APOE ϵ4, rated life experiences, and affect among centenarians

A Re-evaluation of Candidate Gene Studies for Well-Being in Light of Genome-Wide Evidence

Ever since twin-family studies found that a substantial amount (± 40%) of the variation in well-being can be explained by genetic variation, several candidate genes have been proposed explaining this variation. However, these candidate gene and candidate gene-by-environment interaction studies have been surrounded by controversy regarding the validity and replication of their results. In the present study, we review the existing candidate gene literature for well-being. First, we perform a systematic literature search that results in the inclusion of 41 studies. After describing the results of the included studies, we evaluated the included candidate polymorphisms by (1) looking up the results for the studied candidate SNPs in a large well-being genome-wide association study, (2) performing association analyses in UK biobank (UKB) data for the candidate variable number tandem repeats (VNTR) and the APOE ε4 allele, and (3) studying possible candidate interactions with positive and negative environmental moderators using UKB data. We find no support for any of the candidate genes or candidate gene-environment interactions for well-being, with the exception of two SNPs that were chosen based on genome-wide evidence. While the generalizability of our findings is limited by our phenotype and environment definitions, we strongly advise well-being researchers to abandon the candidate gene approach in the field of well-being and move toward genome-wide approaches.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10902-022-00538-x.

A systematic review of the associations, mediators and moderators of life satisfaction, positive affect and happiness in near-centenarians and centenarians

OBJECTIVE

Results from studies investigating life satisfaction, positive affect and happiness of near-centenarians (95+) and centenarians are inconsistent. This is the first systematic review to summarise the extant literature on the subjective well-being of this unique age group.

METHOD

Seven electronic databases (PubMed, MEDLINE, EMBASE, PsycINFO, CINAHL, Web of Science and the Cochrane database for systematic reviews) were systematically searched. Subjective well-being was defined as life satisfaction, positive affect and happiness. A narrative synthesis of relevant articles was undertaken.

RESULTS

Of 28 studies eligible for inclusion in this review, 20 predominantly examined life satisfaction, 11 positive affect and 4 happiness. Sex and other demographic variables were not significant predictors of subjective well-being. In contrast, greater perceived health was significantly associated with higher levels of life satisfaction and positive affect. Fatigue and visual impairment were significantly correlated with lower levels of life satisfaction and positive affect. However, there was considerable heterogeneity in the findings on physical, cognitive and social associations, mediators and moderators.

CONCLUSION

The large discrepancy of results in the literature may be explained by methodological differences between studies. Centenarian research needs a clearer definition of life satisfaction, positive affect and happiness as their operationalisation is inconsistent. An international consortium of centenarian studies could facilitate cross-cultural comparisons on subjective well-being. Future research should be directed towards interventions that promote subjective well-being in the oldest-old.

Impact of Apolipoprotein E gene polymorphism during normal and pathological conditions of the brain across the lifespan

The central nervous system (CNS) is the cellular substrate for the integration of complex, dynamic, constant, and simultaneous interactions among endogenous and exogenous stimuli across the entire human lifespan. Numerous studies on aging-related brain diseases show that some genes identified as risk factors for some of the most common neurodegenerative diseases - such as the allele 4 of APOE gene (APOE4) for Alzheimer's disease (AD) - have a much earlier neuro-anatomical and neuro-physiological impact. The impact of APOE polymorphism appears in fact to start as early as youth and early-adult life. Intriguingly, though, those same genes associated with aging-related brain diseases seem to influence different aspects of the brain functioning much earlier actually, that is, even from the neonatal periods and earlier. The APOE4, an allele classically associated with later-life neurodegenerative disorders as AD, seems in fact to exert a series of very early effects on phenomena of neuroplasticity and synaptogenesis that begin from the earliest periods of life such as the fetal ones.We reviewed some of the findings supporting the hypothesis that APOE polymorphism is an early modifier of various neurobiological aspects across the entire human lifespan - from the in-utero to the centenarian life - during both normal and pathological conditions of the brain.

Gene-environment Interactions in Late Life: Linking Psychosocial Stress with Brain Aging

Gene-environment interactions (GxE) can have lasting consequences on brain structure and function, potentially contributing to diverse neuropsychiatric phenotypes. This has been extensively demonstrated by studies examining GxE in childhood and early adulthood, whereas much fewer studies have addressed this question in late life. The relative paucity of studies examining GxE in late life may stem from the working hypothesis that brains become less malleable to environmental inputs as life progresses. However, while some components of brain plasticity decline with increasing age, others are retained and may even become more pronounced in old ages. Moreover, the micro- and macro-structural brain changes that accrue as a result of aging-related morbidities are likely to accentuate the susceptibility of neural circuits to environmental stressors as life advances. Supporting this hypothesis, psychosocial stress can increase the risk for late-life neuropsychiatric syndromes, especially when afflicting genetically predisposed individuals. This article reviews evidence showing how gene-stress interactions can impact the aging brain and related phenotypes in late life, and it discusses the potential mechanisms underlying such GxE and their implications for the prevention and treatment of late-life neuropsychiatric syndromes.

Metabolic and Genetic Markers of Biological Age

Biological age is a concept that takes into account the heterogeneity of the aging process in different individuals that results in differences in survival and variations in relative health. Any measure of biological age must be better than chronological age at predicting mortality. Several quantitative measures of biological age have been developed. Among them are frailty indices, one of which called FI₃₄ is discussed here in greater detail. FI₃₄ increases exponentially with age reflecting decline in health and function ability. It readily depicts different patterns and trajectories of aging, and it is moderately heritable. Thus, it has been used to identify a genomic region on chromosome 12 associated with healthy aging. FI₃₄ has also been useful in describing the metabolic characteristics of this phenotype, revealing both sex and genetic differences. These differences give rise to specific, testable models regarding healthy aging, which involve cell and tissue damage and mitochondrial metabolism. FI₃₄ has been directly compared to various metrics based on DNA methylation as a predictor of mortality, demonstrating that it outperforms them uniformly. This and other frailty indices take a top-down, systems based view of aging that is cognizant of the integrated function of the complex aging system.

Visual impairment, but not hearing impairment, is independently associated with lower subjective well-being among individuals over 95 years of age: A population-based study

BACKGROUND

Sensory impairment affects an increasing number of elderly adults, with a negative psychological impact. Our objective was to examine the associations of visual and hearing impairment with subjective well-being (SWB), an important psychological concept defined by life satisfaction [LS], positive affect [PA], negative affect [NA], and affect balance [AB] among long-lived individuals (LLIs) over 95 years of age.

METHODS

Data on 442 LLIs from the Rugao longevity cohort, a population-based study in Rugao, China, were analyzed. Graded classifications of visual and hearing impairment (none, mild, moderate, and severe) were constructed from self-reported items. Bivariate correlation and multiple regression analysis were performed to test the associations.

RESULTS

Approximately 66.1% and 87.3% of the subjects reported varying degrees of visual and hearing impairment. Following the degree of vision impairment, LS, PA, and AB decreased linearly, whereas NA increased linearly (all p for trend<0.05). Vision was significantly related to LS (r=0.238, p<0.001), PA (r=0.142, p<0.01), NA (r=-0.157, p<0.001), and AB (r=0.206, p<0.001). After adjustment for multiple variables including functional ability, an important factor of SWB, the associations of vision impairment with LS, NA, and AB, while diminished, still existed.

CONCLUSIONS

Visual impairment, but not hearing impairment, was independently associated with low SWB among LLIs, and functional ability may play a mediating role in the observed relationship. The findings indicate that rehabilitation targeted for those with reduced vision and functioning in long-lived populations may be important for promoting well-being and quality of life.