Disrupted functional connectivity of amygdala-based networks in Parkinson's disease patients with severe olfactory dysfunction. (P6.070)

OBJECTIVE: To elucidate the functional amygdala connectivity in Parkinson9s disease (PD) with severe olfactory dysfunction (sOD). BACKGROUND: sOD is predictive features of PD with dementia. However, the pathophysiological mechanisms underlying the relationship between sOD and dementia remain unclear. DESIGN/METHODS: We reviewed the 3T-MRI findings of 30 PD patients without dementia and 15 healthy controls using voxel-based morphometry (VBM), diffusion tensor imaging (DTI) with tract-based spatial statistics (TBSS) and resting state functional MRI scans. Patients with PD were divided into two groups, PD without severe olfactory dysfunction (PD without sOD) group (n = 15) and PD with severe olfactory dysfunction (PD with sOD) group (n = 15), by Odor Stick Identification Test for Japanese (OSIT-J). All patients did not show hallucination and dementia. Functional connectivity of the centromedial, basolateral, and superficial amygdala subdivisions using Juelich probabilistic atlas was compared between groups. RESULTS: PD with sOD showed significant differences compared to HC and PD without sOD in the connectivity of all amygdala subregions. Particularly, disruptions in laterobasal-based intrinsic functional connectivity networks were widely observed in frontal, parietal, and occipital cortex predominantly seen medial part including dorsal anterior and posterior cingulate cortex, precuneus, primary and secondary visual cortex (FDR cluster corrected, p < 0.05). Dual regression analysis using resting state dataset showed significant difference in only a limited number of networks between PD with sOD and control (TFCE p < 0.05). TBSS analysis using DTI dataset and VBM also showed relatively mild changes between PD with sOD and control as compared to result of seed based analysis. PD without sOD had mild to moderate differences in laterobasal and superficial amygdala, but not centromedial. CONCLUSIONS: Disrupted functional connectivity of the amygdala-based networks were extensively observed and can exceed atrophy and principal microstructural changes assessed by TBSS in PD with sOD. Study Supported by: none Disclosure: Dr. Watanabe has nothing to disclose. Dr. Epifanio has nothing to disclose. Dr. Yoneyama has nothing to disclose. Dr. Hara has nothing to disclose. Dr. Kawabata has nothing to disclose. Dr. Imai has nothing to disclose. Dr. hirayama has nothing to disclose. Dr. Tsuboi has nothing to disclose. Dr. Sobue has received personal compensation for activities with Novartis and CSL Behring as a committee member and/or consultant.