Power, Melinda C.

Background Central arterial stiffening and increased pulsatility, with consequent cerebral hypoperfusion, may result in structural brain damage and cognitive impairment. Methods and Results We analyzed a cross‐sectional sample of ARIC ‐ NCS (Atherosclerosis Risk in Communities–Neurocognitive Study) participants (aged 67–90 years, 60% women) with measures of cognition (n=3703) and brain magnetic resonance imaging (n=1255). Central arterial hemodynamics were assessed as carotid‐femoral pulse wave velocity and pressure pulsatility (central pulse pressure). We derived factor scores for cognitive domains. Brain magnetic resonance imaging using 3‐Tesla scanners quantified lacunar infarcts; cerebral microbleeds; and volumes of white matter hyperintensities, total brain, and the Alzheimer disease signature region. We used logistic regression, adjusted for demographics, apolipoprotein E ɛ4, heart rate, mean arterial pressure, and select cardiovascular risk factors, to estimate the odds of lacunar infarcts or cerebral microbleeds. Linear regression, additionally adjusted for intracranial volume, estimated the difference in log‐transformed volumes of white matter hyperintensities , total brain, and the Alzheimer disease signature region. We estimated the mean difference in cognitive factor scores across quartiles of carotid‐femoral pulse wave velocity or central pulse pressure using linear regression. Compared with participants in the lowest carotid‐femoral pulse wave velocity quartile, participants in the highest quartile of carotid‐femoral pulse wave velocity had a greater burden of white matter hyperintensities ( P =0.007 for trend), smaller total brain volumes (−18.30 cm 3 ; 95% CI , −27.54 to −9.07 cm 3 ), and smaller Alzheimer disease signature region volumes (−1.48 cm 3 ; 95% CI , −2.27 to −0.68 cm 3 ). These participants also had lower scores in executive function/processing speed (β=−0.04 z score; 95% CI , −0.07 to −0.01 z score) and general cognition (β=−0.09 z score; 95% CI , −0.15 to −0.03 z score). Similar results were observed for central pulse pressure . Conclusions Central arterial hemodynamics were associated with structural brain damage and poorer cognitive performance among older adults.

AbstractIntroductionExisting studies predominantly consider the association of late‐life lipid levels and subsequent cognitive change. However, midlife rather than late‐life risk factors are often most relevant to cognitive health.MethodsWe quantified the association between measured serum lipids in midlife and subsequent 20‐year change in performance on three cognitive tests in 13,997 participants of the Atherosclerosis Risk in Communities study.ResultsElevated total cholesterol, low‐density lipoprotein cholesterol, and triglycerides were associated with greater 20‐year decline on a test of executive function, sustained attention, and processing speed. Higher total cholesterol and triglycerides were also associated with greater 20‐year decline in memory scores and a measure summarizing performance on all three tests. High‐density lipoprotein cholesterol was not associated with cognitive change. Results were materially unchanged in sensitivity analyses addressing informative missingness.DiscussionElevated total cholesterol, low‐density lipoprotein cholesterol, and triglycerides in midlife were associated with greater 20‐year cognitive decline.

Background Diffusion tensor imaging measures of white matter ( WM ) microstructural integrity appear to provide earlier indication of WM injury than WM hyperintensities; however, risk factors for poor WM microstructural integrity have not been established. Our study quantifies the association between vascular risk factors in midlife and late life with measures of late‐life WM microstructural integrity. Methods and Results We used data from 1851 participants in ARIC (Atherosclerosis Risk in Communities Study) who completed 3‐T magnetic resonance imaging, including diffusion tensor imaging, as part of the ARIC Neurocognitive Study (ARIC‐NCS). We quantified the association among lipids, glucose, and blood pressure from the baseline ARIC visit (1987–1989, ages 44–65, midlife) and visit 5 of ARIC (2011–2013, ages 67–90, late life, concurrent with ARIC‐NCS) with regional and overall WM mean diffusivity and fractional anisotropy obtained at ARIC visit 5 for ARIC participants. We also considered whether these associations were independent of or modified by WM hyperintensity volumes. We found that elevated blood pressure in midlife and late life and elevated glucose in midlife, but not late life, were associated with worse late‐life WM microstructural integrity. These associations were independent of the degree of WM hyperintensity, and the association between glucose and WM microstructural integrity appeared stronger for those with the least WM hyperintensity. There was little support for an adverse association between lipids and WM microstructural integrity. Conclusions Hypertension in both midlife and late life and elevated glucose in midlife are related to worse WM microstructural integrity in late life.

AbstractIntroductionThe impact of blood pressure on brain volumes may be time‐dependent or pattern‐dependent.MethodsOf 1678 participants from the Atherosclerosis Risk in Communities Neurocognitive Study, we quantified the association between measures and patterns of blood pressure over three time points (∼24 or ∼15 years prior and concurrent with neuroimaging) with late life brain volumes.ResultsHigher diastolic blood pressure ∼24 years prior, higher systolic and pulse pressure ∼15 years prior, and consistently elevated or rising systolic blood pressure from ∼15 years prior to concurrent with neuroimaging, but not blood pressures measured concurrent with neuroimaging, were associated with smaller volumes. The pattern of hypertension ∼15 years prior and hypotension concurrent with neuroimaging was associated with smaller volumes in regions preferentially affected by Alzheimer's disease (e.g., hippocampus: −0.27 standard units, 95% CI: −0.51, −0.03).DiscussionHypertension 15 to 24 years prior is relevant to current brain volumes. Hypertension followed by hypotension appears particularly detrimental.