Windham, B. Gwen

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.

Background: Although associations between hypertension in mid-life and the development of dementia and cognitive decline have been established, the impact of the new 2017 ACC/AHA guidelines on dementia risk at the population level has not been evaluated. Objectives: To assess the association of hypertension categories with the risk of incident dementia and to calculate the population attributable fraction (PAF) for dementia from hypertension categories according to the 2017 ACC/AHA guidelines, and compare these associations with hypertension defined according to JNC7. Methods: We studied dementia-free participants recruited to the Atherosclerosis Risk in Communities (ARIC) cohort in 1987-89. Hypertension was defined by 2003 JNC7 and 2017 ACC/AHA guidelines using blood pressure measured at baseline; participants using antihypertensive medication were included in hypertension stage 2 for both sets of guidelines. Dementia was defined using adjudicated consensus diagnoses at visit 5 (2011-13), informant telephone interviews, and ICD-9 codes from hospitalizations and death certificates through 2013. Cox proportional hazards regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) by hypertension categories, adjusting for potential confounders, including sociodemographic, lifestyle and clinical variables. PAF of dementia by hypertension category was calculated using rate ratios from Poisson regression and the prevalence of the risk factor in the population. Results: Among 13,971 participants followed for a median of 23.0 years, 1381 cases of dementia were identified. Prevalence of elevated BP (systolic BP [SBP] 120-129 and diastolic BP [DBP] <80), hypertension stage 1 (SBP 130-139 or DBP 80-89) and hypertension stage 2 (SBP ≥140 or DPB ≥90) according to 2017 ACC/AHA categories was 13%, 15% and 44%, respectively. Corresponding HR (95%CI) compared to normal BP were 1.35 (95%CI 1.12, 1.61), 1.28 (1.07, 1.52) and 1.36 (1.18, 1.57), respectively. PAF (95%CI) of dementia from hypertension categories were 3% (1%, 5%), 3% (1%, 5%) and 9% (4%, 14%). PAF using JNC7 categories were similar to 2017 ACC/AHA: 6% (3%, 9%) for prehypertension (SBP 120-129 or DBP 80-89), 0% (-2%, 2%) for hypertension stage 1 (SBP 140-159 or DBP 90-99), and 9% (5%, 13%) for hypertension stage 2 (SBP ≥160 or DBP ≥100). Conclusions: Risk of dementia was increased across categories defined by the new ACC/AHA hypertension guidelines. However, the population impact on dementia incidence using 2017 ACC/AHA was similar to the impact of JNC7. These results suggest that the new criteria for diagnosis of hypertension will not increase the number of persons in whom hypertension could be reasonably labeled as a risk for dementia.

Background: Although inflammation has been implicated in the pathogenesis of Alzheimer’s disease, the effects of systemic inflammation on brain amyloid deposition remain unclear. Objective: We examined the association of midlife and late-life systemic inflammation with late-life brain amyloid levels in a community sample of non-demented older adults from the Atherosclerosis Risk in Communities (ARIC) – PET Study. Methods: 339 non-demented participants (age: 75 [SD 5]) were recruited from the ARIC Study to undergo florbetapir PET (amyloid) imaging. Blood levels of high sensitivity C-reactive protein (CRP), a marker of systemic inflammation, were measured 22 years (Visit 2), 16 years (Visit 4), and up to 2 years before PET imaging (Visit 5). Elevated brain amyloid deposition (standardized uptake value ratio >1.2) was the primary outcome. Results: Our primary analyses found no association of midlife and late-life CRP with late-life brain amyloid levels. However, in secondary stratified analyses, we found that higher midlife (Visit 2) CRP was associated with elevated amyloid among males (OR 1.65, 95% CI: 1.13–2.42), and among white (OR 1.33, 95% CI: 1.02–1.75), but not African American, participants ( p-interactions<0.05). Among male participants, those who maintained high CRP levels (≥3 mg/L) throughout mid- and late-life were most likely to have elevated brain amyloid (OR, 8.81; 95% CI: 1.23, 62.91). Conclusions: Although our primary analysis does not support an association between systemic inflammation and brain amyloid deposition, we found evidence for sex- and race-dependent associations. However, findings from subgroup analyses should be interpreted with caution.

Abstract Introduction We tested the hypotheses that higher levels of and persistence of midlife leisure‐time physical activity (LTPA) are associated long‐term with lower cognitive decline and less incident dementia. Methods A total of 10,705 participants (mean age: 60 years) had LTPA (no, low, middle, or high) measured in 1987‐1989 and 1993‐1995. LTPA was assessed in relation to incident dementia and 14‐year change in general cognitive performance. Results Over a median follow‐up of 17.4 years, 1063 dementia cases were observed. Compared with no LTPA, high LTPA in midlife was associated with lower incidence of dementia (hazard ratio [95% confidence interval], 0.71 [0.61, 0.86]) and lower declines in general cognitive performance (−0.07 standard deviation difference [−0.12 to −0.04]). These associations were stronger when measured against persistence of midlife LTPA over 6 years. Discussion LTPA is a readily modifiable factor associated inversely with long‐term dementia incidence and cognitive decline.

Background and Purpose— White matter hyperintensities (WMH) on brain magnetic resonance imaging are typical signs of cerebral small vessel disease and may indicate various preclinical, age-related neurological disorders, such as stroke. Though WMH are highly heritable, known common variants explain a small proportion of the WMH variance. The contribution of low-frequency/rare coding variants to WMH burden has not been explored. Methods— In the discovery sample we recruited 20 719 stroke/dementia-free adults from 13 population-based cohort studies within the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, among which 17 790 were of European ancestry and 2929 of African ancestry. We genotyped these participants at ≈250 000 mostly exonic variants with Illumina HumanExome BeadChip arrays. We performed ethnicity-specific linear regression on rank-normalized WMH in each study separately, which were then combined in meta-analyses to test for association with single variants and genes aggregating the effects of putatively functional low-frequency/rare variants. We then sought replication of the top findings in 1192 adults (European ancestry) with whole exome/genome sequencing data from 2 independent studies. Results— At 17q25, we confirmed the association of multiple common variants in TRIM65 , FBF1 , and ACOX1 ( P <6×10 −7 ). We also identified a novel association with 2 low-frequency nonsynonymous variants in MRPL38 (lead, rs34136221; P EA =4.5×10 −8 ) partially independent of known common signal ( P EA(conditional) =1.4×10 −3 ). We further identified a locus at 2q33 containing common variants in NBEAL1 , CARF , and WDR12 (lead, rs2351524; P all =1.9×10 −10 ). Although our novel findings were not replicated because of limited power and possible differences in study design, meta-analysis of the discovery and replication samples yielded stronger association for the 2 low-frequency MRPL38 variants ( P rs34136221 =2.8×10 −8 ). Conclusions— Both common and low-frequency/rare functional variants influence WMH. Larger replication and experimental follow-up are essential to confirm our findings and uncover the biological causal mechanisms of age-related WMH.