2023 American Academy of Neurology Abstract Website

Objective:

To investigate structural connectivity in people with Parkinson’s disease with or without visual hallucinations.

Background:

Up to 70% of people with Parkinson’s disease (PwP) experience visual hallucinations (VH) during the course of the disease. The mechanisms through which the PD neurodegenerative process leads to VH remain largely undetermined. The purpose of this study was to determine to what extent whole-brain structural connectivity is different in PwP experiencing VH (PD-VH+) from those not experiencing VH (PD-VH-).

Design/Methods:

Sixty-nine PwP and eighteen subjects with essential tremor (ET) participated in a neuropsychological evaluation and MRI imaging to determine eligibility for deep brain stimulation. As a part of the evaluation, participants were asked if they had experienced VH. Diffusion Kurtosis Imaging (DKI) scans were processed using a connectometry approach in DSI studio to determine whole-brain group differences in white-matter connectivity.

Results:

Sixty-nine PwP (mean age = 64 +/- 7.5 years, disease duration = 9.2 +/- 4.8 years) were included in the study. Twenty-four (35%) participants in the PD group reported VH. No subjects with ET reported VH. Relative to PD-VH+ and ET groups, the PD-VH- group had decreased structural connectivity within prefrontal white-matter fibers, including the bilateral anterior frontostriatal tracts and the corpus callosum-forceps minor (FDR corrected p=0.000082). Structural connectivity in these tracts did not differ between the PD-VH+ and ET groups. Analyses included correction for sex, age, handedness, and disease duration.

Conclusions:

These results suggest that the integrity of frontostriatal and callosal structural connectivity is necessary for the emergence of VH in PD. This aligns with the proposed top-down processing mechanisms of VH in PD.