Occupation, Retirement Age, and 20-Year Cognitive Decline: The Atherosclerosis Risk in Communities Neurocognitive Study.

INTRODUCTION: We examined the association of both midlife occupation and age at retirement with cognitive decline in the Atherosclerosis Risk in Communities (ARIC) biracial community-based cohort. METHODS: Current or most recent occupation at ARIC baseline (1987-1989; aged 45-64 years) was categorized based on 1980 US Census major occupation groups and tertiles of the Nam-Powers-Boyd occupational status score (n = 14,090). Retirement status via annual follow-up questionnaires administered ascertained in 1999-2007 was classified as occurring before or after age 70 (n = 7,503). Generalized estimating equation models were used to examine associations of occupation and age at retirement with trajectories of global cognitive factor scores, assessed from visit 2 (1990-1992) to visit 5 (2011-2013). Models were a priori stratified by race and sex and adjusted for demographics and comorbidities. RESULTS: Low occupational status and blue-collar occupations were associated with low baseline cognitive scores in all race-sex strata. Low occupational status and homemaker status were associated with faster decline in white women but slower decline in black women compared to high occupational status. Retirement before age 70 was associated with slower cognitive decline in white men and women and in black men. Results did not change substantially after accounting for attrition. CONCLUSION: Low occupational status was associated with cognitive decline in women but not in men. Earlier retirement was associated with a slower cognitive decline in white participants and in black men. Further research should explore reasons for the observed associations and race-sex differences.

The Role of Brain Integrity in the Association between Occupational Complexity and Cognitive Performance in Subjects with Increased Risk of Dementia.

INTRODUCTION: Mechanisms underlying the positive association between occupational mental demands and late-life cognition are poorly understood. The objective of this study was to assess whether the association between occupational complexity and cognition is related to and moderated by brain integrity in individuals at risk for dementia. Brain integrity was appraised throughout structural measures (magnetic resonance imaging, MRI) and amyloid accumulation (Pittsburgh compound B (PiB)-positron emission tomography, PiB-PET). METHODS: Participants from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) neuroimaging sample - MRI (N = 126), PiB-PET (N = 41) - were included in a post hoc cross-sectional analysis. Neuroimaging parameters comprised the Alzheimer's disease signature (ADS) cortical thickness (FreeSurfer 5.3), medial temporal atrophy (MTA), and amyloid accumulation (PiB-PET). Cognition was assessed using the neuropsychological test battery. Occupational complexity with data, people, and substantive complexity were classified through the Dictionary of Occupational Titles. Linear regression models included cognition as dependent variable, and occupational complexity, measures of brain integrity, and their interaction terms as predictors. RESULTS: Occupational complexity with data and substantive complexity were associated with better cognition (overall cognition, executive function) when adjusting for ADS and MTA (independent association). Significant interaction effects between occupational complexity and brain integrity were also found, indicating that, for some indicators of brain integrity and cognition (e.g., overall cognition, processing speed), the positive association between occupational complexity and cognition occurred only among persons with higher brain integrity (moderated association). CONCLUSIONS: Among individuals at risk for dementia, occupational complexity does not seem to contribute toward resilience against neuropathology. These exploratory findings require validation in larger populations.

Social enrichment on the job: Complex work with people improves episodic memory, promotes brain reserve, and reduces the risk of dementia.

Individuals with more complex jobs experience better cognitive function in old age and a lower risk of dementia, yet complexity has multiple dimensions. Drawing on the Social Networks in Alzheimer Disease study, we examine the association between occupational complexity and cognition in a sample of older adults (N = 355). A standard deviation (SD) increase in complex work with people is associated with a 9% to 12% reduction in the probability of mild cognitive impairment or dementia, a 0.14-0.19 SD increase in episodic memory, and a 0.18-0.25 SD increase in brain reserve, defined as the gap (residual) between global cognitive function and magnetic resonance imaging (MRI) indicators of brain atrophy. In contrast, complexity with data or things is rarely associated with cognitive outcomes. We discuss the clinical and methodological implications of these findings, including the need to complement data-centered activities (e.g., Sudoku puzzles) with person-centered interventions that increase social complexity.

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

Influence of young adult cognitive ability and additional education on later-life cognition.

How and when education improves cognitive capacity is an issue of profound societal importance. Education and later-life education-related factors, such as occupational complexity and engagement in cognitive-intellectual activities, are frequently considered indices of cognitive reserve, but whether their effects are truly causal remains unclear. In this study, after accounting for general cognitive ability (GCA) at an average age of 20 y, additional education, occupational complexity, or engagement in cognitive-intellectual activities accounted for little variance in late midlife cognitive functioning in men age 56-66 (n = 1009). Age 20 GCA accounted for 40% of variance in the same measure in late midlife and approximately 10% of variance in each of seven cognitive domains. The other factors each accounted for <1% of the variance in cognitive outcomes. The impact of these other factors likely reflects reverse causation-namely, downstream effects of early adult GCA. Supporting that idea, age 20 GCA, but not education, was associated with late midlife cortical surface area (n = 367). In our view, the most parsimonious explanation of our results, a meta-analysis of the impact of education, and epidemiologic studies of the Flynn effect is that intellectual capacity gains due to education plateau in late adolescence/early adulthood. Longitudinal studies with multiple cognitive assessments before completion of education would be needed to confirm this speculation. If cognitive gains reach an asymptote by early adulthood, then strengthening cognitive reserve and reducing later-life cognitive decline and dementia risk may really begin with improving educational quality and access in childhood and adolescence.

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.

Impact of occupational complexity on cognitive decline in the oldest-old.

OBJECTIVES: The theory of "Cognitive Reserve" assumes that premorbid factors such as high educational and occupational attainment may enable a better way of coping with brain damage. It has been suggested that more stimulating lifestyles, including more complex work environments, may provide a buffer against cognitive decline in later life. This study aimed to investigate the association between occupational history and cognitive decline in a large cohort of Italian oldest-old. METHODS: 392 individuals (266 women/126 men, mean age 93 ± 3 years) enrolled in the "Mugello study" provided information about their work history. Jobs were classified in nine categories, according to the level of expertise required to perform them, as suggested by the Italian National Institute for Statistics (ISTAT). In addition, socio-demographic characteristics, comorbidities, level of independence, depression, and cognitive status were assessed. The presence of dementia was established based on cognitive status and independence in performing four selected instrumental activities of daily living (ability to manage telephone, transportation, medications, and budget). RESULTS: Neither work complexity (p = 0.995) nor work duration (p = 0.701) showed a significant effect on the likelihood of presenting a lower cognitive profile or developing dementia (p = 0.385 and p = 0.096, for work complexity and work duration, respectively). CONCLUSION: In the observed sample of oldest-old individuals, cognitive decline did not seem to be influenced by cognitive reserve as assessed through the evaluation of cognitive status and level of independence. It is conceivable that in this population, the decline of the brain reserve has a preponderant role in the definition of the cognitive profile.

Different indicators of socioeconomic status and their relative importance as determinants of health in old age.

BACKGROUND: Socioeconomic status has been operationalised in a variety of ways, most commonly as education, social class, or income. In this study, we also use occupational complexity and a SES-index as alternative measures of socioeconomic status. Studies show that in analyses of health inequalities in the general population, the choice of indicators influence the magnitude of the observed inequalities. Less is known about the influence of indicator choice in studies of older adults. The aim of this study is twofold: i) to analyse the impact of the choice of socioeconomic status indicator on the observed health inequalities among older adults, ii) to explore whether different indicators of socioeconomic status are independently associated with health in old age. METHODS: We combined data from two nationally representative Swedish surveys, providing more than 20 years of follow-up. Average marginal effects were estimated to compare the association between the five indicators of SES, and three late-life health outcomes: mobility limitations, limitations in activities of daily living (ADL), and psychological distress. RESULTS: All socioeconomic status indicators were associated with late-life health; there were only minor differences in the effect sizes. Income was most strongly associated to all indicators of late-life health, the associations remained statistically significant when adjusting for the other indicators. In the fully adjusted models, education contributed to the model fits with 0-3% (depending on the outcome), social class with 0-1%, occupational complexity with 1-8%, and income with 3-18%. CONCLUSIONS: Our results indicate overlapping properties between socioeconomic status indicators in relation to late-life health. However, income is associated to late-life health independently of all other variables. Moreover, income did not perform substantially worse than the composite SES-index in capturing health variation. Thus, if the primary objective of including an indicator of socioeconomic status is to adjust the model for socioeconomic differences in late-life health rather than to analyse these inequalities per se, income may be the preferable indicator. If, on the other hand, the primary objective of a study is to analyse specific aspects of health inequalities, or the mechanisms that drive health inequalities, then the choice of indicator should be theoretically guided.

Relationship between lifestyle proxies of cognitive reserve and cortical regions in older adults.

Introduction: With the rapid increase in the population over 65 years old, research on healthy aging has become one of the priorities in the research community, looking for a cost-effective method to prevent or delay symptoms of mild cognitive disorder or dementia. Studies indicate that cognitive reserve theory could be beneficial in this regard. The aim of this study was to investigate the potential relationship between lifestyle socio-behavioral proxies of cognitive reserve and cortical regions in adults with no subjective cognitive decline. Methods: Overall, 58 participants, aged 65-85 years, were included in the data analysis (M = 71.83, SD = 5.02, 20.7% male). Cognitive reserve proxies were measured using the Cognitive Reserve Index questionnaire, while cortical volumes were obtained with the Siemens 1.5 T Avanto MRI scanner and further mapped using the Desikan-Killiany-Tourville (DKT) Atlas. Estimated intracranial volume and age were used as covariates. Results: The results indicated that higher occupational complexity was associated with larger cortical volume in the left middle temporal gyrus, the left and right inferior temporal gyrus, and the left inferior parietal lobule, while a combined proxy (the total CRI score) showed a positive relationship with the volume of left middle temporal gyrus and inferior parietal lobule, and pars orbitalis in the right hemisphere. Discussion: These results might indicate that more complex occupational activities and overall more intellectually and socially active life-style could contribute to better brain health, especially in regions known to be more vulnerable to Alzheimer's disease.

Education, Occupational Complexity, and Incident Dementia: A COSMIC Collaborative Cohort Study.

BACKGROUND: Education and occupational complexity are main sources of mental engagement during early life and adulthood respectively, but research findings are not conclusive regarding protective effects of these factors against late-life dementia. OBJECTIVE: This project aimed to examine the unique contributions of education and occupational complexity to incident dementia, and to assess the mediating effects of occupational complexity on the association between education and dementia across diverse cohorts. METHOD: We used data from 10,195 participants (median baseline age = 74.1, range = 58∼103), representing 9 international datasets from 6 countries over 4 continents. Using a coordinated analysis approach, the accelerated failure time model was applied to each dataset, followed by meta-analysis. In addition, causal mediation analyses were performed. RESULT: The meta-analytic results indicated that both education and occupational complexity were independently associated with increased dementia-free survival time, with 28%of the effect of education mediated by occupational complexity. There was evidence of threshold effects for education, with increased dementia-free survival time associated with 'high school completion' or 'above high school' compared to 'middle school completion or below'. CONCLUSION: Using datasets from a wide range of geographical regions, we found that both early life education and adulthood occupational complexity were independently predictive of dementia. Education and occupational experiences occur during early life and adulthood respectively, and dementia prevention efforts could thus be made at different stages of the life course.

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.

The relationship between cognitive engagement and better memory in midlife.

INTRODUCTION: Engagement in cognitively stimulating work and activities may slow cognitive decline and dementia. We examined the individual and combined associations of four cognitive engagement indices (educational attainment, occupational complexity, social engagement, and cognitively stimulating leisure activities) with objective and subjective cognition. METHODS: Middle-aged adults (n = 1864) enrolled in the Healthy Brain Project completed the Cogstate Brief Battery, the Cognitive Function Instrument, and self-report questionnaires of cognitive engagement. RESULTS: Educational attainment and leisure activity engagement were individually associated with memory performance. Participants were classified based on whether they rated highly in zero to four cognitive engagement indices. Compared to participants with no indices, participants with two or more indices performed moderately better on memory. DISCUSSION: Results suggest that greater variety of cognitive engagement across different areas of life is related to better memory in midlife. Possible explanation for this relationship may be increased opportunity for enhancing cognitive reserve, but further investigations are required.

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.

Complexity of Primary Lifetime Occupation and Cognitive Processing.

Today, there are a lack of studies focusing on the relationship between occupational complexity and executive functioning. This is noteworthy since executive functions are core aspects of cognitive processing. The present study was aimed to investigate if three occupational complexity factors (with data, people, and things) of main lifetime occupation were related to performance in executive tasks (inhibition, switching, updating). We analyzed cross-sectional data that were available for 225 participants aged 50-75 years. Results from structural equation models showed that higher complexity levels of working with data were related to lower error rates in the updating component of cognitive control. In addition, higher rates of complexity working with people was associated with lower error rates in task-switching, which also persisted after adjustment of fluid intelligence. Complexity with things, however, was not related to performance in the executive tasks. Future studies would benefit from a longitudinal design to investigate if the results from this study also hold in the long term and to further investigate the directionality between factors.

Are Occupational Complexity and Socioeconomic Position Related to Psychological Distress 20 Years Later?

OBJECTIVE: To assess occupational complexity in midlife in relation to psychological distress in older adulthood (69+ years) and explore the role of socioeconomic position. METHOD: Baseline data from the Swedish Level of Living Survey and follow-up data from the Swedish Longitudinal Study of Living Conditions of the Oldest Old were combined, resulting in 20+ years of follow-up. Data were analyzed using ordered logistic regressions. RESULTS: Higher occupational complexity was associated with less psychological distress 20 years later adjusted for age, sex, follow-up year, hours worked the year before baseline, and psychological distress at baseline. Higher socioeconomic position yielded the same pattern of results. Socioeconomic position partially accounted for the association between occupational complexity and psychological distress. DISCUSSION: With social gradient not easily amenable to modification, efforts to increase engagement at work may offer a viable option to attenuate the influence of work environment on psychological distress later in life.

La influencia de la educación y la complejidad laboral en el desempeño cognitivo de adultos mayores con deterioro cognitivo leve

El presente estudio tiene como objetivo evaluar el peso relativo de la educación y la complejidad laboral en la determinación del rendimiento cognitivo de sujetos con deterioro cognitivo leve (DCL). Fueron evaluados 80 sujetos con DCL, con los siguientes instrumentos: cuestionario de datos demográficos y sociales, cuestionario de agenciamiento de la actividad laboral y una batería neuropsicológica ampliada: memoria (Memoria lógica Signoret Batería, TAVEC), atención (Digit span, TMTA), lenguaje (Vocabulario WAISIII, Test de denominación de Boston, fluidez verbal), funciones ejecutivas (TMTB, analogías WAIS III, razonamiento matricial WAISIII) y construcción visual (cubos WAISIII). Los resultados muestran que la complejidad laboral tiene un peso mayor que la educación en la cognición como son el vocabulario, la flexibilidad cognitiva y las habilidades visuoconstructivas. La educación, tiene mayor peso en el razonamiento abstracto y la atención sostenida. La complejidad ocupacional y la educación desempeñan un papel diferencial e importante en el mantenimiento de las capacidades cognitivas, siendo factores amortiguadores del deterioro cognitivo en el envejecimiento

O presente estudo tem como objetivo avaliar o peso relativo da educação e da complexidade laboral na determinação do desempenho cognitivo de sujeitos com comprometimento cognitivo leve (CCL). Foram avaliados 80 sujeitos com CCL, com os seguintes instrumentos: questionário de dados demográficos e sociais, questionário de direcionamento da atividade laboral e uma bateria neuropsicológica ampliada: memória (Memória lógica Signoret Bateria, TAVEC), atenção (Digit span, TMTA), linguagem (Vocabulário WAIS III, Teste de denominação de Boston, fluência verbal), funções executivas (TMTB, analogias WAIS III, raciocínio matricial WAIS III) e construção visual (cubos WAIS III). Os resultados mostram que a complexidade laboral tem um peso maior que a educação na cognição, como no vocabulário, na flexibilidade cognitiva e nas habilidades visual-construtivas. A educação tem mais peso no raciocínio abstrato e na atenção sustentada. A complexidade ocupacional e a educação desempenham um papel diferencial e importante na manutenção das habilidades cognitivas, sendo fatores que amenizam o declínio cognitivo no envelhecimento

The objective of this paper is to assess the relative importance of education and occupational complexity to determine the cognitive performance on patients with mild cognitive impairment (MCI). 80 patients with MCI were assessed using the following instruments: questionnaire of sociodemogrhapical data, questionnaire on attainment of occupation, and an extended neuropsychological battery. Abilities tested were: logical memory (Signoret Memory Battery, TAVEC), attention (Digit span, TMTA), language (Vocabulary WAIS III, Boston Naming Test, Verbal Fluency), executive functions (TMTB, Analogies WAIS III, Matrix reasoning WAIS III) and visuoconstruction (Block design WAIS III). Results show that occupational complexity is more relevant than education for cognition of vocabulary, to achieve cognitive flexibility and to obtain visuoconstructive abilities. Education is more important for abstract reasoning and sustained attention. Occupational complexity and education have a unique and important role in the maintenance of cognitive abilities, working as buffers for cognitive impairment during aging.