Citations

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 objective of this study was to investigate whether 10 phospholipids/metabolites previously identified as prospectively predictive of mild cognitive impairment (MCI) or dementia in whites would also be predictive in a mostly African‐American cohort.MethodsWe repeatedly measured 188 phospholipids/metabolites in plasma samples of 221 participants of the Atherosclerosis Risk in Communities study, 97% African American, who were followed between 2004–2006 and 2011–2013.ResultsAfter a mean follow‐up of 7.3 years, 77 were classified as having MCI and 18 as having dementia. Our study failed to replicate previous findings in this mostly African American cohort, in that the 10 phospholipids/metabolites only achieved a C statistic/AUC of 0.609 in predicting development of MCI or dementia (compared to 0.96) and 0.607 in distinguishing normal from MCI or dementia at the follow‐up visit.ConclusionA panel of 10 phospholipids/metabolites previously associated with incident dementia was not predictive of MCI or dementia in an independent cohort.

Alzheimer's disease (AD) is the most common form of dementia and is characterized by impairment in memory, behavioral changes, and gradual loss of autonomy. Since there is a long latent period prior to diagnosis, the aim of this study was to determine whether twenty single nucleotide polymorphisms identified in genome‐wide association analyses of AD are associated with cognitive change in 8,320 white and 2,039 African‐American middle‐aged adults enrolled in the prospective Atherosclerosis Risk in Communities (ARIC) study. Cognition was evaluated using the Delayed Word Recall Test (DWRT; verbal memory), Digit Symbol Substitution Test (DSST; processing speed), and Word Fluency Test (WFT; executive function). General linear models were used to assess mean differences in 6‐year change in test scores among individuals categorized by genotype after adjusting for age, gender, and years of education. Addition of the minor allele for rs670139 (MS4A4E), rs9331896 (CLU), and rs12155159 (NME8) was nominally associated with change on the DWRT, DSST, and WFT, respectively, in whites. The ZCWPW1(rs1476679) andCDS33(rs3865444) variants were nominally associated with change on the DWRT and WFT in African‐Americans. For rs670139 and rs9331896 the association was only significant in individuals bearing at least oneAPOEϵ4 allele in stratified analyses. An unweighted genetic risk score aggregating the risk alleles for 15 polymorphisms was not associated with change in cognitive function. Although the AD‐associated genetic variants appear to have small effects on early cognitive change, replication will be required to establish whether there is a discernible influence on cognitive status in midlife. © 2016 Wiley Periodicals, Inc.

AbstractIntroductionPhospholipids are altered in brains of patients with dementia and some studies suggest their plasma levels may be useful in the detection of mild cognitive impairment (MCI) and dementia.MethodsWe measured 188 plasma metabolites in participants who underwent a detailed neuropsychological assessment and classified as normal (n = 153), MCI (n = 145), or dementia (n = 143) by expert adjudication.ResultsAmong 10 phospholipids recently implicated as altered in dementia, higher concentration of PC aa C36:6 was significantly associated with decreased prevalence of dementia (odds ratio = 0.71, 95% confidence interval = 0.50–1.00 per 1−SD increase). Adding these phospholipids to a model including multiple predictors of dementia led to only minimal improvement in detection (C statistic changed from 0.702 to 0.71).DiscussionSome phospholipids and metabolites were altered in MCI and dementia but cross‐sectional association was relatively weak and did not improve detection of MCI and dementia beyond information provided by clinical variables.

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.