Genetic vulnerability and phenotypic expression of depression and risk for ischemic heart disease in the Vietnam era twin study of aging

An investigation into the sex dependence of post-reperfusion cardiac mitochondrial function and redox balance in chronically stressed rats

Although mitochondrial alterations are implicated in cardiac pathologies, sex-specific changes following chronic stress and ischemia-reperfusion injury are poorly characterized. Male and female Wistar rats underwent chronic restraint stress (CRS) for 4 weeks versus controls, whereafter ex vivo hearts were subjected to regional ischemia and reperfusion. Post-reperfusion hearts were dissected into ischemia-reperfused and non-ischemic regions with high-resolution mitochondrial respirometry, and oxidative stress assays performed. CRS males displayed increased routine and fatty acid β-oxidation respiration in non-ischemic tissues but lowered ETF-linked LEAK contributions to overall electron transfer system capacity ratios in ischemia-reperfused regions versus controls. CRS males exhibited lowered superoxide dismutase activity and increased lipid peroxidation in well-perfused regions versus controls. Female CRS hearts showed attenuated ETF-linked LEAK respiration and increased lipid peroxidation versus controls in non-ischemic tissue but a lowered RE ratio (measure of mitochondrial coupling) with ischemia-reperfusion. Our findings highlight the heart's sexually dimorphic response to chronic stress and ischemic injury, with female hearts showing oxidative damage in non-ischemic tissues together with relatively intact mitochondrial function in ischemia-reperfused tissues.

The Role of Chronic Stress in the Pathogenesis of Ischemic Heart Disease in Women

Psychological stress has emerged as a critical risk factor for cardiovascular disease, especially in women. While female participation in clinical research has improved, sex-specific data analysis and reporting often remain inadequate, limiting our ability to draw definitive conclusions for women. Conversely, preclinical studies consistently demonstrate adverse effects of stress on female health, yet the molecular mechanisms underlying this association remain elusive. Evidence suggests that female IHD pathogenesis is more complex than in males, involving multiple factors, including inflammation, contractile dysfunction, bioenergetic impairment, and remodeling. However, many of these mechanisms are primarily derived from male studies, and molecular investigations in female models are limited, hindering our understanding of the underlying biological pathways. This is particularly concerning given the increasing prevalence of ischemic heart disease in postmenopausal women. In order to fully elucidate the impact of stress on female cardiac health and develop targeted interventions, further preclinical research on female models is essential.

Cardiovascular Disease, Genetic Susceptibility, and Risk of Psychiatric Disorders and Suicide Attempt: A Community-Based Matched Cohort Study Based on the UK Biobank

BACKGROUND

The associations between cardiovascular disease (CVD) and multiple psychiatric disorders and suicide attempt, and whether different genetic susceptibilities affect such links, have not been investigated clearly.

METHODS AND RESULTS

Based on the UK Biobank, we conducted a matched cohort study involving 63 923 patients who were first hospitalized with a CVD diagnosis between 1997 and 2020, and their 127 845 matched unexposed individuals. Cox models were used to examine the subsequent risk of psychiatric disorders and suicide attempt (ie, anxiety, depression, stress-related disorder, substance misuse, psychotic disorder, and suicide behaviors) following CVD. We further performed stratified analyses by polygenic risk score for each studied psychiatric condition to detect the possible effects of genetic susceptibility on the observed associations. We found an increased risk of any psychiatric disorders and suicide attempt among CVD patients, compared with matched unexposed individuals, particularly within 1 year following the CVD (fully adjusted hazard ratio [HR] within 1 year, 1.83 [95% CI, 1.58-2.12]; HR after 1 year, 1.24 [95% CI, 1.16-1.32]). By subtype, the risk elevations existed for any psychiatric disorders and suicide attempt following most categories of CVDs. Analyses stratified by polygenic risk score revealed little impact of genetic predisposition to studied psychiatric conditions on these observed links.

CONCLUSIONS

Patients hospitalized for CVD were at increased subsequent risk of multiple types of psychiatric disorders and suicide attempt, especially in the first year after hospitalization, irrespective of their genetic susceptibilities to studied psychiatric conditions, and these findings underscore the necessity of developing timely psychological interventions for this vulnerable population.

Association Between Traumatic Brain Injury and Cognitive Decline Among Middle-to-Older Aged Men in the Vietnam Era Twin Study of Aging

Traumatic brain injury (TBI) is associated with increased risk of dementia. However, whether TBI is associated with greater cognitive decline over time in specific cognitive domains among older adults is not well understood. This prospective cohort study used data from 1476 male Vietnam Era Twin Study of Aging participants (average age at study entry = 57.9 years, range = 51-71 years; 97.6% non-Hispanic; 92.5% White) collected from 2003 to 2019, who had complete information on prior TBI. Participants completed a comprehensive neuropsychological assessment at up to three visits over up to a 12-year follow-up period during which they also self-reported their history of TBI. Multivariable, linear mixed-effects models were used to assess associations between TBI and cognitive performance trajectories. Effect measure modification by apolipoprotein E (APOE) epsilon 4 (ε4) genotype status was assessed in a subset of participants. Thirty-one percent of participants reported a history of TBI; 29.4% were APOE ε4 carriers. There were no statistically significant associations of TBI with decline in episodic memory, executive function, or processing speed among participants overall. In models stratified by APOE ε4 carrier status, TBI was associated with a larger magnitude of decline in executive function for APOE ε4 carriers (β = -0.0181; 95% confidence interval [CI] -0.0335, -0.0027) compared to noncarriers (β = -0.0031; 95% CI -0.0128, 0.0067; P Interaction = 0.03). In sensitivity analyses, TBI earlier in life (before military induction, average age = 20 years) was associated with faster declines in executive function compared to no TBI, irrespective of APOE ε4 status. In this sample of middle-to-older aged men, TBI was associated with faster declines in executive function among APOE ε4 carriers and among those who reported TBI in early life. These findings support the importance of a life course perspective when considering factors that may influence cognitive health in aging.

Distinct biological signature and modifiable risk factors underlie the comorbidity between major depressive disorder and cardiovascular disease

Major depressive disorder (MDD) and cardiovascular disease (CVD) are often comorbid, resulting in excess morbidity and mortality. Here we show that CVDs share most of their genetic risk factors with MDD. Multivariate genome-wide association analysis of shared genetic liability between MDD and atherosclerotic CVD revealed seven loci and distinct patterns of tissue and brain cell-type enrichments, suggesting the involvement of the thalamus. Part of the genetic overlap was explained by shared inflammatory, metabolic and psychosocial or lifestyle risk factors. Our data indicated causal effects of genetic liability to MDD on CVD risk, but not from most CVDs to MDD, and showed that the causal effects were partly explained by metabolic and psychosocial or lifestyle factors. The distinct signature of MDD-atherosclerotic CVD comorbidity suggests an immunometabolic subtype of MDD that is more strongly associated with CVD than overall MDD. In summary, we identified biological mechanisms underlying MDD-CVD comorbidity and modifiable risk factors for prevention of CVD in individuals with MDD.

Associations between depression and cardiometabolic health: A 27-year longitudinal study

BACKGROUND

Clarifying the relationship between depression symptoms and cardiometabolic and related health could clarify risk factors and treatment targets. The objective of this study was to assess whether depression symptoms in midlife are associated with the subsequent onset of cardiometabolic health problems.

METHODS

The study sample comprised 787 male twin veterans with polygenic risk score data who participated in the Harvard Twin Study of Substance Abuse ('baseline') and the longitudinal Vietnam Era Twin Study of Aging ('follow-up'). Depression symptoms were assessed at baseline [mean age 41.42 years (s.d. = 2.34)] using the Diagnostic Interview Schedule, Version III, Revised. The onset of eight cardiometabolic conditions (atrial fibrillation, diabetes, erectile dysfunction, hypercholesterolemia, hypertension, myocardial infarction, sleep apnea, and stroke) was assessed via self-reported doctor diagnosis at follow-up [mean age 67.59 years (s.d. = 2.41)].

RESULTS

Total depression symptoms were longitudinally associated with incident diabetes (OR 1.29, 95% CI 1.07-1.57), erectile dysfunction (OR 1.32, 95% CI 1.10-1.59), hypercholesterolemia (OR 1.26, 95% CI 1.04-1.53), and sleep apnea (OR 1.40, 95% CI 1.13-1.74) over 27 years after controlling for age, alcohol consumption, smoking, body mass index, C-reactive protein, and polygenic risk for specific health conditions. In sensitivity analyses that excluded somatic depression symptoms, only the association with sleep apnea remained significant (OR 1.32, 95% CI 1.09-1.60).

CONCLUSIONS

A history of depression symptoms by early midlife is associated with an elevated risk for subsequent development of several self-reported health conditions. When isolated, non-somatic depression symptoms are associated with incident self-reported sleep apnea. Depression symptom history may be a predictor or marker of cardiometabolic risk over decades.

Genetic Underpinnings of Increased BMI and Its Association With Late Midlife Cognitive Abilities

Objectives: First, we test for differences in various cognitive abilities across trajectories of body mass index (BMI) over the later life course. Second, we examine whether genetic risk factors for unhealthy BMIs—assessed via polygenic risk scores (PRS)—predict cognitive abilities in late-life. Methods: The study used a longitudinal sample of Vietnam veteran males to explore the associations between BMI trajectories, measured across four time points, and later cognitive abilities. The sample of 977 individuals was drawn from the Vietnam Era Twin Study of Aging. Cognitive abilities evaluated included executive function, abstract reasoning, episodic memory, processing speed, verbal fluency, and visual spatial ability. Multilevel linear regression models were used to estimate the associations between BMI trajectories and cognitive abilities. Then, BMI PRS was added to the models to evaluate polygenic associations with cognitive abilities. Results: There were no significant differences in cognitive ability between any of the BMI trajectory groups. There was a significant inverse relationship between BMI-PRS and several cognitive ability measures. Discussion: While no associations emerged for BMI trajectories and cognitive abilities at the phenotypic levels, BMI PRS measures did correlate with key cognitive domains. Our results suggest possible polygenic linkages cutting across key components of the central and peripheral nervous system.

Genetic risk for coronary heart disease alters the influence of Alzheimer's genetic risk on mild cognitive impairment

Understanding genetic influences on Alzheimer's disease (AD) may improve early identification. AD polygenic risk scores (AD-PRSs) are associated with increased odds of AD and mild cognitive impairment (MCI). Additional sources of genetic risk may also contribute to disease outcomes. Coronary artery disease (CAD) is a risk factor for AD, interacts with AD pathology, and is also heritable. We showed that incidence-based and prevalence-based CAD-PRSs moderate the association between the AD-PRS and MCI, but in opposing directions. Higher incidence-based CAD-PRSs interacted with the AD-PRS to further increase MCI risk. Conversely, the AD-PRS was predictive of MCI when prevalence-based CAD-PRSs were low. The latter finding is likely due to prevalent CAD cases being biased toward longer postevent survival times, perhaps selecting for protective loci that offset AD risk. These results demonstrate (1) the importance of examining multiple PRSs and their interactions; (2) how genetic risk for one disease can modify the impact of genetic risk for another; and (3) the importance of considering ascertainment procedures of GWAS used for genetic risk prediction.

Body mass trajectories and cortical thickness in middle-aged men: a 42-year longitudinal study starting in young adulthood

Evidence strongly suggests that being overweight or obese at midlife confers significantly higher risk for Alzheimer's disease and greater brain atrophy later in life. Few studies, however, examine associations between longitudinal changes in adiposity during early adulthood and later brain morphometry. Measures of body mass index (BMI) were collected in 373 men from the Vietnam Era Twin Study of Aging at average ages 20, 40, 56, and 62 years, yielding 2 BMI trajectories. We then examined associations between BMI phenotypes (trajectories, continuous BMI, obese/nonobese), cortical thickness, and white matter measures from structural magnetic resonance imaging at mean age 62 (time 4, range 56-66 years). Those on the obesity trajectory (N = 171) had a thinner cortex compared with the normal/lean trajectory (N = 202) in multiple frontal and temporal lobe bilateral regions of interest: superior, inferior, middle temporal gyri, temporal pole, fusiform gyrus, banks of the superior temporal sulcus, frontal pole, pars triangularis, caudal and rostral middle frontal gyri (all p < 0.05, false discovery rate corrected). Frontal lobe thinness tended to occur mainly in the right hemisphere. Results were similar for obese versus nonobese adults at age 62. There were no significant differences for white matter volume or abnormalities. Taken in the context of other research, these associations between brain structures and excess BMI at midlife suggest potential for increased risk for cognitive decline in later life.

Negative fateful life events in midlife and advanced predicted brain aging

Negative fateful life events (FLEs) such as interpersonal conflict, death in the family, financial hardship, and serious medical emergencies can act as allostatic stressors that accelerate biological aging. However, the relationship between FLEs and neuroanatomical aging is not well understood. We examined 359 men (mean age 62 years) participating in the Vietnam Era twin study of aging (VETSA) to determine whether negative midlife FLEs are associated with advanced brain aging after controlling for physical, psychological, and lifestyle factors. At two different time points, participants were assessed for negative FLEs, health and well-being, general cognitive ability, socioeconomic status, depression, and ethnicity. Participants underwent a magnetic resonance imaging examination, and T1-weighted images were processed with FreeSurfer. Subsequent neuroanatomical measurements were entered into the Brain-Age Regression Analysis and Computation Utility software (BARACUS) to predict brain age. Having more midlife FLEs, particularly relating to interpersonal relationships, was associated with advanced predicted brain aging (i.e., higher predicted brain age relative to chronological age). This association remained after controlling for the significant covariates of alcohol consumption, cardiovascular risk, adult socioeconomic status, and ethnicity.

Vascular risk factor burden and new-onset depression in the community

Depression is associated with an increased likelihood of cardiac events and stroke. We hypothesized that the vascular risk factor burden might itself predispose to both cardiovascular events and depression. Therefore, we examined whether aggregate scores of vascular risk factor burden were associated with the new-onset of depression in the community. We studied 2023 depression- and dementia-free Framingham Heart Study (Framingham, USA) Offspring participants who attended both examination cycles 7 (1998-2001) and 8 (2005-2008). The American Heart Association Ideal Cardiovascular Health metric and the Framingham stroke risk profile were calculated at exam seven. New-onset depression was adjudicated at examination cycle eight as antidepressant medication use or Centre for Epidemiologic Studies Depression Scale scores ≥16, after a mean follow-up of 6.6years (standard deviation=0.7). Of the 2023 participants, 269 (13%) developed new-onset depression. Following adjustments for age, sex, education, and the time interval between baseline and follow-up, the odds of new-onset depression decreased by 10% for each one-point increase in ideal cardiovascular health scores (Odds Ratio [OR], 0.90; 95% confidence interval [CI] 0.81-0.99) and increased by 4% for each percentage point increase in the Framingham stroke risk profile (OR, 1.04; CI, 1.00-1.07). Results were not explained by interim clinical stroke or cerebral white matter injury. In conclusion, vascular risk factor burden was associated with the new onset of depression. Shared vascular risk factors may contribute to the increased risk of cardiovascular events observed in persons with depression.

Steeper change in body mass across four decades predicts poorer cardiometabolic outcomes at midlife

OBJECTIVE

This study examined patterns of change in adiposity across four decades starting in young adulthood as well as associations between change and midlife cardiometabolic outcomes.

METHODS

BMI was assessed at ages 20, 40, 56, and 62 years in 977 male veterans from the Vietnam Era Twin Study of Aging. Age 62 (range 56-66) cardiometabolic outcomes included hypertension, diabetes, dyslipidemia, inflammation, and ischemic heart disease. Analyses included latent growth modeling (LGM), latent class growth modeling (LCGM), and logistic regression models.

RESULTS

Linear BMI slope was associated with all outcomes. Accelerated (quadratic) BMI slope was significantly associated with greater risk for hypertension, diabetes, dyslipidemia, and inflammation; odds ratios ranged from 1.93 (diabetes) to 3.15 (dyslipidemia). Initial BMI did not predict later outcomes. Linear slope contributed significant unique variance for diabetes and dyslipidemia even controlling for age 62 BMI. LCGM revealed three trajectories. Men with the relatively stable, lower BMI trajectory had significantly better outcomes than those with trajectories with accelerated increases, especially those including obesity.

CONCLUSIONS

How individuals reach late-midlife BMI is important. Steepness of BMI change across 40 years from young adulthood to late midlife, in addition to late-midlife BMI itself, was robustly associated with greater risk for poor cardiometabolic outcomes.

Association between major depression and type 2 diabetes in midlife: findings from the Screening Across the Lifespan Twin Study

OBJECTIVE

Cohort studies suggest that the relationship between major depression (MD) and Type 2 diabetes (T2DM) is bidirectional. However, this association may be confounded by shared genetic or environmental factors. The objective of this study was to use a twin design to investigate the association between MD and T2DM.

METHODS

Data come from the Screening Across the Lifespan Twin Study, a sample of monozygotic and dizygotic twins 40 years or older sampled from the Swedish Twin Registry (n = 37,043). MD was assessed by using the Composite International Diagnostic Inventory. Structural equation twin modeling and Cox proportional hazards modeling were used to assess the relationship between MD and T2DM.

RESULTS

Approximately 19% of respondents had a history of MD and 5% had a history of T2DM. MD was associated with 32% increased likelihood of T2DM (95% confidence interval = 1.00-1.80) among twins aged 40 to 55 years, even after accounting for genetic risk, but was not associated with T2DM among twins older than 55 years. T2DM was associated with 33% increased likelihood of MD (95% confidence interval = 1.02-1.72) among younger, but not older twins. Cholesky decomposition twin modeling indicated that common unique environmental factors contribute to the association between MD and T2DM.

CONCLUSIONS

Environmental factors that are unique to individuals (i.e., not shared within families) but common to both MD and T2DM contribute to their co-occurrence in midlife. However, we cannot exclude the possibility of bidirectional causation as an alternate explanation. It is likely that multiple processes are operating to effect the relation between psychiatric and medical conditions in midlife.

Depression as a risk factor for adverse outcomes in coronary heart disease

BACKGROUND

Depression is firmly established as an independent predictor of mortality and cardiac morbidity in patients with coronary heart disease (CHD). However, it has been difficult to determine whether it is a causal risk factor, and whether treatment of depression can improve cardiac outcomes. In addition, research on biobehavioral mechanisms has not yet produced a definitive causal model of the relationship between depression and cardiac outcomes.

DISCUSSION

Key challenges in this line of research concern the measurement of depression, the definition and relevance of certain subtypes of depression, the temporal relationship between depression and CHD, underlying biobehavioral mechanisms, and depression treatment efficacy.

SUMMARY

This article examines some of the methodological challenges that will have to be overcome in order to determine whether depression should be regarded as a key target of secondary prevention in CHD.