Griswold, Michael

Objectives: Determine relationships between calcification and cognitive function. Background: Dementia affects over 5.4 million Americans; prevalence will quadruple in the next 50 years. Coronary artery calcification (CAC), a measure of subclinical atherosclerosis, may affect cognitive function through microvascular brain effects. Abdominal aortoiliac calcification (AAC) generally precedes CAC and may provide earlier risk determination. Effects of calcification on cognition have not been studied in African Americans (AA). Methods: The 2008-2011 GENOA CAC cohort consists of AA sibships (n=657, mean age 69 [range 40-98], 74% women, 82% hypertensive) enriched with hypertension from Jackson, MS with computed tomography (CT) Agatston calcification measures. Cognition was assessed in 4 domains: global cognitive function (Mini-Mental State Examination); processing speed (Digit Symbol Substitution and Trail Making A); memory (RAVLT and WAIS-III Incidental Learning); and executive function (Trail Making B). Relationships of cognition (standardized) and calcification (log base 2 scale accounting for skewness) were examined using linear regressions with GEE to account for sibship clustering, adjusting parsimoniously for age, sex, and education. Results: Doublings of CAC were significantly associated with poorer processing speed (ß=-0.049 [-0.072, -0.025] p=0.000) and executive function (ß=-0.037 [-0.070, -0.003] p=0.031) in younger subjects and with poorer global function (ß=-0.0648 [-0.096, -0.020] p=0.000), memory (ß=-0.034 [-0.060, -0.007] p=0.013), and processing speed (ß=-0.051 [-0.076, -0.025] p=0.000) in older subjects. Doublings of AAC were significantly associated with poorer processing speed (ß=-0.0381 [-0.056, -0.020] p=0.000) and executive function (ß=-0.045 [-0.070, -0.020] p=0.000) in younger subjects and poorer processing speed (ß=-0.050 [-0.075, -0.025] p=0.000) in older subjects. Conclusions: Calcification is associated with processing speed in young and old AA with prevalent cardiovascular risk factors and may be differentially associated with other cognitive domains by age. Processing speed in particular may be a domain affected early in the calcification process, warranting further study. This supports existing literature addressing the relationship between calcification and cognitive function in ethnically diverse cohorts. Further studies can focus on the temporal and causal relationships between calcification and cognition across age in AA samples enriched for hypertension to identify predictive factors associated with future cognitive decline.

Background: Compared to those with natural nocturnal blood pressure (BP) decreases, those lacking nocturnal BP decreases (“non-dippers”) are at greater risk of cardiovascular disease (CVD). Substantial evidence also supports a role of chronic systemic inflammation in the pathogenesis of CVD. The purpose of this study was to examine associations of markers of inflammation with two common definitions of BP dipping status using 24-hour ambulatory blood pressure (AMBP) readings. Methods: AMBP monitoring and assays of C-reactive protein (CRP), interleukin-6 (IL-6), e-selectin, tissue inhibitor of metalloproteinase-2 (TIMP-2), and a selection of thirteen other inflammatory-pathway biomarkers were performed in 722 participants (mean age 64 [range 42-83] years, 36% men, 39% black, 83% hypertensive) in the Genetic Epidemiology Network of Arteriopathy (GENOA) Study (2001-2004). Non-dippers were classified using two common definitions: (1) nocturnal systolic and diastolic BP both decreased by <10% compared to daytime values [“dual non-dippers”, n=161 (22%)], and (2) nocturnal SBP decreased by <10% [“systolic non-dippers”, n=380 (53%)]. Logistic regressions, fit with generalized estimating equations to account for sibship clustering, yielded odds ratios (OR) of dipping status for log-transformed inflammatory biomarkers, adjusted for age, race, and sex. Results: IL-6 (range 0-37 pg/ml) was associated with dual non-dipping status (OR=1.55 [95%CI: 1.03, 2.32] p=0.035), translating into a 55% increase in the likelihood of being a dual non-dipper for every approximate doubling of IL-6. IL-6 (OR=1.63 [1.13, 2.35] p=0.009) and CRP (OR=1.35 [1.08,1.68] p=0.008) overall, as well as e-selectin (OR=0.49 [0.28, 0.87] p=0.014) and TIMP-2 (OR=0.54 [0.30,0.98] p=0.041) in hypertensive subjects were associated with systolic non-dipping status. Conclusions: These results suggest that non-dipping classification should be approached with prudence, as the two different criteria may influence conclusions about predictive marker associations. In addition, markers involved in direct versus inhibitory inflammation pathways may operate differentially across patient subgroups. Our findings support the link between inflammation and non-dipping circadian BP patterns and provide novel information on markers and definitions which may be useful for early detection and subsequent prevention of CVD.

Introduction: Impairment in the sense of smell is associated with plaques and tangles in the olfactory region of the brain, which connects to the hippocampus where neuropathologic changes related to mild cognitive impairment (MCI) and dementia due to Alzheimer’s disease are first sited. Olfactory impairments may thus be a marker for poor cognitive function and MCI. We assessed olfaction and cognitive function in 6055 White and Black men and women aged 60-99 years. Methods: Sense of smell was measured in ARIC-NCS participants (2011-2013) by the 12-item Sniffin’ Sticks screening test (score range: 0-12, median: 10). A clinically validated threshold (smell score <6) defined olfactory impairment (OI). A multidimensional neuropsychological assessment (10 tests) ascertained performance in domains of memory, language, executive function/processing speed, and global cognition. For relative comparisons across the tests, raw cognitive test scores were standardized to z scores and averaged to yield domain scores. Following review of neuropsychological assessments, medical history, cerebral magnetic resonance imaging, and physical examinations, MCI was classified by a neurologist and neuropsychologist, and adjudicated by a third reviewer. Multivariable linear regression estimated the mean difference in domain-specific z scores among participants with and without OI. Logistic regression was used to quantify the prevalence odds of MCI in participants with vs. those without OI. Models were adjusted for age, sex, race, education, ARIC study center, hypertension, diabetes, smoking, and ApoE4. Race and sex were explored as effect modifiers. Results: The participants’ mean age was 76 years; 41% were male and 23% Black. The prevalence of olfactory impairment was 14%. Compared to participants with no OI, those with OI had a statistically significantly lower mean z score across all cognitive domains [memory: Beta= -0.37 (95% confidence interval [CI]: -0.45, -0.30); language: Beta= -0.39 (95% CI: -0.46, -0.33); executive function/processing speed: Beta= -0.24 (95% CI: -0.32, -0.17); global cognition: Beta= -0.34 (95% CI: -0.41, -0.26). Effect modification by race was observed in the domain of language. Blacks with OI had a greater mean difference in language z score compared to Blacks without OI (Beta= -0.57 (95% CI: -0.70, -0.44)). OI was associated with MCI in Whites, but not Blacks: white participants with OI had greater odds of MCI (Odds Ratio [OR] =1.76, 95% CI: 1.40, 2.21). Sex did not modify these associations. Conclusions: Compared to average cognitive aging (annual rate of decline of 0.04-0.05 standard deviation units/year) relatively large differences in standardized cognitive domain scores are observed between those with and without olfactory impairment among older adults. An impaired sense of smell may serve as a readily accessible early marker of neurodegeneration.

Introduction: Small vessel disease is associated with decreased cognitive function, possibly differential by race. Age-related central arterial stiffening increases pulsatility resulting in hypoperfusion, microvascular damage and remodeling in the brain, potentially impairing cognition. We examined if arterial stiffness and pressure amplification are associated with lacunar infarcts and greater volumes of white matter hyperintensities (WMH) in a sample of Caucasian and African American (AA) older adults. Methods: We analyzed a cross-sectional sample of ARIC participants aged 67-90 years (n=1486) from visit 5 (2011-2013), with brain magnetic resonance imaging (MRI). The Omron VP-1000 Plus was used to measure aortic stiffness (carotid-femoral pulse wave velocity [cfPWV]) and pressure amplification measures (pulse pressure amplification [PPA], central pulse pressure [cPP], and estimated central systolic blood pressure [cSBP]). Aortic stiffness and pressure amplification were dichotomized at race-specific 25th percentile cut points. Brain MRI using 3D-1.5T equipment quantified the presence of lacunar infarcts and volumes of WMH following a standardized protocol. Logistic regression, adjusted for age, sex, education, ApoE4, heart rate, smoking and body mass index, was used to quantify the odds of lacunar infarcts in participants with high vs. low cfPWV, cPP, cSBP, and low vs. high PPA. Linear regression models, additionally adjusted for intracranial volume, estimated the difference in log-transformed volumes of WMH among participants with high vs. low cfPWV, cPP, cSBP, and low vs. high PPA. Probability sampling weights for an MRI were included to allow for generalizability to the full visit 5 cohort. Results: Among the 1486 participants with a brain MRI (mean age: 76, 41% male, 26% AA), measures of aortic stiffness and pressure amplification were associated with lacunar infarcts in Caucasians, but not in AAs. Caucasian participants with a high cfPWV had greater odds of lacunar infarcts (Odds Ratio [OR] =2.02, 95% confidence interval [CI]: 1.23, 2.20). Caucasians with high cSBP had higher odds of lacunar infarcts (OR=1.72, 95% CI: 1.10, 2.69). In Caucasians, high cfPWV was associated with a 21% (95% CI: 6, 38) greater volume of WMH as compared to a low cfPWV; high cSBP was associated with a 28% (95% CI: 14, 45) greater volume of WMH compared to a low cSBP. In AAs, high cfPWV was associated with a 32% (95% CI: 7, 62) greater volume of WMH as compared to low cfPWV. Cerebral microvascular imaging markers did not differ quantitatively with measures of PPA and cPP. Conclusions: Central arterial stiffening and pressure amplification are plausible microvascular contributors to cognitive aging, providing new information on modifiable pathways for previously observed associations between cardiovascular disease risk factors and the rates of cognitive decline and dementia among older adults.

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.

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.

Background Antiplatelets, anticoagulants, and statins are commonly prescribed for various indications. The associations between these medications and the risk of intracerebral hemorrhage (ICH) and cerebral microbleeds (CMBs) are unclear. Methods and Results We performed a retrospective study of the ARIC (Atherosclerosis Risk in Communities) study cohort, recruited from 4 US communities in 1987 to 1989 with follow‐up. In 2011 to 2013, a subset (N=1942) underwent brain magnetic resonance imaging with CMB evaluation. Time‐varying and any antiplatelet, anticoagulant, or statin use was evaluated at subsequent study visits in participants not on each medication at baseline. To determine the hazard of ICH and odds of CMB by medication use, logistic and Cox proportional hazard models were built, respectively, adjusting for the propensity to take the medication, concomitant use of other medications, and cognitive, genetic, and radiographic data. Of 15 719 individuals during up to 20 years of follow‐up, 130 participants experienced an ICH. The adjusted hazard of ICH was significantly lower among participants taking an antiplatelet at the most recent study visit before ICH versus nonusers (hazard ratio [HR], 0.53; 95% CI, 0.30–0.92). Statin users had a significantly lower hazard of an ICH compared with nonusers (adjusted HR, 0.13; 95% CI, 0.05–0.34). There was no association of CMB and antiplatelet, anticoagulant, or statin use in adjusted models. Conclusions In this US community‐based study, antiplatelet and statin use were associated with lower ICH hazard, whereas no association was noted between CMBs and antiplatelets, anticoagulants, and statins. Further study is needed to understand the differential roles of these medications in cerebral microhemorrhages and macrohemorrhages.

Abstract Few studies examined race-regional influences on mild cognitive impairment (MCI) and dementia risk factors. We examined 14 risk factors in 5 race-regions, e.g. cross-sectional age- and sex-adjusted relative prevalence ratios (RPR) from multinomial regression comparing associations of low education (&lt;12yrs) with MCI and dementia (versus normal cognition) across 3 race-region groups, average age 76yrs: whites in the Mayo Clinic Study of Aging[MCSA, Olmsted County, MN—MCSA-MN-Whites); Atherosclerosis Risk in Communities(ARIC) whites in suburban Minneapolis, MN—ARIC-MN-Whites); ARIC-African Americans in Jackson, MS—ARIC-MS-AA. Among 3,787 MCSA-Whites, low education exerted a 2-fold risk for MCI, RPR=2.09(95%CI: 1.57,2.78). Conversely, low education was not a supported MCI risk factor for ARIC-MN-Whites (n=1,901—RPR=0.63(0.31,1.28) or ARIC-MS-AA, (n=1,416—RPR=.0.81 (0.60,1.10)), with substantially differential race-region effects. Low education RPRs for dementia also differed by race-region: RPR=4.43(2.68,7.31-MCSA-MN-W), RPR=0.70 (0.16,2.99-ARIC-MN-Whites), and RPR=2.54 (1.74,3.72-ARIC-MS-AA). Understanding why risk factors differ by race and region likely requires diverse samples and harmonized methods using culturally-appropriate assessments.

Abstract Plasma-based biomarkers of amyloid beta (Aβ), a neuropathological hallmark of Alzheimer’s disease, show promise in predicting cognitive impairment and mapping onto cerebral amyloidosis, but little is known about how midlife plasma Aβ associates with late-life cognitive outcomes. Midlife plasma variants Aβ42 and Aβ40 were measured using a fluorimetric bead-based immunoassay in a subsample of visit 3 ARIC participants (1993-95; n=2585, mean age=59.4±5.2, 57% female, 23% African American). We investigated the relationship between midlife plasma Aβ and late-life mild cognitive impairment (MCI; n=923) and dementia (n=628) diagnosed from 2011-19. Multinomial logistic regressions estimated relative risk ratios (RRR) of MCI, dementia, and death vs normal cognitive status as a function of:(1) Aβ42:Aβ40 ratio, (2) Aβ42 and Aβ40 included as separate terms, and (3) Protected Aβ group (participants with Aβ42≥46 pg/ml and Aβ40 &lt;233 pg/ml). Adjusters included age, sex, education, site-race, and APOE4. Every doubling of midlife plasma Aβ42:Aβ40 up to a threshold of 0.20 was associated with 41% lower risk of developing MCI/dementia in comparison to cognitively normal (RRR=0.59 [95% CI:0.42, 0.82]), with no association for ratio values ≥0.20. Every standard deviation increase in plasma Aβ42 was associated with 17% lower risk of dementia (RRR=0.83 [0.70, 0.99]), whereas every standard deviation increase in plasma Aβ40 was associated with 16% higher risk of MCI (RRR=1.16 [1.02, 1.31]). The protected midlife plasma Aβ group had 86% lower risk of late-life dementia vs all others (RRR=0.14 [0.04, 0.47]). Early measurement of plasma Aβ may prove an accessible and effective population screener for future cognitive impairment.

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.