato-Motor (SMN), Visual (VN) and Language (LN) was estimated and compared between cohorts. Finally, neuropsychological scores were correlated with FC of MCI-LB and HC separately. Compared to HC, MCI-LB exhibited lower FC between DAN, FPN and LN. Higher inter-network FC was found between FPN and SN, FPN and DMN, SN and SMN and DAN and SMN. In MCI-LB the correlational analysis revealed significant positive and negative associations between cognitive performance and FC values between nodes. In conclusion, we found a possible compensation mechanism between nodes in SN and FPN, and FPN and DMN following disconnection between the control system of the FPN and the top down attention system. The complex compensatory mechanisms involving multiple networks may not be efficient to counteract the cognitive impairment in MCI-LB. Overall, in MCI-LB we found an aberrant engagement of the networks that are not primarily involved in the performance of specific tasks.