Abnormal resting‐state functional connectivity in posterior cingulate cortex of Parkinson's disease with mild cognitive impairment and dementia

Summary Objective To investigate changes in the functional connectivity ( FC ) pattern in the posterior cingulate cortex ( PCC ) of Parkinson's disease ( PD ) patients with mild cognitive impairment and dementia by employing resting‐state functional magnetic resonance imaging ( RS ‐ fMRI ). Methods Twenty‐seven PD patients with different cognitive status and 9 healthy control subjects (control group) were enrolled for RS ‐ fMRI . The RS ‐ fMRI data were analyzed with DPARSF and REST software. Regions with changed functional connectivity were determined by the seed‐based voxelwise method and compared between groups. Correlation between the intensity of FC and the Mo CA scores of PD group was analyzed. Results Parametric maps showed statistical increases in PCC functional connectivity in PD ‐ MCI patients and decreases in PCC connectivity in PDD patients. The latter group of patients also showed evidence for increased connectivity between prefrontal cortices and posterior cerebellum. A significant positive correlation was found between the Mo CA scores and the strength of PCC connectivity in the angular gyrus and posterior cerebellum and a negative correlation between Mo CA scores and PCC connectivity in all other brain regions. Conclusion When patients transition from PD ‐ NCI to PD ‐ MCI , there appears to be an increase in functional connectivity in the PCC , suggesting an expansion of the cortical network. Another new network (a compensatory prefrontal cortical‐cerebellar loop) later develops during the transition from PD ‐ MCI to PDD .