Using census data and birth certificates to reconstruct the early-life socioeconomic environment and the relation to the development of Alzheimer's disease

Impact of work type and APOE-e4 status on cognitive functioning in older women

Prior research indicates that APOE-e4 allele(s) and working without compensation may be independently associated with risk for cognitive decline. This study investigated whether the interaction of type of work (paid versus unpaid) and presence of APOE-e4 allele(s) was associated with cognitive dysfunction in women in mid- and late-life. Participants included 340 females (mean age = 74.7 years) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset. A two-way ANOVA to assess the simple main effects of type of work and APOE-e4 allele status on cognition as well as their interaction was performed. A two-way ANCOVA including age, education, and marital status as covariates was also conducted. The presence of one or two APOE-e4 allele(s) and unpaid work was associated with greater cognitive dysfunction. A significant interaction effect revealed engagement in paid work, regardless of the presence of APOE-e4 allele(s), was associated with better cognitive functioning. Consistent with prior literature, women who engage in unpaid forms of labor for the majority of their life may be at higher risk for cognitive decline, regardless of presence of APOE-e4 allele(s). Further research is needed to identify the factors related to unpaid labor that may increase risk for cognitive dysfunction.

Cerebral Small Vessel Disease: Early-Life Antecedents and Long-Term Implications for the Brain, Aging, Stroke, and Dementia

Cerebral small vessel disease is common in older adults and increases the risk of stroke, cognitive impairment, and dementia. While often attributed to midlife vascular risk factors such as hypertension, factors from earlier in life may contribute to later small vessel disease risk. In this review, we summarize current evidence for early-life effects on small vessel disease, stroke and dementia focusing on prenatal nutrition, and cognitive ability, education, and socioeconomic status in childhood. We discuss possible reasons for these associations, including differences in brain resilience and reserve, access to cognitive, social, and economic resources, and health behaviors, and we consider the extent to which these associations are independent of vascular risk factors. Although early-life factors, particularly education, are major risk factors for Alzheimer disease, they are less established in small vessel disease or vascular cognitive impairment. We discuss current knowledge, gaps in knowledge, targets for future research, clinical practice, and policy change.

Using national census data to facilitate healthcare research

National censuses are conducted at varying intervals across both the developed and developing world and collect detailed data on a wide range of societal, economic and health questions. This immense volume of data has many potential uses in the field of healthcare research and can be utilised either in isolation or in conjunction with other information sources such as hospital records. At a governmental level census data can be used for healthcare service planning by providing accurate population density information but also, through the use of more detailed data collection, by helping to identify high-risk populations that may require increased resource allocation. It can also be a key tool in addressing and improving healthcare inequality and deprivation by both identifying those populations with poorer healthcare outcomes and through helping researchers to better understand the causes of this inequality. Similarly, it has utility when studying the complex causes of disease and assessing the success of strategies designed to tackle these aetiologies. However, the maximum benefit from these various uses can only be realised if the data collection and analysis processes utilised are robust and this requires that census bureaus regularly review and modify their methods in a transparent and thorough way.

Racial/Ethnic Disparities in the Alzheimer's Disease Link with Cardio and Cerebrovascular Diseases, Based on Hawaii Medicare Data

Background

There is an expanding body of literature implicating heart disease and stroke as risk factors for Alzheimer's disease (AD). Hawaii is one of the six majority-minority states in the United States and has significant racial health disparities. The Native-Hawaiians/Pacific-Islander (NHPI) population is well-known as a high-risk group for a variety of disease conditions.

Objective

We explored the association of cardiovascular disease with AD development based on the Hawaii Medicare data, focusing on racial disparities.

Methods

We utilized nine years of Hawaii Medicare data to identify subjects who developed heart failure (HF), ischemic heart disease (IHD), atrial fibrillation (AF), acute myocardial infarction (AMI), stroke, and progressed to AD, using multistate models. Propensity score-matched controls without cardiovascular disease were identified to compare the risk of AD after heart disease and stroke. Racial/Ethnic differences in progression to AD were evaluated, accounting for other risk factors.

Results

We found increased risks of AD for AF, HF, IHD, and stroke. Socioeconomic (SE) status was found to be critical to AD risk. Among the low SE group, increased AD risks were found in NHPIs compared to Asians for all conditions selected and compared to whites for HF, IHD, and stroke. Interestingly, these observations were found reversed in the higher SE group, showing reduced AD risks for NHPIs compared to whites for AF, HF, and IHD, and to Asians for HF and IHD.

Conclusions

NHPIs with poor SE status seems to be mostly disadvantaged by the heart/stroke and AD association compared to corresponding whites and Asians.

APOE Peripheral and Brain Impact: APOE4 Carriers Accelerate Their Alzheimer Continuum and Have a High Risk of Suicide in PM2.5 Polluted Cities

This Review emphasizes the impact of APOE4-the most significant genetic risk factor for Alzheimer's disease (AD)-on peripheral and neural effects starting in childhood. We discuss major mechanistic players associated with the APOE alleles' effects in humans to understand their impact from conception through all life stages and the importance of detrimental, synergistic environmental exposures. APOE4 influences AD pathogenesis, and exposure to fine particulate matter (PM_2.5), manufactured nanoparticles (NPs), and ultrafine particles (UFPs) associated with combustion and friction processes appear to be major contributors to cerebrovascular dysfunction, neuroinflammation, and oxidative stress. In the context of outdoor and indoor PM pollution burden-as well as Fe, Ti, and Al alloys; Hg, Cu, Ca, Sn, and Si UFPs/NPs-in placenta and fetal brain tissues, urban APOE3 and APOE4 carriers are developing AD biological disease hallmarks (hyperphosphorylated-tau (P-tau) and amyloid beta 42 plaques (Aβ₄₂)). Strikingly, for Metropolitan Mexico City (MMC) young residents ≤ 40 y, APOE4 carriers have 4.92 times higher suicide odds and 23.6 times higher odds of reaching Braak NFT V stage versus APOE4 non-carriers. The National Institute on Aging and Alzheimer's Association (NIA-AA) framework could serve to test the hypothesis that UFPs and NPs are key players for oxidative stress, neuroinflammation, protein aggregation and misfolding, faulty complex protein quality control, and early damage to cell membranes and organelles of neural and vascular cells. Noninvasive biomarkers indicative of the P-tau and Aβ₄₂ abnormal protein deposits are needed across the disease continuum starting in childhood. Among the 21.8 million MMC residents, we have potentially 4 million APOE4 carriers at accelerated AD progression. These APOE4 individuals are prime candidates for early neuroprotective interventional trials. APOE4 is key in the development of AD evolving from childhood in highly polluted urban centers dominated by anthropogenic and industrial sources of pollution. APOE4 subjects are at higher early risk of AD development, and neuroprotection ought to be implemented. Effective reductions of PM_2.5, UFP, and NP emissions from all sources are urgently needed. Alzheimer's Disease prevention ought to be at the core of the public health response and physicians-scientist minority research be supported.

Do prenatal factors shape the risk for dementia?: A systematic review of the epidemiological evidence for the prenatal origins of dementia

PURPOSE

Prenatal factors such as maternal stress, infection and nutrition affect fetal brain development and may also influence later risk for dementia. The purpose of this systematic review was to provide an overview of all studies which investigated the association between prenatal factors and later risk for dementia.

METHODS

We systematically searched MEDLINE and Embase for original human studies reporting on associations between prenatal factors and dementia from inception to 23 November 2022. Prenatal factors could be any factor assessed during pregnancy, at birth or postnatally, provided they were indicative of a prenatal exposure. Risk of bias was assessed using the Newcastle Ottawa Scale. We followed PRISMA guidelines for reporting.

RESULTS

A total of 68 studies met eligibility criteria (including millions of individuals), assessing maternal age (N = 30), paternal age (N = 22), birth order (N = 15), season of birth (N = 16), place of birth (N = 13), prenatal influenza pandemic (N = 1) or Chinese famine exposure (N = 1), birth characteristics (N = 3) and prenatal hormone exposure (N = 4). We observed consistent results for birth in a generally less optimal environment (e.g. high infant mortality area) being associated with higher dementia risk. Lower and higher birth weight and prenatal famine exposure were associated with higher dementia risk. The studies on season of birth, digit ratio, prenatal influenza pandemic exposure, parental age and birth order showed inconsistent results and were hampered by relatively high risk of bias.

CONCLUSION

Our findings suggest that some prenatal factors, especially those related to a suboptimal prenatal environment, are associated with an increased dementia risk. As these associations may be confounded by factors such as parental socioeconomic status, more research is needed to examine the potential causal role of the prenatal environment in dementia.

The Influence of Birth Cohorts on Future Cognitive Decline

BACKGROUND

Slowed rates of cognitive decline have been reported in individuals with higher cognitive reserve (CR), but interindividual discrepancies remain unexplained. Few studies have reported a birth cohort effect, favoring later-born individuals, but these studies remain scarce.

OBJECTIVE

We aimed to predict cognitive decline in older adults using birth cohorts and CR.

METHODS

Within the Alzheimer's Disease Neuroimaging Initiative, 1,041 dementia-free participants were assessed on four cognitive domains (verbal episodic memory; language and semantic memory; attention; executive functions) at each follow-up visit up to 14 years. Four birth cohorts were formed according to the major historical events of the 20th century (1916-1928; 1929-1938; 1939-1945; 1946-1962). CR was operationalized by merging education, complexity of occupation, and verbal IQ. We used linear mixed-effect models to evaluate the effects of CR and birth cohorts on rate of performance change over time. Age at baseline, baseline structural brain health (total brain and total white matter hyperintensities volumes), and baseline vascular risk factors burden were used as covariates.

RESULTS

CR was only associated with slower decline in verbal episodic memory. However, more recent birth cohorts predicted slower annual cognitive decline in all domains, except for executive functions. This effect increased as the birth cohort became more recent.

CONCLUSION

We found that both CR and birth cohorts influence future cognitive decline, which has strong public policy implications.

Childhood socio-economic circumstances and dementia: prospective register-based cohort study of adulthood socio-economic and cardiovascular health mediators

Background

This study analysed the association between childhood socio-economic circumstances and the risk of dementia, and investigated the mediating role of potentially modifiable risk factors including adulthood socio-economic position and cardiovascular health.

Methods

We used a 10% sample of the 1950 Finnish population census linked with subsequent population and health registers (n = 95 381). Information of socio-economic characteristics, family structure and housing conditions at the age of 0–15 years was obtained from the 1950 census. We identified cohort members who developed dementia in 2000–2018 using national hospital, medication and death registers. Discrete time survival analysis using logistic regression and mediation analysis applying the Karlson–Holm–Breen (KHB) method were employed.

Results

An excess risk of dementia was observed for household crowding [odds ratio (OR) = 1.10; 95% CI 1.02–1.18 for 3 to <4 persons per heated room; OR = 1.19; 95% CI 1.11–1.27 for ≥4 persons], single-father family (OR = 1.27; 95% CI 1.07–1.51) and eastern and northern region of residence (OR = 1.19; 95% CI 1.10–1.28). The effects of single-father family and region of residence were mostly direct with adulthood characteristics mediating 14% and 29% of the total effect, respectively. The largest indirect effect was observed for household crowding mediated through adulthood socio-economic position (47–65%).

Conclusions

The study shows that childhood socio-economic circumstances are associated with dementia, and that the underlying mechanisms only partly relate to adulthood socio-economic position and cardiovascular health. Socio-economic and health interventions targeted at families with children may carry long-term benefits by contributing to a lower dementia risk in later life.

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.

Examining the impact of socioeconomic status, demographic characteristics, lifestyle and other risk factors on adults' cognitive functioning in developing countries: an analysis of five selected WHO SAGE Wave 1 Countries

Background

Though extensive studies have been conducted on assessing the predictors of cognitive functioning among older adults in small community-based samples, very few studies have focused on understanding the impact of socioeconomic status (SES), demographic characteristics and other risk factors such as lifestyle and chronic diseases on the cognitive functioning among adults of all ages in a nationally representative population-based sample across low- and middle-income countries. This study, therefore, seeks to evaluate the impact of SES, demographic characteristics and risk factors on the cognitive functioning of adults across all ages in five selected developing countries.

Methods

Data from 12,430 observations obtained from the WHO Study on Global AGEing and Adult Health (SAGE) Wave 1; consisting of 2,486 observations each for China, Ghana, India, the Russian Federation, and South Africa, were used for the study. A meta-regression and a five-step hierarchical linear regression were used to analyze the data, with cognitive functioning as the dependent variable. Independent variables used in this study include SES; assessed by household income and education, demographic characteristics, other risk factors such as lifestyle, self-reported memory difficulty and chronic diseases.

Results

This study found that SES and lifestyle significantly predicted cognitive functioning in all the five selected countries as obtained by the pooled results of the meta-regression analysis. The hierarchical linear regression results also revealed that demographic characteristics such as age, type of residency, and self-reported memory difficulty significantly impact cognitive functioning in China, Ghana, Russia, and South Africa.

Conclusion

The findings in this study provide new insights for policymakers, caregivers, parents, and individuals, especially those in developing countries, to implement policies and actions targeted at improving SES and eliminating risk factors associated with cognitive decline, as these measures could help improve the cognitive functioning among their populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-022-01622-7.

Birth Cohorts and Cognitive Reserve Influence Cognitive Performances in Older Adults

BACKGROUND

Evidence suggests birth cohort differences in cognitive performance of older adults. Proxies of cognitive reserve (CR), such as educational attainment and occupational complexity, could also partly account for these differences as they are influenced by the sociocultural environment of the birth cohorts.

OBJECTIVE

To predict cognitive performance using birth cohorts and CR and examine the moderating influence of CR on cognitive performance and structural brain health association.

METHODS

Using ADNI data (n = 1628), four birth cohorts were defined (1915-1928; 1929-1938; 1939-1945; 1946-1964). CR proxies were education, occupational complexity, and verbal IQ. We predicted baseline cognitive performances (verbal episodic memory; language and semantic memory; attention capacities; executive functions) using multiple linear regressions with CR, birth cohorts, age, structural brain health (total brain volume; total white matter hyperintensities volume) and vascular risk factors burden as predictors. Sex and CR interactions were also explored.

RESULTS

Recent birth cohorts, higher CR, and healthier brain structures predicted better performance in verbal episodic memory, language and semantic memory, and attention capacities, with large effect sizes. Better performance in executive functions was predicted by a higher CR and a larger total brain volume, with a small effect size. With equal score of CR, women outperformed men in verbal episodic memory and language and semantic memory in all cohorts. Higher level of CR predicted better performance in verbal episodic memory, only when total brain volume was lower.

CONCLUSION

Cohort differences in cognitive performance favor more recent birth cohorts and suggests that this association may be partly explained by proxies of CR.

Childhood Socioeconomic Status Does Not Predict Late-Life Cognitive Decline in the 1936 Lothian Birth Cohort

This study examined childhood socioeconomic status (SES) as a predictor of later life cognitive decline. Data came from 519 participants in the Lothian Birth Cohort 1936 (LBC1936) study. SES measures at 11 years of age included parental educational attainment, father's occupational status, household characteristics and a composite measure of global childhood SES (i.e., a total of low SES childhood indicators). Cognitive abilities were assessed by the Mini-Mental State Exam at ages 69.8, 72.8 and 76.7 years. Most indicators of low childhood SES (i.e., father manual worker, less than secondary school father education, household overcrowding, exterior located toilet, and global childhood SES) did not predict cognitive decline between the ages of 69.8 and 76.7. Participants with less educated mothers showed an increase in cognitive decline (β = -0.132, p = 0.048, and CI = -0.80, -0.00). The relationship between maternal educational attainment and cognitive decline became non-significant when controlling for adult SES (i.e., participant educational attainment and occupation). Adult SES did not mediate the latter relationship. This study provides new evidence that childhood SES alone is not strongly associated with cognitive decline. New knowledge is critical to improving population health by identifying life span stages in which interventions might be effective in preventing cognitive decline.

Lifelong chronic psychosocial stress induces a proteomic signature of Alzheimer's disease in wildtype mice

Late onset, sporadic Alzheimer's disease (AD) accounts for the vast majority of cases. Unlike familial AD, the factors that drive the onset of sporadic AD are poorly understood, although aging and stress play a role. The early onset/severity of neuropathology observed in most genetic mouse models of AD hampers the study of the role of aging and environmental factors; thus alternate strategies are necessary to understand the contributions of these factors to sporadic AD. We demonstrate that mice acquiring a low social status (subordinate) in a lifelong chronic psychosocial stress (CPS) model, accrue widespread proteomic changes in the frontal/temporal cortex during aging. To better understand the significance of these stress-induced changes, we compared the differentially expressed proteins (DEPs) of subordinate mice to those of patients at varying stages of dementia. Sixteen and fifteen DEPs upregulated in subordinate mice were also upregulated in patients with mild cognitive impairment (MCI) and AD, respectively. Six of those upregulated proteins (CPE, ERC2, GRIN2B, SLC6A1, SYN1, WFS1) were shared by subordinate mice and patients with MCI or AD. Finally, comparison with a spatially detailed transcriptomic database revealed that the superior frontal gyrus and hippocampus had the greatest overlap between mice subjected to lifelong CPS and AD patients. Overall, most of the overlapping proteins were functionally associated with enhanced NMDA receptor mediated glutamatergic signaling, an excitotoxicity mechanism known to affect neurodegeneration. These findings support the association between stress and AD progression and provide valuable insight into potential early biomarkers and protein mediators of this relationship.

Is milk and dairy intake a preventive factor for elderly cognition (dementia and Alzheimer's)? A quality review of cohort surveys

Milk and dairy (M&D) is a longstanding human food with widespread use. Many studies showed the preventive capacity of M&D in several human health disorders, but its utility in others is under discussion. Aging has been associated to elderly cognitive decline including dementia-Alzheimer syndrome (Dem-AD). The absence of a therapy to impede or postpone Dem-AD determines the need for its prevention, including nutritional factors. To evaluate the preventive capacity of M&D consumption in elderly Dem-AD we performed a systematic review in the main biomedical databases and information resources, but we present this study as a narrative review to discuss better the complexity of this subject. The elderly Dem-AD has a long pre-symptomatic period and the M&D intake has a widespread use. These determinants and the quality flaws of published studies impeach us to answer whether M&D consumption is preventive for Dem-AD. Moreover, two long Japanese cohorts suggest that M&D intake could prevent Dem-AD. Prospective cohorts beginning in midlife (or early life) could answer this question in the future.

Trauma and depressive symptomatology in middle-aged persons at high risk of dementia: the PREVENT Dementia Study

OBJECTIVE

Depression and trauma are associated with changes in brain regions implicated in Alzheimer's disease. The present study examined associations between childhood trauma, depression, adult cognitive functioning and risk of dementia.

METHODS

Data from 378 participants in the PREVENT Dementia Study aged 40-59 years. Linear and logistic models were used to assess associations between childhood trauma, depression, dementia risk, cognitive test scores and hippocampal volume.

RESULTS

Childhood trauma was associated with depression and reduced hippocampal volume but not current cognitive function or dementia risk. Poorer performance on a delayed face/name recall task was associated with depression. Childhood trauma was associated with lower hippocampal volume however poorer cognitive performance was mediated by depression rather than structural brain differences.

CONCLUSION

Depressive symptomatology may be associated with dementia risk via multiple pathways, and future studies should consider subtypes of depressive symptomatology when examining its relationship to dementia.

Factors Associated with the High Prevalence of Dementia in Older Aboriginal Australians

Dementia prevalence in Aboriginal and Torres Strait Islander Australians is three to five times higher than the general Australian population. A better understanding of the underlying biomedical and social risk factors is needed to guide dementia prevention in Aboriginal Australians. The current study is the first to examine potential risk factors for dementia in the majority urban and regional population, with a representative sample of 336 Aboriginal Australians aged 60 years and older. Participants included 45 people with a dementia diagnosis (n = 27 probable/possible Alzheimer's disease); and 286 people without dementia. Univariate logistic regression analyses (controlling for age) identified childhood trauma, mid-life factors (history of unskilled work, past high-risk alcohol use), and medical factors (history of stroke, head injury with loss of consciousness, epilepsy) as risk factors for dementia. Multivariable analysis revealed age, childhood trauma, unskilled work, stroke, and head injury as independent predictors of all-cause dementia. A range of comorbid factors related to dementia was also identified (i.e., functional impairment, incontinence, recent hospital admission, low body mass index, living in residential care, depression, current high-risk alcohol use, social isolation, low physical activity levels). These findings extend previous outcomes in a remote Aboriginal population by highlighting that life-course social determinants of health, in addition to neurological disorders, likely play an important role in elevating dementia risk. Certain psychosocial and medical exposures are highly prevalent in Aboriginal Australians, similar to other indigenous populations, and should be considered when designing targeted and culturally appropriate prevention initiatives to reduce the burden of dementia.

Stress and Alzheimer's disease: A senescence link?

Chronic stress has been shown to promote numerous aging-related diseases, and to accelerate the aging process itself. Of particular interest is the impact of stress on Alzheimer's disease (AD), the most prevalent form of dementia. The vast majority of AD cases have no known genetic cause, making it vital to identify the environmental factors involved in the onset and progression of the disease. Age is the greatest risk factor for AD, and measures of biological aging such as shorter telomere length, significantly increase likelihood for developing AD. Stress is also considered a crucial contributor to AD, as indicated by a formidable body of research, although the mechanisms underlying this association remain unclear. Here we review human and animal literature on the impact of stress on AD and discuss the mechanisms implicated in the interaction. In particular we will focus on the burgeoning body of research demonstrating that senescent cells, which accumulate with age and actively drive a number of aging-related diseases, may be a key mechanism through which stress drives AD.

Association of Demographic and Early-Life Socioeconomic Factors by Birth Cohort With Dementia Incidence Among US Adults Born Between 1893 and 1949

IMPORTANCE

Early-life factors may be important for later dementia risk. The association between a more advantaged early-life environment, as reflected through an individual's height and socioeconomic status indicators, and decreases in dementia incidence by birth cohort is unknown.

OBJECTIVES

To examine the association of birth cohort and early-life environment with dementia incidence among participants in the Adult Changes in Thought study from 1994 to 2015.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included 4277 participants from the Adult Changes in Thought study, an ongoing longitudinal population-based study of incident dementia in a random sample of adults 65 years and older who were born between 1893 and 1949 and are members of Kaiser Permanente Washington in the Seattle region. Participants in the present analysis were followed up from 1994 to 2015. At enrollment, all participants were dementia-free and completed a baseline evaluation. Subsequent study visits were held every 2 years until a diagnosis of dementia, death, or withdrawal from the study. Participants were categorized by birth period (defined by historically meaningful events) into 5 cohorts: pre-World War I (1893-1913), World War I and Spanish influenza (1914-1920), pre-Great Depression (1921-1928), Great Depression (1929-1939), and World War II and postwar (1940-1949). Participants' height, educational level, childhood financial stability, and childhood household density were examined as indicators of early-life environment, and later-life vascular risk factors for dementia were assessed. Cox proportional hazards regression models, adjusted for competing survival risk, were used to analyze data. Data were analyzed from June 1, 2018, to April 29, 2020.

MAIN OUTCOMES AND MEASURES

Participants completed the Cognitive Abilities Screening Instrument every 2 years to assess global cognition. Those with scores indicative of cognitive impairment completed an evaluation for dementia, with dementia diagnoses determined during consensus conferences using criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th edition.

RESULTS

Among 4277 participants, the mean (SD) age was 74.5 (6.4) years, and 2519 participants (58.9%) were women. The median follow-up was 8 years (interquartile range, 4-12 years), with 730 participants developing dementia over 24 378 person-years. The age-specific dementia incidence was lower for those born in 1929 and later compared with those born earlier. Compared with participants born in the pre-Great Depression years (1921-1928), the age- and sex-adjusted hazard ratio was 0.67 (95% CI, 0.53-0.85) for those born in the Great Depression period (1929-1939) and 0.62 (95% CI, 0.29-1.31) for those born in the World War II and postwar period (1940-1949). Although indicators of a more advantaged early-life environment and higher educational level (college or higher) were associated with a lower incidence of dementia, these variables did not explain the association between birth cohort and dementia incidence, which remained when vascular risk factors were included and were similar by sex.

CONCLUSIONS AND RELEVANCE

Age-specific dementia incidence was lower in participants born after the mid-1920s compared with those born earlier. In this population, the decrease in dementia incidence may reflect societal-level changes or individual differences over the life course rather than early-life environment, as reflected through recalled childhood socioeconomic status and measured height, educational level, and later-life vascular risk.

Association between childhood socioeconomic status and subjective memory complaints among older adults: results from the Japan Gerontological Evaluation Study 2010

BACKGROUND

Subjective memory complaints (SMC) have been suggested as an early marker of mild cognitive impairment and dementia. However, there is a paucity of evidence on the effects of early life conditions on the development of SMC in old age. This study is aimed at investigating the association between childhood socioeconomic status (SES) and SMC in community-dwelling older adults.

METHODS

We used the data of the Japan Gerontological Evaluation Study, a population-based cohort study of people aged 65 years or older enrolled from 28 municipalities across Japan. Childhood SES and SMC in everyday life were assessed from the self-report questionnaire administered in 2010 (n = 16,184). Poisson regression was performed to determine their association, adjusted for potential confounders and life-course mediators and examined cohort effects.

RESULTS

We identified SMC in 47.4% of the participants. After adjusting for sex, age, and number of siblings, low and middle childhood SES were associated with 29% (prevalence ratio [PR]: 1.29, 95% confidence interval [CI]: 1.22, 1.36) and 10% higher prevalence of SMC (PR: 1.10, 95%CI: 1.04, 1.17), respectively, compared with high childhood SES (p for trend <.001). The interaction terms between childhood SES and age groups were not statistically significant.

CONCLUSION

Childhood SES is significantly associated with SMC among community-dwelling older adults. Efforts to minimize childhood poverty may diminish or delay the onset of SMC and dementia in later life.

Corticotropin releasing factor-binding protein (CRF-BP) as a potential new therapeutic target in Alzheimer's disease and stress disorders

Alzheimer's disease is the most common cause of dementia and one of the most complex human neurodegenerative diseases. Numerous studies have demonstrated a critical role of the environment in the pathogenesis and pathophysiology of the disease, where daily life stress plays an important role. A lot of epigenetic studies have led to the conclusion that chronic stress and stress-related disorders play an important part in the onset of neurodegenerative disorders, and an enormous amount of research yielded valuable discoveries but has so far not led to the development of effective treatment strategies for Alzheimer's disease. Corticotropin-releasing factor (CRF) is one of the major hormones and at the same time a neuropeptide acting in stress response. Deregulation of protein levels of CRF is involved in the pathogenesis of Alzheimer's disease, but little is known about the precise roles of CRF and its binding protein, CRF-BP, in neurodegenerative diseases. In this review, we summarize the key evidence for and against the involvement of stress-associated modulation of the CRF system in the pathogenesis of Alzheimer's disease and discuss how recent findings could lead to new potential treatment possibilities in Alzheimer's disease by using CRF-BP as a therapeutic target.

Variety of Enriching Early-Life Activities Linked to Late-Life Cognitive Functioning in Urban Community-Dwelling African Americans

OBJECTIVES

The early environment is thought to be a critical period in understanding the cognitive health disparities African Americans face today. Much is known about the positive role enriching environments have in mid- and late-life and the negative function adverse experiences have in childhood; however, little is known about the relationship between enriching childhood experiences and late-life cognition. The current study examines the link between a variety of enriching early-life activities and late-life cognitive functioning in a sample of sociodemographic at-risk older adults.

METHOD

This study used data from African Americans from the Brain and Health Substudy of the Baltimore Experience Corps Trial (M = 67.2, SD = 5.9; N = 93). Participants completed a battery of neuropsychological assessments and a seven-item retrospective inventory of enriching activities before age 13.

RESULTS

Findings revealed that a greater enriching early-life activity score was linked to favorable outcomes in educational attainment, processing speed, and executive functioning.

DISCUSSION

Results provide promising evidence that enriching early environments are associated with late-life educational and cognitive outcomes. Findings support the cognitive reserve and engagement frameworks, and have implications to extend life-span prevention approaches when tackling age-related cognitive declines, diseases, and health disparities.

Early Secure Attachment as a Protective Factor Against Later Cognitive Decline and Dementia

The etiology of neurodegenerative disorders such as dementia is complex and incompletely understood. Interest in a developmental perspective to these pathologies is gaining momentum. An early supportive social environment seems to have important implications for social, affective and cognitive abilities across the lifespan. Attachment theory may help to explain the link between these early experiences and later outcomes. This theory considers early interactions between an infant and its caregiver to be crucial to shaping social behavior and emotion regulation strategies throughout adult life. Furthermore, research has demonstrated that such early attachment experiences can, potentially through epigenetic mechanisms, have profound neurobiological and cognitive consequences. Here we discuss how early attachment might influence the development of affective, cognitive, and neurobiological resources that could protect against cognitive decline and dementia. We argue that social relations, both early and late in life, are vital to ensuring cognitive and neurobiological health. The concepts of brain and cognitive reserve are crucial to understanding how environmental factors may impact cognitive decline. We examine the role that attachment might play in fostering brain and cognitive reserve in old age. Finally, we put forward the concept of affective reserve, to more directly frame the socio-affective consequences of early attachment as protectors against cognitive decline. We thereby aim to highlight that, in the study of aging, cognitive decline and dementia, it is crucial to consider the role of affective and social factors such as attachment.

Responses to executive demand in young adulthood differ by APOE genotype

Despite evidence of a relationship between Apolipoprotein E (APOE) ε4+ and later-life cognitive decline, the lifespan effects of carrying an ε4+ allele on cognitive ageing are not well understood. Evidence of ε4+ advantages in early-life are inconsistent, but not inconsiderable. We explored the proposal that APOE ε4+ cognitive advantages arise only in response to complex and sensitive tasks targeting specific executive functions. We systematically manipulated executive demand within verbal fluency, decision-making, prospective memory, and sustained attention tasks. Participants aged 18-25 years (21 ε4+, 63 ε33) also completed a measure of subjective effort. Under low executive demand, ε4+ made fewer verbal fluency word repeats compared to ε33 carriers. Under high executive demand, ε4+ showed lower costs associated with performing concurrent tasks, greater switching errors, and more verbal fluency root repetition errors. Overall, ε4+ appeared to be showing working memory updating advantages under conditions of low executive demand, more effective resource allocation under elevated levels of executive demand, and errors indicating different strategy use compared to ε33 carriers, including speed-accuracy trade-offs.

Alzheimer's Disease Mortality according to Socioeconomic Factors: Country Study

Aim of the paper is to quantify effects of socioeconomic factors on Alzheimer's Disease Mortality in the Slovak Republic. We applied potential gains in life expectancy (PGLE) method to measure the impact of elimination of Alzheimer's disease on life expectance in Slovak regions. PGLE is based on life table adjustment according to elimination of mortality caused by specific diagnosis. Our dataset consists of all deceased from Slovak Republic from 2001 to 2015. We analyse the impact of unemployment rate, GDP per capita, average wage, and education on life expectance in Slovak regions. To estimate that impact, ordinary least squares (OLS) is applied. According to our model, gross domestic product, average wage, and education influence mortality caused by Alzheimer's disease.

Tauopathy and neurodegeneration: A role for stress

Neurodegenerative diseases are characterized by an irreversible and progressive loss of neuronal structure and function. While many alterations to normal cellular processes occur during neurodegeneration, a pathological accumulation of aggregated proteins constitutes a hallmark of several neurodegenerative disorders. Alzheimer's disease, specifically, is pathologically defined by the formation of amyloid plaques and tangles of hyperphosphorylated tau protein. Stress has emerged as an important factor in the development and progression of neurodegenerative diseases, including Alzheimer's. Very little is known, however, regarding the effects of stress on the mechanisms controlling abnormal protein aggregation and clearance. Chronic stress activates the hypothalamic-pituitary-adrenal (HPA) axis, causing an excessive secretion of glucocorticoids that are capable of impacting diverse physiological and cellular processes. The present review focuses on the influence of stress on a key feature of Alzheimer's disease pathology, emphasizing the relationship between tau phosphorylation and accumulation and its connection to HPA axis dysfunction.

The Differential Effects of Age on the Association Between Childhood Socioeconomic Disadvantage and Subjective Symptoms of Dementia Among Older Japanese People

Background

Despite increasing evidence of an association between childhood socioeconomic disadvantage and cognitive outcomes, such as dementia and cognitive decline, in Western countries, there are no studies on this association from non-Western societies. We investigated the relationship between childhood socioeconomic status (SES) and subjective symptoms of dementia among community-dwelling older Japanese people and examined age and sex variations in this association.

Methods

Data were derived from a cross-sectional survey for all community-dwelling individuals aged 65 years and over in Adachi, Tokyo (n = 132,005). We assessed subjective dementia symptoms using a self-administered dementia checklist, which was validated by comparison with the Clinical Dementia Rating scale.

Results

Data from 75,358 questionnaires were analyzed. After adjusting for potential covariates, lower childhood SES was associated with greater likelihood of subjective dementia symptoms. We found a significant interaction between childhood SES and age on subjective dementia symptoms but no interaction between childhood SES and sex. Age-stratified analysis indicated that the association between lower childhood SES and subjective dementia symptoms was stronger in the ≥75 years subgroup than in the 65–74 years subgroup, indicating an effect modification of age on this association.

Conclusions

Our findings suggested that low SES in childhood might have a long-term influence on dementia symptoms in late life and that this influence varied by age. This differential association might be explained by the social and historical context in Japan (ie, World War II, postwar chaos, and high economic growth) that has shaped participants’ early experiences.

Childhood socioeconomic status and genetic risk for poorer cognition in later life

The ε4 allele of the APOE gene is associated with poorer cognition in later life. This study aimed to advance understanding of how environments potentially moderate this genetic risk by focusing on childhood socioeconomic status (SES). Previous research across diverse national contexts has found that older adults from higher-SES families in childhood demonstrate better cognitive functioning than their lower-SES counterparts. Nevertheless, few studies have examined whether higher childhood SES might also promote later life cognition by mitigating the effects of ε4 carrier status. To address this gap, we used data from 3017 participants in the Wisconsin Longitudinal Study, which has followed a random sample of people who graduated from Wisconsin high schools in 1957. Childhood SES included parents' educational attainment, father's occupational status, and household income in adolescence. We constructed measures of memory and of language/executive functioning using scores from neurocognitive tests administered when participants were approximately ages 65 and 72. APOE ε4 status was measured through saliva samples. Results from cross-controlled multilevel models indicated that APOE ε4 status-and not childhood SES-independently predicted memory, whereas childhood SES-and not APOE ε4 status-independently predicted language/executive functioning. Moreover, a statistical interaction between APOE ε4 status and childhood SES for memory indicated that at baseline, higher childhood SES protected against the risk of APOE ε4 status, whereas lower childhood SES exacerbated the risk of APOE ε4 status. However, by follow-up, these moderating effects dissipated, and APOE ε4 status alone was associated with memory. We interpret these results in light of theorizing on differential susceptibility for poorer cognition across the life course.

Neuroprotective effects of salidroside administration in a mouse model of Alzheimer's disease

Salidroside administration improves memory in different models of learning. However, its influence on models of Alzheimer's disease (AD) has not been widely studied. In the present study, the therapeutic effect of salidroside was investigated in an animal model of AD. APPswe/PS1ΔE9 mouse (n=20) were randomly divided into either the AD model group or the salidroside + AD model group (n=10 in each group), and C57BL/6J mouse (n=20) of identical age and genetic background were randomly divided into either the normal control (NC) group or the salidroside + NC group (n=10 in each group). The Morris water maze behavioral test was applied to all mice in order to investigate the effects of salidroside administration on learning and memory functions. The concentrations of malondialdehyde (MDA), glutathione (GSH) and nitrate in the hippocampus of the mice were determined, and hippocampal superoxide dismutase (SOD) activity was also determined. In addition, terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling was used to investigate the rate of neuronal apoptosis in the hippocampus. Furthermore, the concentrations of interleukin‑6 (IL‑6) and tumor necrosis factor‑α (TNF‑α) were tested for in the brain tissues of AD mice. Learning and memory functions in AD mice were revealed to improve following administration of salidroside. Furthermore, salidroside administration was revealed to decrease the concentrations of MDA and nitrate in the hippocampus, decrease the apoptotic rate of hippocampal neurons, and increase the activity of SOD and the concentration of GSH in hippocampal tissue. In addition, it was demonstrated that salidroside administration suppressed the expression levels of IL‑6 and TNF‑α. In conclusion, this study revealed that the administration of salidroside could attenuate the effects of AD‑associated memory and learning impairment in mice. Furthermore, it was demonstrated that the effects of salidroside administration on AD mice were, at least partially, via inhibition of brain oxidative/nitrosative damage, suppression of both IL‑6 and TNF‑α expression levels, and suppression of the hippocampal neuronal apoptotic rate.

Head circumference, leg length and its association with dementia among older adult population in Singapore

BACKGROUND

Head circumference and leg length serve as reliable proxy indicators of early-life environment. Research studies have shown that these anthropometric measurements are associated with cognitive impairment and dementia among older adults. The aim of the present study was to assess the associations between dementia with head circumference and leg length among the older adult population in Singapore. This study also aimed to examine the sociodemographic correlates of these anthropometric measurements.

METHODS

Data were collected from 2565 older adults aged 60 years and above, in a population study on the Well-being of the Singapore Elderly. Head circumference and leg length measurements were obtained, and sociodemographic information was recorded. Dementia diagnosis was made using the 10/66 dementia algorithm. Anthropometric measurements were first stratified into quarters, and then logistic regression analysis was used to examine factors associated with head circumference and leg length, as well as to examine the association between dementia with these measurements.

RESULTS

Sociodemographic correlates of head circumference and leg length include age, gender, ethnicity and education level. Smaller head circumference was independently associated with higher odds of 10/66 dementia (OR = 2.173-2.709). When the regression analysis was stratified by gender, the association was found only in the male sample. Leg length was not significantly associated with dementia after controlling for sociodemographic variables.

CONCLUSION

Smaller head circumference is independently associated with dementia among older adults in Singapore. Findings from this study suggest that risk factors for dementia begin their influence in early life. Copyright © 2017 John Wiley & Sons, Ltd.

Childhood Stress and Adversity is Associated with Late-Life Dementia in Aboriginal Australians

OBJECTIVES

High rates of dementia have been observed in Aboriginal Australians. This study aimed to describe childhood stress in older Aboriginal Australians and to examine associations with late-life health and dementia.

DESIGN

A cross-sectional study with a representative sample of community-dwelling older Aboriginal Australians.

SETTING

Urban and regional communities in New South Wales, Australia.

PARTICIPANTS

336 Aboriginal and/or Torres Strait Islander Australians aged 60-92 years, of whom 296 were included in the current analyses.

MEASUREMENTS

Participants completed a life course survey of health, well-being, cognition, and social history including the Childhood Trauma Questionnaire (CTQ), with consensus diagnosis of dementia and Alzheimer disease.

RESULTS

CTQ scores ranged from 25-117 (median: 29) and were associated with several adverse childhood indicators including separation from family, poor childhood health, frequent relocation, and growing up in a major city. Controlling for age, higher CTQ scores were associated with depression, anxiety, suicide attempt, dementia diagnosis, and, specifically, Alzheimer disease. The association between CTQ scores and dementia remained significant after controlling for depression and anxiety variables (OR: 1.61, 95% CI: 1.05-2.45). In contrast, there were no significant associations between CTQ scores and smoking, alcohol abuse, diabetes, or cardiovascular risk factors.

CONCLUSIONS

Childhood stress appears to have a significant impact on emotional health and dementia for older Aboriginal Australians. The ongoing effects of childhood stress need to be recognized as people grow older, particularly in terms of dementia prevention and care, as well as in populations with greater exposure to childhood adversity, such as Aboriginal Australians.

Association of lifelong exposure to cognitive reserve-enhancing factors with dementia risk: A community-based cohort study

BACKGROUND

Variation in the clinical manifestation of dementia has been associated with differences in cognitive reserve, although less is known about the cumulative effects of exposure to cognitive reserve factors over the life course. We examined the association of cognitive reserve-related factors over the lifespan with the risk of dementia in a community-based cohort of older adults.

METHODS AND FINDINGS

Information on early-life education, socioeconomic status, work complexity at age 20, midlife occupation attainment, and late-life leisure activities was collected in a cohort of dementia-free community dwellers aged 75+ y residing in the Kungsholmen district of Stockholm, Sweden, in 1987-1989. The cohort was followed up to 9 y (until 1996) to detect incident dementia cases. To exclude preclinical phases of disease, participants who developed dementia at the first follow-up examination 3 y after the baseline were excluded (n = 602 after exclusions). Structural equation modelling was used to generate latent factors of cognitive reserve from three periods over the life course: early (before 20 y), adulthood (around 30-55 y), and late life (75 y and older). The correlation between early- and adult-life latent factors was strong (γ = 0.9), whereas early-late (γ = 0.27) and adult-late (γ = 0.16) latent factor correlations were weak. One hundred forty-eight participants developed dementia during follow-up, and 454 remained dementia-free. The relative risk (RR) of dementia was estimated using Cox models with life-course cognitive reserve-enhancing factors modelled separately and simultaneously to assess direct and indirect effects. The analysis was repeated among carriers and noncarriers of the apolipoprotein E (APOE) ε4 allele. A reduced risk of dementia was associated with early- (RR 0.57; 95% CI 0.36-0.90), adult- (RR 0.60; 95% CI 0.42-0.87), and late-life (RR 0.52; 95% CI 0.37-0.73) reserve-enhancing latent factors in separate multivariable Cox models. In a mutually adjusted model, which may have been imprecisely estimated because of strong correlation between early- and adult-life factors, the late-life factor preserved its association (RR 0.65; 95% CI 0.45-0.94), whereas the effect of midlife (RR 0.73; 95% CI 0.50-1.06) and early-life factors (RR 0.76; 95% CI 0.47-1.23) on the risk of dementia was attenuated. The risk declined progressively with cumulative exposure to reserve-enhancing latent factors, and having high scores on cognitive reserve-enhancing composite factors in all three periods over the life course was associated with the lowest risk of dementia (RR 0.40; 95% CI 0.20-0.81). Similar associations were detected among APOE ε4 allele carriers and noncarriers. Limitations include measurement error and nonresponse, with both biases likely favouring the null. Strong correlation between early- and adult-life latent factors may have led to a loss in precision when estimating mutually adjusted effects of all periods.

CONCLUSIONS

In this study, cumulative exposure to reserve-enhancing factors over the lifespan was associated with reduced risk of dementia in late life, even among individuals with genetic predisposition.

Sustained Economic Hardship and Cognitive Function: The Coronary Artery Risk Development in Young Adults Study

INTRODUCTION

The relationship between low income and worse health outcomes is evident, yet its association with cognitive outcomes is less explored. Most studies have measured income at one time and none have examined how sustained exposure to low income influences cognition in a relatively young cohort. This study examined the effect of sustained poverty and perceived financial difficulty on cognitive function in midlife.

METHODS

Income data were collected six times between 1985 and 2010 for 3,383 adults from the Coronary Artery Risk Development in Young Adults prospective cohort study. Sustained poverty was defined by the percentage of time participants' household income was <200% of the federal poverty level-"never" in poverty, "0< to <1/3," "≥1/3 to <100%" or "all-time." In 2010, at a mean age of 50 years, participants underwent a cognitive battery. Data were analyzed in 2015.

RESULTS

In demographic-adjusted linear regression models, individuals with all-time poverty performed significantly worse than individuals never in poverty: 0.92 points worse on verbal memory (z-score, -0.28; 95% CI=-0.43, -0.13), 11.60 points worse on processing speed (z-score, -0.72; 95% CI=-0.85, -0.58), and 3.50 points worse on executive function (z-score, -0.32; 95% CI=-0.47, -0.17). Similar results were observed with perceived financial difficulty. Findings were robust when restricted to highly educated participants, suggesting little evidence for reverse causation.

CONCLUSIONS

Cumulative exposure to low income over 2 decades was strongly associated with worse cognitive function of a relatively young cohort. Poverty and perceived hardship may be important contributors to premature aging among disadvantaged populations.

Early Life Epidemiology of Alzheimer's Disease--A Critical Review

BACKGROUND

As adult brain structure is primarily established in early life, genetic and environmental exposures in infancy and childhood influence the risk for Alzheimer disease (AD). In this systematic review, we identified several early life risk factors and discussed the evidence and underlying mechanism for each.

SUMMARY

Early risk factors for AD may alter brain anatomy, causing vulnerability to AD-related dementia later in life. In the perinatal period, both genes and learning disabilities have been associated with the development of distinct AD phenotypes. During early childhood, education and intellect, as well as body growth, may predispose to AD through alterations in cognitive and brain reserve, though the specific mediators of neural injury are disputed. Childhood socioeconomic status (SES) may predispose to AD by influencing adult SES and cognition. Association of these risk factors with underlying AD pathology (rather than just clinical diagnosis) has not been sufficiently examined.

KEY MESSAGES

Factors that impede or alter brain growth during early life could render certain brain regions or networks selectively vulnerable to the onset, accumulation or spread of AD-related pathology during later life. Careful life-course epidemiology could provide clues as to why the brain systematically degenerates during AD.

Correlation of Alzheimer's disease death rates with historical per capita personal income in the USA

Alzheimer’s disease (AD) is a progressive degenerating disease of complex etiology. A variety of risk factors contribute to the chance of developing AD. Lifestyle factors, such as physical, mental and social activity, education, and diet all affect the susceptibility to developing AD. These factors are in turn related to the level of personal income. Lower income usually coincides with lower level of education, lesser mental, leisure—social and physical activity, and poorer diet. In the present paper, we have analyzed the correlation of historical (1929–2011) per capita personal income (PCPI) for all states of the USA with corresponding age-adjusted AD death rates (AADR) for years 2000, 2005 and 2008. We found negative correlations in all cases, the highest one (R ≈ -0.65) for the PCPIs in the year 1970 correlated against the AADRs in 2005. From 1929 to 2005 the R value varies in an oscillatory manner, with the strongest correlations in 1929, 1970, 1990 and the weakest in 1950, 1980, 1998. Further analysis indicated that this oscillatory behavior of R is not artificially related to the economic factors but rather to delayed biological consequences associated with personal income. We conclude that the influence of the income level on the AD mortality in 2005 was the highest in the early years of life of the AD victims. Overall, the income had a significant, lifelong, albeit constantly decreasing, influence on the risk of developing AD. We postulate that the susceptibility of a population to late-onset AD (LOAD) is determined to a large extent by the history of income-related modifiable lifestyle risk factors. Among these risk factors, inappropriate diet has a significant contribution.

Occupational class differences in later life hospital use by women who survived to age 80: the Renfrew and Paisley prospective cohort study

BACKGROUND

population ageing challenges the sustainability of healthcare provision.

OBJECTIVE

to investigate occupational class differences in hospital use in women aged 80+ years.

METHODS

a total of 8,353 female residents, aged 45-64, took part in the Renfrew and Paisley prospective cohort study in 1972-76. Information on general and mental health hospital discharges was provided from computerised linkage with the Scottish Morbidity Records data to 31 December 2012. Numbers of admissions and bed-days after the 80th birthday were calculated for all and specific causes. Rate ratios by occupational class were calculated using negative binomial regression analysis, adjusting for age and a range of risk factors.

RESULTS

four thousand and four hundred and seven (56%) women survived to age 80 and had 17,563 general admissions thereafter, with a mean stay of 19.4 days. There were no apparent relationships with occupational class for all general admissions, but lower occupational class was associated with higher rate ratios for coronary heart disease and stroke and lower rate ratios for cancer. Adjustment for risk factors could not fully explain the raised rate ratios. Bed-day use was higher in lower occupational classes, especially for stroke. There were strong associations with mental health admissions, especially dementia. Compared with the highest occupational class, admission rate ratios for dementia were higher for the lowest occupational class (adjusted rate ratio = 2.60, 95% confidence interval 1.79-3.77).

CONCLUSION

in this population, there were no socio-economic gradients seen in hospital utilisation for general admissions in old age. However, occupational class was associated with mental health admissions, coronary heart disease, stroke and cancer.

Associations between skeletal growth in childhood and cognitive function in mid-life in a 53-year prospective birth cohort study

BACKGROUND

Several studies have found that shorter stature (height and limb length) in late life is associated with dementia and cognitive impairment. The extent to which childhood environment and early life cognitive function accounts for these associations is not clear.

METHODS

We investigated associations of adult trunk height and leg length with cognitive function in middle age, analysing data from the MRC National Survey of Health and Development: a cohort followed from birth to age 53, 1677 of whom had data on all covariates. The four cognitive tests measured verbal ability, word list memory, verbal fluency and speed/concentration. Early life environmental measures included parental education, poverty, parental divorce, physical health, cognitive ability at age 15, own education and own adult social class.

RESULTS

After adjusting for gender, shorter trunk length was associated with lower cognitive function on all four tests and shorter leg length with lower verbal intelligence and word list memory. These associations were only partially attenuated following adjustment for childhood adversity/health but were substantially accounted for by cognitive ability at age 15.

CONCLUSIONS

Shorter stature was associated with lower cognitive function at age 53, the majority of this association being accounted for by cognitive function at age 15. Reduced cognitive reserve may well account for later associations between anthropometric measures and dementia.

The influence of chronic stress on anxiety-like behavior and cognitive function in different human GFAP-ApoE transgenic adult male mice

The apolipoprotein E (ApoE) ɛ4 allele (ApoE4) is an important genetic risk factor for the pathogenesis of Alzheimer's disease (AD). In addition to genetic factors, environmental factors such as stress may play a critical role in AD pathogenesis. This study was designed to investigate the anxiety-like behavioral and cognitive changes in different human glial fibrillary acidic protein (GFAP)-ApoE transgenic adult male mice under chronic stress conditions. On the open field test, anxiety-like behavior was increased in the non-stressed GFAP-ApoE4 transgenic mice relative to the corresponding GFAP-ApoE3 (ApoE ɛ3 allele) mice. Anxiety-like behavior was increased in the stressed GFAP-ApoE3 mice relative to non-stressed GFAP-ApoE3 mice, but was unexpectedly decreased in the stressed GFAP-ApoE4 mice relative to non-stressed GFAP-ApoE4 mice. On the novel object recognition task, both GFAP-ApoE4 and GFAP-ApoE3 mice exhibited long-term non-spatial memory impairment after chronic stress. Interestingly, short-term non-spatial memory impairment (based on the novel object recognition task) was observed only in the stressed GFAP-ApoE4 male mice relative to non-stressed GFAP-ApoE4 transgenic mice. In addition, short-term spatial memory impairment was observed in the stressed GFAP-ApoE3 transgenic male mice relative to non-stressed GFAP-ApoE3 transgenic male mice; however, short-term spatial memory performance of GFAP-ApoE4 transgenic male mice was not reduced compared to non-stressed control mice based on the Y-maze task. In conclusion, our findings suggested that chronic stress affects anxiety-like behavior and spatial and non-spatial memory in GFAP-ApoE transgenic mice in an ApoE isoform-dependent manner.

Impact of offspring death on cognitive health in late life: the Cache County study

OBJECTIVE

Experiencing the death of a child is associated with negative short-term mental health consequences, but less is known about cognitive outcomes and whether such associations extend to late life. We tested the hypothesis that experiencing an offspring death (OD) is associated with an increased rate of cognitive decline in late life.

METHODS

This population-based longitudinal study observed four cognitive statuses spaced 3-4 years apart, linked to an extensive database containing objective genealogic and vital statistics data. Home visits were conducted with 3,174 residents of a rural county in northern Utah, initially without dementia, aged 65-105. Cognitive status was measured with the Modified Mini-Mental State Exam at baseline and at 3-, 7-, and 10-year follow-ups. OD was obtained from the Utah Population Database, which contains statewide birth and death records.

RESULTS

In linear mixed models, controlling for age, gender, education, and apolipoprotein E status, subjects who experienced OD while younger than age 31 years experienced a significantly faster rate of cognitive decline in late life, but only if they had an ε4 allele. Reclassifying all OD (regardless of age) according to subsequent birth of another child, OD was only related to faster cognitive decline when there were no subsequent births.

CONCLUSION

Experiencing OD in early adulthood has a long-term association with cognitive functioning in late life, with a gene-environment interaction at the apolipoprotein E locus. Subsequent birth of another child attenuates this association.

Prevalence of dementia in urban and regional Aboriginal Australians

BACKGROUND

This study aimed to determine the prevalence of dementia in collaboration with urban/regional Aboriginal communities.

METHODS

A census of Aboriginal and Torres Strait Islander men and women aged 60 years and above in the target communities identified 546 potential participants, with 336 (61.5%) participating in this cross-sectional study. Participants completed a structured interview and cognitive screening tests. One hundred fifty-three participants also completed a detailed medical assessment. Assessment data were reviewed by a panel of clinicians who determined a diagnosis of dementia or mild cognitive impairment (MCI) according to standard criteria.

RESULTS

Crude prevalence of dementia was 13.4%, and age-standardized prevalence was 21.0%. The most common types of dementia were Alzheimer's dementia (44%) and mixed dementia diagnoses (29%). Estimated prevalence of MCI was 17.7%.

CONCLUSION

Consistent with previous findings in a remote population, urban and regional Aboriginal Australians face high rates of dementia at younger ages, most commonly Alzheimer's dementia.

The Koori Growing Old Well Study: investigating aging and dementia in urban Aboriginal Australians

BACKGROUND

Dementia is an emerging health priority in Australian Aboriginal communities, but substantial gaps remain in our understanding of this issue, particularly for the large urban section of the population. In remote Aboriginal communities, high prevalence rates of dementia at relatively young ages have been reported. The current study is investigating aging, cognitive decline, and dementia in older urban/regional Aboriginal Australians.

METHODS

We partnered with five Aboriginal communities across the eastern Australian state of New South Wales, to undertake a census of all Aboriginal men and women aged 60 years and over residing in these communities. This was followed by a survey of the health, well-being, and life history of all consenting participants. Participants were also screened using three cognitive instruments. Those scoring below designated cut-offs, and a 20% random sample of those scoring above (i.e. "normal" range), completed a contact person interview (with a nominated family member) and medical assessment (blind to initial screening results), which formed the basis of "gold standard" clinical consensus determinations of cognitive impairment and dementia.

CONCLUSION

This paper details our protocol for a population-based study in collaboration with local Aboriginal community organizations. The study will provide the first available prevalence rates for dementia and cognitive impairment in a representative sample of urban Aboriginal people, across city and rural communities, where the majority of Aboriginal Australians live. It will also contribute to improved assessment of dementia and cognitive impairment and to the understanding of social determinants of successful aging, of international significance.

Life course socioeconomic position and mid-late life cognitive function in Eastern Europe

OBJECTIVES

To investigate whether the positive relation between socioeconomic position (SEP) across the life course and later life cognitive function observed in Western populations exists in former communist countries with apparently smaller income inequalities.

METHOD

Structural equation modeling analysis of cross-sectional data on 30,846 participants aged 45-78 years in four Central and Eastern European centers: Novosibirsk (Russia), Krakow (Poland), Kaunas (Lithuania), and six Czech towns from the HAPIEE (Health, Alcohol, and Psychosocial factors In Eastern Europe) study. SEP was measured using self-reported childhood (maternal education, household amenities), adult (education), and older adult (current material circumstances) indicators. Latent variable for cognition was constructed from word recall, animal naming, and letter search.

RESULTS

Associations between SEP measures over the life course and cognition were similar across study centers. Education had the strongest direct association with cognition, followed by current material circumstances. Indirect path from education to cognition, mediated by current SEP, was small. Direct path from mother's education to cognition was significant but modest, and partially mediated by later SEP measures, particularly education.

DISCUSSION

In these Eastern European populations, late life cognition reflected life course socioeconomic trajectories similarly to findings in Western countries.

Survival of offspring who experience early parental death: early life conditions and later-life mortality

We examine the influences of a set of early life conditions (ELCs) on all-cause and cause-specific mortality among elderly individuals, with special attention to one of the most dramatic early events in a child's, adolescent's, or even young adult's life, the death of a parent. The foremost question is, once controlling for prevailing (and potentially confounding) conditions early in life (family history of longevity, paternal characteristics (SES, age at time of birth, sibship size, and religious affiliation)), is a parental death associated with enduring mortality risks after age 65? The years following parental death may initiate new circumstances through which the adverse effects of paternal death operate. Here we consider the offspring's marital status (whether married; whether and when widowed), adult socioeconomic status, fertility, and later life health status. Adult health status is based on the Charlson Co-Morbidity Index, a construct that summarizes nearly all serious illnesses afflicting older individuals that relies on Medicare data. The data are based on linkages between the Utah Population Database and Medicare claims that hold medical diagnoses data. We show that offspring whose parents died when they were children, but especially when they were adolescents/young adults, have modest but significant mortality risks after age 65. What are striking are the weak mediating influences of later-life comorbidities, marital status, fertility and adult socioeconomic status since controls for these do little to alter the overall association. No beneficial effects of the surviving parent's remarriage were detected. Overall, we show the persistence of the effects of early life loss on later-life mortality and indicate the difficulties in addressing challenges at young ages.

Early life development in a multiethnic sample and the relation to late life cognition

OBJECTIVES

Poor quality of early life conditions has been associated with poorer late life cognition and increased risk of dementia. Early life physical development can be captured using adult measures of height and head circumference. Availability of resources may be reflected by socioeconomic indicators, such as parental education and family size. We sought to determine the association between early life development and experience and late life semantic memory, episodic memory, and executive functioning abilities, as well as rate of cognitive decline.

METHOD

This study was conducted using the UC Davis Aging Diversity cohort, an ethnically diverse sample of Caucasian, African American, and Hispanic individuals from northern California. We used latent variable modeling to measure growth and childhood socioeconomic environment (SES) and examine their associations with longitudinal cognitive outcomes using mixed effects modeling.

RESULTS

Growth was positively related to higher childhood SES. Higher childhood SES was associated with better semantic memory. Both low growth and low SES were associated with increased rate of cognitive decline.

DISCUSSION

These findings demonstrate that early life experiences influence the trajectory of cognitive aging. Early life development and experience appears to provide a distal basis upon which additional risk and protective factors interact in the development of dementia.

The Cache County Study on Memory in Aging: factors affecting risk of Alzheimer's disease and its progression after onset

The Cache County Study on Memory in Aging is a longitudinal, population-based study of Alzheimer's disease (AD) and other dementias. Initiated in 1995 and extending to 2013, the study has followed over 5,000 elderly residents of Cache County, Utah (USA) for over twelve years. Achieving a 90% participation rate at enrolment, and spawning two ancillary projects, the study has contributed to the literature on genetic, psychosocial and environmental risk factors for AD, late-life cognitive decline, and the clinical progression of dementia after its onset. This paper describes the major study contributions to the literature on AD and dementia.

Opposing actions of environmental enrichment and Alzheimer's disease on the expression of hippocampal microRNAs in mouse models

Alzheimer's disease (AD) is the most common form of dementia in the elderly. Although there are no drugs that modify the disease process, exposure to an enriched environment (EE) can slow the disease progression. Here, we characterize the effects of AD and EE on the post-transcriptional regulators, microRNAs (miRNAs), which may contribute to the detrimental and beneficial effects of AD and EE, respectively, on synaptic plasticity-related proteins and AD pathology. We found for the first time miRNAs that were inversely regulated in AD and EE, and may affect synaptic proteins and modulators, molecular factors associated with AD pathology, and survival and neuroprotective factors. MiRNAs that were upregulated only in 3xTgAD mice model of AD compared with their control mice were localized to synapses, predicted to downregulate essential synaptic proteins and are highly associated with regulating apoptosis, AD-associated processes and axon guidance. Studying the progressive change in miRNAs modulation during aging of 3xTgAD mice, we identified miRNAs that were regulated in earlier stages of AD, suggesting them as potential AD biomarkers. Last, we characterized AD- and EE-related effects in the mouse hippocampus on tomosyn protein levels, an inhibitor of the synaptic transmission machinery. While EE reduced tomosyn levels, tomosyn levels were increased in old 3xTgAD mice, suggesting a role for tomosyn in the impairment of synaptic transmission in AD. Interestingly, we found that miR-325 regulates the expression levels of tomosyn as demonstrated by a luciferase reporter assay, and that miR-325 was downregulated in AD and upregulated following EE. These findings improve our understanding of the molecular and cellular processes in AD pathology, following EE, and the interplay between the two processes, and open new avenues for the studies of understanding and controlling AD.