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.

Socioeconomic differences in older adults' unplanned hospital admissions: the role of health status and social network.

BACKGROUND: the socioeconomic distribution of unplanned hospital admissions in older adults is poorly understood. We compared associations of two life-course measures of socioeconomic status (SES) with unplanned hospital admissions while comprehensively accounting for health, and examined the role of social network in this association. METHODS: in 2,862 community-dwelling adults aged 60+ in Sweden, we derived (i) an aggregate life-course SES measure grouping individuals into Low, Middle or High SES based on a summative score, and (ii) a latent class measure that additionally identified a Mixed SES group, characterised by financial difficulties in childhood and old age. The health assessment combined measures of morbidity and functioning. The social network measure included social connections and support components. Negative binomial models estimated the change in hospital admissions over 4 years in relation to SES. Stratification and statistical interaction assessed effect modification by social network. RESULTS: adjusting for health and social network, unplanned hospitalisation rates were higher for the latent Low SES and Mixed SES group (incidence rate ratio [IRR] = 1.38, 95% confidence interval [CI]: 1.12-1.69, P = 0.002; IRR = 2.06, 95% CI: 1.44-2.94, P < 0.001; respectively; ref: High SES). Mixed SES was at a substantially greater risk of unplanned hospital admissions among those with poor (and not rich) social network (IRR: 2.43, 95% CI: 1.44-4.07; ref: High SES), but the statistical interaction test was non-significant (P = 0.493). CONCLUSION: socioeconomic distributions of older adults' unplanned hospitalisations were largely driven by health, although considering SES dynamics across life can reveal at-risk sub-populations. Financially disadvantaged older adults might benefit from interventions aimed at improving their social network.

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.

Life-course trajectories of working conditions and successful ageing.

AIMS: As populations are ageing worldwide, it is important to identify strategies to promote successful ageing. We investigate how working conditions throughout working life are associated with successful ageing in later life. METHODS: Data from two nationally representative longitudinal Swedish surveys were linked (n=674). In 1991, respondents were asked about their first occupation, occupations at ages 25, 30, 35, 40, 45 and 50 years and their last recorded occupation. Occupations were matched with job exposure matrices to measure working conditions at each of these time points. Random effects growth curve models were used to calculate intra-individual trajectories of working conditions. Successful ageing, operationalised using an index including social and leisure activity, cognitive and physical function and the absence of diseases, was measured at follow-up in 2014 (age 70 years and older). Multivariable ordered logistic regressions were used to assess the association between trajectories of working conditions and successful ageing. RESULTS: Intellectually stimulating work; that is, substantive complexity, in the beginning of one's career followed by an accumulation of more intellectually stimulating work throughout working life was associated with higher levels of successful ageing. In contrast, a history of stressful, hazardous or physically demanding work was associated with lower levels of successful ageing. CONCLUSIONS: Promoting a healthy workplace, by supporting intellectually stimulating work and reducing physically demanding and stressful jobs, may contribute to successful ageing after retirement. In particular, it appears that interventions early in one's employment career could have positive, long-term effects.

Metabolic Syndrome Is Associated With Poor Cognition: A Population-Based Study of 70-Year-Old Adults Without Dementia.

BACKGROUND: Individual conditions of metabolic syndrome (MetS) have been related to dementia; however, their combined impact on the preclinical stage is unknown. We investigated the associations between MetS and domain-specific cognitive function as well as the role of sociodemographic, cardiovascular, and genetic factors. METHODS: Within the Gothenburg H70 Birth Cohort Study-Birth cohort 1944, 1131 dementia-free participants (aged 70 years) were examined during 2014-2016. MetS (central obesity plus at least 2 factors [reduced HDL-cholesterol, elevated triglycerides, blood pressure, or blood glucose]) was identified according to the International Diabetes Federation criteria. Five cognitive domains (memory, attention/perceptual speed, executive function, verbal fluency, visuospatial abilities) were generated after z-standardizing raw scores from 10 neuropsychological tests. Education, heart disease, claudication (indicating peripheral atherosclerosis), and apolipoprotein genotype were ascertained by trained staff. Data were analyzed with linear regression models. RESULTS: Overall, 618 participants (55%) had MetS. In multiadjusted linear regressions, MetS was related to poorer performance in attention/perceptual speed (ß -0.14 [95% CI -0.25, -0.02]), executive function (ß -0.12 [95% CI -0.23, -0.01]), and verbal fluency (ß -0.19 [95% CI -0.30, -0.08]). These associations were present only among individuals who did not carry any APOE-ε4 allele or were highly educated. However, among those with MetS, high education was related to better cognitive performance. MetS together with comorbid heart disease or claudication was associated with even worse cognitive performance than each alone. CONCLUSIONS: MetS is associated with poor attention/perceptual speed, executive function, and verbal fluency performance. Education, apolipoprotein E-ε4 allele, and comorbid cardiovascular disease influenced the observed associations.

Sleep disturbances and the speed of multimorbidity development in old age: results from a longitudinal population-based study.

BACKGROUND: Sleep disturbances are prevalent among older adults and are associated with various individual diseases. The aim of this study was to investigate whether sleep disturbances are associated with the speed of multimorbidity development among older adults. METHODS: Data were gathered from the Swedish National study of Aging and Care in Kungsholmen (SNAC-K), an ongoing population-based study of subjects aged 60+ (N = 3363). The study included a subsample (n = 1189) without multimorbidity at baseline (< 2 chronic diseases). Baseline sleep disturbances were derived from the Comprehensive Psychiatric Rating Scale and categorized as none, mild, and moderate-severe. The number of chronic conditions throughout the 9-year follow-up was obtained from clinical examinations. Linear mixed models were used to study the association between sleep disturbances and the speed of chronic disease accumulation, adjusting for sex, age, education, physical activity, smoking, alcohol consumption, depression, pain, and psychotropic drug use. We repeated the analyses including only cardiovascular, neuropsychiatric, or musculoskeletal diseases as the outcome. RESULTS: Moderate-severe sleep disturbances were associated with a higher speed of chronic disease accumulation (ß/year = 0.142, p = 0.008), regardless of potential confounders. Significant positive associations were also found between moderate-severe sleep disturbances and neuropsychiatric (ß/year = 0.041, p = 0.016) and musculoskeletal (ß/year = 0.038, p = 0.025) disease accumulation, but not with cardiovascular diseases. Results remained stable when participants with baseline dementia, cognitive impairment, or depression were excluded. CONCLUSION: The finding that sleep disturbances are associated with faster chronic disease accumulation points towards the importance of early detection and treatment of sleep disturbances as a possible strategy to reduce chronic multimorbidity among older adults.

Working conditions mediate the association between social class and physical function in older age in Sweden: a prospective cohort study.

BACKGROUND: Global demographics are changing as societies all over the world are aging. This puts focus on maintaining functional ability and independence into older age. Individuals from lower social classes are at greater risk of developing limitations in physical function later in life. In this study, we investigated the mediating role of working conditions in the association between occupation-based social class and physical function measured as self-reported mobility limitations and objectively measured physical impairment in older age. METHODS: Two Swedish surveys, linked at the individual level, were used (n = 676-814 depending on the outcome). Follow-up time was 20-24 years. Multiple logistic regression analyses were performed with adjustments for age, sex, level of education, mobility, and health problems at baseline. This was followed by analyses of the size of the mediating effect of working conditions. RESULTS: Working conditions seem to mediate 35-74% of the association between social class and physical impairment in older age. The pattern of mediation was primarily driven by passive jobs, i.e., low psychological demands and low control, among blue-collar workers. Working conditions did not mediate the association between social class and self-reported mobility limitations in older age. CONCLUSIONS: The results of this study indicate that working conditions are important in combating the social gradient in healthy aging, contributing to the evidence regarding the magnitude of impact exerted by both the physical and psychosocial work environment separately and in conjunction.

Can active life mitigate the impact of diabetes on dementia and brain aging?

INTRODUCTION: We investigated whether lifelong exposure to stimulating activities (active life, AL) mitigates diabetes-associated dementia risk and brain aging. METHODS: In the Swedish National Study on Aging and Care-Kungsholmen, 2286 dementia-free older adults (407 with MRI volumetric measures) were followed over 12 years to detect incident dementia. AL index (low, moderate, high) combined education, work complexity, leisure activities, and social network. RESULTS: Participants with diabetes and low AL had higher dementia risk (hazard ratio [HR] = 2.36, 95% confidence interval [CI] 1.45-3.87) than patients who were diabetes-free with moderate-to-high AL (reference). Dementia risk in participants with diabetes and moderate-to-high AL did not differ from the reference. People with diabetes and low AL had the smallest brain volume, but those with diabetes and moderate-to-high AL exhibited total brain and gray-matter volumes that were similar to those of diabetes-free participants. AL did not modify the diabetes microvascular lesions association. DISCUSSION: AL could mitigate the deleterious impact of diabetes on dementia, potentially by limiting the loss of brain tissue volume.

Social engagement in late life may attenuate the burden of depressive symptoms due to financial strain in childhood.

BACKGROUND: It remains poorly understood if childhood financial strain is associated with old-age depression and if active social life may mitigate this relationship. AIMS: To investigate the association between childhood financial strain and depressive symptoms during aging; to examine whether late-life social engagement modifies this association. METHOD: 2884 dementia-free individuals (aged 60+) from the Swedish National study of Aging and Care-Kungsholmen were clinically examined over a 15-year follow-up. Presence of childhood financial strain was ascertained at baseline. Depressive symptoms were repeatedly assessed with the Montgomery-Åsberg Depression Rating Scale. Social engagement comprised information on baseline social network and leisure activities. Linear, logistic and mixed-effect models estimated baseline and longitudinal associations accounting for sociodemographic, clinical, and lifestyle factors. RESULTS: Childhood financial strain was independently associated with a higher baseline level of depressive symptoms (ß = 0.37, 95%CI 0.10-0.65), but not with symptom change over time. Relative to those without financial strain and with active social engagement, depressive burden was increased in those without financial strain but with inactive social engagement (ß = 0.43, 95%CI: 0.15-0.71), and in those with both financial strain and inactive engagement (ß = 0.99, 95%CI: 0.59-1.40). Individuals with financial strain and active social engagement exhibited similar depressive burden as those without financial strain and with active social engagement. LIMITATIONS: Recall bias and reverse causality may affect study results, although sensitivity analyses suggest their limited effect. CONCLUSIONS: Early-life financial strain may be of lasting importance for old-age depressive symptoms. Active social engagement in late-life may mitigate this association.

Psychosocial working conditions across working life may predict late-life physical function: a follow-up cohort study.

BACKGROUND: Increasing life expectancy has made understanding the mechanisms underlying late-life health and function more important. We set out to investigate whether trajectories of change in psychosocial working conditions are associated with late-life physical function. METHODS: Two Swedish surveys, linked at the individual level, were used (n = 803). A psychosocial job exposure matrix was used to measure psychosocial working conditions during people's first occupation, as well as their occupation every five years thereafter until baseline in 1991. Physical function was measured in 2014. Random effects growth curve models were used to calculate intraindividual trajectories of working conditions. Predictors of physical function were assessed with ordered logistic regression. RESULTS: A more active job at baseline was associated with increased odds of late-life physical function (OR 1.15, CI 1.01-1.32). Higher baseline job strain was associated with decreased odds of late-life physical function (OR 0.75, CI 0.59-0.96). A high initial level followed by an upward trajectory of job strain throughout working life was associated with decreased odds of late-life physical function (OR 0.32, CI 0.17-0.58). CONCLUSIONS: Promoting a healthier workplace by reducing chronic stress and inducing intellectual stimulation, control, and personal growth may contribute to better late-life physical function.

Genetic risk of dementia mitigated by cognitive reserve: A cohort study.

OBJECTIVE: We investigated whether cognitive reserve modifies the risk of dementia attributable to apolipoprotein ε4 (APOE-ε4), a well-known genetic risk factor for dementia. METHODS: We followed 2,556 cognitively intact participants aged ≥60 years from the ongoing prospective community-based Swedish National Study on Aging and Care in Kungsholmen (SNAC-K). Dementia was ascertained through clinical and neuropsychological assessments and diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. Structural equation modeling was used to generate a cognitive reserve indicator from 4 previously validated contributors: early life education, midlife substantive work complexity, late life leisure activities, and late life social networks. Cox proportional hazard models estimated dementia risk in relation to cognitive reserve indicator. The interaction between the cognitive reserve indicator and APOE-ε4 was assessed on multiplicative and additive scales. RESULTS: After an average of 6.3 years (range = 2.1-10.7) of follow-up, 232 dementia cases were ascertained. Relative to individuals in the lowest tertile of cognitive reserve indicator, those with moderate and high reserve were at a reduced risk of dementia. There was no multiplicative interaction between APOE-ε4 status and cognitive reserve indicator (p = 0.113). Additive interaction was statistically significant. Relative to APOE-ε4 carriers with low cognitive reserve, ε4 carriers with high reserve had a reduced risk of dementia (hazard ratio [HR] = 0.28, 95% confidence interval [CI] = 0.13-0.59). The magnitude of risk reduction was similar in ε4 noncarriers with a high cognitive reserve indicator (HR = 0.24, 95% CI = 0.15-0.40). INTERPRETATION: Lifelong engagement in reserve-enhancing activities attenuates the risk of dementia attributable to APOE-ε4. Promoting cognitive reserve might be especially effective in subpopulations with high genetic risk of dementia. ANN NEUROL 2019.

Linking financial hardship throughout the life-course with psychological distress in old age: Sensitive period, accumulation of risks, and chain of risks hypotheses.

The primary objective was to investigate the life course hypotheses - sensitive period, chain of risks, and accumulation of risks - in relation to financial hardship and psychological distress in old age. We used two Swedish longitudinal surveys based on nationally representative samples. The first survey includes people 18-75 years old with multiple waves, the second survey is a longitudinal continuation, including people 76 + years old. The analytical sample included 2990 people at baseline. Financial hardship was assessed in childhood (retrospectively), at the mean ages of 54, 61, 70, and 81 years. Psychological distress (self-reported anxiety and depressive symptoms) was assessed at the same ages. Path analysis with WLSMV estimation was used. There was a direct path from financial hardship in childhood to psychological distress at age 70 (0.26, p = 0.002). Financial hardship in childhood was associated with increased risk of psychological distress and financial hardship both at baseline (age 54), and later. Financial hardship, beyond childhood, was not independently associated with psychological distress at age 81. Higher levels of education and employment decreased the negative effects of financial hardship in childhood on the risk of psychological distress and financial hardship later on. There was a bi-directional relationship between psychological distress and financial hardship; support for health selection was slightly higher than for social causation. We found that psychological distress in old age was affected by financial hardship in childhood through a chain of risks that included psychological distress earlier in life. In addition, financial hardship in childhood seemed to directly affect psychological distress in old age, independent of other measured circumstances (i.e., chains of risks). Education and employment could decrease the effect of an adverse financial situation in childhood on later-life psychological distress. We did not find support for accumulation of risks when including tests of all hypotheses in the same model.

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.

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.

Associations between work-related stress in late midlife, educational attainment, and serious health problems in old age: a longitudinal study with over 20 years of follow-up.

BACKGROUND: People spend a considerable amount of time at work over the course of their lives, which makes the workplace important to health and aging. However, little is known about the potential long-term effects of work-related stress on late-life health. This study aims to examine work-related stress in late midlife and educational attainment in relation to serious health problems in old age. METHODS: Data from nationally representative Swedish surveys were used in the analyses (n = 1,502). Follow-up time was 20-24 years. Logistic regressions were used to examine work-related stress (self-reported job demands, job control, and job strain) in relation to serious health problems measured as none, serious problems in one health domain, and serious problems in two or three health domains (complex health problems). RESULTS: While not all results were statistically significant, high job demands were associated with higher odds of serious health problems among women but lower odds of serious health problems among men. Job control was negatively associated with serious health problems. The strongest association in this study was between high job strain and complex health problems. After adjustment for educational attainment some of the associations became statistically nonsignificant. However, high job demands, remained related to lower odds of serious problems in one health domain among men, and low job control remained associated with higher odds of complex health problems among men. High job demands were associated with lower odds of complex health problems among men with low education, but not among men with high education, or among women regardless of level of education. CONCLUSIONS: The results underscore the importance of work-related stress for long-term health. Modification to work environment to reduce work stress (e.g., providing opportunities for self-direction/monitoring levels of psychological job demands) may serve as a springboard for the development of preventive strategies to improve public health both before and after retirement.