The Association of Dilated Perivascular Spaces with Cognitive Decline and Incident Dementia.

Objective: To determine if severe perivascular space (PVS) dilation is associated with longitudinal cognitive decline and incident dementia over four and eight years respectively, we analyzed data from a prospective cohort study. Methods: 414 community dwelling older adults aged 72-92 were assessed at baseline and biennially for up to eight years, with cognitive assessments, consensus dementia diagnoses and 3T MRI imaging. The numbers of PVS in two representative slices in the basal ganglia (BG) and centrum semiovale (CSO) were counted and severe PVS pathology defined as the top quartile. The effects of severe PVS pathology in i) either region; ii) both regions; and those with iii) severe BG PVS and iv) severe CSO PVS were examined. White matter hyperintensity volume, cerebral microbleed number and lacune number were calculated. Results: Participants with severe PVS pathology in both regions or in the CSO alone had greater decline in global cognition over four years, even after adjustment for the presence of other small vessel disease neuroimaging markers. The presence of severe PVS pathology in both regions was an independent predictor of dementia across eight years (OR 2.91, 95%CI 1.43–5.95, p= 0.003). Further, the presence of severe PVS pathology in all groups examined was associated with greater dementia risk at either year four or six. Conclusions: Severe PVS pathology is a marker for increased risk of cognitive decline and dementia, independent of other small vessel disease markers. The differential cognitive associations for BG and CSO PVS may represent differences in their underlying pathology.