Psychosocial Health and the Association Between Cerebral Small Vessel Disease Markers With Dementia: The ARIC Study.

BACKGROUND: Associations between magnetic resonance imaging markers of cerebral small vessel disease (CSVD) and dementia risk in older adults have been established, but it remains unclear how lifestyle factors, including psychosocial health, may modify this association. METHODS: Social support and social isolation were assessed among participants of the community-based ARIC (Atherosclerosis Risk in Communities) Study, via self-reported questionnaires (1990-1992). Following categorization of both factors, participants were classified as having strong or poor mid-life social relationships. At visit 5 (2011-2013), participants underwent 3T brain magnetic resonance imaging quantifying CSVD measures: white matter hyperintensity volume, microbleeds (subcortical), infarcts (lacunar), and white matter integrity (diffusion tensor imaging). Incident dementia cases were identified from the time of imaging through December 31, 2020 with ongoing surveillance. Associations between CSVD magnetic resonance imaging markers and incident dementia were evaluated using Cox proportional-hazard regressions adjusted for demographic and additional risk factors (from visit 2). Effect modification by mid-life social relationships was evaluated. RESULTS: Of the 1977 participants with magnetic resonance imaging, 1617 participants (60.7% women; 26.5% Black participants; mean age at visit 2, 55.4 years) were examined. In this sample, mid-life social relationships significantly modified the association between white matter hyperintensity volume and dementia risk (P interaction=0.001). Greater white matter hyperintensity volume was significantly associated with risk of dementia in all participants, yet, more substantially in those with poor (hazard ratio, 1.84 [95% CI, 1.49-2.27]) versus strong (hazard ratio, 1.26 [95% CI, 1.08-1.47]) mid-life social relationships. Although not statistically significant, subcortical microbleeds in participants with poor mid-life social relationships were associated with a greater risk of dementia, relative to those with strong social relationships, in whom subcortical microbleeds were no longer associated with elevated dementia risk. CONCLUSIONS: The elevated risk of dementia associated with CSVD may be reduced in participants with strong mid-life social relationships. Future studies evaluating psychosocial health through the life course and the mechanisms by which they modify the relationship between CSVD and dementia are needed.

Educational Attainment and Dementia: Mediation by Mid-Life Vascular Risk Factors.

INTRODUCTION: Lower education is associated with higher burden of vascular risk factors in mid-life and higher risk of dementia in late life. We aim to understand the causal mechanism through which vascular risk factors potentially mediate the relationship between education and dementia. METHODS: In a cohort of 13,368 Black and White older adults in the Atherosclerosis Risk in Communities Study, we assessed the relationship between education (grade school, high school without graduation, high school graduate or equivalent, college, graduate/professional school) and dementia among all participants and among those with incident stroke. Cox models were adjusted for age, race-center (a variable stratified by race and field center), sex, apolipoprotein E (APOE) ε4 genotype, and family history of cardiovascular disease. Causal mediation models assessed mediation by mid-life systolic blood pressure, fasting blood glucose, body mass index, and smoking. RESULTS: More education was associated with 8 to 44% lower risk of dementia compared to grade school-level education in a dose-response pattern, while the relationship between education and post-stroke dementia was not statistically significant. Up to 25% of the association between education and dementia was mediated through mid-life vascular risk factors, with a smaller percentage mediated for lower levels of education. INTERPRETATION: A substantial proportion of the relationship between education and dementia was mediated through mid-life vascular risk factors. However, risk factor modification is unlikely to fully address the large educational disparities in dementia risk. Prevention efforts must also address disparities in socioeconomic resources leading to divergent early-life education and other structural determinants of mid-life vascular risk factors. ANN NEUROL 2023;94:13-26.

Timing of Cognitive Test Score Decline Prior to Incident Dementia Diagnosis in Blacks and Whites: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: Commonly occurring dementias include those of Alzheimer's, vascular, and mixtures of these and other pathologies. They are believed to evolve over many years, but that time interval has been difficult to establish. Our objective was to determine how many years in advance of a dementia diagnosis cognitive scores begin to change. METHODS: 14,086 dementia-free ARIC participants underwent a cognitive exam at baseline visit 2 (1990-1992, mean age 57 ± 5.72), and 11,244 at visit 4 (1996-1998), 5,640 at visit 5 (2011-2013), and 3,574 at visit 6 (2016-2017) with surveillance for dementias of all-causes combined. Within 5-year intervals after each visit, we compared performance on the Delayed Word Recall Test (DWRT), the Digit Symbol Substitution Test (DSST), the Word Fluency Test (WFT), and the combined mean of three cognitive tests at baseline in participants who were diagnosed with dementia within each interval versus those who survived the interval without a dementia diagnosis. Z-scores were adjusted for demographics and education in separate regression models for each visit. We plotted adjusted z-score means by time interval following each visit. RESULTS: During follow-up 3,334, 2,821, 1,218, and 329 dementia cases were ascertained after visits 2, 4, 5, and 6, respectively. Adjusted DWRT z-scores were significantly lower 20-25 years before dementia than those who did not experience dementia within 25 years. DSST z-scores were significantly lower at 25-30 years and 3-test combination z-scores were significantly lower as early as 30-31 years before onset. The difference between dementia and non-dementia group in the visit 2 3-test combination z-score was -0.20 at 30-31 years prior to dementia diagnosis. As expected, differences between the dementia and non-dementia groups increased closer to the time of dementia occurrence, up to their widest point at 0-5 years prior to dementia diagnosis. The difference between dementia and non-dementia groups in the visit 2 3-test combination z-score at 0-5 years was -0.90. WFT z-score differences were smaller than for the DSST or DWRT and began later. Patterns were similar in Black and White participants. CONCLUSION: DWRT, DSST, and combined 3-test z-scores were significantly lower more than 20 years prior to diagnosis in the dementia group versus the non-dementia group. Findings contribute to our knowledge of the long prodromal period in Blacks and Whites.

Occupation, Retirement Age, and 20-Year Cognitive Decline: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: We examined the association of both midlife occupation and age at retirement with cognitive decline in the Atherosclerosis Risk in Communities (ARIC) biracial community-based cohort. METHODS: Current or most recent occupation at ARIC baseline (1987-1989; aged 45-64 years) was categorized based on 1980 US Census major occupation groups and tertiles of the Nam-Powers-Boyd occupational status score (n = 14,090). Retirement status via annual follow-up questionnaires administered ascertained in 1999-2007 was classified as occurring before or after age 70 (n = 7,503). Generalized estimating equation models were used to examine associations of occupation and age at retirement with trajectories of global cognitive factor scores, assessed from visit 2 (1990-1992) to visit 5 (2011-2013). Models were a priori stratified by race and sex and adjusted for demographics and comorbidities. RESULTS: Low occupational status and blue-collar occupations were associated with low baseline cognitive scores in all race-sex strata. Low occupational status and homemaker status were associated with faster decline in white women but slower decline in black women compared to high occupational status. Retirement before age 70 was associated with slower cognitive decline in white men and women and in black men. Results did not change substantially after accounting for attrition. CONCLUSION: Low occupational status was associated with cognitive decline in women but not in men. Earlier retirement was associated with a slower cognitive decline in white participants and in black men. Further research should explore reasons for the observed associations and race-sex differences.

Changes in Alzheimer Disease Blood Biomarkers and Associations With Incident All-Cause Dementia.

Importance: Plasma biomarkers show promise for identifying Alzheimer disease (AD) neuropathology and neurodegeneration, but additional examination among diverse populations and throughout the life course is needed. Objective: To assess temporal plasma biomarker changes and their association with all-cause dementia, overall and among subgroups of community-dwelling adults. Design, Setting, and Participants: In 1525 participants from the US-based Atherosclerosis Risk in Communities (ARIC) study, plasma biomarkers were measured using stored specimens collected in midlife (1993-1995, mean age 58.3 years) and late life (2011-2013, mean age 76.0 years; followed up to 2016-2019, mean age 80.7 years). Midlife risk factors (hypertension, diabetes, lipids, coronary heart disease, cigarette use, and physical activity) were assessed for their associations with change in plasma biomarkers over time. The associations of biomarkers with incident all-cause dementia were evaluated in a subpopulation (n = 1339) who were dementia-free in 2011-2013 and had biomarker measurements in 1993-1995 and 2011-2013. Exposure: Plasma biomarkers of amyloid-ß 42 to amyloid-ß 40 (Aß42:Aß40) ratio, phosphorylated tau at threonine 181 (p-tau181), neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) were measured using the Quanterix Simoa platform. Main Outcomes and Measures: Incident all-cause dementia was ascertained from January 1, 2012, through December 31, 2019, from neuropsychological assessments, semiannual participant or informant contact, and medical record surveillance. Results: Among 1525 participants (mean age, 58.3 [SD, 5.1] years), 914 participants (59.9%) were women, and 394 participants (25.8%) were Black. A total of 252 participants (16.5%) developed dementia. Decreasing Aß42:Aß40 ratio and increasing p-tau181, NfL, and GFAP were observed from midlife to late life, with more rapid biomarker changes among participants carrying the apolipoprotein E epsilon 4 (APOEε4) allele. Midlife hypertension was associated with a 0.15-SD faster NfL increase and a 0.08-SD faster GFAP increase per decade; estimates for midlife diabetes were a 0.11-SD faster for NfL and 0.15-SD faster for GFAP. Only AD-specific biomarkers in midlife demonstrated long-term associations with late-life dementia (hazard ratio per SD lower Aß42:Aß40 ratio, 1.11; 95% CI, 1.02-1.21; per SD higher p-tau181, 1.15; 95% CI, 1.06-1.25). All plasma biomarkers in late life had statistically significant associations with late-life dementia, with NfL demonstrating the largest association (1.92; 95% CI, 1.72-2.14). Conclusions and Relevance: Plasma biomarkers of AD neuropathology, neuronal injury, and astrogliosis increase with age and are associated with known dementia risk factors. AD-specific biomarkers' association with dementia starts in midlife whereas late-life measures of AD, neuronal injury, and astrogliosis biomarkers are all associated with dementia.

Patterns of cognitive domain abnormalities enhance discrimination of dementia risk prediction: The ARIC study.

INTRODUCTION: The contribution of neuropsychological assessments to risk assessment for incident dementia is underappreciated. METHODS: We analyzed neuropsychological testing results in dementia-free participants in the Atherosclerosis Risk in Communities (ARIC) study. We examined associations of index domain-specific neuropsychological test performance with incident dementia using cumulative incidence curves and Cox proportional hazards models. RESULTS: Among 5296 initially dementia-free participants (mean [standard deviation] age of 75.8 [5.1] years; 60.1% women, 22.2% Black) over a median follow-up of 7.9 years, the covariate-adjusted hazard ratio varied substantially depending on the pattern of domain-specific performance and age, in an orderly manner from single domain language abnormalities (lowest risk) to single domain executive or memory abnormalities, to multidomain abnormalities including memory (highest risk). DISCUSSION: By identifying normatively defined cognitive abnormalities by domains based on neuropsychological test performance, there is a conceptually orderly and age-sensitive spectrum of risk for incident dementia that provides valuable information about the likelihood of progression. HIGHLIGHTS: Domain-specific cognitive profiles carry enhanced prognostic value compared to mild cognitive impairment. Single-domain non-amnestic cognitive abnormalities have the most favorable prognosis. Multidomain amnestic abnormalities have the greatest risk for incident dementia. Patterns of domain-specific risks are similar by sex and race.

Prediabetes, intervening diabetes and subsequent risk of dementia: the Atherosclerosis Risk in Communities (ARIC) study.

AIMS/HYPOTHESIS: The aim of this work was to evaluate whether the association of prediabetes with dementia is explained by the intervening onset of diabetes. METHODS: Among participants of the Atherosclerosis Risk in Communities (ARIC) study we defined baseline prediabetes as HbA1c 39-46 mmol/mol (5.7-6.4%) and subsequent incident diabetes as a self-reported physician diagnosis or use of diabetes medication. Incident dementia was ascertained via active surveillance and adjudicated. We quantified the association of prediabetes with dementia risk before and after accounting for the subsequent development of diabetes among ARIC participants without diabetes at baseline (1990-1992; participants aged 46-70 years). We also evaluated whether age at diabetes diagnosis modified the risk of dementia. RESULTS: Among 11,656 participants without diabetes at baseline, 2330 (20.0%) had prediabetes. Before accounting for incident diabetes, prediabetes was significantly associated with the risk of dementia (HR 1.12 [95% CI 1.01, 1.24]). After accounting for incident diabetes, the association was attenuated and non-significant (HR 1.05 [95% CI 0.94, 1.16]). Earlier age of onset of diabetes had the strongest association with dementia: HR 2.92 (95% CI 2.06, 4.14) for onset before 60 years; HR 1.73 (95% CI 1.47, 2.04) for onset at 60-69 years; and HR 1.23 (95% CI 1.08, 1.40) for onset at 70-79 years. CONCLUSIONS/INTERPRETATION: Prediabetes is associated with dementia risk but this risk is explained by the subsequent development of diabetes. Earlier age of onset of diabetes substantially increases dementia risk. Preventing or delaying progression of prediabetes to diabetes will reduce dementia burden.

Association of Kidney Function Measures With Signs of Neurodegeneration and Small Vessel Disease on Brain Magnetic Resonance Imaging: The Atherosclerosis Risk in Communities (ARIC) Study.

RATIONALE & OBJECTIVE: Chronic kidney disease (CKD) is a risk factor for cognitive decline, but evidence is limited on its etiology and morphological manifestation in the brain. We evaluated the association of estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) with structural brain abnormalities visible on magnetic resonance imaging (MRI). We also assessed whether this association was altered when different filtration markers were used to estimate GFR. STUDY DESIGN: Cross-sectional study nested in a cohort study. SETTING & PARTICIPANTS: 1,527 participants in the Atherosclerosis Risk in Communities (ARIC) Study. PREDICTORS: Log(UACR) and eGFR based on cystatin C, creatinine, cystatin C and creatinine in combination, or ß2-microglobulin (B2M). OUTCOMES: Brain volume reduction, infarcts, microhemorrhages, white matter lesions. ANALYTICAL APPROACH: Multivariable linear and logistic regression models fit separately for each predictor based on a 1-IQR difference in the predictor value. RESULTS: Each 1-IQR lower eGFR was associated with reduced cortex volume (regression coefficient: -0.07 [95% CI, -0.12 to-0.02]), greater white matter hyperintensity volume (logarithmically transformed; regression coefficient: 0.07 [95% CI, 0.01-0.15]), and lower white matter fractional anisotropy (regression coefficient: -0.08 [95% CI, -0.17 to-0.01]). The results were similar when eGFR was estimated with different equations based on cystatin C, creatinine, a combination of cystatin C and creatinine, or B2M. Higher log(UACR) was similarly associated with these outcomes as well as brain infarcts and microhemorrhages (odds ratios per 1-IQR-fold greater UACR of 1.31 [95% CI, 1.13-1.52] and 1.30 [95% CI, 1.12-1.51], respectively). The degree to which brain volume was lower in regions usually susceptible to Alzheimer disease and LATE (limbic-predominant age-related TDP-43 [Tar DNA binding protein 43] encephalopathy) was similar to that seen in the rest of the cortex. LIMITATIONS: No inference about longitudinal effects due to cross-sectional design. CONCLUSIONS: We found eGFR and UACR are associated with structural brain damage across different domains of etiology, and eGFR- and UACR-related brain atrophy is not selective for regions typically affected by Alzheimer disease and LATE. Hence, Alzheimer disease or LATE may not be leading contributors to neurodegeneration associated with CKD.

Associations of Vascular Risk and Amyloid Burden with Subsequent Dementia.

OBJECTIVE: Midlife vascular risk factors (MVRFs) are associated with incident dementia, as are amyloid ß (Aß) deposition and neurodegeneration. Whether vascular and Alzheimer disease-associated factors contribute to dementia independently or interact synergistically to reduce cognition is poorly understood. METHODS: Participants in the Atherosclerosis Risk in Communities-Positron Emission Tomography study were followed from 1987-1989 (45-64 years old) through 2016-2017 (74-94 years old), with repeat cognitive assessment and dementia adjudication. In 2011-2013, dementia-free participants underwent brain magnetic resonance imaging (with white matter hyperintensity [WMH] and brain volume measurement) and florbetapir (Aß) positron emission tomography. The relative contributions of vascular risk and injury (MVRFs, WMH volume), elevated Aß standardized uptake value ratio (SUVR), and neurodegeneration (smaller temporoparietal brain regions) to incident dementia were evaluated with adjusted Cox models. RESULTS: In 298 individuals, 36 developed dementia (median follow-up = 4.9 years). Midlife hypertension and Aß each independently predicted dementia risk (hypertension: hazard ratio [HR] = 2.57, 95% confidence interval [CI] = 1.16-5.67; Aß SUVR [per standard deviation (SD)]: HR = 2.57, 95% CI = 1.72-3.84), but did not interact significantly, whereas late life diabetes (HR = 2.50, 95% CI = 1.18-5.28) and Aß independently predicted dementia risk. WMHs (per SD: HR = 1.51, 95% CI = 1.03-2.20) and Aß SUVR (HR = 2.52, 95% CI = 1.83-3.47) independently contributed to incident dementia, but WMHs lost significance when MVRFs were included. Smaller temporoparietal brain regions were associated with incident dementia, independent of Aß and MVRFs (HR = 2.18, 95% CI = 1.18-4.01). INTERPRETATION: Midlife hypertension and late life Aß are independently associated with dementia risk, without evidence for synergy on a multiplicative scale. Given the independent contributions of vascular and amyloid mechanisms, multiple pathways should be considered when evaluating interventions to reduce the burden of dementia. ANN NEUROL 2022;92:607-619.

Dementia occurring over a 32-year follow-up attributable to hypertension observed at different ages: Implications for dementia prevention.

INTRODUCTION: The fraction of dementia attributable to hypertension might vary depending on the age of the population considered and the age through which dementia occurs. METHODS: In the Atherosclerosis Risk in Communities study, we quantified population attributable fractions (PAF) of dementia by age 80 and 90 from hypertension assessed at ages of 45-54 (n = 7572), 55-64 (n = 12,033), 65-74 (n = 6561), and 75-84 (n = 2086). RESULTS: The PAF for dementia by age 80 from all non-normal blood pressure at ages 45-54 was 15.3% (95% confidence interval [CI] = 6.9%-22.3%), 19.1% (95% CI = 9.9%-26.9%) at ages 55-64, and 19.9% (95% CI = -4.4%-38.5%) at ages 65-74. The strongest PAFs were from stage 2 hypertension (11.9%-21.3%). For dementia by age 90, PAFs from non-normal blood pressure up through age 75 were smaller (10.9%-13.8%), and non-significant by age 75-84. DISCUSSION: Interventions targeting hypertension even in early late life might reduce a sizeable proportion of dementia. HIGHLIGHTS: We estimated prospective population attributable risks of dementia for hypertension. 15%-20% of dementia cases by age 80 are from non-normal blood pressure (BP). Associations between hypertension and dementia persisted through age 75. Midlife to early late-life BP control might reduce a large proportion of dementia.

Association Between Acute Kidney Injury and Dementia in the Atherosclerosis Risk in Communities (ARIC) Study.

RATIONALE & OBJECTIVE: Acute kidney injury (AKI) causes biochemical changes in the brain in animal models and is associated with adverse neurological complications in hospitalized patients. This study tested the association between AKI and incident dementia in a community-based cohort. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Adult participants in the Atherosclerosis Risk in Communities (ARIC) study who experienced hospitalized AKI compared with participants hospitalized for other reasons (primary analysis, mean follow-up period 4.3 years) or participants without hospitalized AKI (secondary analysis). PREDICTORS: Incident AKI, defined by ICD codes from hospital records. OUTCOME: Incident dementia, diagnosed based on a combination of neurocognitive testing, informant interviews, ICD codes, and death certificates. ANALYTICAL APPROACH: In the primary analysis, we estimated the propensity for hospitalized AKI and matched these participants with those hospitalized for another reason to examine the association of AKI with subsequent onset of dementia (N = 1,708). In the secondary analysis, we estimated the association between time-varying hospitalized AKI and subsequent onset of dementia using multivariable Cox proportional hazards regression models, adjusted for age, sex, race/center, education, smoking status, body mass index, baseline estimated glomerular filtration rate, baseline urinary albumin-creatinine ratio, systolic blood pressure, coronary heart disease, diabetes, hypertension, apolipoprotein E (APOE) ε4 allele, and C-reactive protein. RESULTS: The mean age in the propensity-matched cohort was 76.1 ± 6.5 (SD) years, and 53.2% of the participants were women. People who were hospitalized with AKI had a higher risk of dementia (HR, 1.25 [95% CI, 1.02-1.52]; P = 0.03) compared with those without a hospitalization for AKI. The associations were slightly stronger in the time-varying analysis (HR, 1.69 [95% CI, 1.48-1.92]; P < 0.001). Other risk factors for dementia included older age, male sex, higher albuminuria, diabetes, current smoker status, and presence of the APOE risk alleles. LIMITATIONS: Observational study, with AKI identified through diagnosis codes. CONCLUSIONS: Participants who experienced a hospitalization for AKI were at increased risk of dementia.

Brain Imaging Features Associated with 20-Year Cognitive Decline in a Community-Based Multiethnic Cohort without Dementia.

INTRODUCTION: This study aimed to characterize the association of cognitive decline starting in midlife with brain pathology in late life in the absence of dementia. METHODS: Nondemented Atherosclerosis Risk in Communities participants with brain imaging, all cognitive factor scores (CFSs), and nonmissing covariates were included. CFSs were collected at three visits across 21 years (1990-2013) (short-term cognitive change [1990-1996], long-term cognitive change [1990-2013]), and brain magnetic resonance imaging and florbetapir positron emission tomography (PET) imaging were collected in 2011-13 (PET subset n = 327). Outcomes of interest were total and regional brain volumes (cm3), log2 (white matter hyperintensity volume), white matter integrity (fractional anisotropy, mean diffusivity), ≥1 lacunar infarct (3-20 mm), and elevated brain ß-amyloid (SUVR >1.2). Multivariable linear/logistic regression related outcomes to CFS slopes after adjusting for demographics and total intracranial volume. RESULTS: At baseline, the 1,734 participants had a mean (SD) age of 55 (5.2) years, and were 60% female and 26% Black. After adjustment, a 1-SD larger long-term decline in CFS was associated with a smaller relative total brain volume by 1.2% (95% CI: 1.0, 1.5), a smaller relative temporal lobe meta region volume by 1.9% (1.5, 2.3), a 13% (9, 17) larger volume of white matter hyperintensities, a 1.3-fold (1.2, 1.4) higher odds of having ≥1 lacune, and 1.7-fold (1.3, 2.2) higher odds of elevated brain ß-amyloid deposition and worse white matter integrity. Some long-term associations were also found for midlife short-term declines in CFS. CONCLUSIONS: This study provides evidence that starting in midlife, short-term and long-term declines in cognition are associated with multiple deleterious late-life differences in nondemented brains.

Association between Circulating Protein C Levels and Incident Dementia: The Atherosclerosis Risk in Communities Study.

INTRODUCTION: Hemostasis depends on the delicate balance between coagulants and anticoagulants. Higher levels of circulating coagulants have been associated with higher risk of cerebral infarctions and dementia. In contrast, higher levels of circulating protein C, an endogenous anticoagulant, have been associated with lower risk of cerebral infarctions, and the association between protein C levels and the risk of dementia is unknown. The goal of this study was to evaluate the association of circulating protein C levels in midlife and late life with incident dementia. METHODS: Circulating protein C levels were measured using blood samples collected at the midlife baseline (1987-1989) and the late-life baseline (2011-2013) among 14,462 and 3,614 participants, respectively, in the Atherosclerosis Risk in Communities study. Protein C levels were measured using enzyme-linked immunosorbent assay at midlife and a modified aptamer-based assay at late life. Participants were followed up to 2013 from midlife and up to 2017 from late life. Incident dementia was ascertained during the follow-up periods using in-person cognitive and functional assessment, informant interviews, and International Classification of Diseases codes at hospitalization discharge and on death certificates. Cause-specific Cox regression models were used to evaluate the association between quintiles of circulating protein C and incident dementia. RESULTS: From midlife (mean age of 54), 1,389 incident dementia events were observed over a median follow-up of 23 years. From late life (mean age of 75), 353 incident dementia events were observed over a median follow-up of 4.9 years. At both midlife and late life, circulating protein C had an inverse association with incident dementia after adjusting for demographic, vascular, and hemostatic risk factors, incident stroke as time-dependent covariate, and incorporating stabilized weights based on propensity scores (quintile 5 vs. quintile 1 as the reference, midlife hazard ratio 0.80, 95% confidence interval 0.66-0.96, p value for trend 0.04; late-life hazard ratio 0.84, 95% confidence interval: 0.55-1.28, p value for trend 0.04). DISCUSSION/CONCLUSION: Circulating protein C has an inverse association with incident dementia independent of established risk factors, including stroke. Our results suggest studying anticoagulants in addition to coagulants can increase our understanding on the relationship between hemostasis and dementia.

Hearing impairment and missing cognitive test scores in a population-based study of older adults: The Atherosclerosis Risk in Communities neurocognitive study.

INTRODUCTION: Hearing impairment is associated with poor cognitive test performance in older adults. However, hearing's impact on cognitive test completion is poorly described, and missing cognitive data due to hearing impairment could misestimate the association. METHODS: We investigated if hearing impairment is associated with missing neurocognitive scores in 3678 adults (72-94 years). Hearing impairment was defined by the better-ear pure tone average of speech-frequency thresholds (0.5-4 kHz) >25 decibels. RESULTS: Hearing impairment was associated with greater missingness on all auditory-only tests, including Logical Memory (prevalence ratio [PR] comparing ≥ moderate impairment vs normal hearing:1.68, 95% confidence interval [CI] 1.26, 2.25) and Digits Backwards (PR 1.62; 95% CI 1.21, 2.17); and two non-auditory tests, Boston Naming (PR 1.61; 95% CI 1.21, 2.17) and Trail Making B (PR 1.55; 95% CI 1.29, 1.86). Models that imputed missing cognitive scores showed the strongest hearing-cognition associations. DISCUSSION: Older adults with hearing impairment are less likely to complete cognitive testing, thereby underestimating the hearing impairment-cognition relationship.

Albuminuria and Estimated GFR as Risk Factors for Dementia in Midlife and Older Age: Findings From the ARIC Study.

RATIONALE & OBJECTIVE: Evidence is limited on how estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) relate to dementia at different ages. We evaluated eGFR and UACR in midlife and older age as risk factors for dementia. Additionally, we assessed whether the association between eGFR and dementia is altered when cystatin C and ß2-microglobulin (B2M) levels are used for GFR estimation. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Two baselines from the Atherosclerosis Risk in Communities (ARIC) Study were used: visit 4 (1996-1998), including 9,967 participants 54 to 74 years old, and visit 5 (2011-2013), including 4,626 participants 70 to 90 years old. Participants were followed up until 2017. PREDICTORS: Log(UACR); eGFR based on creatinine, cystatin C, creatinine and cystatin C, or B2M levels (denoted as eGFRcr, eGFRcys, eGFRcr-cys, and eGFRB2M). OUTCOME: Incident dementia. ANALYTICAL APPROACH: Multivariable Cox proportional hazards regression models fit separately for each of the 5 predictors and based on a change in the predictor equivalent to the interquartile range for that predictor at visit 4 (IQRV4). eGFR models were adjusted for log(UACR) and log(UACR) models were adjusted for eGFRcys. RESULTS: We observed 1,821 dementia cases after visit 4 and 438 cases after visit 5. Dementia risk increased with higher albuminuria levels (HRs per IQRV4 [equivalent to 4.2-fold greater log albuminuria] of 1.15 [95% CI, 1.09-1.21] after visit 4 and 1.27 [95% CI, 1.13-1.42] after visit 5). An association with lower eGFR was seen for only eGFRcys (HRs per IQRV4 [equivalent to 24.3mL/min/1.73m2 lesser eGFRcys] of 1.12 [95% CI, 1.04-1.21] after visit 4 and 1.30 [95% CI, 1.12-1.52] after visit 5) and eGFRB2M (HRs per IQRV4 [equivalent to 18.3mL/min/1.73m2 lesser eGFRB2M] of 1.15 [95% CI, 1.07-1.23] after visit 4 and 1.34 [95% CI, 1.17-1.55] after visit 5). Differences between these associations in midlife and older age were not statistically significant. LIMITATIONS: Changes in potentially time-varying covariates were not measured. Dementia was not subclassified by cause. CONCLUSIONS: Albuminuria was consistently associated with dementia incidence. Lower eGFR based on cystatin C or B2M, but not creatinine, levels was also associated with dementia. Risk associations were similar when kidney measures were assessed at midlife and older age.

Association of Surgical Hospitalization with Brain Amyloid Deposition: The Atherosclerosis Risk in Communities-Positron Emission Tomography (ARIC-PET) Study.

BACKGROUND: As more older adults undergo surgery, it is critical to understand the long-term effects of surgery on brain health, particularly in relation to the development of Alzheimer's disease. This study examined the association of surgical hospitalization with subsequent brain ß-amyloid deposition in nondemented older adults. METHODS: The Atherosclerosis Risk in Communities-Positron Emission Tomography (ARIC-PET) study is a prospective cohort study of 346 participants without dementia who underwent florbetapir PET imaging. Active surveillance of local hospitals and annual participant contact were used to gather hospitalization and surgical information (International Classification of Disease, Ninth Revision, Clinical Modification codes) over the preceding 24-yr period. Brain amyloid measured using florbetapir PET imaging was the primary outcome. Elevated amyloid was defined as a standardized uptake value ratio of more than 1.2. RESULTS: Of the 313 participants included in this analysis (age at PET: 76.0 [SD 5.4]; 56% female), 72% had a prior hospitalization, and 50% had a prior surgical hospitalization. Elevated amyloid occurred in 87 of 156 (56%) participants with previous surgical hospitalization, compared with 45 of 87 (52%) participants who had no previous hospitalization. Participants with previous surgical hospitalizations did not show an increased odds of elevated brain amyloid (odds ratio, 1.32; 95% CI, 0.72 to 2.40; P = 0.370) after adjusting for confounders (primary analysis). Results were similar using the reference group of all participants without previous surgery (hospitalized and nonhospitalized; odds ratio, 1.58; 95% CI, 0.96 to 2.58; P = 0.070). In a prespecified secondary analysis, participants with previous surgical hospitalization did demonstrate increased odds of elevated amyloid when compared with participants hospitalized without surgery (odds ratio, 2.10; 95% CI, 1.09 to 4.05; P = 0.026). However, these results were attenuated and nonsignificant when alternative thresholds for amyloid-positive status were used. CONCLUSIONS: The results do not support an association between surgical hospitalization and elevated brain amyloid.

Migraine Headache and Risk of Dementia in the Atherosclerosis Risk in Communities Neurocognitive Study.

OBJECTIVE: We aimed to assess the association between migraine headache and incident dementia. BACKGROUND: Migraine is a risk factor for white matter hyperintensities and ischemic stroke, which are both associated with increased risk of dementia. However, it is unknown whether migraine is independently associated with dementia. METHODS: History of migraine was ascertained via questionnaire. Adjudicated cases of dementia were identified using cognitive tests, neuropsychological exams, and clinician review of suspected cases. Incident dementia was identified using adjudicated cases, follow-up calls, and surveillance of hospital and death codes. We assessed hazards of incident dementia by migraine status. Sex differences were also examined and stratified results were presented. RESULTS: Analysis included 12,495 White and African American participants ages 51-70 with a median follow-up time of 21 years. Prevalence of dementia was 18.5% (1821/9955) among those with no migraine history, 15.8% (196/1243) among those with severe non-migraine heading, and 16.7% (233/1397) among migraineurs. There was no association between migraine and incident dementia [hazard ratio: 1.04 (0.91, 1.20)]. There was also no statistically significant interaction between sex and migraine status on risk of dementia. CONCLUSION: Despite evidence of brain abnormalities in migraineurs, there was no association between migraine and incident dementia in this prospective cohort.

Frailty and Changes in Cognitive Function after Kidney Transplantation.

BACKGROUND: Restoration of kidney function after kidney transplant generally improves cognitive function. It is unclear whether frail recipients, with higher susceptibility to surgical stressors, achieve such post-transplant cognitive improvements or whether they experience subsequent cognitive decline as they age with a functioning graft. METHODS: In this two-center cohort study, we assessed pretransplant frailty (Fried physical frailty phenotype) and cognitive function (Modified Mini-Mental State Examination) in adult kidney transplant recipients. To investigate potential short- and medium-term effects of frailty on post-transplant cognitive trajectories, we measured cognitive function up to 4 years post-transplant. Using an adjusted mixed effects model with a random slope (time) and intercept (person), we characterized post-transplant cognitive trajectories by pretransplant frailty, accounting for nonlinear trajectories. RESULTS: Of 665 recipients (mean age 52.0 years) followed for a median of 1.5 years, 15.0% were frail. After adjustment, pretransplant cognitive scores were significantly lower among frail patients compared with nonfrail patients (89.0 versus 90.8 points). By 3 months post-transplant, cognitive performance improved for both frail (slope =0.22 points per week) and nonfrail (slope =0.14 points per week) recipients. Between 1 and 4 years post-transplant, improvements plateaued among nonfrail recipients (slope =0.005 points per week), whereas cognitive function declined among frail recipients (slope =-0.04 points per week). At 4 years post-transplant, cognitive scores were 5.8 points lower for frail recipients compared with nonfrail recipients. CONCLUSIONS: On average, both frail and nonfrail recipients experience short-term cognitive improvement post-transplant. However, frailty is associated with medium-term cognitive decline post-transplant. Interventions to prevent cognitive decline among frail recipients should be identified.

Hearing loss and microstructural integrity of the brain in a dementia-free older population.

INTRODUCTION: As 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. METHODS: A 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. RESULTS: Hearing 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. CONCLUSION: Our results demonstrate that hearing loss is indepedently associated with lower microstructural integrity in brain regions that are important for different cognitive processes.

Mid-life serum Vitamin D concentrations were associated with incident dementia but not late-life neuropsychological performance in the Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: Activated Vitamin D has anti-inflammatory properties and adequate 25-hydroxyvitamin D [25(OH)D] concentrations may be important for neurocognitive function and protection against neurologic injury. We examined whether mid-life 25(OH) D concentrations were associated with later-life performance on neuropsychological testing, functional ability, depressive symptoms, and incident dementia. METHODS: We studied 13,039 white and black ARIC participants who had serum 25(OH) D measured mid-life at visit 2 (1990-1992). Over the next ~ 20 years through visit 5 (2011-2013), participants underwent 3 additional in-person visits, annual telephone calls, and hospitalization surveillance. An extensive battery of neuropsychological outcomes were assessed at visit 5 using standardized protocols. Incident dementia was ascertained through a formal algorithm that included data from in-person cognitive testing, telephone interviews, hospital discharge codes, and death certificate codes. Diagnoses of dementia were adjudicated by expert clinician committee. For the primary cognitive analyses, we imputed for missing covariates and outcomes and used linear regression to evaluate non-concurrent cross-sectional associations of mid-life 25(OH) D (visit 2) with late-life neuropsychological outcomes (visit 5). We also used Cox regression models to examine associations of mid-life 25(OH) D and incident dementia. RESULTS: In mid-life, the mean (SD) age of participants was 57 (6) years, 57% were women, and 24% black. Mean (SD) 25(OH) D was 24.3 (8.6) ng/mL; 33% had deficient (< 20 ng/mL), 44% intermediate (20- < 30 ng/mL), and 23% sufficient (≥30 ng/mL) 25(OH) D concentrations. Association between mid-life 25(OH) D and late-life performance on neuropsychological testing were mostly null. There was no significant association with functional ability or depressive symptoms. Results were similar in a sensitivity analysis using complete-case data (no imputation). However, after a median follow-up of 20 years, low 25(OH) D concentrations were associated with increased risk for incident dementia (p = 0.01 for trend across categories), with HR of 1.26 (95% CI 1.06, 1.49) for participants with deficient 25(OH) D, compared to sufficient concentrations. CONCLUSION: In this community cohort, mid-life serum 25(OH) D concentrations were associated with incident dementia but not with performance on neuropsychological testing, functional ability, or depressive symptoms, 20 years later. Whether serum 25(OH) D concentrations are causally related to dementia or confounded by poorer health status remains uncertain. TRIAL REGISTRATION: Registered on clinicaltrials.gov NCT00005131 .