Hippocampal Functional Connectivity in Parkinson’s Disease

<b><i>Background:</i></b> While the hippocampus is not part of the nigrostriatal dopaminergic pathway, influence of Parkinson’s disease (PD) on the hippocampus has been consistently implicated. However, it is not clear how the hippocampal changes contribute to the pathology of PD. <b><i>Objectives:</i></b> We aimed to elucidate the physiological changes of the hippocampus in its orchestration with the rest of the brain. <b><i>Methods:</i></b> Using the resting-state fMRI data from Parkinson’s Progression Markers Initiative (PPMI), functional connectivity of the hippocampus was analyzed in 93 individuals with PD and 18 individuals without PD. <b><i>Results:</i></b> A whole brain voxel-wise analysis showed that the bilateral paracingulate gyri were less connected to the hippocampus in the PD group compared to the control group. The hippocampus-paracingulate dysconnectivity did not show association with cognitive indices. <b><i>Conclusions:</i></b> The hippocampus in PD shows dysconnectivity to the paracingulate gyri.