Power, Melinda C.

AbstractBackgroundRecently, hearing loss has been identified as a promising modifiable risk factor for dementia. Several hypotheses explaining a potential underlying pathway have been proposed, including the sensory deprivation hypothesis, describing a direct causal relationship in which hearing loss leads to neuroplastic changes in the brain. Indeed, hearing loss has been associated with smaller macrostructural brain volumes, which is believed to at least partly explain the association between hearing loss and neurodegenerative disease. However, microstructural changes precede macrostructural changes. Therefore, we aimed to assess the association between hearing loss and microstructural integrity of the brain.Methods1,086 dementia‐free older adults from the Atherosclerosis Risk in Communities (ARIC) study (mean age = 75.2 [SD: 4.9], 61.4% female) underwent hearing assessment (2016‐2017) and magnetic resonance imaging (MRI) of the brain (2011‐2013). Hearing was assessed with pure‐tone audiometry. Microstructural integrity (fractional anisotropy (FA) and mean diffusivity (MD)) of multiple brain regions was determined with diffusion tensor imaging (DTI). Multivariable linear regression models were used to investigate the association between hearing loss and microstructural integrity of the lobes, temporal lobe gyri, medial temporal lobe structures and white matter (WM) tracts, adjusting for relevant confounders.ResultHearing loss was associated with lower WM microstructural integrity in the temporal lobe (difference in SD FA for moderate/severe hearing loss as compared to normal hearing: ‐0.19 [95% CI: ‐0.35, ‐0.03]; and difference in SD MD for moderate/severe hearing loss as compared to normal hearing: 0.15 [95% CI: 0.01, 0.28]). Hearing loss was associated with lower gray matter (GM) microstructure of the hippocampus, but not the amygdala. Moreover, hearing loss was associated with lower WM microstructural integrity of the limbic tracts and the uncinate fasciculus (Figure 1).ConclusionOur results demonstrate that age‐related hearing loss is associated with lower WM microstructural integrity in the temporal lobe, the limbic tracts and the uncinate fasciculus and lower GM microstructure in the hippocampus. These associations suggest that poorer hearing may affect brain regions that are important for different cognitive processes. However, the results should be interpreted with caution as this study is of a cross‐sectional design.

AbstractIntroductionAs hearing loss has been identified as an important risk factor for dementia, we aimed to assess the association between hearing loss and microstructural integrity of the brain.MethodsA total of 1086 dementia‐free participants (mean age = 75.2 [standard deviation: 4.9], 61.4% female) of the population‐based Atherosclerosis Risk in Communities (ARIC) study underwent hearing assessment (2016–2017) and magnetic resonance imaging of the brain (2011–2013). Microstructural integrity was determined with diffusion tensor imaging. Multivariable linear regression was used to investigate associations between hearing loss and microstructural integrity of different brain regions and white matter (WM) tracts.ResultsHearing loss was associated with lower WM microstructural integrity in the temporal lobe, lower gray matter integrity of the hippocampus, and with lower WM microstructural integrity of the limbic tracts and the uncinate fasciculus.ConclusionOur results demonstrate that hearing loss is indepedently associated with lower microstructural integrity in brain regions that are important for different cognitive processes.

Background Changes in white matter microstructural integrity are detectable before appearance of white matter lesions on magnetic resonance imaging as a manifestation of cerebral small‐vessel disease. The information relating poor white matter microstructural integrity to aortic stiffness, a hallmark of aging, is limited. We aimed to examine the association between aortic stiffness and white matter microstructural integrity among older adults. Methods and Results We conducted a cross‐sectional study to examine the association between aortic stiffness and white matter microstructural integrity among 1484 men and women (mean age, 76 years) at the 2011 to 2013 examination of the ARIC‐NCS (Atherosclerosis Risk in Communities Neurocognitive Study). Aortic stiffness was measured as carotid‐femoral pulse wave velocity. Cerebral white matter microstructural integrity was measured as fractional anisotropy and mean diffusivity using diffusion tensor imaging. Multivariable linear regression was used to examine the associations of carotid‐femoral pulse wave velocity with fractional anisotropy and mean diffusivity of the overall cerebrum and at regions of interest. Each 1‐m/s higher carotid‐femoral pulse wave velocity was associated with lower overall fractional anisotropy (β=−0.03; 95% CI , −0.05 to −0.02) and higher overall mean diffusivity (β=0.03; 95% CI , 0.02–0.04). High carotid‐femoral pulse wave velocity (upper 25th percentile) was associated with lower fractional anisotropy (β=−0.40; 95% CI , −0.61 to −0.20) and higher overall mean diffusivity (β=0.27; 95% CI , 0.10–0.43). Similar associations were observed at individual regions of interest. Conclusions High aortic stiffness is associated with low cerebral white matter microstructural integrity among older adults. Aortic stiffness may serve as a target for the prevention of poor cerebral white matter microstructural integrity.

Introduction: Cerebrovascular small vessel disease, seen on brain imaging as lacunes and white matter hyperintensities (WMH), is a substrate for dementia in older adults. Diffusion tensor imaging (DTI) is thought to provide early signs of loss of white matter (WM) integrity due to microvascular disease and predicts WM hyperintensity volume. Retinal fundus photography provides surrogate measures of cerebral microvasculature. No studies have quantified the long-term association between retinal signs and DTI measures. Hypothesis: Microvascular retinal signs measured in midlife are associated with small vessel disease measured on brain magnetic resonance imaging (MRI) 18 years later, including reduced WM microstructural integrity (lower fractional anisotrophy [FA] and greater mean diffusivity [MD] by DTI), greater WM hyperintensity volume and greater lacune prevalence. Methods: In a biracial prospective cohort study, retinal signs were measured using fundus photography (1993-1995) with 3-T magnetic resonance imaging conducted in 2011-13. Multivariable-adjusted linear regression was used to quantify the relationships of retinal signs with WM measures. Prevalence of lacunar infarcts by retinal sign status was estimated using log binomial regression. Analyses were adjusted for age [linear and quadratic terms], education, sex, race, intracranial volume, body mass index, smoking, diabetes, hypertension, and ≥1 APOE ε4 alleles. Results: In 1829 men and women (60% [N=1100] female, 27% [N=489] black race, aged 50-72 years when retinal signs were measured), a binary measure comprised of two retinal signs suggestive of arteriolar damage due to hypertension (focal arteriolar narrowing and/or arteriovenous nicking) was associated with worse (lower) FA (standardized β=-0.19, 95% confidence interval [CI]=-0.35, -0.02), worse (higher) MD (β=0.15, 95% CI=0.00, 0.30), greater WM hyperintensity volume (β=0.15, 95% CI=0.01, 0.30), and greater prevalence of lacunes (prevalence ratio=1.33, 95% CI: 0.99, 1.80). Generalized arteriolar narrowing, measured as the central retinal arteriolar equivalent (CRAE, narrowest quartile vs. widest three quartiles) was associated with worse FA (β=-0.13, 95% CI=-0.24, -0.01) and worse MD (β=0.12, 95% CI=0.01, 0.23). Results did not differ by sex, race, hypertension status or APOE ε4 genotype. No associations were found for retinopathy, but only 56 participants had retinopathy. Conclusions: Consistent with prior work, and as expected based on a common underlying pathology, retinal signs predicted WM disease and lacunar infarcts 18 years later. Novel to this study, we found that retinal signs related to arteriolar damage also predicted loss of white matter microvascular integrity measured using DTI.

OBJECTIVES Cardiac troponin T, measured using a high‐sensitive assay (hs‐cTnT), and N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) are associated with increased stroke risk and perhaps with cognitive decline. However, few well‐designed prospective studies with extended follow‐up have been conducted. We aimed to estimate the association of hs‐cTnT and NT‐proBNP with 15‐year cognitive change in the Atherosclerosis Risk in Communities (ARIC) study. DESIGN Prospective cohort study. SETTING Four US communities. PARTICIPANTS A total of 9114 and 9108 participants from the Atherosclerosis Risk in Communities study for analyses of hs‐cTnT and NT‐proBNP, respectively. MEASUREMENTS We examined association of hs‐cTnT and NT‐proBNP with 15‐year change (1996‐1998 to 2011‐2013) in three cognitive tests of executive function (Digit Symbol Substitution Test), verbal learning memory (Delayed Word Recall Test), and semantic fluency (Word Fluency Test), and an overall score combining the three tests using multivariable linear mixed effect models. We conducted several sensitivity analyses including multiple imputations to address bias due to missing data and attrition, and we compared associations within groups combining hs‐cTnT and NT‐proBNP into a three‐level categorical variable. RESULTS At baseline (1996‐1998), mean age was 63.4 (standard deviation [SD] = 5.7) years; 56.4% were women, and 17.5% were black. The hs‐cTnT at baseline was not associated with cognitive change in any measure. Some evidence indicated accelerated decline in verbal learning and memory when comparing those in the highest with the lowest NT‐proBNP quintiles; however, this association was not replicated when considering clinically relevant cutoffs or deciles of exposure in survivors. Sensitivity analyses were consistent with our primary analyses. There was little evidence to support effect modification by any considered factors. People with highest levels of both biomarkers had excessive decline in global z scores vs people with lowest levels (−.34; 95% confidence interval = −.63 to −.04). CONCLUSION Markers of myocardial injury and stretch were not associated with cognitive decline following 15 years among survivors, but when combined together they were suggestive in post hoc analysis. Whether this represents targets of intervention should be examined in the future. J Am Geriatr Soc 67:2353–2361, 2019

OBJECTIVE We sought to examine associations in older adults among diabetes, glycemic control, diabetes duration, and biomarkers of hyperglycemia with incident mild cognitive impairment (MCI) and incident dementia. RESEARCH DESIGN AND METHODS We conducted a prospective analysis of 5,099 participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended the fifth (2011–2013) exam. Cognitive status was assessed during follow-up via telephone calls, death certificate codes, surveillance, and a follow-up examination (2016–2017). We defined incident cognitive impairment as incident MCI or incident dementia in persons dementia-free at the index examination; we also examined each outcome separately. Diabetes was defined using self-report, medications, or HbA1c ≥6.5%; poor glycemic control in persons with diabetes was defined as HbA1c ≥7%. We examined the following biomarkers of hyperglycemia: HbA1c, fructosamine, glycated albumin, and 1,5-anhydroglucitol. RESULTS Mean age at baseline was 76 years, 59% were female, and 21% were black. Diabetes (hazard ratio [HR] 1.14 [95% CI 1.00, 1.31]), poor glycemic control in persons with diabetes (HR 1.31 [95% CI 1.05, 1.63]), and longer diabetes duration (≥5 vs. <5 years; HR 1.59 [95% CI 1.23, 2.07]) were significantly associated with incident cognitive impairment. We found a J-shaped association between HbA1c and incident dementia. Glycated albumin and fructosamine were also associated with incident dementia, independently of HbA1c. HbA1c and fructosamine were also associated with incident MCI. CONCLUSIONS Diabetes status, poor glycemic control, and longer diabetes duration were associated with worse cognitive outcomes over a median follow-up of 5 years.

Abstract White matter hyperintensities (WMHs) are frequently seen on brain magnetic resonance imaging scans of older people. Usually interpreted clinically as a surrogate for cerebral small vessel disease, WMHs are associated with increased likelihood of cognitive impairment and dementia (including Alzheimer's disease [AD]). WMHs are also seen in cognitively healthy people. In this collaboration of academic, clinical, and pharmaceutical industry perspectives, we identify outstanding questions about WMHs and their relation to cognition, dementia, and AD. What molecular and cellular changes underlie WMHs? What are the neuropathological correlates of WMHs? To what extent are demyelination and inflammation present? Is it helpful to subdivide into periventricular and subcortical WMHs? What do WMHs signify in people diagnosed with AD? What are the risk factors for developing WMHs? What preventive and therapeutic strategies target WMHs? Answering these questions will improve prevention and treatment of WMHs and dementia.

Background and Purpose— Evidence suggests that atrial fibrillation (AF) is associated with increased risk of cognitive decline and dementia, even in the absence of stroke. White matter disease (WMD) is a potential mechanism linking AF to cognitive impairment. In this study, we explored the association between prevalent AF and WMD. Methods— We performed a cross-sectional analysis of participants attending the ARIC-NCS (Atherosclerosis Risk in Communities–Neurocognitive Study) in 2011 to 2013 who underwent brain magnetic resonance imaging. AF was ascertained from study visit electrocardiograms or prior hospitalization codes. Extent of WMD was defined by measures of white matter (WM) microstructural integrity and WM hyperintensity volume. Multivariable linear regression models were used to assess the association between AF and WMD. Results— Among 1899 participants (mean age, 76 years; 28% black; 60% women), 133 (7%) had prevalent AF. After multivariable adjustment, differences between participants with and without AF were −0.001 (95% CI, −0.006 to 0.004) for global WM fractional anisotropy, 0.031×10 −4 mm 2 /s (95% CI, −0.075 to 0.137) for global WM mean diffusivity, and 0.08 mm 3 (95% CI, −0.14 to 0.30) for WM hyperintensity volume. Conclusions— The results suggest that there is no association between prevalent AF and WMD.