Pathways explaining racial/ethnic and socio-economic disparities in brain white matter integrity outcomes in the UK Biobank study

Pathways explaining racial/ethnic and socio-economic status (SES) disparities in white matter integrity (WMI) reflecting brain health, remain underexplored, particularly in the UK population. We examined racial/ethnic and SES disparities in diffusion tensor brain magnetic resonance imaging (dMRI) markers, namely global and tract-specific mean fractional anisotropy (FA), and tested total, direct and indirect effects through lifestyle, health-related and cognition factors using a structural equations modeling approach among 36,184 UK Biobank participants aged 40-70 y at baseline assessment (47% men). Multiple linear regression models were conducted, testing independent associations of race/ethnicity, socio-economic and other downstream factors in relation to global mean FA, while stratifying by Alzheimer's Disease polygenic Risk Score (AD PRS) tertiles. Race (Non-White vs. White) and lower SES predicted poorer WMI (i.e. lower global mean FA) at follow-up, with racial/ethnic disparities in FAmean involving multiple pathways and SES playing a central role in those pathways. Mediational patterns differed across tract-specific FA outcomes, with SES-FAmean total effect being partially mediated (41% of total effect = indirect effect). Furthermore, the association of poor cognition with FAmean was markedly stronger in the two uppermost AD PRS tertiles compared to the lower tertile (T2 and T3: β±SE: -0.0009 ± 0.0001 vs. T1: β±SE: -0.0005 ± 0.0001, P < 0.001), independently of potentially confounding factors. Race and lower SES were generally important determinants of adverse WMI outcomes, with partial mediation of socio-economic disparities in global mean FA through lifestyle, health-related and cognition factors. The association of poor cognition with lower global mean FA was stronger at higher AD polygenic risk.

Helicobacter pylori, persistent infection burden and structural brain imaging markers

Persistent infections, whether viral, bacterial or parasitic, including Helicobacter pylori infection, have been implicated in non-communicable diseases, including dementia and other neurodegenerative diseases. In this cross-sectional study, data on 635 cognitively normal participants from the UK Biobank study (2006-21, age range: 40-70 years) were used to examine whether H. pylori seropositivity (e.g. presence of antibodies), serointensities of five H. pylori antigens and a measure of total persistent infection burden were associated with selected brain volumetric structural MRI (total, white, grey matter, frontal grey matter (left/right), white matter hyperintensity as percent intracranial volume and bi-lateral sub-cortical volumes) and diffusion-weighted MRI measures (global and tract-specific bi-lateral fractional anisotropy and mean diffusivity), after an average 9-10 years of lag time. Persistent infection burden was calculated as a cumulative score of seropositivity for over 20 different pathogens. Multivariable-adjusted linear regression analyses were conducted, whereby selected potential confounders (all measures) and intracranial volume (sub-cortical volumes) were adjusted, with stratification by Alzheimer's disease polygenic risk score tertile when exposures were H. pylori antigen serointensities. Type I error was adjusted to 0.007. We report little evidence of an association between H. pylori seropositivity and persistent infection burden with various volumetric outcomes (P > 0.007, from multivariable regression models), unlike previously reported in past research. However, H. pylori antigen serointensities, particularly immunoglobulin G against the vacuolating cytotoxin A, GroEL and outer membrane protein antigens, were associated with poorer tract-specific white matter integrity (P < 0.007), with outer membrane protein serointensity linked to worse outcomes in cognition-related tracts such as the external capsule, the anterior limb of the internal capsule and the cingulum, specifically at low Alzheimer's disease polygenic risk. Vacuolating cytotoxin A serointensity was associated with greater white matter hyperintensity volume among individuals with mid-level Alzheimer's disease polygenic risk, while among individuals with the highest Alzheimer's disease polygenic risk, the urease serointensity was consistently associated with reduced bi-lateral caudate volumes and the vacuolating cytotoxin A serointensity was linked to reduced right putamen volume (P < 0.007). Outer membrane protein and urease were associated with larger sub-cortical volumes (e.g. left putamen and right nucleus accumbens) at middle Alzheimer's disease polygenic risk levels (P < 0.007). Our results shed light on the relationship between H. pylori seropositivity, H. pylori antigen levels and persistent infection burden with brain volumetric structural measures. These data are important given the links between infectious agents and neurodegenerative diseases, including Alzheimer's disease, and can be used for the development of drugs and preventive interventions that would reduce the burden of those diseases.

Growth Differentiation Factor 15 and Diet Quality Trajectory Interact to Determine Frailty Incidence among Middle-Aged Urban Adults

BACKGROUND

Elevated plasma growth differentiation factor 15 (GDF15) and poor diet quality may be associated with increased frailty incidence, although their interactive associations have not been assessed in urban middle-aged adults.

OBJECTIVES

We aimed to examine GDF15 and its interactive association with diet quality in relation to frailty incidence among a sample of middle-aged urban adults.

METHODS

The relationship between GDF15 and diet quality trajectories in relation to incident frailty was examined in a longitudinal study of participants in the Healthy Aging in Neighborhoods of Diversity across the Life Span (2004-2017). Serum GDF15 concentration and frailty incidence were primary exposure and outcome, respectively. Group-based trajectory models were used to assess diet quality trajectories (≤3 visits/participant, N = 945, N' = 2247 observations) using the Healthy Eating Index 2010 version (HEI-2010), Dietary Inflammatory Index, and mean adequacy ratio (MAR). Cox proportional hazards models were used, testing interactive associations of GDF15 and diet quality trajectories with frail/prefrail incidence (N = 400 frailty-free at first visit, N' = 604 observations, n = 168 incident frail/prefrail).

RESULTS

Both elevated GDF15 and lower diet quality trajectories were associated with a lower probability of remaining nonfrail (≤13 y follow-up). Among females, the "high diet quality" HEI-2010 trajectory had a hazard ratio (HR) of 0.15 [95% confidence interval (CI): 0.04, 0.54; P = 0.004; fully adjusted model] when compared with the "low diet quality" trajectory group. Among males only, there was an antagonistic interaction between lower HEI-2010 trajectory and elevated GDF15. Specifically, the HR for GDF15-frailty in the higher diet quality trajectory group (high/medium combined), and among males, was 2.69 (95% CI: 1.06, 6.62; P = 0.032), whereas among the lower diet quality trajectory group, the HR was 0.94 (95% CI: 0.49, 1.80; P = 0.86). Elevated GDF15 was independently associated with frailty among African American adults.

CONCLUSIONS

Pending replication, we found an antagonistic interaction between GDF15 and HEI-2010 trajectory in relation to frailty incidence among males.

Negative aging stereotypes in U.S. military veterans: results from the National Health and Resilience in Veterans Study

U.S. military veterans are an average 20 years older than non-veterans and have elevated rates of certain health conditions. While negative aging stereotypes have been linked to increased risk for various health conditions, little is known about the prevalence and correlates of these stereotypes in this population. Using data from a nationally representative sample of 4,069 U.S. veterans surveyed between 11/19 and 3/20, we examined (1) the current prevalence of negative aging stereotypes related to physical, mental, and cognitive health and (2) sociodemographic, health, and psychosocial factors associated with these stereotypes. Multivariable regression and relative weight analyses were conducted to identify independent correlates of negative aging stereotypes. Results revealed that 82.3%, 71.1%, and 30.0% of veterans endorsed negative aging stereotypes related to physical, cognitive, and emotional health, respectively. Older age (36.6% relative variance explained), grit (23.6%), and optimism (17.5%) explained the majority of the variance in negative age stereotypes related to physical aging; grit (46.6%), openness to experiences (31.5%), and older age (15.1%) in negative age stereotypes related to cognitive aging; and emotional stability (28.8%), purpose in life (28.8%), and grit (25.3%) in negative age stereotypes related to emotional aging. This study provides an up-to-date characterization of the prevalence and correlates of negative aging stereotypes in U.S. veterans. Results underscore the importance of targeting key correlates of negative aging stereotypes, such as lower grit, as part of efforts to promote health and functioning in this population.

Pro-Inflammatory Diets Are Associated with Frailty in an Urban Middle-Aged African American and White Cohort

Diet quality is a modifiable risk factor for frailty, but research on the association of frailty with dietary inflammatory potential is limited. The objective was to determine associations between diet quality assessed by the dietary inflammatory index (DII) with frailty status over time. Participants with both dietary and frailty data from the longitudinal Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study were used (n = 2901, 43.5% male, 43.8% African American, 48.5 y mean baseline age, with a mean 8.7 y of follow-up). Group-based trajectory modeling identified two frailty (remaining non-frail or being pre-frail/frail over time) and three diet quality trajectory groups (high or medium pro-inflammatory and anti-inflammatory potentials). Multiple logistic regression found both medium pro-inflammatory and anti-inflammatory DII trajectory groups, compared to the high pro-inflammatory group, were positively associated with being non-frail over time for the overall sample, both sexes and races. Kaplan-Meier curves and log-rank test revealed anti-inflammatory DII scores were associated with lower risk for being pre-frail or frail. No longitudinal relationship existed between frailty status at baseline and annualized DII change, a check on reverse causality. This study contributes to our current knowledge providing longitudinal evidence of the link between anti-inflammatory DII score with lower frailty risk.

Pathways explaining racial/ethnic and socio-economic disparities in dementia incidence: the UK Biobank study

BACKGROUND

Pathways explaining racial/ethnic disparities in dementia risk are under-evaluated.

METHODS

We examine those disparities and their related pathways among UK Biobank study respondents (50-74 y, N = 323,483; 3.6% non-White minorities) using a series of Cox proportional hazards and generalized structural equations models (GSEM).

RESULTS

After ≤15 years, 5,491 all-cause dementia cases were diagnosed. Racial minority status (RACE_ETHN, Non-White vs. White) increased dementia risk by 24% (HR = 1.24, 95% CI: 1.07-1.45, P = 0.005), an association attenuated by socio-economic status (SES), (HR = 1.12, 95% CI: 0.96-1.31). Total race-dementia effect was mediated through both SES and Life's Essential 8 lifestyle sub-score (LE8LIFESTYLE), combining diet, smoking, physical activity, and sleep factors. SES was inversely related to dementia risk (HR = 0.69, 95% CI: 0.67, 0.72, P < 0.001). Pathways explaining excess dementia risk among racial minorities included 'RACE_ETHN(-) → SES(-) → DEMENTIA', 'RACE_ETHN(-) → SES(-) → Poor cognitive performance, COGN(+) → DEMENTIA' and 'RACE_ETHN(-) → SES(+) → LE8LIFESTYLE(-) → DEMENTIA'.

CONCLUSIONS

Pending future interventions, lifestyle factors including diet, smoking, physical activity, and sleep are crucial for reducing racial and socio-economic disparities in dementia.

Psychological Resilience in U.S. Military Veterans: Results from the 2019-2020 National Health and Resilience in Veterans Study

Following exposure to traumatic life events, most individuals are psychologically resilient, and experience minimal-to-no symptoms of posttraumatic stress, major depressive, or generalized anxiety disorders. To date, however, most research has focused on factors associated with adverse post-trauma mental health outcomes rather than understanding those associated with psychological resilience. In particular, little is known about factors associated with psychological resilience in veterans, despite their high rates of trauma exposure, such as combat and military sexual trauma. To address this gap, we used a discrepancy-based psychiatric resilience (DBPR) analytic approach to operationalize psychological resilience, and to identify modifiable health and psychosocial factors associated with resilience in a nationally representative sample of U.S. veterans (N = 4,069). DBPR scores were computed by regressing a composite measure of distress (posttraumatic stress, major depressive, and generalized anxiety disorder symptoms) onto measures of adverse childhood experiences, combat exposure, military sexual trauma, and cumulative potentially traumatic events (e.g., natural disaster, life-threatening illness/injury). Psychological resilience was operationalized as lower actual, relative to predicted, composite distress scores. Results revealed that greater emotional stability (22.9% relative variance explained [RVE]) and mindfulness (13.4% RVE), lower likelihood of lifetime histories of MDD or PTSD (12.8% RVE), greater purpose in life (11.9% RVE), and lower severity of somatic symptoms (10.8% RVE) explained the majority of the variance in resilience scores (total R2 = 0.40). Taken together, results of this study illustrate the utility of a DBPR score approach to operationalizing psychological resilience to traumatic stress in U.S. veterans, and identify several modifiable health and psychosocial factors that can be targeted in prevention and treatment efforts designed to bolster resilience in this population.

Diet Quality Trajectories over Adulthood in a Biracial Urban Sample from the Healthy Aging in Neighborhoods of Diversity across the Life Span Study

Limited investigation has been done on diet quality trajectories over adulthood. The main study objectives were to determine the diet quality group trajectories (GTs) over time and to detect changes in a socio-economically and racially diverse middle-aged cohort. Data from three waves of the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study were used to determine diet quality with group-based trajectory modeling (GBTM). Three quality indices-the Healthy Eating Index (HEI), the Dietary Inflammatory Index (DII), and the Mean Adequacy Ratio (MAR)-were explored. The rate of change in quality over time was determined by mixed-effects regression analysis. Three diet quality GTs, low, middle, and high quality, were identified for each index and confirmed with spaghetti plots. Within each GT, only small changes in diet quality scores were observed, with improvements for the HEI and DII indices and a slight decline in MAR scores. Weighted kappa values revealed that the DII had better agreement with the HEI-2010 and MAR indices compared with the agreement between the HEI-2010 and MAR. Bayesian estimates revealed that the annualized rate of change in diet quality per person across the GTs was similar. There was minimal change in diet quality over time, regardless of the diet quality index used.

Life's simple 7 and its association with trajectories in depressive symptoms among urban middle-aged adults

BACKGROUND

The American Heart Association Life's Simple 7 (LS7) is a composite metric assessing cardiovascular health on a scale of 0-14 comprised of nutrition, physical activity, cigarette use, body mass index, blood pressure, cholesterol and glucose.

METHODS

Using data from the Healthy Aging in Neighborhoods of Diversity across the Life Span study [n = 1465, Age at visit 1 (v1: 2004-2009): 30-66 y, 41.7 % male, 60.6 % African American], we investigated associations of trajectories in depressive symptoms (2004-2017) with Life's simple 7 scores after ~8.6 years follow-up (2013-2017). Analyses used group-based zero-inflated Poisson trajectory (GBTM) models and multiple linear or ordinal logistic regression. GBTM analyses generated two classes of depressive symptoms trajectories ("low declining" and "high declining"), based on intercept and slope direction and significance.

RESULTS

Overall, "high declining depressive symptoms" vs. the "low declining" group was associated with -0.67 ± 0.10 lower scores on LS7 total score (P < 0.001) in analyses adjusted for age, sex, race and the inverse mills ratio. This effect was markedly attenuated to -0.45 ± 0.10 score-points (P < 0.001) upon adjustment for socio-economic factors and to -0.27 ± 0.10 score-points (P < 0.010) in fully adjusted analyses, with a stronger association detected among women (β ± SE: -0.45 ± 0.14, P = 0.002). An association between elevated depressive symptoms over time ("high declining" vs "low declining") and LS7 total score was detected among African American adults (β ± SE: -0.281 ± 0.131, p = 0.031, full model). Moreover, the "high declining" vs. "low declining" depressive symptoms group was associated with a lower score on LS7 physical activity (β ± SE: -0.494 ± 0.130, P < 0.001).

CONCLUSIONS

Poorer cardiovascular health was linked to higher depressive symptoms over time.