The burden of white matter hyperintensities is a predictor of progressive mild cognitive impairment in patients with Parkinson's disease
Background and purpose
To evaluate whether white matter hyperintensities (WMHs) may act as an independent predictor for progression of cognitive status, the authors analyzed the longitudinal effects of WMHs on cognitive dysfunction in non-demented patients with Parkinson's disease (PD).
A total of 111 patients with PD were enrolled, including subjects with mild cognitive impairment (MCI, n = 65) and cognitively normal subjects (CN, n = 46). These individuals were classified as MCI converters (n = 22) or MCI non-converters (n = 43) and CN converters (n = 18) or CN non-converters (n = 28) based on whether they were subsequently diagnosed with PD dementia or PD-MCI during a minimum 24-month follow-up. The WMH burden and the Cholinergic Pathway Hyperintensities Scale (CHIPS) and their relationships to longitudinal changes in cognitive performance were examined.
PD-MCI converters had larger WMH volume (14421.0 vs. 5180.4, P < 0.001) and higher CHIPS score (22.6 vs. 11.2, P = 0.001) compared with PD-MCI non-converters. Logistic regression analysis revealed in patients with PD-MCI that WMH volume (odds ratio 1.616, P = 0.009) and CHIPS score (odds ratio 1.084, P = 0.007) were independently associated with PD dementia conversion. However, WMH volume and CHIPS score did not differ between PD-CN converters and PD-CN non-converters. In patients with PD-MCI, both WMH volume and CHIPS score were closely associated with longitudinal decline in general cognition, semantic fluency and Stroop test scores.
The present study demonstrates that WMH burden is a significant predictor of conversion from PD-MCI to PD dementia and is related to ongoing decline in frontal-lobe-based cognitive performance.