Objective: We investigated the pattern of resting state functional connectivity in patients with PD according to olfactory performance to elucidate olfactory-dependent cortical-subcortical functional networks.

Background: Olfactory dysfunction is a salient non-motor feature of Parkinson’s disease (PD), occurring in at least 90% of PD patients. Olfactory dysfunction is associated with poorer performance on verbal memory and frontal executive tasks, and that diminished olfactory performance in the early stages of PD is associated with an increased risk of ongoing cognitive decline. In the present study, we hypothesized that olfactory performance as a predictor of cognitive impairment influences the functional connectivity within key brain areas of patients with PD.

Methods: A total of 110 non-demented drug-naïve patients with PD were subdivided into three groups of high score (PD-H, n=23), middle score (PD-M, n=64), and low score (PD-L, n=23) based on olfactory performance. We performed the resting-state functional connectivity with seed region of interest in the posterior cingulate cortex (PCC) and caudate.

Results: An analysis of functional connectivity revealed that PD-L patients exhibited a significant attenuation of cortical functional connectivity with the PCC in the bilateral primary sensory areas, right frontal areas, and right parietal areas compared to PD-H or PD-M patients. Meanwhile, PD-L patients exhibited a significant enhancement of striato-cortical functional connectivity in the bilateral occipital areas and right frontal areas compared to PD-H or PD-M patients. In the voxel-wise correlation analysis, olfactory performance was positively associated with cortical functional connectivity with the PCC in similar areas of attenuated cortical connectivity in PD-L patients relative to PD-H patients. On the other hand, the cortical functional connectivity with the caudate was negatively correlated with olfactory performance in similar areas of increased connectivity in PD-L patients relative to PD-H patients.

Conclusions: The present study demonstrated that resting state functional connectivity exhibits a distinctive pattern depending on olfactory performance, which might shed light on a meaningful relationship between olfactory impairment and cognitive dysfunction in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/olfactory-performance-and-resting-state-functional-connectivity-in-non-demented-drug-nave-patients-with-parkinsons-disease/