Late-life Factors Research Articles

Temporal trends in population attributable fractions of modifiable risk factors for dementia: a time-series study of the English Longitudinal Study of Ageing (2004–2019)

BackgroundInterest in modifiable risk factors (MRFs) for dementia is high, given the personal, social, and economic impact of the disorder, especially in ageing societies such as the United Kingdom. Exploring the population attributable fraction (PAF) of dementia attributable to MRFs and how this may have changed over time remains unclear. Unravelling the temporal dynamics of MRFs is crucial for informing the development of evidence-based and effective public health policies. This investigation examined the temporal trajectories of MRFs for dementia in England.MethodsWe used data from the English Longitudinal Study of Ageing, a panel study over eight waves collected between 2004 and 2019 (76,904 interviews in total). We calculated the PAFs for twelve MRFs (including six early- to mid-life factors and six late-life factors), as recommended by the Lancet Commission, and the individual weighted PAFs (IW-PAFs) for each risk factor. Temporal trends were analysed to understand the changes in the overall PAF and IW-PAF over the study period. Subgroup analyses were conducted by sex and socioeconomic status (SES).ResultsThe overall PAF for dementia MRFs changed from 46.73% in 2004/2005 to 36.79% in 2018/2019, though this trend was not statistically significant. During 2004–2019, hypertension, with an average IW-PAF of 8.21%, was the primary modifiable determinant of dementia, followed by obesity (6.16%), social isolation (5.61%), hearing loss (4.81%), depression (4.72%), low education (4.63%), physical inactivity (3.26%), diabetes mellitus (2.49%), smoking (2.0%), excessive alcohol consumption (1.16%), air pollution (0.42%), and traumatic brain injury (TBI) (0.26%). During 2004–2019, only IW-PAFs of low education, social isolation, and smoking showed significant decreasing trends, while IW-PAFs of other factors either did not change significantly or increased (including TBI, diabetes mellitus, and air pollution). Upon sex-specific disaggregation, a higher overall PAF for MRFs was found among women, predominantly associated with later-life risk factors, most notably social isolation, depression, and physical inactivity. Additionally, hearing loss, classified as an early- to mid-life factor, played a supplementary role in the identified sex disparity. A comparable discrepancy was evident upon PAF evaluation by SES, with lower income groups experiencing a higher dementia risk, largely tied to later-life factors such as social isolation, physical inactivity, depression, and smoking. Early- to mid-life factors, in particular, low education and obesity, were also observed to contribute to the SES-associated divergence in dementia risk. Temporal PAF and IW-PAF trends, stratified by sex and SES, revealed that MRF PAF gaps across sex or SES categories have persisted or increased.ConclusionsIn England, there was little change over time in the proportion of dementia attributable to known modifiable risk factors. The observed trends underscore the continuing relevance of these risk factors and the need for targeted public health strategies to address them.

ASSOCIATION OF CHILDHOOD EXPOSURE TO SCHOOL RACIAL SEGREGATION WITH LATE-LIFE COGNITION AMONG AMERICAN ADULTS

Abstract Racial segregation may contribute to enduringly worse health outcomes and aging. Prior research mainly focuses on residential segregation, yet the long-term effects of school segregation and the effects for different racial/ethnic groups are largely unknown. Linking measures of primary school segregation using administrative data with a nationally representative population survey in the US, we examine how childhood exposure to school racial segregation shapes the late-life cognitive function. 23,752 non-Hispanic White (White), 6,364 non-Hispanic Black (Black) American adults aged 50 and older were identified from the Health and Retirement Study; and state-level school dissimilarity indexes in late 1960s were linked to participants’ latest wave of cognitive assessment using childhood residence. Multivariate regression analyses demonstrated that exposure to White-Black school segregation had strong, negative effects on cognitive outcomes for both White and Black participants. One standard deviation increase in dissimilarity index was associated with lower cognitive score (White: = -0.16 [95%CI, -0.22, -0.11]; Black: = -0.42 [95%CI, -0.53, -0.30]) and more cognitive impairment (White: Odds Ratio (OR) = 1.10 [95%CI, 1.06, 1.13]; Black: OR = 1.21 [95%CI, 1.14, 1.27]) adjusting for age and sex. Educational attainment and other socioeconomic characteristics explained most associations (40-70%), and the effects remained significant even after accounting for a rich set of late-life factors. Overall, these findings suggest that childhood exposure to school segregation has long-lasting effects on late-life cognition for both White and Black Americans. Educational policy and reform should be promoted to reduce school racial segregation within and between school districts to address health inequities.

BIRTHPLACE AND COGNITION AMONG US OLDER ADULTS: EVIDENCE FROM THE HARMONIZED COGNITIVE ASSESSMENT PROTOCOL (HCAP)

Abstract Growing evidence shows that place of birth and related circumstances may impose lasting and multiplicative impacts on a host of late-life outcomes; yet how it affects various domains of cognitive function in late-life is less understood. In this paper, we exploit the comprehensive cognitive assessments in the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) and HRS geographic data at birth to determine to what extent birth location measured at the state level is associated with cognitive status in later life for a representative sample of Americans over age 50 (N=3,324). We found that state of birth significantly influenced various cognitive domains later in life (including episodic memory, executive function, attention, visuospatial function, language fluency and orientation); and the regional rankings tended to be highly consistent across the cognitive assessments in each domain. Regression analysis demonstrated that the geographic disparities in cognition across birth states could be partly explained by the late-life differences in socioeconomic statuses. Nevertheless, Shapley decompositions demonstrated that, after accounting for mid-life to late-life factors, state of birth still contributed 20%-30% of the explained variations in cognitive outcomes. Particularly, foreign-born individuals and those born in the southern states tended to score the lowest on average on each of the cognitive tests/domains and can account for most of the explained differences in cognition. These findings suggest that place of birth may have lasting impacts on disparities in cognition later in life. Public policy should play pivotal roles in leveling the playing field in early life.

Understanding the preterm human heart: What do we know so far?

Globally, preterm birth affects more than one in every 10 live births. Although the short‐term cardiopulmonary complications of prematurity are well known, long‐term health effects are only now becoming apparent. Indeed, preterm birth has been associated with elevated cardiovascular morbidity and mortality in adulthood. Experimental animal models and observational human studies point toward changes in heart morphology and function from birth to adulthood in people born preterm that may contribute to known long‐term risks. Moreover, recent data support the notion of a heterogeneous cardiac phenotype of prematurity, which is likely driven by various maternal, early, and late life factors. This review aims to describe the early fetal‐to‐neonatal transition in preterm birth, the different structural and functional changes of the preterm human heart across developmental stages, as well as potential factors contributing to the cardiac phenotype of prematurity.

The contrasting human gut microbiota in early and late life and implications for host health and disease

The gut microbiota plays a significant role in health and development from birth and continues to affect several processes throughout life and into old age. During both infancy and old age, the trajectory of the gut microbiota changes with contrasting consequences at both stages for the host. The infant gut is unstable, and colonization is influenced by a variety of perinatal and postnatal factors. Many of these factors can contribute to an altered microbiota profile in infancy which can be associated with negative consequences later in life such as allergies, obesity, and neuropsychiatric disorders. The late-life gut microbiota is influenced by physiological changes within the host, illness, diet and lifestyle that impact its composition and functionality. Indeed, reduced microbial diversity, loss of beneficial microorganisms and increased pathobionts are key signatures of the elderly microbiome. Such changes have been associated with degenerative diseases including inflammaging, Alzheimer’s disease, Parkinson’s disease, and increased risk of infection with Clostridioides difficile. Here, we examine early- and late-life factors that contribute to contrasting gut microbiota disturbances and the consequences associated with these disruptions. Finally, we provide compelling evidence of nutritional and probiotic/prebiotic interventions that may help alleviate the effects of gut microbiota changes into old age.

Cognitive reserve and resilience: Possible mechanisms of dementia prevention

AbstractBackgroundPredictions about future dementia prevalence vary but usually suggest large increases in numbers of people with dementia as the population ages. However, in some countries, for example, the US, UK and Netherlands, while overall numbers of people with dementia are growing as predicted, the age‐specific incidence rates of dementia have decreased substantially. This is probably due to educational, socio‐economic, health and lifestyle changes.MethodWe reviewed known risk factors listed in the 2017 Lancet commission: education, hypertension, hearing impairment, smoking, obesity, depression, exercise, diabetes and social contact; literature about cognitive reserve and considered effective interventions for these risks.ResultCognitive reserve is the brain resilience which allows for cognition maintenance despite neuropathological damage. Early, mid and late life factors are all important. Early‐life factors, such as education, are important for cognitive reserve and those with more education build greater cognitive reserve. Lifelong higher educational attainment also reduces dementia risk. Cognitive reserve is not static and is affected by a number of factors. Quantifying it uses proxy measures such as education, residual approaches (the variance of cognition not explained by demographic variables and brain measures) or identifying underlying brain functional. People in more cognitively demanding jobs tend to show less cognitive deterioration before, and sometimes after retirement than those in less demanding jobs. Hypertension and obesity in mid‐life are risk factors for dementia, as is hearing impairment. More frequent social contacts at age 60 years is associated with lower dementia risk over 15 years of follow‐up. Smoking in late life increases the risk of dementia. In later life people’s physical health may moderate the susceptibility to neuropathology. Those who are frail may develop Alzheimer’s disease with a lesser burden of neuropathology. Older people otherwise in good physical health can sustain a higher burden of neuropathology without cognitive impairment. There are however relatively few evidence based interventions and we will discuss what interventions we found in systematic review and what developments are still needed.ConclusionThere are clinically and economically effective interventions. It is important to consider the stage of the life course when thinking about possible effective interventions to prevent dementia.

Neurodegenerative Dementias: Improving Brain Health to Decrease Risk.

Neurodegenerative Dementias: Improving Brain Health to Decrease Risk.

Cohort profile: Women's Healthy Ageing Project (WHAP)- a longitudinal prospective study of Australian women since 1990.

BackgroundThe cohort was commenced to examine women’s health from midlife (45–55 years) before the menopausal transition and into ageing.MethodsRandomised selection and assessment of 2,001 women living in the Melbourne metropolitan area was conducted by the Roy Morgan Centre in 1990/91. Of the 779 women who met the entry criteria for the longitudinal follow-up (aged 45–55 years, menstruating, having a uterus and at least one ovary and not taking hormone therapy) 438 agreed to be seen annually across the menopausal transition from 1992 to 1999. Longitudinal prospective follow-up since 2000 has continued intermittently (2002/03, 2004/05, 2012/13, 2014/15). Data collection has included fasting biomarkers in each year since 1992, clinical assessment, lifestyle and quality of life data, physical measures and validated questionnaire data. Participants have consented to data linkage and, to date, mammogram and BioGrid data have been accessed. Biobank storage including serum, deoxyribonucleic acid (DNA) storage and PAXgene tubes are maintained.DiscussionThe WHAP has contributed to over 200 published research findings, several books, and book chapters in a variety of areas, including: health and wellbeing; mental and cognitive health; bone health; lifestyle, vascular risk and prevention; women’s health and hormonal transition; and cross-cultural research.With all participants now aged over 70 years, the cohort is ideally placed to answer key questions of healthy ageing in women. With more than 25 years of longitudinal prospective follow-up this Australian dataset is unique in its duration, breadth and detail of measures including clinical review and specialized disease-specific testing and biomarkers. Ongoing follow-up into older ages for this long-running cohort will enable the association between mid to late-life factors and healthy ageing to be determined. This is particularly valuable for the examination of chronic diseases which have a 20–30 year prodrome and to provide knowledge on multiple morbidities. The dataset has a unique opportunity to improve our understanding of temporal relationships and the interactions between risk factors and comorbidities.Electronic supplementary materialThe online version of this article (doi:10.1186/s40695-016-0018-y) contains supplementary material, which is available to authorized users.

Late-life factors associated with healthy aging in older men.

To identify potentially modifiable late-life biological, lifestyle, and sociodemographic factors associated with overall and healthy survival to age 85. Prospective longitudinal cohort study with 21 years of follow-up (1991-2012). Hawaii Lifespan Study. American men of Japanese ancestry (mean age 75.7, range 71-82) without baseline major clinical morbidity and functional impairments (N = 1,292). Overall survival and healthy survival (free from six major chronic diseases and without physical or cognitive impairment) to age 85. Factors were measured at late-life baseline examinations (1991-1993). Of 1,292 participants, 1,000 (77%) survived to 85 (34% healthy) and 309 (24%) to 95 (<1% healthy). Late-life factors associated with survival and healthy survival included biological (body mass index, ankle-brachial index, cognitive score, blood pressure, inflammatory markers), lifestyle (smoking, alcohol use, physical activity), and sociodemographic factors (education, marital status). Cumulative late-life baseline risk factor models demonstrated that age-standardized (at 70) probability of survival to 95 ranged from 27% (no factors) to 7% (≥ 5 factors); probability of survival to 100 ranged from 4% (no factors) to 0.1% (≥ 5 factors). Age-standardized (at 70) probability of healthy survival to 90 ranged from 4% (no factors) to 0.01% (≥ 5 factors). There were nine healthy survivors at 95 and one healthy survivor at 100. Several potentially modifiable risk factors in men in late life (mean age 75.7) were associated with markedly greater probability of subsequent healthy survival and longevity.

Declines in late-life disability: The role of early- and mid-life factors

Investigations into the reasons for declines in late-life disability have largely focused on the role of contemporaneous factors. Adopting a life-course perspective as a backdrop, in this paper we ask whether there also has been a role for selected early- and mid-life factors in the decline, and if so whether these factors have been operating through changes in the risks of disability onset or recovery. Drawing on five waves from 1995 to 2004 of the U.S. Health and Retirement Study, we found for the 75 years and older population in the United States that the prevalence of difficulty with activities of daily living (ADL) declined from 30.2% in 1995 to 26.0% in 2004, whereas the trend in difficulty with instrumental activities of daily living (IADL) was flat. Onset of ADL limitations also was reduced during this period while recovery increased. Changes in the educational composition of the older population were linked to declines in the prevalence of ADL limitations, but there were also modest contributions of changes in mother's education, self-rated childhood health, and lifetime occupation. Declines in late-life vision impairments and increases in wealth also contributed substantially to the downward trend, and had chronic conditions not increased, it would have been even larger. Reductions in the onset of ADL limitations were partly driven by changes in educational attainment of respondents and their mothers and, in late-life, better vision and wealth. In contrast, the recovery trend was not accounted for by changes in early- or mid-life factors. We conclude that early- and mid-life factors have contributed along with late-life factors to U.S. late-life disability trends mainly through their influence on the onset of, rather than recovery from, limitations.