Cerebral perfusion and the risk of cognitive decline and dementia in community dwelling older people.

Background: The arterial spin labeling-spatial coefficient of variation (sCoV) is a new vascular magnetic resonance imaging (MRI) parameter that could be a more sensitive marker for dementia-associated cerebral microvascular disease than the commonly used MRI markers cerebral blood flow (CBF) and white matter hyperintensity volume (WMHV). Methods: 195 community-dwelling older people with hypertension were invited to undergo MRI twice, with a three-year interval. Cognition was evaluated every two years for 6-8 years using the mini-mental state examination (MMSE). We assessed relations of sCoV, CBF and WMHV with cognitive decline during follow-up. We also registered dementia diagnoses, up to 9 years after the first scan. In an additional analysis, we compared these MRI parameters between participants that did and did not develop dementia. Results: 136/195 completed the second scan. sCoV and CBF were not associated with MMSE changes during 6-8 years of follow-up. Higher WMHV was associated with declining MMSE scores (-0.02 points/year/ml, 95%CI=-0.03 to -0.00). ScOv and CBF did not differ between participants who did (n=15) and did not (n=180) develop dementia, whereas higher WMHV was reported in participants who developed dementia after the first MRI (13.3 vs 6.1mL, p<0.001). There were no associations between longitudinal change in any of the MRI parameters and cognitive decline or subsequent dementia. Conclusion: Global sCoV and CBF were less sensitive longitudinal markers of cognitive decline and dementia compared to WMHV in community-dwelling older people with hypertension. Larger longitudinal MRI perfusion studies are needed to identify possible (regional) patterns of cerebral perfusion preceding cognitive decline and dementia diagnosis.