Cross-lagged relationships between sense of purpose in life, memory performance, and subjective memory beliefs in adulthood over a 9-year interval

Factors Affecting Resilience and Prevention of Alzheimer's Disease and Related Dementias

Alzheimer's disease (AD) is a devastating, age-associated neurodegenerative disorder and the most common cause of dementia. The clinical continuum of AD spans from preclinical disease to subjective cognitive decline, mild cognitive impairment, and dementia stages (mild, moderate, and severe). Neuropathologically, AD is defined by the accumulation of amyloid β (Aβ) into extracellular plaques in the brain parenchyma and in the cerebral vasculature, and by abnormally phosphorylated tau that accumulates intraneuronally forming neurofibrillary tangles (NFTs). Development of treatment approaches that prevent or even reduce the cognitive decline because of AD has been slow compared to other major causes of death. Recently, the United States Food and Drug Administration gave full approval to 2 different Aβ-targeting monoclonal antibodies. However, this breakthrough disease modifying approach only applies to a limited subset of patients in the AD continuum and there are stringent eligibility criteria. Furthermore, these approaches do not prevent progression of disease, because other AD-related pathologies, such as NFTs, are not directly targeted. A non-mutually exclusive alternative is to address lifestyle interventions that can help reduce the risk of AD and AD-related dementias (ADRD). It is estimated that addressing such modifiable risk factors could potentially delay up to 40% of AD/ADRD cases. In this review, we discuss some of the many modifiable risk factors that may be associated with prevention of AD/ADRD and/or increasing brain resilience, as well as other factors that may interact with these modifiable risk factors to influence AD/ADRD progression. ANN NEUROL 2024.

A review of the literature on wellbeing and modifiable dementia risk factors

Wellbeing-defined broadly as experiencing one's life as enjoyable and fulfilling-has been associated with lower risk for Alzheimer's disease and related dementias. The mechanisms underlying this association are largely unknown. However, prior research and theory suggest that wellbeing impacts health behaviors and biological systems that are relevant to cognitive and brain health. Several of these factors have also been identified by the 2020 Lancet Commission on Dementia Prevention, Intervention, and Care as modifiable dementia risk factors. In the current review, we summarize and evaluate the evidence for associations between wellbeing and each of the 12 Lancet Commission risk factors. We found relatively consistent evidence for associations between higher wellbeing and lower levels of most of the risk factors: physical inactivity, social isolation, smoking, depression, hypertension, diabetes, hearing loss, traumatic brain injury, and air pollution. By contrast, we found evidence for only modest associations between wellbeing and education and mixed evidence for associations of wellbeing with alcohol use and body weight. Although most of the reviewed evidence was observational, longitudinal and experimental evidence suggests that many of the observed associations are likely bidirectional. These findings suggest that modifiable dementia risk factors may be mediators (i.e., intermediate steps in the causal chain) and/or confounders (i.e., variables that impact both wellbeing and dementia, and thus could induce a spurious association) of the association between wellbeing and dementia. We conclude by discussing next steps to test mediation hypotheses and to account for potential confounding in the relation between wellbeing and dementia.

An exploration of neighborhood characteristics, psychosocial resilience resources, and cognitive functioning among midlife and older black adults

OBJECTIVES

While existing research has shown that Black adults have worse cognitive functioning than their White counterparts, the psychosocial correlates of cognitive functioning for Black older adults are understudied. The objective of this study was to investigate the relationships among perceived neighborhood characteristics, psychosocial resilience resources, and cognitive functioning among midlife and older Black adults.

METHODS

Data were from 3,191 Black adults ages 51+ in the 2008-2016 waves of the Health and Retirement Study to examine associations among neighborhood characteristics, psychosocial resilience (sense of purpose, mastery, and social support), and cognitive functioning among Black adults. Multilevel linear regression models assessed direct effects of neighborhood characteristics and psychosocial resources on cognitive functioning. We then tested whether psychosocial resources moderated the association between neighborhood characteristics and cognitive functioning.

RESULTS

Mean levels of cognitive functioning, sense of purpose, social support, and mastery were significantly related to neighborhood disorder and discohesion. Regression results showed that levels of neighborhood disorder and high discohesion were significantly associated with cognitive functioning. Sense of purpose was positively associated with cognitive functioning, net of neighborhood characteristics. However, only social support moderated the association between neighborhood discohesion and cognition.

CONCLUSIONS

These findings demonstrate the importance of examining psychosocial and contextual risk and resilience resources among midlife and older Black adults. This work may inform the development of cognitive behavioral interventions aimed at increasing sense of purpose to promote and enhance cognitive resiliency among Black adults. Altogether, this work may have implications for policy aimed at advancing cognitive health equity.

Sense of purpose in life and extending the cognitive healthspan: evidence from multistate survival modeling

Having a sense of purpose in life predicts better maintenance of cognitive function in older adulthood and reduced risk of mild cognitive impairment (MCI) and dementia. However, little research has examined its influence on the rate of cognitive decline and length of cognitive healthspan. This study evaluated the role of sense of purpose on the risk and timing of transitions between normal cognition, MCI, and dementia. Older adults from the Memory and Aging Project (MAP; n = 1821) and the Health and Retirement Study (HRS; n = 10,542) were followed annually for 19 years and biennially for 12 years, respectively. Multistate survival models assessed whether sense of purpose predicted transitions across normal cognition, MCI, dementia, and death. More purposeful older adults had lower risk of developing MCI (HR = 0.82 in MAP; HR = 0.93 in HRS), higher likelihood of cognitive improvement, and longer cognitively healthy life expectancies. Results suggest sense of purpose may extend the cognitive healthspan.

Contributions of Eudaimonic Well-Being to Mental Health Practice

Purpose

Synergies between a eudaimonic model of psychological well-being (Ryff, 1989) and mental health practice are examined. The model grew out of clinical, developmental, existential, and humanistic perspectives that emphasized psychological strengths and capacities, in contrast to the focus on emotional distress and dysfunction in clinical psychology.

Design/Approach

Conceptual foundations of the eudaimonic approach are described, along with the six components positive functioning that are used to measure well-being. These qualities may be important in facilitating the recovery experiences, which are of interest in Mental Health and Social Inclusion.

Findings

Four categories of empirical evidence about eudaimonia are reviewed: (1) how it changes with aging, (2) how it matters for health, (3) what are its biological and neurological underpinnings, and (4) whether it can be promoted. Major contemporary forces against eudaimonia are also considered, including ever-widening inequality, the enduring pandemic, and world-wide strife. In contrast, encounters with the arts and nature are put forth as forces for eudaimonia. The relevance of these ideas for mental health research and practice is considered.

Originality

Mental health is often defined as the absence of mental illness. The novelty of the eudaimonic approach is to define mental health as the presence of well-being, assessed with different components of positive functioning.

Practical Implications

Enormous suffering defines our contemporary world. Such realities call for greater attention to factors that undermine as well as nurture the realization of human potential, the core of eudaimonic well-being.

Well-Being and Cognitive Resilience to Dementia-Related Neuropathology

Not all older adults with dementia-related neuropathology in their brains experience cognitive decline or impairment. Instead, some people maintain relatively normal cognitive functioning despite neuropathologic burden, a phenomenon called cognitive resilience. Using a longitudinal, epidemiological, clinical-pathologic cohort study of older adults in the United States (N = 348), the present research investigated associations between well-being and cognitive resilience. Consistent with preregistered hypotheses, results showed that higher eudaimonic well-being (measured via the Ryff Psychological Well-Being Scale) and higher hedonic well-being (measured via the Satisfaction with Life Scale) were associated with better-than-expected cognitive functioning relative to one's neuropathological burden (i.e., beta-amyloid, neurofibrillary tangles, Lewy bodies, vascular pathologies, hippocampal sclerosis, and TDP-43). The association of eudaimonic well-being in particular was present above and beyond known cognitive resilience factors (i.e., socioeconomic status, education, cognitive activity, low neuroticism, low depression) and dementia risk factors (i.e., apolipoprotein E [ApoE] genotype, medical comorbidities). This research highlights the importance of considering eudaimonic well-being in efforts to prevent dementia.

Sense of Purpose in Life and Subjective Cognitive Failures

A greater sense of purpose in life is an aspect of well-being associated with markers of cognitive health across adulthood, including subjective cognition. The current research extends this work to examine how purpose is associated with cognitive failures, which are momentary lapses in cognitive function, whether this association varies by age, sex, race, or education, and whether it is accounted for by depressed affect. Adults across the United States (N=5,100) reported on their sense of purpose in life, recent cognitive failures in four domains (memory, distractibility, blunders, names), and depressed affect. Purpose was associated with fewer cognitive failures overall and within each domain (median d=.30, p<.01), controlling for sociodemographic covariates. These associations were similar across sex, education, and racial groups but were stronger at relatively older than younger ages. Depressed affect accounted for all the association between purpose and cognitive failures among adults younger than 50; the association was reduced by half but remained significant among participants 50 and older. Purpose was associated with fewer cognitive failures, especially in the second half of adulthood. Purpose may be a psychological resource that helps support subjective cognition among relatively older adults, even after accounting for depressed affect.

Sense of purpose as a potential buffer between mental health and subjective cognitive decline

OBJECTIVES

Purposeful adults may experience greater cognitive resilience because sense of purpose may help buffer against the effects of depressive symptoms and loneliness. We also evaluated whether these associations differed by race.

DESIGN

This study uses a wave of self-report data from the SPAN study of psychosocial aging.

SETTING

Participants come from a representative sample of older adults in St. Louis.

PARTICIPANTS

Participants (N = 595) ages range from 65 to 78 (Mage = 71.46), with 18.3% of participants identifying as Black/African-American.

MEASURES

Sense of purpose was assessed with the Life Engagement Test, depressive symptoms with the Beck Depression Inventory-II, loneliness with the UCLA Loneliness Scale, and subjective cognitive decline with the AD-8.

RESULTS

Correlational analyses supported predictions that sense of purpose was negatively related to subjective cognitive decline, whereas depressive symptoms and loneliness were positively related (|r|s > .30, ps < .001). For loneliness, but not depression, this association was moderated by sense of purpose (b = -0.43, p < .001). A relatively high sense of purpose attenuated associations between loneliness and subjective cognitive decline. A three-way race × purpose × loneliness interaction (b = -0.25, p = .021) revealed that the buffering effects of sense of purpose on subjective cognitive decline were stronger for Black adults.

DISCUSSION

This study provided partial support for the buffering hypothesis, showing that sense of purpose may help mitigate the cognitive decrements associated with loneliness. Future research needs to consider how purpose-promoting programs may support healthy cognitive aging, particularly among Black older adults and those who experience greater social isolation.

Purposeful retirement expectations and their associations with retirement planning

OBJECTIVE

Previous research has demonstrated that retirees tend to report lower levels for sense of purpose compared to working adults. However, it remains unclear whether adults show differences in the extent to which they expect to be purposeful during retirement, and what that may mean for the propensity to plan for retirement.

METHOD

The current study examined this question in a cross-sectional sample of 492 adults (Age: M = 39.28, SD = 8.35) prior to retirement. Participants completed an adapted measure to capture expected purposeful engagement during retirement, along with sense of purpose, retirement planning, and the Big Five personality traits.

RESULTS

Factor analyses and zero-order correlations suggested that purposeful retirement perceptions are related yet distinct from sense of purpose in general, and adults on average expect a moderately purposeful retirement. Purposeful retirement scores were associated with multiple retirement planning scales, and remained predictive of retirement preparation even when accounting for the Big Five and demographic factors.

CONCLUSION

Adults differ in how purposeful they expect to be during their future retirement. Moreover, these differences may be a valuable consideration when understanding how to promote retirement planning.

Self-reported sense of purpose in life and proxy-reported behavioral and psychological symptoms of dementia in the last year of life

Objectives:Behavioral and psychological symptoms of dementia (BPSD) are among the most challenging aspects of dementia for individuals living with dementia and their caregivers. Identifying factors associated with resilience to BPSD may inform interventions to reduce them. The present research examines whether purpose in life is associated with BPSD in the last year of life.Method:Participants from the Health and Retirement Study were selected if they reported on their sense of purpose, had evidence of a memory impairment, died across the follow-up, and a proxy completed the End of Life survey that included BPSD (N = 2473). Self-reported sense of purpose was tested as a predictor of the sum of symptoms and each indivdual symptom in the last year of life.Results:Purpose in life was associated with fewer BPSD overall. Of the individual symptoms, purpose was associated with less risk of psychological symptoms, specfiically less depression, periodic confusion, uncontrolled temper, but not with motor or perceptual symptoms.Conclusion: These results are consistent with growing evidence that purpose is associated with better cognitive outcomes. Purpose may be a useful target of intervention to improve outcomes across the spectrum of dementia.

Longitudinal Associations between Personal Growth and Cognitive Functioning in Adulthood

OBJECTIVES

While personal growth has been found to be associated with multiple aspects of health in adulthood, its associations with cognitive functioning have not been fully understood. The present study aimed to assess both directions of such longitudinal associations.

METHOD

Using data from the second wave (T1) and third wave (T2) of the Midlife in the United States (MIDUS) study (N = 4,206; mean age = 56.0 [SD = 12.3]), a longitudinal measurement model containing latent variables of episodic memory and executive function was first constructed. Built on the measurement model, a cross-lagged panel model was analyzed to assess relationships between personal growth and the two areas of cognitive functioning, in which T1 personal growth predicted residualized changes in episodic memory and executive function, and T1 episodic memory and executive function predicted change in personal growth, controlling for covariates.

RESULTS

T1 personal growth significantly predicted smaller decreases in episodic memory, whereas it did not predict change in executive function. T1 episodic memory, but not T1 executive function, significantly predicted smaller decreases in personal growth.

DISCUSSION

The present findings were unique, particularly implying potential longitudinal reciprocity between personal growth and episodic memory. These findings and implications can inform future research aimed at exploring approaches to promoting personal growth and cognitive functioning among aging adults.

Torn Between Valences: Mixed Emotions Predict Poorer Psychological Well-Being and Job Burnout

Conflicting perspectives on whether mixed emotions are adaptive states which promote integrative processes or uncomfortable states which are agonizing make divergent predictions on whether mixed emotions in daily life are conducive towards psychological well-being. We examined this across three studies. Study 1 (N = 335, 135 males; M _age = 41.31) examined associations between state mixed emotions and psychological well-being. Study 2 (N = 389; 160 males; M _age = 40.86) examined associations between workplace-specific mixed emotions and workplace ill-being assessed based on burnout. Both direct measures and indirect measures were examined in Study 1 and 2, allowing some comparison of methodological issues related to their predictive validity. Study 3 (N = 3444; 1587 males; M _age = 55.34) examined bidirectional relationships between an index of emotional ambivalence and psychological well-being about ten years later, controlling for baselines. Demographic covariates, positive emotions, and negative emotions were controlled for in all studies. Analyses were performed using latent variable structural equation modelling. After adjusting for all covariates, the direct measures of mixed emotions predicted poorer psychological well-being (Study 1) and greater burnout (Study 2). However, indirect measures were found to suffer from relatively greater multicollinearity and poorer predictive validity upon controlling for positive and negative emotions. In Study 3, emotional ambivalence predicted poorer long-term psychological well-being, while psychological well-being also predicted lower emotional ambivalence, supporting bidrectionality. The findings provide preliminary evidence that naturalistically experienced mixed emotions may be conflicting and unpleasant, with potentially negative implications for psychological well-being over and above positive and negative emotions.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10902-021-00493-z.

Sense of Purpose Promotes Resilience to Cognitive Deficits Attributable to Depressive Symptoms

Objective

Individuals higher in depressive symptoms commonly present with neuropsychological deficits including poorer memory performance. Sense of purpose in life has been shown to promote resilience to cognitive impairment in older adulthood, but it is unclear whether it may also protect against cognitive deficits associated with higher depressive symptoms.

Method

Cognitive functioning among 4599 older American adults (M_age = 74.33 years, range = 65–104 years, 56.84% female) was examined across a 12-year follow-up period. Depressive symptomatology was assessed at each wave using the 8-item Center for Epidemiologic Studies Depression Scale. Multilevel models assessed the influence of depressive symptoms and the interaction with sense of purpose in life on changes in memory performance and mental status.

Results

Higher depressive symptoms were associated with poorer memory performance at baseline, but did not predict rate of change over time. A negative interaction was observed between sense of purpose in life and depressive symptoms such that individuals higher in purpose experienced a less negative association between depressive symptoms and baseline memory performance. No significant interaction of sense of purpose and depressive symptoms was observed on mental status.

Conclusion

Having a sense of purpose in life may help protect older adults from memory deficits associated with higher depressive symptoms. The present findings underscore the potential for sense of purpose to promote cognitive reserve in older adulthood, allowing individuals to maintain cognitive performance in the face of accruing neurological insults.