Early parental death and psychosocial risk factors for dementia: A case-control study in Europe

Lifetime chronic stress exposures, stress hormones, and biological aging: Results from the Midlife in the United States (MIDUS) study

Psychosocial stress and adversity have been linked to accelerated aging and increased risk for age-related diseases. Animal and in vitro studies have shown that exposure to stress hormones (catecholamines, glucocorticoids) can impact biological aging processes such as DNA damage and cellular senescence, suggesting they play a key role in links between stress and aging; however, these associations have not been well investigated in humans. We examined cross-sectional associations between chronic stress exposures, stress hormones, and biological aging markers in midlife adults and whether stress hormones mediated associations between stress and aging. Participants were 531 adults aged 26-78 years (Mage = 53.9, 50.1% female) in the nationally representative Midlife in the United States Refresher cohort. They reported chronic stress exposures in childhood and adulthood (Stressful Life Event Inventory) and provided 12-hour urine samples used to assess norepinephrine, epinephrine, and cortisol. RNA sequencing of peripheral blood mononuclear cells derived aging biomarkers: the DNA damage response (DDR; 30-gene composite), cellular senescence signal p16INK4a (CDKN2A), and the pro-inflammatory senescence-associated secretory phenotype (SASP; 57-gene composite). Regression models adjusting for age, sex, race/ethnicity, BMI, smoking status, alcohol use, and medications revealed that more childhood exposures were associated with higher norepinephrine (β = 0.09, p = 0.04), independent from adult exposures. Higher norepinephrine was associated with elevated DDR expression (β = 0.17, p < 0.001). Higher norepinephrine (β = 0.14, p = 0.003) and epinephrine (β = 0.10, p = 0.02) were both associated with elevated SASP expression. Statistical mediation analyses implicated elevated norepinephrine as a plausible mediator of associations between childhood exposures and both DDR (unstandardized b = 0.005, 95% CI [0.0002, 0.011]) and SASP (b = 0.002, 95% CI [0.0001, 0.05]). Findings provide preliminary evidence in humans that stress hormones may impact key biological aging processes and may be a mechanism linking chronic stress exposures in childhood to accelerated aging later in life.

Deprivation-related adverse childhood experiences and cognitive function among older adults: Mediating role of depression symptoms

BACKGROUND

Cognitive dysfunction imposes a heavy economic burden on families and society. Depression and deprivation-related adverse childhood experiences (ACEs) are important factors that contribute to cognitive dysfunction. However, few studies have explored these complex interactions.

OBJECTIVE

This study aimed to elucidate the mediating effect of depression on the relationship between deprivation-related ACEs and cognitive function in older adults.

METHODS

This national, cross-sectional study used data from the 2020 Chinese Longitudinal Aging Social Survey. Information regarding depression, ACEs, and cognitive function was collected from individuals aged 60 years and older. A structural equation model was used to examine the mediating effect of depression on the relationship between deprivation-related ACEs and cognitive function.

RESULTS

A total of 9828 participants were included in this study. Their mean total cognitive function score was 13.488 ± 3.006. The results showed that sex, age, educational level, marital status, body mass index, registered residence, chronic disease situation, health, smoking, living alone, life satisfaction, social security, and internet use were all related to cognitive function (P < 0.05). Deprivation-related ACEs were negatively correlated with cognitive function (r = -0.132, P < 0.01). And depression symptoms were negatively correlated with cognitive function (r = -0.158, P < 0.01). The mediating effect analysis indicated that depression symptoms had a significant mediating effect between the 3 dimensions of deprivation-related ACEs and cognitive function.

CONCLUSIONS

This study highlighted that improvement of deprivation-related ACEs was indirectly related to a reduced likelihood of cognitive dysfunction through depression in older adults. With the limitations of cross-sectional studies, validation through longitudinal design studies is deemed necessary. Future interventions should focus on alleviating depression symptoms to prevent cognitive decline and impairment in this population.

How Can Early Stress Influence Later Alzheimer's Disease Risk? Possible Mediators and Underlying Mechanisms

Alzheimer's disease (AD) is a progressive, age-related neurodegenerative disorder to which genetic mutations and risk factors contribute. Evidence is increasing that environmental and lifestyle-related factors, such as exercise, nutrition, education, and exposure to (early-life) stress modify the onset, incidence, and progression of AD. Here, we discuss recent preclinical findings on putative substrates that can explain or contribute to the effects of stress early in life on the risk of developing AD. We focus in particular on stress hormones, neural networks, synapses, mitochondria, nutrient and lipid metabolism, adult neurogenesis, engram cell ensembles, and neuroinflammation. We discuss the idea that stress exposure early in life can alter these processes, either combined or in isolation, thereby reducing the capacity of the brain to resist deleterious consequences of, for example, amyloid-β accumulation, thereby accelerating cognitive decline and progression of Alzheimer-related changes in model systems of the disease. A better understanding of whether experiences early in life also modify trajectories of cognitive decline and pathology in AD and how the substrates discussed translate to humans may help develop novel preventive and/or therapeutic strategies to mitigate the consequences of stressors early in life and increase resilience to developing dementia.

Childhood Peer Relationships and Dementia Risk in Chinese Older Adults: A Mediation Analysis

BACKGROUND

Early-life social experiences significantly influence later-life health, yet the association between childhood peer relationships and dementia, as well as the underlying mechanisms, remains underexplored. This study aimed to investigate this association and the mediating roles of social disengagement and loneliness.

METHODS

Leveraging data from 7574 adults aged ≥ 60 in the China Health and Retirement Longitudinal Study (2011-2018), we employed marginal structural models to assess the associations between childhood peer relationships and dementia risk in later life. Inverse odds ratio weighting was used to examine the mediating roles of formal and informal social disengagement and loneliness.

RESULTS

Individuals with deficits in childhood peer relationships had a higher risk of dementia (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.10-1.34) compared with those with more positive experiences. This association was partially mediated by formal social disengagement (proportion mediated, 21.44%; 95% CI, 12.20%-40.94%), loneliness (proportion mediated, 22.00%; 95% CI, 13.42%-33.82%), and their combination with informal social disengagement (proportion mediated, 41.50%; 95% CI, 30.76%-66.07%). Informal social disengagement alone did not show a significant mediating effect.

CONCLUSIONS

In this cohort study of older Chinese adults, negative childhood peer relationship experiences were associated with an elevated risk of dementia in later life. Formal social disengagement and loneliness partially mediated this association. These findings underscore the importance of fostering positive social relationships in early life and suggest potential psychosocial strategies to mitigate dementia risk in older adults due to childhood peer relationship deficits.

Gender differences in the associations of psychosocial trauma and acute medical stressors with immune system activation and dementia risk

Objective: The purpose of this article is to provide a narrative review synthesizing the literature on differences between women and men in relationships among certain stressors associated with immune system activation and their relationship to cognitive dysfunction and dementia. Method: We review the cycle of stress leading to neuroinflammation via cortisol and neurochemical alterations, cell-mediated immune system activation, and pro-inflammatory cytokines, and how this is implicated in the development of dementia. We follow this by discussing sex differences in stress physiology and immune function. We then review the work on early life adversity (ELA) and adverse childhood experiences (ACEs), post-traumatic stress disorder, acute medical stressors, and their associations with cognitive dysfunction and dementia. Throughout, we emphasize women's presentations and issues unique to women (e.g. trauma disorder prevalence). Conclusions: There is a need for more mechanistic and longitudinal studies that consider trauma accumulation, both physical and emotional, as well as a greater focus on traumas more likely to occur in women (e.g. sexual abuse), and their relationship to early cognitive decline and dementia.

The longitudinal association between adverse childhood experiences, childhood socioeconomic status, and lung function among middle-aged and older adults

OBJECTIVES

This study aims to investigate the association between adverse childhood experiences (ACEs), childhood socioeconomic status (SES) with lung function among general Chinese middle-aged and older adults.

METHODS

Participants at baseline were 9052 individuals aged 45 years old and above from the China Health and Retirement Longitudinal Study (CHARLS), a population-based cohort of Chinese adults. Analyses were conducted with data from three waves (2011, 2013, and 2015). The ACEs included five threat-related indicators (i.e., physical abuse, household substance abuse, domestic violence, unsafe neighborhood, and bullying) and five deprivation-related adversities (i.e., emotional neglect, household mental illness, incarcerated household member, parental separation or divorce, and parental death). The cumulative score of threat-related and deprivation-related ACEs was used for analysis. Lung function was assessed by peak expiratory flow (PEF). Two-level linear mixed growth models were used to evaluate the longitudinal association between and ACEs, childhood SES, and PEF.

RESULTS

Participants with more than three deprivation-related ACEs were significantly associated with lower PEF (b = -11.45 L/min, 95%CI: -18.40, -4.49) after adjusting for multiple confounding factors. Threat-related ACEs were not associated with PFF. Father's illiterate education predicted lower lung function (b = -8.49 L/min, 95%CI: -11.68, -5.31) for all middle-aged and older adults while mother's illiterate education was only significantly associated with PEF among the men (b = -9.21 L/min, 95%CI: -18.20, -0.22), and middle-aged adults (b = -7.96 L/min, 95%CI: -14.35, -1.57).

DISCUSSION

ACEs and disadvantaged childhood SES are important predictors of lower lung function during adulthood. Reducing ACEs and improving childhood SES may be beneficial for long-term health development.

The embodiment of parental death in early life through accelerated epigenetic aging: Implications for understanding how parental death before 18 shapes age-related health risk among older adults

Parental death in early life has been linked to various adverse health outcomes in older adulthood. This study extends prior research to evaluate how parental death in early life is tied to accelerated epigenetic aging, a potentially important biological mechanism from which social and environmental exposures impact age-related health. We used data from the 2016 Venous Blood Study (VBS), a component of the Health and Retirement Study (HRS), to examine the association between parental death in early life and accelerated epigenetic aging as measured by three widely used epigenetic clocks (PCPhenoAge, PCGrimAge, and DunedinPACE). We also assessed whether some of the association is explained by differences in educational attainment, depressive symptoms, and smoking behavior. Methods included a series of linear regression models and formal mediation analysis. Findings indicated that parental death in early life is associated with accelerated epigenetic aging for PCPhenoAge and DunedinPACE. The inclusion of educational attainment, depressive symptoms, and smoking behavior attenuated this association, with formal mediation analysis providing additional support for these observations. Parental death in early life may be one of the most difficult experiences an individual may face. The elevated biological risk associated with parental death in early life may operate through immediate changes but also through more downstream risk factors. This study highlights how early life adversity can set in motion biological changes that have lifelong consequences.

Parental Death Across the Life Course, Social Isolation, and Health in Later Life: Racial/Ethnic Disadvantage in the U.S

Bereavement is a risk factor for poor health, yet prior research has not considered how exposure to parental death across the life course may contribute to lasting social isolation and, in turn, poor health among older adults. Moreover, prior research often fails to consider the racial context of bereavement in the United States wherein Black and Hispanic Americans are much more likely than White Americans to experience parental death earlier in life. The present study uses longitudinal data from the Health and Retirement Study (HRS; 1998-2016) to consider linkages of parental death, social isolation, and health (self-rated health, functional limitations) for Black, Hispanic, and White older adults. Findings suggest that exposure to parental death is associated with higher levels of isolation, greater odds of fair/poor self-rated health, and greater odds of functional limitations in later life. Moreover, social isolation partially explains associations between parental bereavement and later-life health. These patterns persist net of psychological distress-an additional psychosocial response to bereavement. Racial inequities in bereavement are central to disadvantage: Black and Hispanic adults are more likely to experience a parent's death earlier in the life course, and this differential exposure to parental death in childhood or young adulthood has implications for racial and ethnic inequities in social isolation and health throughout life.

Early learning difficulties, childhood stress, race, and risk of cognitive impairment among US adults over age 50: A cross-sectional analysis

Background and Aims

Most literature linking childhood factors to cognitive health outcomes has focused on educational attainment-defined as years of education attained. However, less has been studied about the other aspects of education, such as early learning problems, and stressful family environments. This study examined whether early learning problems and childhood stressors were associated with mid- and later life cognitive impairment among US adults, and if these associations varied by race.

Methods

We conducted a cross-sectional analysis using the Health and Retirement Study (HRS) along with respondents' early educational experiences from the 2015 to 2017 Life History Mail Survey (N = 9703). Early learning problems were defined as having any of the following: scholastic problems (reading, writing, mathematics), speaking/language issues, and sensorimotor issues- hearing, vision, speech, and motor-coordination. Cognitive status was classified as three levels (normal, cognitively impaired not demented [CIND], and demented) using the HRS Langa-Weir algorithm. Multinomial logistic regression models using generalized logits, estimated relative risk ratios (RRRs), and 95% confidence intervals (CI) with adjustment for sociodemographic factors.

Results

Having at least one early learning problem was associated with increased risk of later life cognitive impairment (RRR: 1.75, 95% CI: 1.34-2.29 for dementia, RRR: 1.42, 95% CI: 1.20-1.67 for CIND). Parental death before the age of 16 was associated with 17% higher risk of CIND in later life (RRR: 1.17, 95% CI: 1.01-1.34). However, learning problem-related differences in risk of cognitive impairment were dependent on race (learning problems × race, p = 0.0001). In the demented group, Blacks were 2.7 times more likely to be demented (RRR: 2.66, 95% CI: 1.69-4.17) amongst older adults that experienced childhood learning problems.

Conclusions

Early life exposures predicted risk of cognitive impairment. Policies and interventions that enhance diagnosis of early learning problems and improve childhood social contexts are needed to promote healthy cognitive aging amongst Americans, regardless of race.

Is Stress an Overlooked Risk Factor for Dementia? A Systematic Review from a Lifespan Developmental Perspective

Stress exposure and stress reactivity may be potent factors associated with increased risk of dementia. The 2017 Lancet Commission on Dementia and its 2020 update reviewed modifiable risk factors associated with dementia, but stress was not addressed directly. The present study provides a focused review of the association between stress and dementia across the lifespan, with measures of stress including stress exposure, psychological stress, posttraumatic stress disorder (PTSD), and biological markers of stress. Published research articles were identified in the American Psychological Association PsycINFO database (1887-2021), Web of Science database, and Google Scholar. A total of 53 samples from 40 studies published from 1985 to 2020 met inclusion criteria. Results suggest that stressful life events that occur earlier in the lifespan, such as loss of a parent, psychological stress experienced in midlife, and extreme stress responses, i.e., PTSD, correlate with higher risk of dementia. Although results generally are mixed, a consistent theme is that stress experienced earlier in the lifespan and chronic stress portend the greatest risk of dementia. Reducing stress exposure and improving stress management when stress exposure cannot be changed are thus relevant strategies in dementia risk reduction.

Childhood Social Isolation as a Predictor of Retinal Neuronal Thickness in Middle Age: A Lifecourse Birth Cohort Study

OBJECTIVE

We investigated whether childhood social isolation was associated with retinal neural layer changes in adulthood, and whether this association was independent of other childhood or adulthood risk factors, including adult social isolation.

METHODS

Participants were members of the Dunedin Multidisciplinary Health and Development Study, a longitudinal population-based birth cohort from Aotearoa New Zealand ( n = 1037), born 1972 to 1973 and followed until age 45 years, with 94% of the living cohort still participating. Social isolation was recorded prospectively at ages 5, 7, 9, and 11 years, from teacher and parent report. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer thicknesses were measured via optical coherence tomography at age 45 years.

RESULTS

Childhood social isolation was associated with thinner average RNFL ( B = -0.739, p = .02), nasal RNFL ( B = -1.118, p = .005), and inferior RNFL ( B = -1.524, p = .007), although only nasal RNFL remained significant after adjustment. These associations were not fully explained by other psychosocial or physical health risk factors in childhood or adulthood, nor were they mediated by adult loneliness or social support.

CONCLUSIONS

Childhood social isolation was an independent predictor of RNFL thickness in middle age. Highlighting prospective links between childhood psychosocial adversity and retinal neuronal measures will help to inform future research into the utility of retinal neuronal thickness as a biomarker for neurodegeneration.

Development of a novel dementia risk prediction model in the general population: A large, longitudinal, population-based machine-learning study

BACKGROUND

The existing dementia risk models are limited to known risk factors and traditional statistical methods. We aimed to employ machine learning (ML) to develop a novel dementia prediction model by leveraging a rich-phenotypic variable space of 366 features covering multiple domains of health-related data.

METHODS

In this longitudinal population-based cohort of the UK Biobank (UKB), 425,159 non-demented participants were enrolled from 22 recruitment centres across the UK between March 1, 2006 and October 31, 2010. We implemented a data-driven strategy to identify predictors from 366 candidate variables covering a comprehensive range of genetic and environmental factors and developed the ML model to predict incident dementia and Alzheimer's Disease (AD) within five, ten, and much longer years (median 11.9 [Interquartile range 11.2-12.5] years).

FINDINGS

During a follow-up of 5,023,337 person-years, 5287 and 2416 participants developed dementia and AD, respectively. A novel UKB dementia risk prediction (UKB-DRP) model comprising ten predictors including age, ApoE ε4, pairs matching time, leg fat percentage, number of medications taken, reaction time, peak expiratory flow, mother's age at death, long-standing illness, and mean corpuscular volume was established. Our prediction model was internally evaluated based on five-fold cross-validation on discrimination and calibration, and it was further compared with existing prediction scales. The UKB-DRP model can achieve high discriminative accuracy in dementia (AUC 0.848 ± 0.007) and even better in AD (AUC 0.862 ± 0.015). The model was well-calibrated (Hosmer-Lemeshow goodness-of-fit p-value = 0.92), and the predictive power was solid in different incidence time groups. More importantly, our model presented an apparent superiority over existing models like Cardiovascular Risk Factors, Aging, and Incidence of Dementia Risk Score (AUC 0.705 ± 0.008), the Dementia Risk Score (AUC 0.752 ± 0.007), and the Australian National University Alzheimer's Disease Risk Index (AUC 0.584 ± 0.017). The model was internally validated in the general population of European ancestry and White ethnicity; thus, further validation with independent datasets is necessary to confirm these findings.

INTERPRETATION

Our ML-based UKB-DRP model incorporated ten easily accessible predictors with solid predictive power for incident dementia and AD within five, ten, and much longer years, which can be used to identify individuals at high risk of dementia and AD in the general population.

FUNDING

This study was funded by grants from the Science and Technology Innovation 2030 Major Projects (2022ZD0211600), National Key R&D Program of China (2018YFC1312904, 2019YFA070950), National Natural Science Foundation of China (282071201, 81971032, 82071997), Shanghai Municipal Science and Technology Major Project (2018SHZDZX01), Research Start-up Fund of Huashan Hospital (2022QD002), Excellence 2025 Talent Cultivation Program at Fudan University (3030277001), Shanghai Rising-Star Program (21QA1408700), Medical Engineering Fund of Fudan University (yg2021-013), and the 111 Project (No. B18015).

Are Brain and Cognitive Reserve Shaped by Early Life Circumstances?

When growing older, many people are faced with cognitive deterioration, which may even amount to a form of dementia at some point in time. Although neuropathological signs of dementia disorders can often be demonstrated in brains of patients, the degree to which clinical symptoms are present does mostly not accurately reflect the amount of neuropathology that is present. Sometimes existent pathology even goes without any obvious clinical presentation. An explanation for this phenomenon may be found in the concept of reserve capacity. Reserve capacity refers to the ability of the brain to effectively buffer changes that are associated with normal aging processes and to cope with pathological damage. A larger reserve capacity has been suggested to increase resilience against age-associated cognitive deterioration and dementia disorders. Traditionally, a division has been made between brain reserve, which is based on morphological characteristics of the brain, and cognitive reserve, which is based on functional characteristics of the brain. The present review discusses the premises that brain and cognitive reserve capacity are shaped by prenatal and early postnatal factors. Evidence is accumulating that circumstances during the first 1,000 days of life are of the utmost importance for the lifelong health of an individual. Cognitive deterioration and dementia disorders may also have their origin in early life and a potentially important pathway by which the early environment affects the risk for neurodegenerative diseases is by developmental programming of the reserve capacity of the brain. The basic idea behind developmental programming of brain and cognitive reserve is explained and an overview of studies that support this idea is presented. The review is concluded by a discussion of potential mechanisms, synthesis of the evidence and relevance and future directions in the field of developmental origins of reserve capacity.

Parental Death and Cognitive Impairment: An Examination by Gender and Race-Ethnicity

OBJECTIVES

We provide the first nationally representative longitudinal study of cognitive impairment in relation to parental death from childhood through early adulthood, midlife, and later adulthood, with attention to heterogeneity in the experience of parental death.

METHODS

We analyzed data from the Health and Retirement Study (2000-2016). The sample included 13,392 respondents, contributing 72,860 person-periods. Cognitive impairment was assessed using the modified version of the Telephone Interview for Cognitive Status. Discrete-time hazard regression models were estimated to predict the odds of cognitive impairment.

RESULTS

Both exposure and timing of parental death were related to the risk of cognitive impairment in late life and associations vary by gender. The detrimental effect of a father's death was comparable for daughters and sons although exposure to a mother's death had stronger effects on daughter's than son's risk of cognitive impairment. Father's death at younger ages had the strongest effect on sons' late-life risk of cognitive impairment, whereas mother's death in middle adulthood had the strongest effect on daughters' risk. We found no significant racial-ethnic variation in the association between parental death and cognitive impairment.

DISCUSSION

It is important to explore the gender-specific pathways through which parental death leads to increased risk of cognitive impairment so that effective interventions can be implemented to reduce risk.

Intimate Partner Violence and Risk for Mortality and Incident Dementia in Older Women

The aim of this study was to assess the long-term risk for mortality and incident dementia associated with exposure to intimate partner violence (IPV) at any time over the life course. Data were taken from the Australian Longitudinal Study of Women's Health, a population-based cohort study initiated in 1996. Analysis is based on 12,085 community-dwelling women aged 70 to 75 years at baseline from all states and territories. Self-reported exposure to violence was separated into historical (any time before baseline), current (past 12 months), or both. Date of death was obtained from the National Death Index, and dementia status was self-reported or obtained from administrative data. We modeled mortality risk using Cox regression, and risk for incident dementia using Fine-Gray proportional hazards modeling with death as a competing risk. Follow up continued to December 2017. At baseline, 728 women (6.0%) reported historical IPV, 121 (1.0%) reported current violence, and 38 reported both (0.3%). Historical IPV increased 20-year mortality risk after controlling for demographic, socioeconomic, and lifestyle variables (hazard ratio 1.10, 95% confidence interval = [1.00, 1.20]). There was no relationship between current violence and mortality (hazard ratio 1.04, 95% confidence interval = [0.85, 1.29]). There was also no association between IPV and risk for incident dementia (hazard ratio 1.02, 95% confidence interval = [0.89, 1.17]). Older women who self-report exposure to IPV over the lifespan die significantly earlier than women who do not. Further research that considers the mediating role of psychological trauma is needed to examine the relationship between IPV and dementia.