PERIVASCULAR SPACES ARE ASSOCIATED WITH LONGITUDINAL COGNITIVE DECLINE AND INCIDENT DEMENTIA IN A HEALTHY OLDER COHORT

Dilated perivascular spaces (PVS) are a marker of small vessel disease (SVD) and a common MRI finding in the elderly. Their association with cognitive impairment, particularly longitudinal decline and incident dementia is unclear. Understanding this relationship has implications for our knowledge of both SVD pathology and dementia more broadly. 414 community dwelling older adults aged 70–90 were assessed and followed up biennially for four years. The number of PVS in single axial slices in the basal ganglia (BG) and centrum semi-ovale (CSO) were counted according to a validated PVS scale, using T1-weighted and T2-FLAIR sequences. Cognitive impairment was measured at baseline and follow-up via a comprehensive neuropsychological assessment (domains tested: attention and processing speed, language, executive function, visuospatial function, memory and global cognition) and dementia diagnosis made by expert consensus group. Longitudinal decline over four year was assessed by linear mixed modelling and incident dementia by logistic regression, in two main analyses – 1) the number of BG and CSO PVS as a continuous measure and 2) dichotomising BG and CSO PVS around the top quartile of severity. All analyses were adjusted for age, sex and education (Model 1) and then additionally for vascular risk factors and other neuroimaging markers of SVD; white matter hyperintensities, lacunes and cerebral microbleeds (Model 2). When analysed as a continuous variable, there were no significant associations between the numbers of BG and CSO PVS and declines in any cognitive domain, global cognition or incident dementia. However, when dichotomised into a binary variable, there were differential associations by brain area. Participants with the most severe BG PVS had greater declines in attention and processing speed and participants with the most severe CSO PVS had greater declines in global cognition, after adjusting for all covariates. Those with severe CSO PVS also had a higher rate of incident dementia, but this failed to achieve significance after adjusting for other neuroimaging markers.