White matter hyperintensities: a marker for apathy in Parkinson's disease without dementia?

OBJECTIVE: The objective of this study was to assess the relationship between white matter hyperintensities (WMH) and the occurrence and progression of apathy in Parkinson's disease (PD). METHODS: We recruited patients with PD who underwent baseline evaluation, which included apathy assessment and magnetic resonance imaging (MRI) head scans. After 2.5 years of follow-up, we re-evaluated patient apathy symptoms. The severity and location of WMH were assessed with fluid-attenuated inversion recovery (FLAIR) sequences using the Fazekas visual rating scale. Logistic regression and linear regression analyses of baseline WMH characteristics were conducted to explore the potential association between apathy and WMH. RESULTS: A total of 141 PD patients were recruited. The apathy group had a higher proportion of male patients, advanced disease, and depression, which was coupled with a lower quality of life. Morever, higher WMH severity was significantly associated with apathy. Logistic regression analyses demonstrated that WMH severity was a risk factor for apathy. In addition, linear regression analysis also suggests that apathy severity is positively correlated with baseline WMH Fazekas scales (ϐ = 0.959, P < 0.001). Baseline WMH severity was also a risk factor for apathy progression. INTERPRETATION: WMH is associated with apathy and could be a promising marker to predict apathy progression in PD.