Objective: To examine direct interhemispheric functional connectivity (FCi) in Parkinson’s disease (PD) during resting-state fMRI and to investigate the relations between observed connectivity changes and performance on clinical features.

Background: FCi, important for a variety of functions has typically been seen to be unaffected in PD as anatomically connectivity is typically intact. Recent studies have challenged that view, and suggested that tremor and PIGD subtypes may be differentiated based on FCi patterns[1].

Methods:  We performed both exploratory and hypothesis driven analyses on FCi patterns derived from resting state fMRI from 50 subjects (PD=26, N=24). We jointly examined instantaneous correlations as well as lag1 correlations between the two hemispheres in 28 pairs of homologous regions.

Results: With the data-driven approach, Principal Component Analysis (PCA) was performed on the FCi correlation values. The PCs that discriminated between PD and controls had prominent interhemispheric connections (Fig.1). In a hypothesis driven approach, we determined if interhemispheric connectivity predicted clinical indices. FCi values accurately predicted disease duration but not cognitive performances on the MMSE. Significant gender differences were found in FCi that interacted with PD status. Smell detection was predicted with FCi with similar patterns between PD and controls. FCi predicted smoking, with differences between PD and controls. Similarly, we confirmed a prior report that tremor predominance can also be

predicted by FCi.

Conclusions: Our results suggest that FCi is widely disrupted in PD, and associated with a variety of clinically relevant symptomatology.

References: [1] Hu X, Zhang J, Jiang X, Zhou C, Wei L, Yin X, Wu Y, Li J, Zhang Y, Wang J (2015) Decreased interhemispheric functional connectivity in subtypes of Parkinson’s disease. Journal of Neurology 262:760-767

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-resting-state-functional-interhemispheric-connectivity-in-parkinsons-disease-2/