Walker, Keenan A.

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.

Objectives To examine the association between hospitalization, critical illness, and infection occurring during middle‐ and late‐life and structural brain abnormalities in older adults. Design Prospective cohort study. Setting Atherosclerosis Risk in Communities (ARIC) Study. Participants A community sample of adults who were 44 to 66 years of age at study baseline. Measurements Active surveillance of local hospitals and annual participant contact were used to gather hospitalization information (including International Classification of Diseases, Ninth Revision , codes) on all participants over a 24‐year surveillance period. Subsequently, a subset of participants underwent 3‐Tesla brain magnetic resonance imaging (MRI) to quantify total and regional brain volumes, white matter hyperintensity (WMH) volume, and white matter microstructural integrity (fractional anisotropy (FA) and mean diffusivity (MD) as measured using diffusion tensor imaging (DTI)). Results Of the 1,689 participants included (mean age at MRI 76±5), 72% were hospitalized, 14% had a major infection, and 4% had a critical illness during the surveillance period. Using covariate‐adjusted regression, hospitalization was associated with 0.12–standard deviation (SD) greater WMH volume (95% confidence interval (CI)=0.00–0.24) and poorer white matter microstructural integrity (0.17‐SD lower FA, 95% CI=–0.27 to –0.06; 0.16‐SD greater MD, 95% CI=0.07–0.25) than no hospitalization. There was a dose‐dependent relationship between number of hospitalizations, smaller brain volumes, and lower white matter integrity ( p ‐trends ≤.048). In hospitalized participants, critical illness was associated with smaller Alzheimer's disease (AD) signature region (–1.64 cm 3 , 95% CI=–3.16 to –0.12); major infection was associated with smaller AD signature region (–1.28 cm 3 , 95% CI=–2.21 to –0.35) and larger ventricular volume (3.79 cm 3 , 95% CI= 0.81–6.77). Conclusions Whereas all‐cause hospitalization was primarily associated with lower white matter integrity, critical illness and major infection were associated with smaller brain volume, particularly within regions implicated in AD.