Cognitive Function In Old Age Research Articles

Correction for: Prediction of cognitive performance in old age from spatial probability maps of white matter lesions.

Correction for: Prediction of cognitive performance in old age from spatial probability maps of white matter lesions.

Transient neural network dynamics in cognitive ageing

It is important to maintain cognitive function in old age, yet the neural substrates that support successful cognitive ageing remain unclear. One factor that might be crucial, but has been overlooked due to limitations of previous data and methods, is the ability of brain networks to flexibly reorganize and coordinate over a millisecond time-scale. Magnetoencephalography (MEG) provides such temporal resolution, and can be combined with Hidden Markov Models (HMMs) to characterise transient neural states. We applied HMMs to resting-state MEG data from a large cohort (N=595) of population-based adults (aged 18-88), who also completed a range of cognitive tasks. Using multivariate analysis of neural and cognitive profiles, we found that decreased occurrence of “lower-order” brain networks, coupled with increased occurrence of “higher-order” networks, was associated with both increasing age and decreased fluid intelligence. These results favour theories of age-related reductions in neural efficiency over current theories of age-related functional compensation, and suggest that this shift might reflect a stable property of the ageing brain.

Bodyweight change and cognitive performance in the older population.

Preservation of cognitive function is one of the major concerns in contemporary ageing societies. At the same time, overweight and obesity, which have been identified as risk factors for poor health development, have been increasing in many countries all over the world. This study examines the relationship between bodyweight change and cognitive decline in old age and it aims to determine whether and how changes in body mass index (BMI) affect the development of cognitive functioning in old age. Using longitudinal data from the Survey of Health, Ageing and Retirement in Europe (SHARE), covering four waves between 2006 and 2016 with 58,389 participants from 15 countries aged 50+, we estimated asymmetric fixed effects models by gender, adding possible confounding variables such as age, grip strength, health conditions, and physical activity. Additionally, we investigated possible heterogeneity in the BMI-cognition relation. We found a positive association between BMI change and change in cognitive performance, which was dominantly driven by BMI decrease. Weight loss was typically negatively related to cognition, particularly at low levels of BMI and mainly due to health conditions affecting both bodyweight and cognitive performance. Weight gain was, on average, not significantly related to cognitive performance; only respondents with preceding weight loss profited from small increases in BMI. Our analyses provide no support for an "obesity paradox" in cognition, according to which higher weight preserves cognition in old age. The association between weight change and cognitive performance in older age is based on weight changes being related to illness and recovery.

On the Origin of Cognition: How Childhood Conditions Shape Cognitive Function in Old Age

This paper examines the long-term impact of early childhood conditions on cognitive function in old age. Using unique data from a longitudinal survey of Chinese elderly, we find that people with adverse childhood conditions measured by the paternal occupation, parental education, nutrition and medical conditions, not only have lower cognitive ability, but also exhibit faster cognitive deterioration at older ages. The results also indicate that female elderly suffer more from the adverse childhood conditions than males. Further mechanism analyses suggest that the educational attainment accounts for 16 to 26 percent of the association between early-life circumstances and cognitive function in old age.

Dietary Total Antioxidant Capacity and Late-Life Cognitive Impairment: The Singapore Chinese Health Study.

With the dramatically rapid rate of aging worldwide, the maintenance of cognitive function in old age is a major public health priority. The association between total antioxidant capacity (TAC) of midlife diet and cognitive function in late life is still unclear. The study included 16 703 participants from a prospective cohort study in Singapore. Dietary intakes and selected supplementary use were assessed with a validated 165-item food frequency questionnaire at baseline (1993-1998). Two dietary TACs were calculated from the intake of antioxidant nutrients: the Comprehensive Dietary Antioxidant Index (CDAI) and the Vitamin C Equivalent Antioxidant Capacity (VCEAC). Cognitive function was assessed 20.2 years later using a Singapore-modified version of the Mini-Mental State Examination when subjects were 61-96 years old. Cognitive impairment was defined using education-specific cutoffs. Multivariable logistic regression models were utilized to estimate the associations between dietary TACs, component nutrients, and cognitive impairment. A total of 2 392 participants (14.3%) were defined to have cognitive impairment. Both CDAI and VCEAC scores were inversely associated with odds of cognitive impairment in a dose-dependent manner. The odds ratio (95% confidence interval; p-trend) comparing the highest with the lowest quartile was 0.84 (0.73, 0.96; p-trend = .003) for the CDAI and 0.75 (0.66, 0.86; p-trend < .001) for the VCEAC. Higher intakes of vitamin C, vitamin E, carotenoids, and flavonoids were all inversely associated with cognitive impairment. Higher dietary TAC was associated with lower odds of cognitive impairment in later life in a Chinese population in Singapore.

Socioeconomic inequalities in physical and cognitive functioning: cross-sectional evidence from 37 cohorts across 28 countries in the ATHLOS project

BackgroundPhysical and cognitive functioning in older age follows a socioeconomic gradient but it is unclear whether the strength of the association differs between populations. Using harmonised data from an international...

Metformin treatment in late middle age improves cognitive function with alleviation of microglial activation and enhancement of autophagy in the hippocampus

Metformin, a drug widely used for treating diabetes, can prolong the lifespan in several species. Metformin also has the promise to slow down age-related cognitive impairment. However, metformin's therapeutic use as an anti-aging drug is yet to be accepted because of conflicting animal and human studies results. We examined the effects of metformin treatment in late middle age on cognitive function in old age. Eighteen-month-old male C57BL6/J mice received metformin or no treatment for 10weeks. A series of behavioral tests revealed improved cognitive function in animals that received metformin. Such findings were evident from a better ability for pattern separation, object location, and recognition memory function. Quantification of microglia revealed that metformin treatment reduced the incidence of pathological microglial clusters with alternative activation of microglia into an M2 phenotype, displaying highly ramified processes in the hippocampus. Metformin treatment also seemed to reduce astrocyte hypertrophy. Additional analysis demonstrated that metformin treatment in late middle age increased adenosine monophosphate-activated protein kinase activation, reduced proinflammatory cytokine levels, and the mammalian target of rapamycin signaling, and enhanced autophagy in the hippocampus. However, metformin treatment did not alter neurogenesis or synapses in the hippocampus, implying that improved cognitive function with metformin did not involve enhanced neurogenesis or neosynaptogenesis. The results provide new evidence that metformin treatment commencing in late middle age has promise for improving cognitive function in old age. Modulation of microglia, proinflammatory cytokines, and autophagy appear to be the mechanisms by which metformin facilitated functional benefits in the aged brain.

Longitudinal Within-Person Associations Between Quality of Social Relations, Structure of Social Relations, and Cognitive Functioning in Older Age.

Individuals' social connections and interpersonal experiences can both shape and be shaped by cognitive functioning. This study examines longitudinal within-person associations between quality of social relations, structure of social relations, and cognitive functioning in older age. We examined 16-year longitudinal data (3 waves) from 497 older adults (M = 66.07 years, SD = 0.83, range = 64-68 years) from the Interdisciplinary Longitudinal Study of Adult Development and Aging. Quality of social relations was measured by scales on perceived emotional support, instrumental support, and social integration. Structure of social relations was measured by self-reported number of leisure time partner types, indicating social network diversity. Cognitive functioning was assessed as a latent construct consisting of five cognitive tests (i.e., Information, Similarities, Letter Fluency, Picture Completion, Block Design). We used a random intercept cross-lagged panel model in the analysis. At the within-person level, prior quality of social relations, but not structure of social relations, was positively associated with subsequent cognitive functioning. Moreover, prior cognitive functioning was positively associated with subsequent structure of social relations, but not with quality of social relations. Quality of social relations is a protective factor of cognitive aging. Additionally, responding to prior lower cognitive functioning, social network diversity reduced, but quality of social relations did not seem to change. Overall, this study suggested that social relations and cognitive functioning mutually influence each other, but different aspects of social relations (i.e., quality, structure) might have different directional associations with cognitive functioning.

Do Cardiovascular Risk Factors and Cardiovascular Disease Explain Sex Differences in Cognitive Functioning in Old Age?

Background:Sex differences in cognitive functioning in old age are known to exist yet are still poorly understood.Objective:This study examines to what extent differences in cardiovascular risk factors and cardiovascular disease between men and women explain sex differences in cognitive functioning.Methods:Data from 2,724 older adults from the Longitudinal Aging Study Amsterdam were used. Information processing speed and episodic memory, measured three times during six years of follow-up, served as outcomes. The mediating role of cardiovascular risk factors and cardiovascular disease was examined in single and multiple mediator models. Determinant-mediator effects were estimated using linear or logistic regression, and determinant-outcome and mediator-outcome effects were estimated using linear mixed models. Indirect effects were estimated using the product-of-coefficients estimator.Results:Women scored 1.58 points higher on information processing speed and 1.53 points higher on episodic memory. Several cardiovascular risk factors had small mediating effects. The sex difference in information processing speed was mediated by smoking, depressive symptoms, obesity, and systolic blood pressure. The sex difference in episodic memory was mediated by smoking, physical activity, and depressive symptoms. Effects of smoking, LDL cholesterol, and diabetes mellitus on information processing speed differed between men and women.Conclusion:Differences in cardiovascular risk factors between women and men partially explained why women had better cognitive functioning. A healthy cardiovascular lifestyle seems beneficial for cognition and sex-specific strategies may be important to preserve cognitive functioning at older age.

Contemporary Approaches to the Study of Cognitive Aging

Cognitive aging research is gaining societal and practical importance because of population aging. Current research is focused on describing age differences and age-related changes in cognitive performance, understanding potential causes underlying these differences and changes, and identifying factors that promote maintenance of cognitive functioning in old age. The goal of this research group is to showcase new developments in research studying age differences in cognitive performance and longitudinal cognitive change in the second half of life. Hülür et al. examine associations between midlife occupational factors and trajectories of cognitive change using data from the German Interdisciplinary Longitudinal Study of Adult Development and Aging (ILSE). Luo et al. use 12-year longitudinal data from 499 older participants in ILSE to study bidirectional associations between social relationships and cognitive performance. Small et al. examine the correspondence between objective and subjective cognitive performance, and measures of fatigue and depressed mood in experience sampling data from breast cancer survivors. Haas et al. compare laboratory and at-home online assessments of cognitive status and prospective memory over the adult lifespan and evaluate the quality of self-administered tests. The discussion by Elizabeth Stine-Morrow will focus on how these approaches contribute to our understanding of processes of cognitive aging and how they can be utilized to promote maintenance of cognitive functioning in old age.

Age-Related Social Selection and Its Associated Emotional and Cognitive Costs Across Adulthood

Socioemotional selectivity theory maintains that goal prioritization differs across adulthood as a function of future time horizons. To prepare for a long and nebulous future, young adults prioritize learning and exploration over emotional meaning. Relieved from the burden to prepare, older adults prioritize emotionally meaningful goals. In the context of social relationships, younger adults include proportionally fewer familiar social partners in their social networks, whereas older adults’ social networks encompass proportionally fewer unfamiliar social partners. Although social selection is considered adaptive, it inevitably involves gains and losses. The current study examined whether age-related selectivity correlates with (1) greater concurrent negative emotions in younger people, and (2) poorer cognitive performance in old age. A life-span sample (N = 258) completed a social networks questionnaire and cognitive tests. Daily emotional experience was assessed using experience sampling. A subset (N = 119) completed the cognitive tests again five years later. Results of multiple regression analysis, controlling for physical health and trait neuroticism, indicate that smaller proportions of familiar social partners in one’s social network correlated with more frequent experience of negative emotions. Age moderated this association with a stronger association in younger than older people. Results of separate multiple regression analysis, controlling for baseline cognition, physical health, age, SES, and trait openness, indicate that a smaller proportion of social partners in one’s outer social circle negatively predicted older adults’ Digit Span Backward performance assessed five years later. We discuss our findings within the framework of gains and losses in life-span development.

Gender differences in the association of childhood socioeconomic status and late‐life cognition among African Americans: Findings from the STAR study

AbstractBackgroundLow socioeconomic status in childhood has been linked with poor cognitive function in old age. But few studies have focused on African Americans or evaluated gender differences. We examined cross‐sectional associations of childhood socioeconomic factors with late‐life cognition and effect modification by gender.MethodsStudy of Healthy Aging in African Americans (STAR) participants were 722 African Americans (69% women; mean age = 68.4 and education: 60% &lt;High school) community‐residing long‐term members of Kaiser Permanente Northern California. Summary scores in 3 cognitive domains (executive function, semantic memory, verbal memory) and a global cognition composite were based on the Spanish and English Neuropsychological Assessment Scales (SENAS). Participants rated frequency of experiencing hunger as a child (sometimes/often vs. rarely/never), their family’s financial status (average/high vs. poor), and parental education (&gt;= high school vs. &lt; high school), as indicators of childhood SES. Linear regression models adjusted for age were used to examine childhood SES and late‐life cognition, and effect modification by gender.ResultsThere were no gender differences in experiencing childhood hunger (p=.08), having poor family finances (p=0.30), or parental education (p=0.17). In the pooled model with women and men, higher frequency of childhood hunger was associated with worse cognition overall (β=‐0.36, 95% CI=‐0.66, ‐0.06) and in all domains (executive: β=‐0.32, 95% CI=‐0.63, ‐0.01; semantic: β=‐0.38, 95% CI=‐0.53, ‐0.23; verbal: β=‐0.42, 95% CI=‐0.73, ‐0.12). Low parental education was only associated with lower global cognition β=‐0.18, 95% CI=‐0.33, ‐0.02 and semantic memory (β=‐0.40, 95% CI=‐0.57, ‐0.23). Childhood family financial status was not associated with late‐life cognition. In gender‐stratified models, women who reported greater frequency of childhood hunger had worse cognition in every domain except semantic memory (overall: β=‐0.53, 95% CI=‐0.94, ‐0.13; executive: β=‐0.61, 95% CI=‐1.01, ‐0.20; semantic: β=‐0.21 95% CI=‐0.64, 0.21; verbal: β=‐0.46, 95% CI=‐0.87, ‐0.06). In contrast, childhood hunger was not associated with cognition in men (overall: β=‐0.14, 95% CI=‐0.59, 0.32; executive: β=0.11, 95% CI=‐0.35, 0.58; semantic: β=‐0.05 95% CI=‐0.57, 0.48; verbal: β=‐0.40, 95% CI=‐0.88, 0.08), but low parental education was associated with semantic memory (β=‐0.43, 95% CI=‐0.73, ‐0.14).ConclusionChildhood hunger is associated with worse cognition in old age, particularly among women.

Longitudinal aortic stiffness is associated with brain microstructure and cognition: A voxel‐wise magnetic resonance imaging study

AbstractBackgroundAortic stiffness, assessed by carotid‐femoral pulse wave velocity (PWV), is closely linked with hypertension, heart disease and stroke. Recent research has suggested that rapid aortic stiffening may also be a risk factor for cognitive decline and dementia. However, the age of onset of this risk and its underlying brain physiology is unknown. We examined whether aortic stiffening over a 5‐year period in mid‐life affects later‐life brain structure and cognition in community‐dwelling adults.MethodData from 544 participants from the Whitehall II Imaging Sub‐study were analysed. Aortic PWV was measured at baseline in 2007‐09 (mean age 63.92±5.23) and at a 5‐year follow‐up visit in 2012‐13 (mean age 67.99±5.25) using applanation tonometry (SphygmoCor, AtCor Medical, Australia). After the latter visit, they also received cognitive tests and a 3T brain MRI scan (2012‐2016, mean age 69.82±5.23). Voxel‐based morphometry and tract‐based spatial statistics were used to extract grey matter (GM) volume, fractional anisotropy (FA), mean diffusivity (MD), and white matter hyperintensity (WMH) volumes. Baseline and follow‐up arterial stiffness were entered as predictors of MRI and cognitive outcomes in two separate general linear models, each adjusting for age, sex, education, mean arterial pressure, body mass index, socio‐economic status, scanner model, and follow‐up time interval.ResultHigher aortic stiffness at baseline was associated with significantly poor performance in semantic fluency (category ‘animals’, B(SE)=‐0.42(0.15), Bonferroni‐corrected p&lt;0.008) and short‐term verbal memory (immediate recall on the Hopkins Verbal Learning Test‐R, B(SE)=‐0.36, (0.12), Bonferroni‐corrected p&lt;0.008) at the time of the scan. Follow‐up aortic stiffness was associated with significantly lower FA and higher MD in widespread brain areas including the corpus callosum, corona radiata, cingulum, and superior longitudinal fasciculus (p&lt;0.05, corrected for voxel‐wise comparisons). No significant associations with GM or WMH were observed.ConclusionElevated aortic stiffness after age 60 is associated with poor WM microstructural integrity and cognitive performance in older age independently of standard vascular risk factors, likely due to increased transmission of pulsatile energy to the delicate cerebral microvasculature. To offer cognitive benefit in older age, strategies to prevent arterial stiffening may be more effective in midlife than in later‐life.

Illiteracy and risk of mild cognitive impairment among Mexican older adults: Data from the Mexican Health and Aging Study (MHAS)

AbstractBackgroundMild cognitive impairment (MCI) is a diagnostic entity associated with increased risk of incident dementia. Prior epidemiological studies have associated illiteracy and low to no formal education with increased prevalence of MCI and dementia. A recent study using a robust neuropsychological approach with the harmonized cognitive assessment ancillary study (Mex‐Cog) of the Mexican Health and Aging Study (MHAS) found that low education as well as older age, depression, diabetes, and rurality were independently associated with MCI among older adults. Rates of illiteracy are relatively high among older adults in Mexico, due to limited access to formal education, but some people attained literacy despite not attending school. To assess the unique contribution of literacy to MCI independent of educational achievement in a Mexican population, we evaluated literate and illiterate older adults with no formal schooling.MethodAnalyses included a sample of literate and illiterate non‐demented adults over the age of 55 living in both urban and rural areas of Mexico who reported that they never attended school (N = 231). MCI diagnosis was assigned based on a comprehensive cognitive assessment for domains of memory, executive functioning, language, and visuospatial ability. Cognitive impairment was defined using a robust norms approach and a 1.5‐SD cut‐off per cognitive domain correcting for age, years of education, and sex. Multinomial logistic regressions evaluated the association of self‐reported literacy, age, and sex with risk of MCI. We then evaluated whether the relationship between literacy and MCI remained after controlling for sociodemographic and health factors.ResultIlliteracy was associated with increased risk of MCI (OR=6.05 [3.33, 11.34]) compared to literate participants. The relationship between literacy and risk of MCI persisted after taking into account depression, rurality, hypertension, and diabetes.ConclusionWe found that illiteracy was independently associated with higher risk of prevalent MCI. Our findings suggest that independent of formal education, attainment of literacy has a long‐lasting impact on brain health at older ages. Future studies in low socioeconomic populations should consider functional literacy as a powerful predictor of cognitive function in old age.

Cognitive reserve, brain reserve, and cognitive performance in old age: A population‐based study

AbstractBackgroundThe reserve theory has been proposed to account for the discrepancies between the load of brain pathologies and cognitive phenotypes in aging. We sought to explore the interplay of cognitive reserve and markers of brain reserve and brain lesions in determining cognitive performance in old age.MethodsThis population‐based cross‐sectional study included 215 people (age ≥65 years; 43.7% women; 28.4% illiterate) who were living in the rural communities of Yanggu County, Shandong Province, China. We used the Mini‐Mental State Examination to assess global cognitive function. We evaluated markers of brain reserve and brain lesions from the structural MRI scans, i.e., total intracranial volumes (ICV), deep white‐matter hyperintensity (DWMH) volumes, and cerebral microbleeds (CMBs). We used the structural equation modeling to generate a composite score of cognitive reserve capacity from multiple cognitive‐enhancing factors over the lifespan. We used the general linear regression model and the marginal effect model to disentangle the relations of cognitive reserve and brain reserve markers with MMSE score.ResultsThe composite cognitive reserve score ranged from 6.80 to 16.55. Overall, a higher cognitive reserve score was associated with multiple‐adjusted β‐coefficient of 0.04 (95% CI 0.03−0.76) for MMSE score. There was a stronger relationship between cognitive reserve score and MMSE score in people with lower ICV (β=1.16; 95% CI 0.99−2.24) than in those with larger ICV (β=0.44; ‐0.01−0.89, p=0.053). Furthermore, the association of cognitive reserve score with MMSE score was statistically significant in people with severe DWMH load (β=0.84; 95% CI 0.22−1.45) and CMBs (β=1.50; 0.60−2.40), but not in those with mild DWMH load or without CMBs. Compared to people with a higher cognitive reserve score, those with lower cognitive reserve capacity showed stronger correlations of MMSE score with ICV (β=2.66; 95% CI 0.08−5.25) and presence of CMBs (β=‐0.24; ‐0.43−‐0.04).ConclusionHigher cognitive reserve is associated with better cognitive performance among rural‐dwelling older adults with limited education, and such association is stronger in people with lower brain reserve. In addition, lower brain reserve is associated with poorer cognitive performance, and such association is stronger among people with lower cognitive reserve capacity.

Participation in activities mediates the effect of Internet use on cognitive functioning in old age.

Research indicates that Internet use positively influences cognitive functioning in later life, but we do not know the behavioral pathways that explain this association. This study explored the role of participation in activities as a potential mediator of the relationship between Internet use and cognitive functioning over a 4-year period. We analyzed representative data from the Survey of Health, Ageing and Retirement in Europe (SHARE). The sample included 8353 European participants between 50 and 97 years of age. We used data from 2013 (T1), 2015 (T2), and 2017 (T3). Participants reported whether they participated in a diverse range of social and leisure activities. In addition, they provided information about their Internet use as well as cognitive functioning measures. Findings from cross-lagged panel analysis indicated a positive association between Internet use and change in cognition over the course of 4 years. This relationship was partly mediated by the number of reported activities. Internet use was positively associated with the change in activities after 2 years, which, in turn, positively predicted cognitive functioning 2 more years later. This is the first study that explores the temporal sequence of Internet use, participation in activities, and cognitive functioning. It sheds light on the mechanisms that account for the positive effects of Internet use on healthy aging.

Immediate effects of a single session of physical exercise on cognition and cerebral blood flow: A randomized controlled study of older adults

BackgroundRegular physical activity is beneficial for cognitive performance in older age. A single bout of aerobic physical exercise can transiently improve cognitive performance. Researchers have advanced improvements in cerebral circulation as a mediator of long-term effects of aerobic physical exercise on cognition, but the immediate effects of exercise on cognition and cerebral perfusion are not well characterized and the effects in older adults are largely unknown. MethodsForty-nine older adults were randomized to a 30-min aerobic exercise at moderate intensity or relaxation. Groups were matched on age and cardiovascular fitness (VO2 max). Average Grey Matter Blood Flow (GMBF), measured by a pulsed arterial-spin labeling (pASL) magnetic resonance imaging (MRI) acquisition, and working memory performance, measured by figurative n-back tasks with increasing loads were assessed before and 7 min after exercising/resting. ResultsAccuracy on the n-back task increased from before to after exercising/resting regardless of the type of activity. GMBF decreased after exercise, relative to the control (resting) group. In the exercise group, higher n-back performance after exercise was associated with lower GMBF in the right hippocampus, left medial frontal cortex and right orbitofrontal cortex, and higher cardiovascular fitness was associated with lower GMBF. ConclusionThe decrease of GMBF reported in younger adults shortly after exercise also occurs in older adults and relates to cardiovascular fitness, potentially supporting the link between cardiovascular fitness and cerebrovascular reactivity in older age.

Physical Activity’s Impact on Quality of Life in Older Adults with Dementia: A Systematic Review

Individuals with dementia frequently report poor quality of life (QOL), which declines as their disease progresses. Some evidence suggests that physical activity may help maintain cognitive function in older age, but it is unclear whether physical activity affects quality of life in older adults with dementia. The purpose of this review paper is to explore whether and how physical activity impacts QOL in patients with diagnosed dementia in different residential settings. To conduct this systematic review, the following search terms were inputted into the search bars of three databases:(dementia OR Alzheimer) AND (walking OR physical activity OR exercise OR fitness) AND (community OR nursing home OR independent living OR green care) AND (Quality of Life). A total of ten articles met the study inclusion criteria. Several studies reported a positive correlation between physical activity intervention programs and QOL outcome measures, pertaining to socialization and positive emotions, and an increase in physical endurance capacity among program participants. However, most results were not statistically significant. We conclude that more large studies need to be conducted in order to establish whether there is a significant positive dose-response relationship between physical activity intervention programs and QOL measures among individuals with diagnosed dementia.

Childhood infectious diseases and old age cognitive functioning: a nationally representative sample of community-dwelling older adults

Cumulative evidence suggests that health-related risk factors during midlife and old-age are associated with cognitive impairment. However, studies are needed to clarify the association between early-life risk factors and impaired cognitive functioning to increment existing knowledge. To examine the association between childhood infectious diseases and late-life cognitive functioning in a nationally representative sample of older adults. Eligible respondents were 2994 community-dwelling individuals aged 65-85. Cognitive functioning was assessed using the Mini-Mental State Examination (MMSE). Childhood infectious diseases (i.e. chicken pox, measles, and mumps) were self-reported. The study covariates were age, sex, highest educational level achieved, smoking status, body mass index, and depression. The primary statistical analysis examined the association between the number of childhood infectious diseases and total MMSE scores, accounting for all study covariates. Regression models of progressive complexity were examined for parsimony. The robustness of the primary results was tested in 17 sensitivity analyses. The most parsimonious model was a linear adjusted model (Bayesian Information Criterion = 12646.09). Late-life cognitive functioning significantly improved as the number of childhood infectious diseases increased (β = 0.18; 95% CI = 0.11, 0.26; p < 0.001). This effect was not significantly attenuated in all sensitivity analyses. The current study results are consistent with prior ecological findings indicating that some childhood infectious diseases are associated with better cognitive functioning in old-age. This points to an early-life modifiable risk factor associated with older-life cognitive functioning. Our results may reflect selective mortality and/or beneficial effects via hormetic processes.

Do cognitively stimulating activities affect the association between retirement timing and cognitive functioning in old age?

AbstractIn response to the rising financial pressure on old-age pension systems in industrialised economies, many European countries plan to increase the eligibility age for retirement pensions. We used data from Sweden to examine whether (and if so, how) retirement after age 65 – the eligibility age for basic pension – compared to retiring earlier affects older adults’ (between ages 70 and 85) cognitive functioning. Using a propensity score matching (PSM) approach, we addressed the selection bias potentially introduced by non-random selection into either early or late retirement. We also examined average and heterogeneous treatment effects (HTEs). HTEs were evaluated for different levels of cognitive stimulation from occupational activities before retirement and from leisure activities after retirement. We drew from a rich longitudinal data-set linking two nationally representative Swedish surveys with a register data-set and found that, on average, individuals who retire after age 65 do not have a higher level of cognitive functioning than those who retire earlier. Similarly, we did not observe HTEs from occupational activities. With respect to leisure activities, we found no systematic effects on cognitive functioning among those working beyond age 65. We conclude that, in general, retirement age does not seem to affect cognitive functioning in old age. Yet, the rising retirement age may put substantial pressure on individuals who suffer from poor health at the end of their occupational career, potentially exacerbating social- and health-related inequalities among older people.