Influence of White Matter Hyperintensities on the Cognition of Patients With Parkinson Disease

Background: White matter hyperintensities (WMH) have been associated with cognitive impairment in elderly persons and in patients with Alzheimer disease. However, the role of WMH in Parkinson disease (PD) dementia remains to be elucidated. Methods: The cohort for this study comprised 71 consecutive patients with PD, all of whom completed a clinical assessment, neuropsychologic investigation, and magnetic resonance imaging of brain. WMH were rated using the semiquantitative visual rating system proposed by Scheltens et al. Results: The PD dementia group had significantly more WMH than the PD without dementia group in the evaluated brain regions except for the infratentorial area. The WMH showed a significant correlation with age, Unified Parkinson's Disease Rating Scale, Mini-Mental State Examination, sum of the box of Clinical Dementia Rating, and many of the cognitive domains. The linear regression model showed that the WMH was independently associated with cognitive impairment in patients with PD, regardless of age, sex, duration or severity of PD symptoms, and vascular risk factors. Conclusions: These findings confirm that WMH might be associated with cognitive decline in patients with PD, regardless of age, sex, education status, duration or severity of PD symptoms, and vascular risk factors. This result suggests that other nonvascular factors contribute to the progression of dementia in patients with PD.