Mosley, Thomas H.

Dementia affects approximately 5 million people in the United States and cost $183 billion in 2011, with African Americans (AA) experiencing a disproportionate burden of dementia compared to European Americans (EA). Inflammation is considered by many to be a potential mediator in the development of cognitive dysfunction. High sensitivity C-reactive protein (CRP) and tumor necrosis factor-α (TNF-α), increasingly measured by the soluble TNF receptors 1 & 2 (sTNFRI1, sTNFR2), are among the most frequently cited inflammatory markers associated with dementia and are also elevated in vascular disease. Few studies have compared associations of inflammatory markers with cognitive function in EA and AA. We examined the association of CRP, sTNFR1 and sTNFR2 with cognitive function using detailed neuropsychological assessments in the Genetic Epidemiology Network of Arteriopathy (GENOA)-Genetics of Microangiopathic Brain Injury (GMBI) participants, a cohort considered at high risk of vascular disease due to family history (> 2 individuals in sibships with hypertension at age <60 years) and high prevalence rates of hypertension (74%), diabetes (27%), and obesity (51%). Cognitive function was measured across 5 cognitive domains: global cognitive function, processing speed, language, memory, and executive function. In AA, higher sTNFR2 was associated with poorer performance across all five domains. Higher sTNFR1 and CRP were associated with slower processing speed. In EA, higher sTNFR1 was associated with slower processing speed. CRP and sTNFR2 were not associated with cognitive function in EA. Inflammatory markers in this cohort were associated differentially across cognitive domains in AA and EA, and may reflect racial differences in vascular responses to inflammation.

Background: Brain infarcts, white matter hyperintensities (WMH), and brain atrophy appear to contribute to the development of mild cognitive impairment (MCI) and dementia in selected populations, but few prospective studies are available in general populations. Methods: The study included 732 black and white participants, sampled from the original ARIC cohort, who had 3T brain Magnetic Resonance Imaging (MRI) scans, were free of MCI and dementia during 2011-13 (Visit 5), and were evaluated for cognitive impairment during 2016-17 (Visit 6, about 90% complete). We assessed the associations of brain infarcts, WMH, and brain volumes measured on MRI from 2011-2013 with incident MCI and dementia (combined), diagnosed using a computer algorithm based on specified criteria and comprehensive assessment at Visit 6. We used logistic regression, incorporating sampling weights, to evaluate the risk for incident MCI/dementia with adjustment for demographic covariates, major dementia risk factors, and history of cardiovascular diseases. Results: Participants had a median age of 75 (IQR: 71, 79) at Visit 5 (baseline); 62% (453) were female and 33% (242) were African American. There were 156 newly identified cases of MCI or dementia during a median follow-up time of 4.9 (IQR: 3.4, 5.2) years. The presence of any brain infarct was associated with a nonsignificantly higher risk of MCI/dementia (OR: 1.50; 95%CI: 0.87 to 2.58), but the only significant individual association was with cortical infarcts (OR: 1.99; 95%CI: 1.03 to 3.85). WMH volume above the median value was nonsignificantly associated with conversion to MCI/dementia. Smaller Alzheimer’s disease (AD) signature region was an independent predictor for greater risk of MCI/dementia (OR: 1.49; 95%CI: 1.00 to 2.22). A similar but nonsignificant association was observed for total brain volume. Conclusions: Brain infarcts (cortical infarcts) and lower brain volume (AD signature region), measured in community-based older residents, are risk factors for MCI and dementia incidence.

Introduction: Several studies report late-life physical activity (PA) to be associated with less brain atrophy. Associations of PA and subclinical brain markers evaluated at older ages may be subject to reverse causality due to comorbidity, age-related changes in lifestyle, or incipient cognitive impairment. Therefore, we aimed to compare late-life cross-sectional estimates of PA and ROI brain volumes to those using prospective PA measures from mid- to late-life. Methods: Participants (n=1549, mean age: 75, 39% male, 20% Black) with repeat assessments of PA from visit 1 (1987-1989) and a brain magnetic resonance imaging (MRI) in 2011-2013 were included. Total volume of PA in metabolic equivalent-min/week was estimated using the Baecke Physical Activity Questionnaire and classified as no, low, middle or high at each visit. Based on visit 1 and 3 (1993-1995) PA assessments, a subset of participants (n=663) were further categorized as habitually inactive or having habitually low, middle, or high PA in mid-life. Brain MRI using 3D-1.5T equipment quantified ROI volumes following a standardized protocol. Weighted linear regression adjusted for intracranial volume, demographics, select cardiovascular risk factors and ApoE4 estimated the standardized difference in ROI volumes. Results: Compared to no PA, high PA was associated with larger ROI brain volumes cross-sectionally in late-life (Table). High mid-life PA was only modestly associated with larger frontal cortical and deep gray matter volumes in late-life (Table). Habitually high PA in mid-life was not associated with less atrophy across brain regions in late-life. Conclusions: Our results do not support a causal interpretation of the cross-sectional associations between PA and brain volumes reported in late-life. Drawing on long-term population-based data, this study provides novel information on the associations of PA across life epochs with brain health, which can inform translational and intervention efforts to reduce age-related cognitive impairment.

Introduction: The microvascular contribution to dementia may be under-recognized because of the inability to visualize the brain microvasculature in vivo. Although the easily-imaged retinal vasculature may be a surrogate measure for that in the brain, large prospective studies of the relationship between retinal vascular signs and dementia are scarce. Hypothesis: Retinal signs are associated with greater subsequent risk of all-cause dementia and etiologic subtype over 20 years in 12482 men and women (mean age of 60 years when retinal signs were measured, 22% African American). Methods: Retinal signs were measured using fundus photography (1993-1995). Presence and etiology of dementia and mild cognitive impairment (MCI) were adjudicated using data collected in 2011-13, including a complete neuropsychological battery and brain magnetic resonance imaging (subset of participants). For participants not attending the 2011-13 visit, dementia cases were identified using the Telephone Interview for Cognitive Status–Modified or informant interview, or by hospitalization or death certificate code. Multivariable-adjusted Cox proportional hazards models and logistic regression were used to quantify the relationship of retinal signs with dementia risk and with etiologic subtype, respectively. Results: During a mean 16 years of follow-up, 1259 (10%) participants developed dementia. Moderate or severe (vs. no) retinopathy (hazard ratio [HR], 1.86; 95% CI: 1.36, 2.55) and generalized arteriolar narrowing, measured as the central retinal arteriolar equivalent (CRAE, narrowest quartile vs. widest three quartiles), (HR, 1.26; 95% CI: 1.09, 1.45) were associated with all-cause dementia. Results did not differ by diabetes, race or APOE ε4 genotype. Retinopathy was associated with cerebrovascular-related dementia and MCI (odds ratio, 2.66; 95% CI: 1.30, 5.42). Conclusions: Retinal photography captures small vascular signs in the eye that are related to increased dementia risk. Emerging techniques, such as optical coherence tomography angiography, may have the sensitivity to provide surrogate indices of microvascular lesions relevant to dementia in older adults.

Background: Midlife vascular risk factors (MVRF) are associated with incident dementia. Similarly, amyloid β(Aβ) and neurodegeneration (e.g.brain volumes), as parts of the Alzheimer’s Disease (AD) ATN framework, are associated with cognition. Whether vascular and AD-associated factors contribute to dementia independently or interact synergistically to reduce cognitive ability is not well understood. Methods: Recruited from 3 U.S. communities, ARIC-PET participants were followed from 1987-89 (45-64 yo) through 2016-17 (74-94 yo). Cognition was evaluated in 2011-13 (ages 69-88), and twice more, every 2-3 years. In 2011-13, nondemented ARIC-PET participants had a brain MRI, with measurement of white matter hyperintensities (WMH) and brain volumes, with florbetapir (Aβ) PET scans in 2012-14; global cortical standardized uptake value ratio (SUVR) was log-transformed and standardized. Dementia was classified by expert review, as well as phone and medical record surveillance. The relative contributions of vascular risk (MVRF, WMH volume) and AD pathology (elevated Aβ SUVR, smaller AD signature region volumes) to incident dementia were evaluated with Cox proportional hazards regression. Results: In 298 individuals, 36 developed dementia. In models with key MVRF, demographics, and Aβ SUVR, hypertension and Aβ each independently predicted dementia risk (per SD of Aβ SUVR: HR 2.57, 95% CI 1.72-3.84; hypertension: HR 2.57, 95% CI 1.16-5.67), but didn’t interact on dementia risk. WMH (per SD: HR 1.51, 95% CI 1.03-2.20) and Aβ SUVR (per SD: HR 2.52, 95% CI 1.83-3.47) each contributed to incident dementia but WMH lost significance when MVRF were added to the model. Smaller AD signature regions were associated with incident dementia, independent of Aβ SUVR, and remained significant after adjustment for MVRF (HR per SD 2.18, 95% CI 1.18-4.01). Conclusions: Midlife hypertension and late-life Aβ independently contribute to dementia risk, but don’t synergize on a multiplicative scale. Neurodegeneration (e.g.smaller AD signature region volume) is also associated with incident dementia, independent of Aβ and MVRF. Multiple pathways leading to dementia should be considered when evaluating risk factors and interventions to reduce the burden of dementia.

Background: Vascular risk factors have been associated with risk of cognitive decline, with increasing evidence that midlife exposure to these risk factors may be most important in conferring late-life risk of cognitive impairment. We explored associations between vascular risk factors measured in midlife and the development of dementia over 25 years in the biracial Atherosclerosis Risk in Communities (ARIC) cohort. Methods: Participants in the ARIC study were recruited from four U.S. communities in 1987-1989, at ages 45-64, with four additional in-person visits, surveillance for hospitalizations, annual phone calls, and repeated cognitive evaluations over a 25-year period. In 2011-2013, ARIC participants were seen for the ARIC Neurocognitive Study (ARIC-NCS), and underwent a detailed neurocognitive battery and informant interviews. Through adjudicated review, dementia cases were defined. Additional dementia cases were identified through the telephone interview for cognitive status (TICS) or informant interview for those participants not attending ARIC-NCS; or by a prior dementia ICD-9 code during a hospitalization. Results: Of 15,744 participants in the cohort, 1516 cases of dementia were identified, of whom over one third were among black participants. Risk of dementia was highest in individuals of black race, with less than a high school education, older age, APOE ε4 carriage, and who, at ARIC baseline, had hypertension, diabetes, or were current smokers (table). APOE ε4 and smoking were each stronger risk factors for dementia in whites than in blacks. Discussion: Vascular risk factors measured in midlife are associated with increased risk of dementia in this biracial cohort, in black and white participants. The risk associated with diabetes nears the increased risk associated with having an APOE ε4 allele. Further studies are needed to evaluate the mechanism of and opportunities for prevention of the cognitive sequelae of these risk factors in midlife.

Background: A healthy diet may be protective against cognitive decline by mechanisms that involve improved vascular risk factors such as hypertension and dysglycemia, and reduced systemic inflammation. In this population-based study, we hypothesized that midlife diet pattern would be associated with cognitive decline over 21-years. Methods: This study included 13,603 participants in the ARIC population-based cohort recruited from four U.S. sites who were aged 45 to 64 at baseline (1987-89) when diet was measured. Participants recorded diet using a 66-item food frequency questionnaire. Two dietary patterns, called “Meat and Fried” and the “Balanced Diet”, were named after the most representative foods that emerged from constructs derived from a principal component analysis of 30 food groups. A higher diet pattern score represented greater adherence. Cognitive testing, including the digit symbol substitution, the word fluency and delayed word recall tests, were combined to a z-score at each visit (visits 2, 1990-92; 4, 1996-98 and 5, 2011-2013). Test scores for participants not attending subsequent visits were imputed using Multiple Imputation by Chained Equations to account for cohort attrition. Cognitive performance at visit 2 was compared by tertile (T) of each diet pattern. Using mixed effects models with a random slope and intercept , we determined the 21-year change in cognitive function by diet pattern tertile, adjusting for demographics and medical history. Results: At visit 2, adherence to the Meat and Fried pattern was associated with lower cognitive test scores (z-score T3: -0.172, SD 0.985; T1: 0.149, SD 0.981, p-trend <0.001). Adherence to the Balanced Diet was not associated with differences in cognitive performance (z-score T3: 0.013, SD 0.988; T1 -0.036, SD 1.001, p-trend 0.10). 21-year change in cognitive function did not differ by adherence to diet pattern with adjustments (difference of the change in z-score for Meat and Fried, T3 vs. T1: 0.02, [CI -0.05 to 0.08]; Balanced Diet T3 vs. T1: -0.03, [CI -0.09 to 0.02]). Conclusion: Although participants with a diet pattern high in meat and fried foods had lower cognition at time of first assessment, diet patterns at midlife did not carry independent associations with cognitive decline.

Introduction: Cerebral microbleed (CMB) location may predict underlying pathology. Deep CMBs are more associated with hypertensive vascular disease, while lobar CMBs are more associated with cerebral amyloid angiopathy (CAA). The objective of this study was to determine the neuroimaging pathology associated with CMBs. Methods: We analyzed 1,831 nondemented ARIC participants (mean age=76.3 ±5.3 years, 40% male, 27% black) with 3T MRI scans at the fifth exam (2011-13). We fit multinomial logistic regression models to assess the effect of brain volumes (AD signature region atrophy, total gray matter, frontal, and log 2 -transformed white matter hyperintensities (WMH) volume), infarct frequencies (lacunar, non-lacunar, and total), and APOE (number of ε4 alleles) on CMB location (no, any deep, or lobar only CMBs). Models were weighted for the sample selection scheme and adjusted for age, male, education, hypertension, ever smoking status, diabetes, race-site membership, and estimated intracranial volume (brain volume models only). Results: The frequency of CMBs was 24.1%. A larger WMH volume, greater total infarct frequency, and smaller total grey volume increased the relative risks (RR) of both deep and lobar CMBs compared to no CMBs; increasing the WMH volume also increased the RR of deep to lobar CMBs. Additional lacunar infarcts increased the RR of deep compared to no CMBs, whereas AD signature region atrophy and APOE ε4 homozygosity increased the RR of lobar CMBs. Conclusion: CMBs are a common vascular pathology in the elderly. Deep CMB presence is associated with MRI features of hypertensive small vessel disease, while lobar CMB presence is associated with MRI features of CAA and Alzheimer’s disease.

Stroke is a leading cause of the adult disability epidemic in the United States, with a major contribution from poststroke cognitive impairment and dementia (PSCID), the rates of which are disproportionally high among the health disparity populations. Despite the PSCID’s overwhelming impact on public health, a knowledge gap exists with regard to the complex interaction between the acute stroke event and highly prevalent preexisting brain pathology related to cerebrovascular and Alzheimer disease or related dementia. Understanding the factors that modulate PSCID risk in relation to index stroke event is critically important for developing personalized prognostication of PSCID, targeted interventions to prevent it, and for informing future clinical trial design. The DISCOVERY study (Determinants of Incident Stroke Cognitive Outcomes and Vascular Effects on Recovery), a collaborative network of thirty clinical performance clinical sites with access to acute stroke populations and the expertise and capacity for systematic assessment of PSCID will address this critical challenge. DISCOVERY is a prospective, multicenter, observational, nested-cohort study of 8000 nondemented ischemic and hemorrhagic stroke patients enrolled at the time of index stroke and followed for a minimum of 2 years, with serial cognitive evaluations and assessments of functional outcome, with subsets undergoing research magnetic resonance imaging and positron emission tomography and comprehensive genetic/genomic and fluid biomarker testing. The overall scientific objective of this study is to elucidate mechanisms of brain resilience and susceptibility to PSCID in diverse US populations based on complex interplay between life-course exposure to multiple vascular risk factors, preexisting burden of microvascular and neurodegenerative pathology, the effect of strategic acute stroke lesions, and the mediating effect of genomic and epigenomic variation.

Background: Periodontal disease (PD) is associated positively with neurocognitive outcomes. Few studies have investigated the relationship between PD and indicators of brain aging and vascular changes. Hypothesis: PD is associated with greater cerebral small vessel disease, lower total and regional brain volumes and elevated β-amyloid (Aβ) deposition. Methods: We included 6,793 participants who received full-mouth periodontal examinations and tooth counts at Visit 4 (1996-1998) of the Atherosclerosis Risk in Communities Study. We used a modified 3-level version of the Periodontal Profile Class to categorize PD based on severity and extent of gingival inflammation and tissue loss. Among participants who attended Visit 5 (2011-2013), n=1,306 received a brain MRI and n=248 received a PET scan. Total brain volume, Alzheimer’s disease signature volume, and presence of microhemorrhages and cerebral infarctions were ascertained via 3T MRI; Aβ deposition was assessed from PET. We regressed brain volumes on baseline PD status using weighted multivariable linear regression. Presence of cerebrovascular microhemorrhages, infarctions, or elevated Aβ (standardized uptake value ratio>1.2) were regressed on PD category using logistic models. We examined the interaction between Apolipoprotein E ε4 ( APOE ) allele possession and PD categories on the Aβ outcome. Results: Prevalence of baseline periodontal disease was 73% (959/1306) and 87% (206/248) among the MRI and PET subgroups, respectively. PD was not associated with volumetric brain measures nor microhemorrhages. PD was inversely associated with the odds of subcortical and lacunar infarctions. PD and Aβ were not associated in main effect or interaction analyses, although there was a notably stronger association among carriers of APOE . Conclusion: PD was not associated with altered brain structure, cerebral microhemorrhages or elevated Aβ deposition. Counter to the hypothesis, PD and complete tooth loss were inversely associated with cerebral infarctions.