Koton, Silvia

Abstract INTRODUCTION Understanding comorbidities’ combined impacts on dementia risk may offer a more comprehensive understanding of individuals’ risk. Using machine‐learning, we grouped individuals with similar midlife risk profiles into clusters and explored associations with dementia risk. METHODS Participants without dementia at baseline (1987–1989) from the prospective Atherosclerosis Risk in Communities (ARIC) study were included (ages 45–64 years; N = 15,250). Using unsupervised hierarchical cluster analysis, nine clusters were created and defined based on 14 midlife morbidities. The associations with incident dementia ( N = 3272 cases, median follow‐up 25 years) and deaths ( N = 9099) were evaluated using time‐to‐event regression models. RESULTS Compared with the healthiest cluster (Cluster 1), Clusters 2 (smoking) (hazard ratio [HR](95% confidence interval [CI]) = 1.62 (1.08, 2.43)), 5 (obesity, diabetes, hypertension, and hypertriglyceridemia) (HR(95%CI) = 1.91 (1.35,2.70)), and 7/8 (atrial fibrillation/heart failure) (HR(95%CI) = 2.69 (1.59,4.57)) were associated with dementia. Accounting for competing risk of death in the Fine‐Gray subdistribution model negated the cluster‐dementia association. DISCUSSION Midlife morbidity clusters are important for dementia and mortality risk.

Background: Stroke is a leading cause of death and disability despite advances in risk factor management. Many risk factors for stroke have also been implicated as risk factors for mild cognitive impairment (MCI) and dementia. Given these shared risk factors, cognitive impairment (CI) may represent an accumulation of neurological injury that is associated with an elevated risk of stroke. In ARIC-NCS, we aimed to 1) understand the independent relationship between pre-stroke CI (MCI or Dementia) and incident stroke; 2) explore mortality differences in stroke patients with vs without pre-stroke CI; and 3) evaluate modifiers of these relationships. Methods: 5434 stroke-free participants were evaluated for cognitive status at an in-person visit in 2011-13 (visit 5; ages 66-90), based on cognitive testing and informant interviews. Incident definite or probable strokes (ischemic or hemorrhagic) from visit 5 through 2022 were identified via ongoing surveillance (semi-annual telephone calls, with expert classification). Using Cox proportional hazards regression models adjusted for demographics and vascular risk factors, we evaluated associations between CI (MCI or dementia) and incident stroke, and between CI and death among individuals with stroke. Finally, we tested effect modification by age at visit 5, sex, education, and race, via stratified models and formal interaction terms. Results: Compared to those without CI, individuals with CI (23%) were older (77 vs 75 years, p<0.001), and more frequently male (48% vs 40%). Over 10+ years, CI was independently associated with an increased risk of incident stroke (HR:1.52, 95% CI:1.18-1.96). Among individuals with stroke, risk of death was also higher in CI vs non-CI patients (HR 1.78, 95% CI 1.27-2.50). In stratified analysis, we found a significant interaction by sex (p-interaction=0.04): in males, CI was associated with elevated stroke risk (HR:2.01, 95% CI:1.39-2.91) without a similar risk in females (HR:1.22, 95% CI:0.85-1.75). Interactions by race, age, and educational level were not statistically significant, but effect sizes were qualitatively larger in White participants and individuals with more education. Conclusion: CI is associated with incident stroke independent of shared risk factors, especially in men. This work adds to our understanding of populations at risk for stroke, thus aiding efforts to optimize stroke prevention in at-risk populations.

AbstractBackgroundWeakened white matter (WM) integrity is highly associated with dementia risk. Still, not everyone with WM changes develops dementia, suggesting the important role modifiable lifestyle factors may have in reducing dementia risk. We investigated how social relationships in mid‐life may modify the association between WM integrity and incident dementia risk within race and sex subgroups.MethodIn 1,679 Atherosclerosis Risk in Community (ARIC) study participants who were dementia‐free in mid‐life, psychosocial health was assessed via self‐reported questionnaires and participants were classified as having strong or poor social relationships in mid‐life (visit 2: 1990‐1992). Through diffusion tensor imaging, WM integrity was evaluated with 3T brain MRI (visit 5: 2011 – 2013); fractional anisotropy (FA) and mean diffusivity (MD) were estimated. Incident dementia cases were identified from visit 5 through December 31, 2019, with ongoing surveillance. Relative contributions of social relationships and WM integrity to incident dementia were evaluated in Cox‐proportional hazard regression models with race and race‐sex as interaction terms, and in stratified models (White Females, Black Females, White Males, Black Males).ResultSignificant three‐way interactions were observed between race, WM integrity, and mid‐life social relationships (p‐interaction<0.01). In Black participants with strong mid‐life social relationships, higher MD (hazard ratio (HR): 0.93, 95% CI: 0.63 – 1.38) and lower FA (HR: 1.25, 95% CI: 0.84 – 1.86) were not associated with the risk of dementia, although in Black participants with poor social relationships, higher MD remained a significant risk factor for dementia. However, across all White participants, higher MD and lower FA were associated with the risk of dementia, regardless of mid‐life social relationships (Table 1; Figure 1). Analysis of three‐way interactions between race‐sex, WM integrity, and mid‐life social relationships suggested that effect modification by mid‐life social relationships was most evident in Black Females, respective to other groups (Table 2; Figure 1).ConclusionThe contribution of WM integrity to dementia risk may be lower in Black participants with strong social relationships in mid‐life, particularly in Black Females. Further understanding of how contextual social factors may influence brain health in diverse populations should be examined in future studies and intervention efforts.

AbstractBackgroundWeakened white matter (WM) integrity is highly associated with dementia risk. Still, not everyone with WM changes develops dementia, suggesting the important role modifiable lifestyle factors may have in reducing dementia risk. We investigated how social relationships in mid‐life may modify the association between WM integrity and incident dementia risk within race and sex subgroups.MethodIn 1,679 Atherosclerosis Risk in Community (ARIC) study participants who were dementia‐free in mid‐life, psychosocial health was assessed via self‐reported questionnaires and participants were classified as having strong or poor social relationships in mid‐life (visit 2: 1990‐1992). Through diffusion tensor imaging, WM integrity was evaluated with 3T brain MRI (visit 5: 2011 – 2013); fractional anisotropy (FA) and mean diffusivity (MD) were estimated. Incident dementia cases were identified from visit 5 through December 31, 2019, with ongoing surveillance. Relative contributions of social relationships and WM integrity to incident dementia were evaluated in Cox‐proportional hazard regression models with race and race‐sex as interaction terms, and in stratified models (White Females, Black Females, White Males, Black Males).ResultSignificant three‐way interactions were observed between race, WM integrity, and mid‐life social relationships (p‐interaction<0.01). In Black participants with strong mid‐life social relationships, higher MD (hazard ratio (HR): 0.93, 95% CI: 0.63 – 1.38) and lower FA (HR: 1.25, 95% CI: 0.84 – 1.86) were not associated with the risk of dementia, although in Black participants with poor social relationships, higher MD remained a significant risk factor for dementia. However, across all White participants, higher MD and lower FA were associated with the risk of dementia, regardless of mid‐life social relationships (Table 1; Figure 1). Analysis of three‐way interactions between race‐sex, WM integrity, and mid‐life social relationships suggested that effect modification by mid‐life social relationships was most evident in Black Females, respective to other groups (Table 2; Figure 1).ConclusionThe contribution of WM integrity to dementia risk may be lower in Black participants with strong social relationships in mid‐life, particularly in Black Females. Further understanding of how contextual social factors may influence brain health in diverse populations should be examined in future studies and intervention efforts.

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.

AbstractINTRODUCTIONThis study aimed to assess whether social relationships in mid‐life reduce the risk of dementia related to amyloid burden.METHODSParticipants in the Atherosclerosis Risk in Communities (ARIC) study were assessed for social support and isolation (visit 2; 1990–1992). A composite measure, “social relationships,” was generated. Brain amyloid was evaluated with florbetapir positron emission tomography (PET); (visit 5; 2012–2014). Incident dementia cases were identified following visit 5 through 2019 using ongoing surveillance. Relative contributions of mid‐life social relationships and elevated brain amyloid to incident dementia were evaluated with Cox regression models.RESULTSAmong 310 participants without dementia, strong mid‐life social relationships were associated independently with lower dementia risk. Elevated late‐life brain amyloid was associated with greater dementia risk.DISCUSSIONAlthough mid‐life social relationships did not moderate the relationship between amyloid burden and dementia, these findings affirm the importance of strong social relationships as a potentially protective factor against dementia.

AbstractBackgroundAlthough amyloid deposition in the brain is often associated with subsequent dementia risk, not everyone with brain amyloid will develop dementia. This discrepancy illustrates the potential importance that risk factors and lived experiences may have in modifying this association. Compared to participants with low social engagement (SE) in mid‐life, we hypothesized that participants with high mid‐life SE will show a weaker association between amyloid burden and incident dementia.MethodWe included data from 310 non‐demented participants of the Atherosclerosis Risk in Communities (ARIC)‐PET study. Social support and isolation were assessed via interviewer‐administered questionnaires (Visit 2; 1990 – 1992). Based upon categorization of both factors, participants were classified as having high, intermediate, or low mid‐life SE (Table 1). Brain amyloid was evaluated with florbetapir PET (Visit 5; 2011‐2014). Elevated amyloid burden was defined as standardized uptake value ratio (SUVR) >1.2 in the global cortex. Incident dementia cases were identified from visit 5 through 2019 through ongoing surveillance utilizing in‐person neurocognitive testing, informant interviews, and hospitalization codes. Relative contributions of mid‐life SE and elevated florbetapir SUVR to incident dementia, independently and with multiplicative interaction terms, were evaluated with Cox regression models, adjusted for demographics, APOEε4 and vascular risk factorsResultAmong 310 participants, 48 developed dementia (median follow‐up: 4.7 years). Mid‐life SE and elevated SUVR each independently predicted dementia risk but did not interact on a multiplicative scale. Participants with high or intermediate mid‐life SE, relative to low mid‐life SE, were less likely to develop dementia (Table 2). Although the interaction between mid‐life SE and elevated SUVR was not significant, stratified models suggested a stronger association between amyloid burden and dementia in participants with high mid‐life SE (Table 3).ConclusionGreater mid‐life SE was associated with lower odds of developing dementia, independent of elevated SUVR. Although protective, there was no strong evidence for effect modification of mid‐life SE on the association between amyloid and dementia risk. Future longitudinal studies evaluating the potential influence of social factors measured throughout the life course are needed to inform our understanding as to what factors may preserve cognition in the presence of elevated brain pathology.

AbstractBackgroundAlthough amyloid deposition in the brain is often associated with subsequent dementia risk, not everyone with brain amyloid will develop dementia. This discrepancy illustrates the potential importance that risk factors and lived experiences may have in modifying this association. Compared to participants with low social engagement (SE) in mid‐life, we hypothesized that participants with high mid‐life SE will show a weaker association between amyloid burden and incident dementia.MethodWe included data from 310 non‐demented participants of the Atherosclerosis Risk in Communities (ARIC)‐PET study. Social support and isolation were assessed via interviewer‐administered questionnaires (Visit 2; 1990 – 1992). Based upon categorization of both factors, participants were classified as having high, intermediate, or low mid‐life SE (Table 1). Brain amyloid was evaluated with florbetapir PET (Visit 5; 2011‐2014). Elevated amyloid burden was defined as standardized uptake value ratio (SUVR) >1.2 in the global cortex. Incident dementia cases were identified from visit 5 through 2019 through ongoing surveillance utilizing in‐person neurocognitive testing, informant interviews, and hospitalization codes. Relative contributions of mid‐life SE and elevated florbetapir SUVR to incident dementia, independently and with multiplicative interaction terms, were evaluated with Cox regression models, adjusted for demographics, APOEe4 and vascular risk factorsResultAmong 310 participants, 48 developed dementia (median follow‐up: 4.7 years). Mid‐life SE and elevated SUVR each independently predicted dementia risk but did not interact on a multiplicative scale. Participants with high or intermediate mid‐life SE, relative to low mid‐life SE, were less likely to develop dementia (Table 2). Although the interaction between mid‐life SE and elevated SUVR was not significant, stratified models suggested a stronger association between amyloid burden and dementia in participants with high mid‐life SE (Table 3).ConclusionGreater mid‐life SE was associated with lower odds of developing dementia, independent of elevated SUVR. Although protective, there was no strong evidence for effect modification of mid‐life SE on the association between amyloid and dementia risk. Future longitudinal studies evaluating the potential influence of social factors measured throughout the life course are needed to inform our understanding as to what factors may preserve cognition in the presence of elevated brain pathology.

Background: Ischemic Stroke (IS) is associated with an increased risk of dementia, but the relative contribution of IS severity or recurrence to cognition is not known. We aimed to determine the risk of dementia after incident IS and how it varies by stroke severity and recurrence in the Atherosclerosis Risk in Communities (ARIC) study. Methods: 15,405 ARIC participants free of stroke and dementia at baseline (1987-9) were followed for IS and dementia through 2019. Incident and recurrent IS were classified by expert review of hospital records, with stroke severity by the National Institutes of Health Stroke Scale (NIHSS) classified as NIHSS≤5, 6-10, 11-15, ≥16. Dementia cases were adjudicated through expert review of in-person evaluations, informant interviews, phone assessments, hospitalization code or death certificates. Poisson regression models with robust error variance were used to estimate dementia incidence in participants with and without IS, and associations between time-dependent IS incidence (excluding dementia in the first year after stroke), frequency and severity, and dementia were studied with Cox proportional hazards models, adjusting for demographics, APOE ε4 and vascular risk factors . Results: 1151 IS (970 incident) and 2807 dementia cases were identified. NIHSS was available for 877 IS (76%). Adjusted incidence rates (95% CI) of dementia per 100 person-years were 0.45 (0.42-0.49) in participants without IS vs. 1.33 (1.15-1.55) in those with IS. Compared to no IS, risk of dementia (adjusted HR, 95% CI) increased with IS number and severity from 1.71 (1.47-1.99) for participants with one IS to 6.68 (3.58-12.46) for those with ≥3 events, and from 1.64 (1.36-1.98) for NIHSS≤5 to 4.43 (1.84-10.68) for NIHSS≥16 ( Table ). Conclusion: Risk of dementia is significantly increased after stroke, independent of vascular risk factors. These data suggest a dose-response relationship between number of stroke events and stroke severity, and risk of dementia.