Objective: To evaluate the relation between olfactory functioning and gray matter (GM) volume in patients with Parkinson’s disease (PD).

Background: Olfactory impairment is one of the most common non-motor symptoms in PD. A few studies showed evidence for a relationship between olfactory deficits and GM volume. In the present study, we specify this relationship including a large sample of patients with PD as well as healthy controls assessing different olfactory dimensions.

Methods: We included 49 PD patients and 27 healthy controls. To assess olfactory functioning, the odor threshold test and the odor identification test from the Sniffin’ Sticks Test Battery (Burghart Messtechnik, Wedel) was used. T1-weighted MRI images (3 tesla) were acquired. Voxel-based morphometry was used to detect grey matter volume changes associated with olfactory performance. Preprocessing and statistical analyses were performed with SPM8.

Results: In the patient group, we found significant positive correlations between GM volume and odor threshold in primary olfactory areas (parahippocampal gyrus, insula; p<0.05, family-wise error corrected) as well as in some other brain regions (e.g., angular gyrus; p<0.001, uncorrected). Odor identification performance was associated with volume increases in areas known to be involved in the processing of semantic information (e.g., superior temporal gyrus; p<0.001, uncorrected). In healthy controls, we found an opposed pattern of GM changes for olfactory threshold. Here, better odor threshold was associated with GM atrophy in olfactory brain areas.

Conclusions: Our findings suggest that sensory and complex olfactory functions are associated with different cortical patterns of GM density. PD specific GM volume increase in primary olfactory areas indicates a successful structural compensation of an impaired afferent pathway in the olfactory system. We hypothezise that the impaired ability for structural plasticity might reflect an endophenotype of Parkinson’s disease; further investigations are needed to verify this hypothesis.

Poster (Deutscher Parkinson-Kongress 2014; Deutsche Parkinson Gesellschaft (DPG)).

« Back to 2016 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/olfaction-and-gray-matter-volume-in-parkinsons-disease-a-voxel-based-morphometry-study/