Possible association between cerebral white matter atrophy and impaired performance of activities of daily living in patients with Parkinson’s disease

Introduction:
The contribution of brain abnormalities in patients with Parkinson’s disease (PD) to impaired functional status remains uncertain. Our study assessed whether global and regional brain structural abnormalities are associated with impaired performance of activities of daily living (ADL) in PD patients.

Material and methods:
A retrospective analysis was conducted of 46 patients with PD, recruited prospectively from a movement disorder clinic. Motor impairment and disability were assessed using the Hoehn and Yahr (H-Y) scale and Unified Parkinson’s Disease Rating Scale Part III (UPDRS-III). Cognitive status was evaluated with Montreal Cognitive Assessment (MoCA). The performance of ADL was indexed by the sum score of the Physical Self-Maintenance Scale (PSMS) and Lawton Instrumental ADL scale. Brain magnetic resonance imaging (MRI) was performed to assess white matter hyperintensities and medial temporal lobe atrophy (MTLA). Global brain atrophy, indexed by the relative grey matter volume (RGM), relative white matter volume (RWM) and average cortical thickness of the whole brain, was quantified by voxel-based morphometry (VBM).

Results:
The ADL score (where higher scores indicate poorer performance) negatively correlated with RWM (where greater volume indicates less severe atrophy; r = –0.41, p = 0.004) and RGM (where greater volume indicates less severe atrophy; r = –0.43, p = 0.003) but not with the average cortical thickness (r = –0.16, p = 0.29). With ADL score as the dependent variable in a linear regression model, H-Y stage and RWM significantly correlated with the ADL score after adjusting for age and MoCA score, and together accounted for 51% of the variance therein. RGM was not significantly correlated with the ADL score after adjusting for age and MoCA score.

Conclusions:
Cerebral white matter atrophy may be associated with the performance of ADL in patients with PD, indicating an important role of white matter impairment in their functional status.