Occupational cognitive requirements and late-life cognitive aging

Non-employment over the working life: Implications for cognitive function and decline in later life

Objectives

Disuse theory predicts that cognitive function is vulnerable to transitions that remove factors that support cognitive skills. We sought to investigate whether non-employment over the working life was associated with cognitive function and decline in later life (≥60 years old), and possible gender differences in the association.

Study design

Longitudinal study.

Method

We used data from the MRC National Survey of Health and Development (NSHD). Cognitive function was measured by verbal memory and processing speed. Linear regression was used to test associations between non-employment duration and cognitive function at age 60-64, and conditional change models were used to examine associations between non-employment and cognitive decline from age 60-64 to 69. Gender specific models were adjusted for childhood factors and educational attainment, adult occupational features, and adult health and lifestyle indicators. Missing data was accounted for using multiple imputation by chained equations.

Results

In fully adjusted models >15 years non-employment was associated with lower cognitive function at age 60-64 in men (verbal memory: -0.72, 95%CI -1.18, -0.26; processing speed: -0.61, 95%CI -1.00, -0.28), but not women. Fully adjusted models also indicated that long-term and intermediate lengths of non-employment were associated with faster decline in verbal memory (-0.38, 95%CI -0.75, -0.02) and processing speed (-0.28, 95%CI -0.52, -0.03) in men. There was no association between non-employment and cognitive decline among women.

Conclusion

Long-term non-employment in men, but not women, is associated with accelerated cognitive ageing.

ChatGPT-estimated occupational complexity predicts cognitive outcomes and cortical thickness above and beyond socioeconomic status among older adults

Many aging cohort studies have collected data on participants' job titles, yet these job titles were seldom analyzed within the cognitive aging context despite their relevance to neurocognition, due to difficulties in analyzing these job titles quantitatively. While it is possible to rate these jobs' occupational complexity (OC) using job classification systems, this can be somewhat labor-intensive and prone to human errors. To this end, we demonstrate a novel and simple method to extract OC ratings from job titles using ChatGPT. Then, we showcased the utility of these ratings in predicting cognitive and structural brain outcomes, especially compared to other socioeconomic status (SES) indicators. Community-dwelling older adults (N = 238, agemean = 70) completed cognitive assessments and underwent MRI scans. Regression models were fitted to predict 14 different cognitive outcomes, vertex-wise cortical thickness (CT), and subcortical gray matter volumes, using OC scores and/or SES predictors (e.g., education, housing type, and income levels), controlling for demographical covariates. OC scores outperformed SES indicators in predicting clusters of CT increases and most cognitive outcomes, including diagnoses of mild cognitive impairment. Furthermore, OC scores significantly predicted clusters of CT increases and various cognitive outcomes, even after controlling for SES. Meta-analytic decoding suggests these clusters of CT increases occurred in regions typically associated with sensorimotor and memory processing. These results highlight the significant and unique contribution of ChatGPT-derived OC scores in predicting cognitive and brain aging outcomes. These scores are easy to derive and can be helpful in fine-tuning predictions of cognitive and brain aging outcomes.

A systematic review of epidemiological studies of life course socioeconomic status and adult structural brain changes

INTRODUCTION

Disadvantaged socioeconomic status (SES) are linked with adverse cognitive outcomes in ageing and heightened dementia risk. Few studies have examined relationships between life course SES and adult structural brain changes that may be associated with cognitive decline.

AIMS

This systematic review assesses evidence from neuroimaging based epidemiological studies that have explored relationships between life course SES and adult structural brain changes.

METHODS

Embase, PsycINFO and Medline from inception to November 2020 were systematically searched according to strict search criteria which captured studies examining relationships between life course SES and adult structural neuroimaging changes. Bibliographies and citations of relevant papers were selected. Searches were limited to English language publications.

RESULTS

Amongst 8134 search results, 91 unique titles were screened and 24 studies selected. All 24 studies demonstrated at least partial relationships between disadvantaged life SES and adverse structural brain changes. Selected studies utilised diverse structural imaging techniques, neuroanatomical sites and operational definitions of life course SES. The methodological approaches and statistical analysis varied significantly between studies. We specifically discuss the neurobiological interpretation of Diffusion weighted MRI based studies and MRI volumetric studies investigating associations between life course SES and adult brain structural changes and the wider global health implications of these studies.

CONCLUSION

Disadvantaged life course SES may have associations with structural brain changes which underlie adverse ageing outcomes. Given heterogeneity of study designs and operationalisation of SES, the cross-sectional design of studies and wide-ranging neuroimaging modalities any association should be considered with caution. Mediatory mechanisms including malnutrition, stress, markers of inflammation, hormonal changes and cognitive reserve and health behaviour are presented in selected studies. Targeting life course SES in public health-based interventions may offer approaches to maintain healthy brain structure and function in ageing.

Life Course Patterns of Work History and Cognitive Trajectories Among Community-Dwelling Older Adults

OBJECTIVES

Prior research indicated that diverse work experiences in early and middle life stages are associated with cognitive function in later life. However, whether life course patterns of work history are associated with later life cognitive function in China remains unknown.

METHODS

Data were derived from the China Health and Retirement Longitudinal Study, and 5,800 participants aged 60 years or older were included. We used sequence analysis to identify the work history patterns between ages 18 and 60. Growth curve modeling was performed to evaluate how the work-history patterns are associated with global and domain-specific (i.e., mental intactness and episodic memory) cognitive function.

RESULTS

We identified 8 work patterns, distinguished by duration, transitions, timing, and sequence of work history. Compared with individuals exposed to lifelong agricultural work, those engaged in lifelong nonagricultural employed work had better cognitive function in later life and experienced slower rates of cognitive decline in both global cognitive function and the mental intactness domain. In addition, individuals who shifted from agricultural to nonagricultural employed work early (around age 30) had better global cognitive function in later life, whereas the association was not significant for such a transition later (around age 50).

DISCUSSION

Our study highlights the importance of the duration, sequence, and timing of transitions in work history for cognitive health among older Chinese. Future interventions and policies aimed at improving cognitive function should fully consider the cumulative and dynamic nature of work from a life course perspective.

Cognitive Health Disparities by Race and Ethnicity: The Role of Occupational Complexity and Occupational Status

Disparities in older age cognitive health by race/ethnicity persist even after controlling for individual-level indicators of childhood and adult socioeconomic status. High levels of labor market segregation mean that Black and Latino workers, on average, may not have the same exposure to jobs involving complex work with data and people as their White counterparts, aspects of work that appear to be protective of older adult cognition. However, the role of variation in exposure to occupational complexity by race/ethnicity remains understudied as an explanation for cognitive disparities at older ages. This paper uses detailed work histories constructed from the Health and Retirement Study (HRS) Occupation and Industry life history data to understand the role of occupational complexity in the development of dementia at older ages. It also addresses a conjecture that complexity reflects occupational status. Findings highlight that: (a) occupations involving complex work with data during working ages may be protective against dementia at older ages, potentially contributing to the differentials in dementia prevalence for Black, Latino, and White workers, and (b) occupational complexity reflects occupational status. This research increases understanding of the implications of labor market segregation for cognitive health disparities by race/ethnicity.

Review on pathogenesis and treatment of Alzheimer's disease

The rising incidence of Alzheimer's disease (AD) and the associated economic impacts has prompted a global focus in the field. In recent years, there has been a growing understanding of the pathogenic mechanisms of AD, including the aggregation of β-amyloid, hyperphosphorylated tau, and neuroinflammation. These processes collectively lead to neurodegeneration and cognitive decline, which ultimately results in the loss of autonomy in patients. Currently, there are three main types of AD treatments: clinical tools, pharmacological treatment, and material interventions. This review provides a comprehensive analysis of the underlying etiology and pathogenesis of AD, as well as an overview of the current prevalence of AD treatments. We believe this article can help deepen our understanding of the AD mechanism, and facilitate the clinical translation of scientific research or therapies, to address this global problem of AD.

Study on the age-period-cohort effects of cognitive abilities among older Chinese adults based on the cognitive reserve hypothesis

BACKGROUND

Cognitive abilities serves as a critical indicator of healthy aging. As China progresses into a stage of advanced population aging, there has been a significant increase in the number of elderly individuals experiencing age-related cognitive decline. Despite this demographic shift, there is a paucity of longitudinal research examining cognitive abilities among older Chinese adults over extended time periods. This study aims to investigate changes in cognitive abilities and explore group differences among older Chinese adults aged 65 to 110 years, employing a multidimensional temporal approach that encompasses age, period, and birth cohort effects.

METHODS

This study utilizes data from eight waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), spanning from 1998 to 2018. The dataset comprises 94,116 observations from 36,157 unique participants. Cognitive abilities are assessed using Mini-Mental State Examination (MMSE) scores as a proxy measure. To address the issue of perfect collinearity in the temporal dimension, the study employs the Hierarchical Age-Period-Cohort Cross-Classified Random Effects Model (HAPC-CCREM). This model allows for the examination of age effects, period effects, and cohort effects on cognitive abilities among older Chinese adults. In the model specification, age is treated as a fixed effect, while period and birth cohort are incorporated as random effects. Drawing upon the cognitive reserve hypothesis, the study investigates significant factors influencing cognitive abilities in this population.

RESULTS

At the fixed-effect level, demographic factors, health behaviors, self-rated health, subjective well-being, and childhood adversity significantly influence cognitive abilities among older Chinese adults. The age effects are significant, with cognitive abilities exhibiting an inverted U-shaped curve across the lifespan. At the random-effect level, period effects are significant, revealing a gradual annual increase in overall cognitive levels among older Chinese adults since 2008. Cohort effects are also significant, demonstrating an increasing trend in overall cognitive levels for the earlier-born cohorts in the first six groups. Conversely, later-born cohorts in the latter five groups show a declining trend in overall cognitive levels. Notably, period effects significantly enhance cohort effects.

CONCLUSIONS

The cognitive reserve hypothesis supports the significance of the majority of identified influencing factors. Cognitive abilities demonstrate an accelerating decline with increasing age, following an evolutionary trajectory consistent with physiological principles among older Chinese adults. Since 2008, cognitive abilities have shown a monotonic increasing trend annually, further validating the Flynn effect in this population. The cognitive abilities of the six earlier-born cohorts exhibit an increasing trend, supporting the compression of morbidity hypothesis. Conversely, the cognitive abilities of the five later-born cohorts show a declining trend, supporting the expansion of morbidity hypothesis. These findings collectively contribute to our understanding of cognitive aging patterns and their underlying mechanisms among older Chinese adults.

The Mediating Effects of Education and Occupational Complexity Between Race and Longitudinal Change in Late Life Cognition in ACTIVE

This study examined educational and occupational inequality as two aspects of social determinants of health that might mediate the longitudinal relationship between racialization and late life cognitive level and change. Participants were 2371 individuals racialized as Black and White from the ACTIVE study who provided occupational data. Data were analyzed from baseline and five assessments over 10-years using structural equation modeling. Black/White race served as the predictor, occupational complexity (OC) and years of education as mediators, and cognitive (memory, reasoning, and speed of processing) intercept, linear slope, and quadratic slope as the dependent variables. Black/White race showed significant indirect associations through education and OC on level of performance in cognition, linear change in reasoning and memory, and quadratic change in reasoning. Education and OC accounted for 11-16% of the association between race and cognitive level and represent modifiable social determinants of health that are associated with disparities in cognitive aging.

Intergenerational Educational Mobility and Cognitive Trajectories Among Middle-Aged and Older Chinese People: An Application of Growth Mixture and Mobility Contrast Models in Longitudinal Analysis

OBJECTIVES

Due to statistical challenges in disentangling the mobility effect (i.e., intergenerational educational mobility) from the position effect (i.e., parental and person's own education), the impact of intergenerational educational mobility on cognitive function remains unclear. We employed a novel approach to identify the mobility effect and investigate the net impact of intergenerational educational mobility on heterogeneous patterns of cognition among middle-aged and older adults in China.

METHODS

Participants aged 45 and older were recruited from the China Health and Retirement Longitudinal Study, a population-based prospective cohort study between 2011 and 2018. We identified cognitive trajectories using the growth mixture model (GMM) and subsequently employed the mobility contrast model (MCM) to examine the effects of intergenerational educational mobility on cognitive patterns stratified by gender.

RESULTS

Almost two thirds of respondents experienced intergenerational educational mobility, and 55% experienced upward mobility. Men had a higher rate of upward mobility than women. Three population-based cognitive patterns were identified: the low cognitive function with decline group (28%), the moderate cognitive function group (47%), and the high cognitive function group (26%). MCM analysis revealed that both upward and downward intergenerational educational mobility negatively affected cognitive trajectory patterns, extending beyond the influence of individuals' current and parental education.

DISCUSSION

In future research, the impact of mobility can be studied in longitudinal data sets by combining the GMM and MCM approaches. The net negative effect of intergenerational educational mobility on cognitive trajectory patterns indicates that it should be recognized as an independent predictor of cognitive decline.

Cognitive reserve modulates mental health in adulthood

Cognitive Reserve (CR) reflects acquired knowledge, skills, and abilities throughout life, and it is known for modulating cognitive efficiency in healthy and clinical populations. CR, which was initially proposed to explain individual differences in the clinical presentation of dementia, has subsequently been extended to healthy ageing, showing its role in cognitive efficiency also during middle age. Recently, CR has been linked to affective processes in psychiatric conditions such as schizophrenia, major depressive and anxiety symptoms, and psychological distress, suggesting its potential role in emotional expression and regulation. Whether the role of CR in mental health extends to non-pathological adults, and whether this is only relevant in older age is not yet clear. The aim of this work was therefore to explore the relationship between CR and mental health in healthy adults, with a focus on middle adulthood (40-60). In a sample of 96 participants, we found a positive association between CR and mental health outcomes, such that a higher cognitive reserve index corresponded to fewer mental health reported symptoms. Specifically, a higher CR reflecting professional activities was associated with lower stress levels, especially in middle agers. Taken together, these data therefore suggest that engaging occupations may help maintain a robust mental health, especially by reducing stress symptoms during middle age. These results broaden previous findings suggesting that CR relates to affective components of mental health in middle aged and older adults.

Trajectories of Occupational Cognitive Demands and Risk of Mild Cognitive Impairment and Dementia in Later Life: The HUNT4 70+ Study

BACKGROUND AND OBJECTIVES

The cognitive reserve hypothesis posits that cognitively stimulating work delays the onset of mild cognitive impairment (MCI) and dementia. However, the effect of occupational cognitive demands across midlife on the risk of these conditions is unclear.

METHODS

Using a cohort study design, we evaluated the association between registry-based trajectories of occupational cognitive demands from ages 30-65 years and clinically diagnosed MCI and dementia in participants in the HUNT4 70+ Study (2017-19). Group-based trajectory modeling identified trajectories of occupational cognitive demands, measured by the routine task intensity (RTI) index (lower RTI indicates more cognitively demanding occupation) from the Occupational Information Network. Multinomial regression was implemented to estimate the relative risk ratios (RRRs) of MCI and dementia, after adjusting for age, sex, education, income, baseline hypertension, obesity, diabetes, psychiatric impairment, hearing impairment, loneliness, smoking status, and physical inactivity assessed at HUNT1-2 in 1984-1986 and 1995-1997. To handle missing data, we used inverse probability weighting to account for nonparticipation in cognitive testing and multiple imputation.

RESULTS

Based on longitudinal RTI scores for 305 unique occupations, 4 RTI trajectory groups were identified (n = 7,003, 49.8% women, age range 69-104 years): low RTI (n = 1,431, 20.4%), intermediate-low RTI (n = 1,578, 22.5%), intermediate-high RTI (n = 2,601, 37.1%), and high RTI (n = 1,393, 19.9%). Participants in the high RTI group had a higher risk of MCI (RRR 1.74, 95% CI 1.41-2.14) and dementia (RRR 1.37, 95% CI 1.01-1.86), after adjusting for age, sex, and education compared with participants in the low RTI group. In a sensitivity analysis, controlling for income and baseline health-related factors, the point estimates were not appreciably changed (RRR 1.66, 95% CI 1.35-2.06 for MCI, and RRR 1.31, 95% CI 0.96-1.78 for dementia).

DISCUSSION

People with a history of cognitively stimulating occupations during their 30s, 40s, 50s, and 60s had a lower risk of MCI and dementia older than 70 years, highlighting the importance of occupational cognitive stimulation during midlife for maintaining cognitive function in old age. Further research is required to pinpoint the specific occupational cognitive demands that are most advantageous for maintaining later-life cognitive function.

2024 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including prevalence and incidence, mortality and morbidity, use and costs of care and the ramifications of AD for family caregivers, the dementia workforce and society. The Special Report discusses the larger health care system for older adults with cognitive issues, focusing on the role of caregivers and non-physician health care professionals. An estimated 6.9 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060, barring the development of medical breakthroughs to prevent or cure AD. Official AD death certificates recorded 119,399 deaths from AD in 2021. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death in the United States. Official counts for more recent years are still being compiled. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2021, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 140%. More than 11 million family members and other unpaid caregivers provided an estimated 18.4 billion hours of care to people with Alzheimer's or other dementias in 2023. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $346.6 billion in 2023. Its costs, however, extend to unpaid caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Members of the paid health care and broader community-based workforce are involved in diagnosing, treating and caring for people with dementia. However, the United States faces growing shortages across different segments of the dementia care workforce due to a combination of factors, including the absolute increase in the number of people living with dementia. Therefore, targeted programs and care delivery models will be needed to attract, better train and effectively deploy health care and community-based workers to provide dementia care. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2024 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $360 billion. The Special Report investigates how caregivers of older adults with cognitive issues interact with the health care system and examines the role non-physician health care professionals play in facilitating clinical care and access to community-based services and supports. It includes surveys of caregivers and health care workers, focusing on their experiences, challenges, awareness and perceptions of dementia care navigation.

Sex differences in cognitive decline among middle-aged and older adults: a cohort study in Europe

OBJECTIVES

Previous studies on sex differences in cognitive decline provide inconsistent findings, with many European countries being underrepresented. We determined the association between sex and cognitive decline in a sample of Europeans and explored differences across birth cohorts and regions.

METHODS

Participants 50+ years old enrolled in the Survey of Health, Ageing and Retirement in Europe had their cognition measured by tests of immediate recall, delayed recall and verbal fluency biennially up to 17 years of follow-up (median 6, interquartile range 3-9 years). We used linear mixed-effects models to assess the relationship between sex and the rate of cognitive decline, adjusting for sociodemographic and health-related characteristics.

RESULTS

Of 66,670 participants (mean baseline age 63.5 ± standard deviation 9.4), 55% were female. Males and females had similar rates of decline in the whole sample in immediate recall (beta for interaction sex × time B = 0.002, 95% CI -0.001 to 0.006), delayed recall (B = 0.000, 95% CI -0.004 to 0.004), and verbal fluency (B = 0.008, 95% CI -0.005 to 0.020). Females born before World War II had a faster rate of decline in immediate recall and delayed recall compared to males, while females born during or after World War II had a slower rate of decline in immediate recall. Females in Central and Eastern Europe had a slower rate of cognitive decline in delayed recall compared to males.

DISCUSSION

Our study does not provide strong evidence of sex differences in cognitive decline among older Europeans. However, we identified heterogeneity across birth cohorts and regions.

Lifetime occupational skill and later-life cognitive function among older adults in the United States, Mexico, India, and South Africa

INTRODUCTION

We conducted a cross-national comparison of the association between main lifetime occupational skills and later-life cognitive function across four economically and socially distinct countries.

METHODS

Data were from population-based studies of aging and their Harmonized Cognitive Assessment Protocols (HCAPs) in the US, South Africa, India, and Mexico (N = 10,037; Age range: 50 to 105 years; 2016 to 2020). Main lifetime occupational skill was classified according to the International Standard Classification of Occupations. Weighted, adjusted regression models estimated pooled and country-specific associations between main lifetime occupational skill and later-life general cognitive function in men and women.

RESULTS

We observed positive gradients between occupational skill and later-life cognitive function for men and women in the US and Mexico, a positive gradient for women but not men in India, and no association for men or women in South Africa.

DISCUSSION

Main lifetime occupations may be a source of later-life cognitive reserve, with cross-national heterogeneity in this association.

HIGHLIGHTS

No studies have examined cross-national differences in the association of occupational skill with cognition. We used data from Harmonized Cognitive Assessment Protocols in the US, Mexico, India, and South Africa. The association of occupational skill with cognitive function varies by country and gender.

Over ninety years old: Does high cognitive reserve still help brain efficiency?

Nonagenarians and centenarians, also called oldest-old, are a very heterogeneous population that counts a limited number of individuals as it is a real challenge to reach this goal. Even if it is well known that cognitive reserve can be considered a factor in maintaining good cognitive functioning in ageing, only very few studies have been carried out on the role of cognitive reserve (CR) in the oldest-old people. The aim of this study is to investigate the relationship between cognitive reserve and cognitive functioning in a population living in a specific region of Italy, the Blue Zone in Sardinia. This population is characterised by extreme longevity and distinctive historical, geographic, social, linguistic and nutritional features. The cognitive Reserve Index questionnaire (CRIq) and the short cognitive Esame Neuropsicologico Breve-2 (ENB-2, Brief Neuropsychological Examination) were administered to 67 participants, all aged between 90 and 105 years old. The CRIq was a predictor of neuropsychological performance for the global score of the battery of tests, ENB-2 (ENB-tot) and also for 7 out of 16 of its sub-tests. All except one (Token) tapped executive functions (Interference memory at 10 and 30 s, TMT-B, Overlapping figures, Abstraction, Fluency). Results highlight that also in the oldest-old population CR has a positive effect on cognition, especially on executive functioning.

Mid-life employment trajectories and subsequent memory function and rate of decline in rural South Africa, 2000-22

AIM

To investigate mid-life employment trajectories in relation to later-life memory function and rate of decline in rural South Africa.

METHODS

Data from the Agincourt Health and Socio-Demographic Surveillance System were linked to the 'Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa' (HAALSI) in rural Agincourt, South Africa (N = 3133). Employment was assessed every 4 years over 2000-12 as being employed (0, 1, 2 and ≥3 time points), being employed in a higher-skill occupation (0, 1, 2 and ≥3 time points) and dynamic employment trajectories identified using sequence analysis. Latent memory z-scores were assessed over 2014-22. Mixed-effects linear regression models were fitted to examine the associations of interest.

RESULTS

Sustained mid-life employment from 2000-12 (β = 0.052, 95% CI: -0.028 to 0.132, 1 vs 0 time points; β = 0.163, 95% CI: 0.077 to 0.250, 2 vs 0 time points; β = 0.212, 95% CI: 0.128 to 0.296, ≥3 vs 0 time points) and greater time spent in a higher-skill occupation (β = 0.077, 95% CI: -0.020 to 0.175, 1 vs 0 time points; β = 0.241, 95% CI: 0.070 to 0.412, 2 vs 0 time points; β = 0.361, 95% CI: 0.201 to 0.520, ≥3 vs 0 time points) were associated with higher memory scores in 2014/15, but not subsequent rate of memory decline. Moving from a lower-skill to higher-skill occupation was associated with higher memory function, but a faster rate of decline over 2014-22.

CONCLUSIONS

Sustained mid-life employment, particularly in higher-skill occupations, may contribute to later-life memory function in this post-Apartheid South African setting.

The relevance of perceived work environment and work activities for personality trajectories in midlife

OBJECTIVES

Work is an important developmental context in adulthood, yet little is known about how it contributes to personality trajectories in midlife. The present study examines how subjectively perceived work environment (autonomy, innovation, social integration, stress) and objectively measured work activities (activities related to information and people, physical/manual activities) are related to levels of Big Five personality traits at age 44 and to change over 20 years.

METHODS

We analyzed four-wave longitudinal data from N = 374 participants (born 1950-1952; Mage T1 = 44 years, SD = 1; 44% women) from the Interdisciplinary Longitudinal Study of Adult Development and Aging (ILSE) within the structural equation modeling framework.

RESULTS

At baseline, subjective perceptions of work environments showed a higher number of significant associations with personality than objective work activities. Over time, small declines in neuroticism and extraversion and small increases in agreeableness and conscientiousness were observed, which were largely independent of work characteristics.

CONCLUSIONS

Our findings show slight changes in most Big Five traits from age 44 to 64, which were mostly unrelated to work characteristics. More research is needed to uncover the sources and dynamics of personality trait change in midlife and the role of work for personality trajectories.

Systematic examination of methodological inconsistency in operationalizing cognitive reserve and its impact on identifying predictors of late-life cognition

BACKGROUND

Cognitive reserve (CR) is the ability to maintain cognitive performance despite brain pathology. CR is built through lifecourse experiences (e.g., education) and is a key construct in promoting healthy aging. However, the operationalization of CR and its estimated association with late-life cognition varies. The purpose of this study was to systematically examine the operationalization of CR and the relationship between its operationalization and late-life cognition.

METHODS

We performed a comprehensive review of experiences (proxies) used to operationalize CR. The review informed quantitative analyses using data from 1366 participants of the Memory and Aging Project to examine 1) relationships between proxies and 2) the relationship between operationalization and late-life cognition. We also conducted a factor analysis with all identified CR experiences to create a composite lifecourse CR score. Generalized linear mixed models examined the relationship between operationalizations and global cognition, with secondary outcomes of five domains of cognition to examine consistency.

RESULTS

Based on a review of 753 articles, we found the majority (92.3%) of the 28 commonly used proxies have weak to no correlation between one another. There was substantial variability in the association between operationalizations and late-life global cognition (median effect size: 0.99, IQR: 0.34 to 1.39). There was not strong consistency in the association between CR operationalizations and the five cognitive domains (mean consistency: 56.1%). The average estimate for the 28 operationalizations was 0.91 (SE = 0.48), compared to 2.48 (SE = 0.40) for the lifecourse score and it was associated with all five domains of cognition.

CONCLUSIONS

Inconsistent methodology is theorized as a major limitation of CR research and barrier to identification of impactful experiences for healthy cognitive aging. Based on the weak associations, it is not surprising that the relationship between CR and late-life cognition is dependent on the experience used to operationalize CR. Scores using multiple experiences across the lifecourse may help overcome such limitations. Adherence to a lifecourse approach and collaborative movement towards a consensus operationalization of CR are imperative shifts in the study of CR that can better inform research on risk factors related to cognitive decline and ultimately aid in the promotion of healthy aging.

Integrative blood-based characterization of oxidative mitochondrial DNA damage variants implicates Mexican American's metabolic risk for developing Alzheimer's disease

Alzheimer's Disease (AD) continues to be a leading cause of death in the US. As the US aging population (ages 65 +) expands, the impact will disproportionately affect vulnerable populations, e.g., Hispanic/Latino population, due to their AD-related health disparities. Age-related regression in mitochondrial activity and ethnic-specific differences in metabolic burden could potentially explain in part the racial/ethnic distinctions in etiology that exist for AD. Oxidation of guanine (G) to 8-oxo-guanine (8oxoG) is a prevalent lesion and an indicator of oxidative stress and mitochondrial dysfunction. Damaged mtDNA (8oxoG) can serve as an important marker of age-related systemic metabolic dysfunction and upon release into peripheral circulation may exacerbate pathophysiology contributing to AD development and/or progression. Analyzing blood samples from Mexican American (MA) and non-Hispanic White (NHW) participants enrolled in the Texas Alzheimer's Research & Care Consortium, we used blood-based measurements of 8oxoG from both buffy coat PBMCs and plasma to determine associations with population, sex, type-2 diabetes, and AD risk. Our results show that 8oxoG levels in both buffy coat and plasma were significantly associated with population, sex, years of education, and reveal a potential association with AD. Furthermore, MAs are significantly burdened by mtDNA oxidative damage in both blood fractions, which may contribute to their metabolic vulnerability to developing AD.

Association of primary lifetime occupational cognitive complexity and cognitive decline in a diverse cohort: Results from the KHANDLE study

INTRODUCTION

Higher occupational complexity has been linked to favorable cognitive outcomes, but rarely examined in racially and ethnically diverse populations.

METHODS

In a diverse cohort (n = 1536), linear mixed-effects models estimated associations between main lifetime occupational complexity and domain-specific cognitive decline (z-standardized). Occupational complexity with data, people, and things were classified using the Dictionary of Occupational Titles.

RESULTS

For occupational complexity with data, highest tertile (vs. lowest) was associated with higher baseline executive function (β = 0.11; 95% confidence interval [CI] 0.00-0.22) and slower annual rate of decline (β = 0.03; 95% CI 0.01-0.06), and higher baseline semantic memory (β = 0.14; 95% CI 0.04-0.25). Highest tertile of occupational complexity with people was associated with higher baseline executive function (β = 0.29; 95% CI 0.18-0.40), verbal episodic memory (β = 0.12; 95% CI 0.00-0.24), and semantic memory (β = 0.23; 95% CI 0.12-0.34).

DISCUSSION

In a diverse cohort, higher occupational complexity is associated with better cognition. Findings should be verified in larger cohorts.

HIGHLIGHT

Few studies have examined associations of occupational complexity with cognition in diverse populations. Racial and ethnic minorities are disproportionately exposed to lower occupational complexity. Occupational complexity with data and people are associated with better cognition.

Cognitive reserve and individual differences in brain tumour patients

The aim of the paper is to determine the effects of the cognitive reserve on brain tumour patients' cognitive functions and, specifically, if cognitive reserve helps patients cope with the negative effects of brain tumours on their cognitive functions. We retrospectively studied a large sample of around 700 patients, diagnosed with a brain tumour. Each received an MRI brain examination and performed a battery of tests measuring their cognitive abilities before they underwent neurosurgery. To account for the complexity of cognitive reserve, we construct our cognitive reserve proxy by combining three predictors of patients' cognitive performance, namely, patients' education, occupation, and the environment where they live. Our statistical analysis controls for the type, side, site, and size of the lesion, for fluid intelligence quotient, and for age and gender, in order to tease out the effect of cognitive reserve on each of these tests. Clinical neurological variables have the expected effects on cognitive functions. We find a robust positive effect of cognitive reserve on patients' cognitive performance. Moreover, we find that cognitive reserve modulates the effects of the volume of the lesion: the additional negative impact of an increase in the tumour size on patients' performance is less severe for patients with higher cognitive reserve. We also find substantial differences in these effects depending on the cerebral hemisphere where the lesion occurred and on the cognitive function considered. For several of these functions, the positive effect of cognitive reserve is stronger for patients with lesions in the left hemisphere than for patients whose lesions are in the right hemisphere. The development of prevention strategies and personalized rehabilitation interventions will benefit from our contribution to understanding the role of cognitive reserve, in addition to that of neurological variables, as one of the factors determining the patients' individual differences in cognitive performance caused by brain tumours.

Cognitive reserve in ALS: The role of occupational skills and requirements

Background

Amyotrophic Lateral Sclerosis (ALS) is a heterogeneous neurodegenerative condition featuring variable degrees of motor decline and cognitive impairment. We test the hypothesis that cognitive reserve (CR), defined by occupational histories involving more complex cognitive demands, may protect against cognitive decline, while motor reserve (MR), defined by working jobs requiring complex motor skills, may protect against motor dysfunction.

Methods

Individuals with ALS (n=150) were recruited from the University of Pennsylvania's Comprehensive ALS Clinic. Cognitive performance was evaluated using the Edinburgh Cognitive and Behavioral ALS Screen (ECAS), and motor functioning was measured using Penn Upper Motor Neuron (PUMNS) scale and ALS Functional Rating Scales (ALSFRS-R). The Occupational Information Network (O*NET) Database was used to derive 17 factors representing distinct worker characteristics, occupational requirements, and worker requirements, which were related to ECAS, PUMNS, and ALSFRS-R scores using multiple linear regression.

Results

A history of working jobs involving greater reasoning ability (β=2.12, p<.05), social ability (β=1.73, p<.05), analytic skills, (β=3.12, p<.01) and humanities knowledge (β=1.83, p<.01) was associated with better performance on the ECAS, while jobs involving more exposure to environmental hazards (β=-2.57, p<.01) and technical skills (β=-2.16, p<.01) were associated with lower ECAS Total Scores. Jobs involving greater precision skills (β=1.91, p<.05) were associated with greater disease severity on the PUMNS. Findings for the ALSFRS-R did not survive correction for multiple comparisons.

Discussion

Jobs requiring greater reasoning abilities, social skills, and humanities knowledge were related to preserved cognitive functioning consistent with CR, while jobs with greater exposure to environmental hazards and technical demands were linked to poorer cognitive functioning. We did not find evidence of MR as no protective effects of occupational skills and requirements were found for motor symptoms, and jobs involving greater precision skills and reasoning abilities were associated with worse motor functioning. Occupational history provides insight into protective and risk factors for variable degrees of cognitive and motor dysfunction in ALS.

Direct Effect of Life-Course Socioeconomic Status on Late-Life Cognition and Cognitive Decline in the Rush Memory and Aging Project

The role of socioeconomic status (SES) across the life course in late-life cognition is unclear. We tested the hypotheses that: 1) High SES in childhood, young adulthood, midlife, and late life have independent causal effects on higher cognition level and slower cognitive decline; 2) Compared with stable low SES (referent), stable high SES has the largest estimated effect for higher cognition level and slower decline among life-course SES combinations. The Rush Memory and Aging Project enrolled 1,940 dementia-free older adults in northeastern Illinois (1997-2018). We used inverse probability-weighted marginal structural models to estimate the joint and independent effect of each life-course SES on global and domain-specific cognition. A total of 1,746 participants had, on average, 6 years of follow-up. High SES at each life-course stage starting in young adulthood had a protective estimated effect on global and domain-specific cognition intercepts. Compared with consistently low SES, consistently high SES (β = 0.64, 95% confidence interval: 0.48, 0.93) and high SES beyond childhood (β = 0.64, 95% confidence interval: 0.47, 0.83) had the largest benefit for global cognition intercepts. None of the life-course SES measures influenced rate of global or domain-specific decline. Additional understanding of life-course SES components influencing cognitive level is warranted.

2023 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease, including prevalence and incidence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report examines the patient journey from awareness of cognitive changes to potential treatment with drugs that change the underlying biology of Alzheimer's. An estimated 6.7 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, and Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States. In 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death, Alzheimer's was the seventh-leading cause of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated by the COVID-19 pandemic in 2020 and 2021. More than 11 million family members and other unpaid caregivers provided an estimated 18 billion hours of care to people with Alzheimer's or other dementias in 2022. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $339.5 billion in 2022. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the paid health care workforce are involved in diagnosing, treating and caring for people with dementia. In recent years, however, a shortage of such workers has developed in the United States. This shortage - brought about, in part, by COVID-19 - has occurred at a time when more members of the dementia care workforce are needed. Therefore, programs will be needed to attract workers and better train health care teams. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2023 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $345 billion. The Special Report examines whether there will be sufficient numbers of physician specialists to provide Alzheimer's care and treatment now that two drugs are available that change the underlying biology of Alzheimer's disease.

Distinct reserve capacity impacts on default-mode network in response to left angular gyrus-navigated repetitive transcranial magnetic stimulation in the prodromal Alzheimer disease

Default-mode network (DMN) may be the earliest affected network and is associated with cognitive decline in Alzheimer's disease (AD). Repetitive transcranial magnetic stimulation (rTMS) may help to modulate DMN plasticity. Still, stimulation effects substantially vary across studies and individuals. Global left frontal cortex (gLFC) connectivity, a substitute for reserve capacity, may contribute to the heterogeneous physiological effects of neuro-navigated rTMS. This study investigated the effects of left angular gyrus-navigated rTMS on DMN connectivity in different reserve capacity participants. gLFC connectivity, was computed through resting-state fMRI correlations. Thirty-one prodromal AD patients were divided into low connection group (LCG) and high connection group (HCG) by the median of gLFC connectivity. Distinct reserve capacity impacts on DMN in response to rTMS were identified in these two groups. Then, brain-behavior relationships were examined. gLFC connectivity within a certain range is directly proportional to cognitive reserve ability (i.e., LCG), and the effectiveness of functional connectivity beyond this range decreases (i.e, HCG). Moreover, LCG exhibited increased DMN connectivity and significantly positive memory improvements, while HCG showed a contrary connectivity decline and maintained or slightly improved their cognitive function after neuro-navigated rTMS treatment. The prodromal AD patients with the distinct reserve capacity may benefit differently from left angular gyrus-navigated rTMS, which may lead to increasing attention in defining personalized medicine approach of AD.

Association Between Paid Work and Health-Related Quality of Life Among Community-Dwelling Older Adults: The Sukagawa Study

In this study, we aimed to determine whether paid work has an impact on health-related quality of life (HRQOL) among older adults. Over three years, we longitudinally collected data from 5,260 community-dwelling older adults aged 75 years or older from a city in Japan. We assessed HRQOL using the Short-Form-8. We estimated the mean difference between the physical component summary (PCS) and the mental component summary (MCS) scores, which were stratified based on gender using multivariate, generalized estimating equation models. We further conducted a subgroup analysis based on the participants' occupational backgrounds. Engagement in paid work was associated with increased MCS scores across both genders and with increased PCS scores among women. In the subgroup analysis, only women who had previously worked as managerial workers showed an inverse association with MCS scores. In this population, engagement in paid work may be a crucial factor associated with well-being.

Socioeconomic Status, Race/Ethnicity, and Unexpected Variation in Dementia Classification in Longitudinal Survey Data

OBJECTIVES

As dementia affects a growing number of older adults, it is important to understand its detection and progression. We identified patterns in dementia classification over time using a longitudinal, nationally representative sample of older adults. We examined the relationship between socioeconomic status and race/ethnicity, and patterns in dementia classification.

METHODS

Data for 7,218 Medicare beneficiaries from the 2011-2017 National Health and Aging Trends Study (NHATS) were classified into five categories: consistently no dementia, consistently cognitive impairment, "typical" dementia progression, "expected" variation, and "unexpected" variation. Multivariable multinomial logistic regression assessed relative risk of dementia classification by sociodemographic and health factors.

RESULTS

Among NHATS respondents, 59.5% consistently were recorded as having no dementia, 7% consistently cognitively impaired, 13% as having typical progression, 15% as having expected variation, and 5.5% as having unexpected variation. In multivariable models, compared with consistent dementia classification, less education, Medicare-Medicaid-dual enrollment, and identifying as non-Hispanic Black were associated with increased likelihood of unexpected variation (e.g., non-Hispanic Black adjusted risk ratio: 2.12, 95% CI: 1.61-2.78, p < .0001).

DISCUSSION

A significant minority of individuals have unexpected patterns of dementia classification over time, particularly individuals with low socioeconomic status and identifying as non-Hispanic Black. Dementia classification uncertainty may make it challenging to activate resources (e.g., health care, caregiving) for effective disease management, underscoring the need to support persons from at-risk groups and to carefully evaluate cognitive assessment tools to ensure they are equally reliable across groups to avoid magnifying disparities.

Midlife occupational cognitive requirements protect cognitive function in old age by increasing cognitive reserve

Introduction

Several lifestyle factors promote protection against Alzheimer's disease (AD) throughout a person's lifespan. Although such protective effects have been described for occupational cognitive requirements (OCR) in midlife, it is currently unknown whether they are conveyed by brain maintenance (BM), brain reserve (BR), or cognitive reserve (CR) or a combination of them.

Methods

We systematically derived hypotheses for these resilience concepts and tested them in the population-based AgeCoDe cohort and memory clinic-based AD high-risk DELCODE study. The OCR score (OCRS) was measured using job activities based on the O*NET occupational classification system. Four sets of analyses were conducted: (1) the interaction of OCR and APOE-ε4 with regard to cognitive decline (N = 2,369, AgeCoDe), (2) association with differentially shaped retrospective trajectories before the onset of dementia of the Alzheimer's type (DAT; N = 474, AgeCoDe), (3) cross-sectional interaction of the OCR and cerebrospinal fluid (CSF) AD biomarkers and brain structural measures regarding memory function (N = 873, DELCODE), and (4) cross-sectional and longitudinal association of OCR with CSF AD biomarkers and brain structural measures (N = 873, DELCODE).

Results

Regarding (1), higher OCRS was associated with a reduced association of APOE-ε4 with cognitive decline (mean follow-up = 6.03 years), consistent with CR and BR. Regarding (2), high OCRS was associated with a later onset but subsequently stronger cognitive decline in individuals converting to DAT, consistent with CR. Regarding (3), higher OCRS was associated with a weaker association of the CSF Aβ42/40 ratio and hippocampal volume with memory function, consistent with CR. Regarding (4), OCR was not associated with the levels or changes in CSF AD biomarkers (mean follow-up = 2.61 years). We found a cross-sectional, age-independent association of OCRS with some MRI markers, but no association with 1-year-change. OCR was not associated with the intracranial volume. These results are not completely consistent with those of BR or BM.

Discussion

Our results support the link between OCR and CR. Promoting and seeking complex and stimulating work conditions in midlife could therefore contribute to increased resistance to pathologies in old age and might complement prevention measures aimed at reducing pathology.

Occupational complexity and cognition in the FINGER multidomain intervention trial

INTRODUCTION

Lifetime exposure to occupational complexity is linked to late-life cognition, and may affect benefits of preventive interventions.

METHODS

In the 2-year multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), we investigated, through post hoc analyses (N = 1026), the association of occupational complexity with cognition. Occupational complexity with data, people, and substantive complexity were classified through the Dictionary of Occupational Titles.

RESULTS

Higher levels of occupational complexity were associated with better baseline cognition. Measures of occupational complexity had no association with intervention effects on cognition, except for occupational complexity with data, which was associated with the degree of intervention-related gains for executive function.

DISCUSSION

In older adults at increased risk for dementia, higher occupational complexity is associated with better cognition. The cognitive benefit of the FINGER intervention did not vary significantly among participants with different levels of occupational complexity. These exploratory findings require further testing in larger studies.

Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease

An important step towards the development of treatments for cognitive impairment in ageing and neurodegenerative diseases is to identify genetic and environmental modifiers of cognitive function and understand the mechanism by which they exert an effect. In Huntington's disease, the most common autosomal dominant dementia, a small number of studies have identified intellectual enrichment, i.e. a cognitively stimulating lifestyle and genetic polymorphisms as potential modifiers of cognitive function. The aim of our study was to further investigate the relationship and interaction between genetic factors and intellectual enrichment on cognitive function and brain atrophy in Huntington's disease. For this purpose, we analysed data from Track-HD, a multi-centre longitudinal study in Huntington's disease gene carriers and focused on the role of intellectual enrichment (estimated at baseline) and the genes FAN1, MSH3, BDNF, COMT and MAPT in predicting cognitive decline and brain atrophy. We found that carrying the 3a allele in the MSH3 gene had a positive effect on global cognitive function and brain atrophy in multiple cortical regions, such that 3a allele carriers had a slower rate of cognitive decline and atrophy compared with non-carriers, in agreement with its role in somatic instability. No other genetic predictor had a significant effect on cognitive function and the effect of MSH3 was independent of intellectual enrichment. Intellectual enrichment also had a positive effect on cognitive function; participants with higher intellectual enrichment, i.e. those who were better educated, had higher verbal intelligence and performed an occupation that was intellectually engaging, had better cognitive function overall, in agreement with previous studies in Huntington's disease and other dementias. We also found that intellectual enrichment interacted with the BDNF gene, such that the positive effect of intellectual enrichment was greater in Met66 allele carriers than non-carriers. A similar relationship was also identified for changes in whole brain and caudate volume; the positive effect of intellectual enrichment was greater for Met66 allele carriers, rather than for non-carriers. In summary, our study provides additional evidence for the beneficial role of intellectual enrichment and carrying the 3a allele in MSH3 in cognitive function in Huntington's disease and their effect on brain structure.

Job demands may determine cognitive and physical aging after retirement

During adulthood, we spend most of our time and efforts at work. However, the impact of employment in aging is poorly explored. Our study addressed how job demands can affect aging after retirement. We have developed a descriptive observational study carried out in 367 older adults with a mean age of 73.9 years (66.5% women and 33.5% men), measuring cognition and functional status. Our results demonstrate that older adults who had high mental demands in their jobs, show better scores in cognition. However, they show poor functional development of basic and instrumental activities of daily life (p< .05). In contrast, former workers who had high physical demands, display lower scores in cognition and lower functional performance in instrumental activities (p< .05). Work life activities contribute to cognitive and physical decline after retirement. Therefore, healthy aging should include interventions that consider the job influence on the age impairment.

Work Demands and Cognitive Health Inequities by Race and Ethnicity: A Scoping Review

BACKGROUND AND OBJECTIVES

This scoping review aimed to chart the scientific literature on the association between workplace demands with cognitive health, and whether race and ethnicity have a direct or indirect relationship between occupational complexity and cognitive health.

RESEARCH DESIGN AND METHODS

PRISMA scoping review guided this study. Peer-reviewed articles were drawn from 5 databases. Inclusion criteria were populations aged 18 and older, U.S.-based studies, a comprehensive conceptualization of workplace demands, and cognitive health outcomes. All articles were screened by title and abstract; qualifying articles proceeded to full-text review.

RESULTS

The majority of studies drew from theories that did not interrogate heterogeneity and minority aging experiences. Consequently, the majority of studies did not include race and ethnicity in their analyses. A small and growing body of research drew from critical perspectives and interrogated cognitive health inequities by race and ethnicity within the context of workplace demands. The association between workplace demands and cognitive health is not linear when race and ethnicity are examined. Emerging evidence suggests interventions to improve substantive complexity among racial and ethnic minorities, and individuals with low education are a promising avenue for intervention research.

DISCUSSION AND IMPLICATIONS

We discuss integrating emerging theories, such as minority stress and revised social determinants of health frameworks, to sharpen the focus and broaden our understanding on racial and ethnic cognitive health inequities in an emerging area of prevention research. This research can advance our basic understanding of preventable health inequities as well as provide important information for interventions.

Gender differences in cognitive reserve: implication for subjective cognitive decline in women

BACKGROUND

Subjective Cognitive Decline (SCD) is a self-experienced decline in cognitive capacity with normal performance on standardized cognitive tests, showing to increase risk of Alzheimer's Disease (AD). Cognitive reserve seems to influence the progression from SCD to Mild Cognitive Impairment (MCI) and to AD. The aim of our study was to investigate gender differences in cognitive reserve evaluating how sex might modulate the role of cognitive reserve on SCD.

METHODS

We included 381 SCD patients who underwent clinical evaluation, neuropsychological assessment, evaluation of premorbid intelligence by the Test di Intelligenza Breve (TIB), cognitive complaints by the Memory Assessment Clinics Questionnaire (MAC-Q), and apolipoprotein E (APOE) genotyping.

RESULTS

The proportion between women and men was significantly different (68.7% [95% CI 63.9-73.4 vs 31.4%, 95% CI 26.6-36.0]). Women were younger than men at onset of SCD and at the baseline visit (p = 0.021), had lower years of education (p = 0.007), lower TIB scores (p < 0.001), and higher MAC-Q scores (p = 0.012). TIB was directly associated with age at onset of SCD in both women and men, while years of education was inversely associated with age at onset only in women. Multivariate analysis showed that sex influences TIB independently from years of education. TIB was directly associated with MAC-Q in men.

CONCLUSIONS

Sex interacts with premorbid intelligence and education level in influencing the age at onset and the severity of SCD. As the effect of education was different between men and women, we speculated that education might act as a minor contributor of cognitive reserve in women.

2022 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on family caregivers, the dementia workforce and society. The Special Report discusses consumers' and primary care physicians' perspectives on awareness, diagnosis and treatment of mild cognitive impairment (MCI), including MCI due to Alzheimer's disease. An estimated 6.5 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available. Alzheimer's disease was officially listed as the sixth-leading cause of death in the United States in 2019 and the seventh-leading cause of death in 2020 and 2021, when COVID-19 entered the ranks of the top ten causes of death. Alzheimer's remains the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. More than 11 million family members and other unpaid caregivers provided an estimated 16 billion hours of care to people with Alzheimer's or other dementias in 2021. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $271.6 billion in 2021. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Members of the dementia care workforce have also been affected by COVID-19. As essential care workers, some have opted to change jobs to protect their own health and the health of their families. However, this occurs at a time when more members of the dementia care workforce are needed. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are almost three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 22 times as great. Total payments in 2022 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $321 billion. A recent survey commissioned by the Alzheimer's Association revealed several barriers to consumers' understanding of MCI. The survey showed low awareness of MCI among Americans, a reluctance among Americans to see their doctor after noticing MCI symptoms, and persistent challenges for primary care physicians in diagnosing MCI. Survey results indicate the need to improve MCI awareness and diagnosis, especially in underserved communities, and to encourage greater participation in MCI-related clinical trials.

Depression Mediates the Association Between Occupational Complexity and Late-Life Cognition in Hispanics

There is a dearth of research in Latin America regarding risk and protective factors affecting older adults’ cognition. This study aimed to investigate the factors mediating the association between occupational complexity and late-life cognition and daily function in a sample of Hispanic older adults. Participants (n = 588) aged 65 years and older underwent clinical, functional, and cognitive assessments. Mediation analyses revealed that depressive symptoms mediated the relationship between occupational complexity and cognitive as well as functional outcomes. Results provide evidence that depression may act as a risk factor for worse outcomes, even if older adults had a cognitively demanding occupation.

How Welfare Regimes Moderate the Associations Between Cognitive Aging, Education, and Occupation

OBJECTIVES

Previous studies have shown the importance of individual markers of cognitive reserve, such as education and occupation, for cognitive health in old age. However, there has been only little investigation so far on how this relationship varies across contexts.

METHODS

We analyzed data from the Survey of Health, Ageing, and Retirement in Europe, using second-order latent growth models, to assess the moderating role of welfare regimes on the relationship between education and occupation skill level in explaining overall cognitive functioning and decline in old age. Our sample includes 13 European countries using data from 5 regular waves of the survey (2004-2007 and 2011-2015) and 2 retrospective ones (2008-2009 and 2017). Cognitive functioning was modeled as a latent variable measured by immediate and delayed recall, verbal fluency, and numeracy.

RESULTS

74,193 participants were included from the survey. Our analysis showed that the association of education with cognition was weaker overall in Scandinavian countries, but stronger in Southern European countries, relative to Bismarckian ones. However, educational differences in the decline of cognition were more pronounced only in Scandinavian compared to Bismarckian countries. Additionally, higher-skilled occupations in Scandinavian countries had better overall functioning compared to the same occupations in Bismarckian countries, but there was no difference in the decline in cognitive functioning.

DISCUSSION

Our findings indicate that the associations of cognitive functioning and its decline with individuals' cognitive reserve markers (education and occupational skill level) vary according to welfare regimes, showing the importance of contextual factors in cognitive aging processes.

Association of mental demands in the workplace with cognitive function in older adults at increased risk for dementia

Objectives

Growing evidence suggests a protective effect of high mental demands at work on cognitive function in later life. However, evidence on corresponding associations in older adults at increased risk for dementia is currently lacking. This study investigates the association between mental demands at work and cognitive functioning in the population of the AgeWell.de-trial.

Methods

Cross-sectional investigation of the association between global cognitive functioning (Montreal Cognitive Assessment) and mental demands at work in older individuals at increased risk for dementia (Cardiovascular Risk Factors, Aging, and Incidence of Dementia (CAIDE)score ≥ 9; n = 941, age: 60–77 years). Occupational information was matched to Occupational Information Network (O*NET)-descriptors. Associations between cognitive function and O*NET-indices executive, verbal and novelty were investigated using generalized linear models.

Results

Higher values of index verbal (b = .69, p = .002) were associated with better cognitive function when adjusting for covariates. No association was observed for indices executive (b = .37, p = .062) and novelty (b = .45, p = .119). Higher education, younger age, and employment were linked to better cognitive function, while preexisting medical conditions did not change the associations. Higher levels of depressive symptomatology were associated with worse cognitive function.

Conclusions

Higher levels of verbal demands at work were associated with better cognitive function for older adults with increased dementia risk. This suggests an advantage for older persons in jobs with high mental demands even after retirement and despite prevalent risk factors. Longitudinal studies are warranted to confirm these results and evaluate the potential of workplaces to prevent cognitive decline through increased mental demands.

Protective factors for subjective cognitive decline individuals: trajectories and changes in a longitudinal study with Italian elderly

BACKGROUND AND PURPOSE

Many different factors have been hypothesized to modulate cognition in an aging population according to their functioning at baseline.

METHODS

This retrospective study quantifies the relative contribution of age and sex as demographic factors, comorbidity, education and occupation (classified with the International Standard Classification of Occupation 2008) as cognitive reserve proxies in accounting for cognitive aging. All participants (3081) were evaluated at baseline with a complete neuropsychological test battery (T1) and those with unimpaired profiles were classified as subjective cognitive decline, those mildly impaired as mild neurocognitive decline and those severely impaired as major neurocognitive decline. From the first assessment 543 individuals were assessed a second time (T2), and 125 a third time (T3). Depending on whether they maintained or worsened their profile, based on their initial performance, participants were then classified as resistant or declining.

RESULTS

At baseline, all individuals showed education and occupation as the best predictors of performance, in addition to age. Furthermore, across assessments, the resistant had higher levels of education and occupation than the declining. In particular, the education and occupation predicted cognitive performance in all groups considered, from the subjective cognitive decline to the one with the most severely impaired participants.

CONCLUSIONS

This study highlights the role of working activity in protecting from cognitive decline across all fragile elderly groups and even more so the individuals who are at very high risk of decline.

Status and Factors of Cognitive Function Among Older Adults in Urban China

The present study aimed to examine the current status and influencing mechanisms of different demographic factors associated with cognitive function in urban Chinese older adults. A total of 644 older adults from 14 communities in urban China (e.g., Shanghai, Beijing, and Wuxi) were investigated by using the Mini-Mental State Examination and the Repeatable Battery for the Assessment of Neuropsychological Status. The results indicated that the overall cognitive function of older adults in urban China was normal. We found an aging effect on cognitive level, and cognitive function declined more rapidly after age 80. Older age, unmarried status, and lower occupational cognitive requirements increased the likelihood of cognitive risk. Higher educational levels and active engagement in exercise may contribute to cognitive reserve and have a protective effect on cognitive decline in late life. Further study is needed to develop appropriate interventions to improve the mental health of older people.

Mentally Challenging Occupations Are Associated With More Rapid Cognitive Decline at Later Stages of Cognitive Aging

OBJECTIVES

Engaging in mentally challenging activities is associated with reduced risk for cognitive impairment and dementia; however, its association with rates of cognitive decline has been inconsistent. The aim of this study is to test whether working in mentally challenging occupations is related to rates of cognitive change at later older adulthood.

METHOD

The sample consisted of 1,520 individuals (baseline mean age = 78.6 ± 5.1, range = 64-100) from the Einstein Aging Study. Occupation information of each participant was collected retrospectively and linked with the substantive complexity of work score from the Dictionary of Occupational Titles. Cognitive changes in memory, speed, and executive function (EF) domains were represented using two time metrics (i.e., time from retirement, time from study enrollment).

RESULTS

Results from mixed models showed that occupational complexity was associated with significantly faster rates of cognitive decline in speed and EF in the "time from retirement" model but not in the "time from baseline" model. Despite faster cognitive loss, the protective effect of occupational complexity persisted for decades after retirement due to higher initial levels of cognition.

DISCUSSION

The result suggests that protective factors for cognitive health may be associated with delayed onset but more rapid cognitive decline afterwards at later stages of cognitive aging.

Strategies and cognitive reserve to preserve lexical production in aging

In the absence of any neuropsychiatric condition, older adults may show declining performance in several cognitive processes and among them, in retrieving and producing words, reflected in slower responses and even reduced accuracy compared to younger adults. To overcome this difficulty, healthy older adults implement compensatory strategies, which are the focus of this paper. We provide a review of mainstream findings on deficient mechanisms and possible neurocognitive strategies used by older adults to overcome the deleterious effects of age on lexical production. Moreover, we present findings on genetic and lifestyle factors that might either be protective or risk factors of cognitive impairment in advanced age. We propose that "aging-modulating factors" (AMF) can be modified, offering prevention opportunities against aging effects. Based on our review and this proposition, we introduce an integrative neurocognitive model of mechanisms and compensatory strategies for lexical production in older adults (entitled Lexical Access and Retrieval in Aging, LARA). The main hypothesis defended in LARA is that cognitive aging evolves heterogeneously and involves complementary domain-general and domain-specific mechanisms, with substantial inter-individual variability, reflected at behavioral, cognitive, and brain levels. Furthermore, we argue that the ability to compensate for the effect of cognitive aging depends on the amount of reserve specific to each individual which is, in turn, modulated by the AMF. Our conclusion is that a variety of mechanisms and compensatory strategies coexist in the same individual to oppose the effect of age. The role of reserve is pivotal for a successful coping with age-related changes and future research should continue to explore the modulating role of AMF.

Development of a protective mental work demands questionnaire

OBJECTIVES

Research shows that mental demands at work affect later-life cognitive functioning and dementia risk, but systematic assessment of protective mental work demands (PMWDs) is still missing. The goal of this research was to develop a questionnaire to assess PMWDs.

DESIGN

The instrument was developed in accordance with internationally recognized scientific standards comprising conceptualization, pretesting, and validation via confirmatory factor analysis (CFA), principal component analysis (PCA), and multiple regression analyses.

PARTICIPANTS

We included 346 participants, 72.3% female, with an average age of 56.3 years.

MEASUREMENT

Item pool, sociodemographic questions, and cognitive tests: Trail-Making Test A/B, Word List Recall, Verbal Fluency Test, Benton Visual Retention Test, Reading Minds in the Eyes Test.

RESULTS

CFAs of eight existing PMWD-concepts revealed weaker fit indices than PCA of the item pool that resulted in five concepts. We computed multivariate regression analyses with all 13 PMWD-concepts as predictors of cognitive functioning. After removing PMWD-concepts that predicted less than two cognitive test scores and excluding others due to overlapping items, the final questionnaire contained four PMWD-concepts: Mental Workload (three items, Cronbach's α = .58), Verbal Demands (four, Cronbach's α = .74), Information Load (six, Cronbach's α = .83), and Extended Job Control (six, Cronbach's α = .83).

CONCLUSIONS

The PMWD-Questionnaire intends to assess protective mental demands at the workplace. Information processing demands and job control make up the primary components emphasizing their relevance regarding cognitive health in old age. Long-term follow-up studies will need to validate construct validity with respect to dementia risk.

Influence of childhood socioeconomic position and ability on mid-life cognitive function: evidence from three British birth cohorts

BACKGROUND

Childhood socioeconomic position (SEP) is robustly associated with cognitive function later in life. However, it is unclear whether this reflects a direct relationship, or an indirect association via modifiable factors such as educational attainment and occupation. We sought to clarify these associations using retrospectively harmonised data from three ongoing British birth cohorts.

METHODS

We analysed data from the 1946 National Survey of Health and Development (n=2283), the 1958 National Child Development Study (n=9385) and the 1970 British Cohort Study (n=7631). Retrospective harmonisation was used to derive equivalent indicators of cognition, SEP, education and occupation across the three cohorts. Structural equation modelling was used to examine the association between childhood SEP and mid-life cognitive function, via childhood cognitive ability, educational attainment and mid-life occupation.

RESULTS

Across all three cohorts, no direct pathways were observed between childhood SEP and mid-life cognitive function. Rather, this association was indirect via the three temporally ordered mediators. In addition, the direct pathway between childhood cognition and adult cognitive function was weaker in the two younger studies.

CONCLUSIONS

Across three British birth cohorts, we found that the association between early life SEP and mid-life cognitive function was fully mediated by childhood cognitive ability, educational attainment and occupational status. Furthermore, the association between early cognitive ability and mid-life cognitive function has decreased in younger generations. Therefore, cognitive function in adulthood may be influenced by modifiable factors and societal change.

Loneliness, Sense of Control, and Risk of Dementia in Healthy Older Adults: A Moderated Mediation Analysis

Objectives: Despite the rising prevalence of dementia, little research has been conducted to identify modifiable psychological factors that alleviate the risk of dementia in older adults and the underlying mechanisms. Given that loneliness is, in part, concomitant with a weakened sense of control, we examined whether sense of control would mediate the relation between loneliness and dementia risk. Further, considering that working -memory capacity is a critical cognitive resource that serves as a buffer against age-related cognitive decline, we examined a second-order moderated mediational model whereby working-memory capacity moderates the relation between control beliefs and dementia risk in older adults.

METHODS

We administered a series of measures to older community-dwelling adults (ages 60-93; N = 69), including the participant-rated AD8 to assess the risk of dementia. Using the PROCESS macro, we examined the moderated mediation model for the relation between loneliness, sense of control, and dementia risk.

RESULTS

We found that sense of control significantly mediated the relation between loneliness and risk of dementia. Moreover, the indirect effect of loneliness on dementia risk via lowered sense of control was significant only in individuals with poorer working-memory capacity. Notably, these findings held true when important covariates were controlled for.

CONCLUSIONS

Our findings underscore the critical role of control beliefs and working memory in protecting against dementia risk.

CLINICAL IMPLICATIONS

Our findings have implications for intervention programs that target alleviating dementia risk and promoting healthy aging in older adults by improving socioemotional health and cognitive functioning.

Cumulative employment intensity and complexity across the life course and cognitive function in later life among European women and men

PURPOSE

Relatively little is known about how working-age life course cumulative exposure to employment intensity and job complexity informs older-age cognitive function. We investigate these associations, separately for men and women, and net of known confounders.

METHODS

Using retrospective lifetime employment histories of Europeans born 1923-1959 (2004-2009, N = 22 266), we calculate cumulative working-age exposure to nonemployment, full-time and part-time employment, and a professional occupation. In gender-stratified linear regression models, these indicators predict cognitive function score based on the DemTect scale and Mini Mental State Exam.

RESULTS

Nonemployment ≥25% of the working life course was associated with poorer cognitive function for men by -0.43 points (95% CI = -0.79, -0.06) on a 19-point scale. Women's full-time employment, even if <25% of the working lifetime, was associated with a cognitive advantage over never-employment by 0.60 points (95% CI = 0.17, 1.02). Compared to predominantly nonprofessionally employed men, those working professionally for ≥75% of the life course had better cognition by 0.38 points (95% CI = 0.16, 0.60).

CONCLUSIONS

This paper provides novel evidence that older-age cognitive functioning is associated with cumulative exposure to both employment intensity and complexity, but that these relationships vary by sex.

Multifaceted Demands of Work and Their Associations with Cognitive Functioning: Findings From the Health and Retirement Study

OBJECTIVES

The present study examines the associations among mental, social, and physical demands of work with cognitive functioning among older adults in the United States.

METHODS

Data from 3,176 respondents in the Health and Retirement Study were analyzed using growth curve modeling (2004-2014). The study investigated differences by gender, race, ethnicity, and education.

RESULTS

Higher mental and social demands of work were associated with higher levels of initial cognitive functioning, but not significantly associated with slower cognitive decline over time. Physical demands of work were negatively associated with initial cognitive functioning and also marginally associated with a slower rate of decline in cognitive functioning going into older adulthood. In stratified analyses, results varied by sociodemographic characteristics.

DISCUSSION

The results partially support the environmental complexity hypothesis and the productive aging framework in that higher mental and social demands and lower physical demands relate to better cognitive functioning at baseline, with the differences appearing stable throughout older adulthood. The stratified results shed light on addressing disparities in cognitive aging and work environments.

Mitigating the negative impacts of aging on cognitive function; modifiable factors associated with increasing cognitive reserve

Research suggests that social, physical, and cognitively challenging activities during lifetime, could mitigate the negative effects of aging on cognitive function. This effect is explained by the increased cognitive reserve (CR) resulting from such factors; in fact, such activities, by altering structural and functional properties of the human brain, equip one with more effective compensatory mechanisms to resist brain damage before the presentation of severe clinical symptoms. Therefore, applying appropriate modifications in one's lifestyle and activities may be effective in lowering the risk of developing dementia and cognitive dysfunction in old age, especially in brain areas that are susceptible to aging. In this paper, we are going to review relevant studies discussing the association between important modifiable factors, known as CR proxies (i.e., educational attainment, occupational complexity, physical activity, social engagement, bilingualism, leisure activities, and Mediterranean diet), and different domains of cognitive function, which are affected either in the process of healthy aging or neurodegenerative diseases.

2021 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on caregivers and society. The Special Report discusses the challenges of providing equitable health care for people with dementia in the United States. An estimated 6.2 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available, making Alzheimer's the sixth-leading cause of death in the United States and the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated in 2020 by the COVID-19 pandemic. More than 11 million family members and other unpaid caregivers provided an estimated 15.3 billion hours of care to people with Alzheimer's or other dementias in 2020. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $256.7 billion in 2020. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are more than three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 23 times as great. Total payments in 2021 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $355 billion. Despite years of efforts to make health care more equitable in the United States, racial and ethnic disparities remain - both in terms of health disparities, which involve differences in the burden of illness, and health care disparities, which involve differences in the ability to use health care services. Blacks, Hispanics, Asian Americans and Native Americans continue to have a higher burden of illness and lower access to health care compared with Whites. Such disparities, which have become more apparent during COVID-19, extend to dementia care. Surveys commissioned by the Alzheimer's Association recently shed new light on the role of discrimination in dementia care, the varying levels of trust between racial and ethnic groups in medical research, and the differences between groups in their levels of concern about and awareness of Alzheimer's disease. These findings emphasize the need to increase racial and ethnic diversity in both the dementia care workforce and in Alzheimer's clinical trials.