Objective: Determine whole brain functional connectivity changes in Parkinson’s disease (PD) with mild Cognitive Impairment (MCI), using bootstrap analysis of stable cluster (BASC) method to select region of interest (ROI) in the brain.

Background: Several studies published to investigate the change of connectivity in PD without MCI (PD-NMCI) and PD-MCI. However, the results varied. This may attribute to the number and location of ROIs.

Methods: Thirty-two non-demented patients with PD and twenty-five aged healthy volunteers (HV) were recruited. They underwent neuropsychological assessment and functional MRI during resting state. The patients were divided into 15 PD-NMCI and 17 PD-MCI. There were no significant differences in age between the groups except for HV being older than PD nonMCI (p=0.02). Applying BASC methods, ROIs were selected in a data-driven manner forming seven different resolutions. The strength of the connectivity between all the ROIs were compared across groups.

Results: Compared with HV, PD-MCI showed increased connectivity, but this didn’t survive after age was covaried-out. Compared with HV, PD-MCI showed decreased connectivity only when age was covaried-out. These results depended on the resolution. In contrast, strong differences was observed between PD-NMCI and PD-MCI with and without age covaried-out. More than 11% of all the connectivity showed significant difference in all resolutions. Significant decreased functional connectivity was observed between the frontal and posterior part of the medial cortices as well as the lateral prefrontal cortex (PFC), and the orbitofrontal, occipital, insular cortices, caudate, putamen, ventral striatum, hippocampus, and thalamus in PD-MCI. Similarly, significant decreased connectivity was observed between the motor cortex and the medial cortices, the lateral PFC and the premotor cortex, and also between the occipital regions and the PFC and parietal cortex. The cerebellum showed increased connectivity with the caudate, hippocampus, and parahipocampal gyrus in PD-MCI.

Conclusions: We reliably observed decrease of coritico-coritcal and coritco-subcortical connectivity, and increase of subcortico-cerebellum connectivity in PD-MCI. Nevertheless, change between HV and PD-MCI was less stable. We speculate that PD-NMCI may have compensating mechanism in brain connectivity, and that this mechanism is weakened in PD-MCI.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/functional-connectivity-during-resting-state-in-parkinsons-disease-patients-with-and-without-mild-cognitive-impairment/