The Danish Aging and Cognition (DanACo) cohort

BACKGROUND

With aging populations worldwide, identification of predictors of age-related cognitive decline is becoming increasingly important. The Danish Aging and Cognition Cohort (DanACo) including more than 5000 Danish men was established to investigate predictors of age-related cognitive decline from young adulthood to late mid-life.

CONSTRUCTION AND CONTENT

The DanACo cohort was established through two separate data collections with identical designs involving a follow-up examination in late mid-life of men for whom intelligence test scores were available from their mandatory conscription board examination. The cohort consists of 5,183 men born from 1949 through 1961, with a mean age of 20.4 years at baseline and a mean age of 64.4 years at follow-up. The baseline measures consisted of height, weight, intelligence test score and educational level collected at the conscription board examination. The follow-up assessment consisted of a re-administration of the same intelligence test and a comprehensive questionnaire covering socio-demographic factors, lifestyle, and health-related factors. The data were collected in test sessions with up to 24 participants per session. Using the unique personal identification number assigned to all Danes, the cohort has been linked to data from national administrative and health registers for prospectively collected data on socioeconomic and health-related factors.

UTILITY AND DISCUSSION

The DanACo cohort has some major strengths compared to existing cognitive aging cohorts such as a large sample size (n = 5,183 men), a validated global measure of cognitive ability, a long retest interval (mean 44.0 years) and the availability of prospectively collected data from registries as well as comprehensive questionnaire data. The main weakness is the low participation rate (14.3%) and that the cohort consists of men only.

CONCLUSION

Cognitive decline is a result of a summary of factors across the life-course. The DanACo cohort is characterized by a long retest interval and contains data on a wealth of factors across adult life which is essential to establish evidence on predictors of cognitive decline. Moreover, the size of the cohort ensures sufficient statistical power to identify even relatively weak predictors of cognitive decline.

Inflammatory markers and lung function in relation to indoor and ambient air pollution

Ambient air pollution causes a range of adverse health effects, whereas effects of indoor sources of air pollution are not well described in high-income countries. We compared hazards of ambient air pollution and indoor sources with respect to important biomarkers of cardiorespiratory effects in terms of lung function and systemic inflammation in a middle-aged Danish cohort. Our cohort comprised 5199 men and women aged 49-63 years at the recruitment during April 2009 to March 2011, with information on exposure to second-hand smoke (SHS) and use of candles, wood stove, kerosene heater and gas cooker as well as relevant covariates. Ambient air pollution exposure was assessed as 2-year mean nitrogen dioxide (NO₂) at the address (mean ± SD: 17.1 ± 9.9 μg/m³) and 4-day average levels of particulate matter with diameter <2.5 μm (PM_2.5; mean ± SD: 12.5 ± 6.0 μg/m³) in urban background. Lung function was assessed as % predicted forced expiratory volume in the first second (FEV1) and inflammatory markers comprised interleukin-6 (IL-6), IL-10, IL-18, interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and high sensitivity C-reactive protein (hs-CRP). We used random-effect regression models controlling for potential confounders as well as models with further adjustment for self-reported health or for all other exposures. In models adjusted for confounders FEV1 was inversely associated with exposure to NO₂, (-0,83% per 10 μg/m³; 95% CI: -1.26; -0.41%), SHS (-0.56% per 1 of 5 categories increment; 95% CI: -0.89; -0.23%), and gas cooker without hood (-0.89%; 95% CI: -1.62; -0.17%), whereas use of wood stove and candles showed positive associations, although these attenuated by mutual adjustment for all exposures or self-reported health. IL-6 showed positive associations with NO₂ (6.30% increase in log-transformed values per 10 μg/m³; 95% CI: 3.54; 9.05%), PM_2.5 (7.82% per 10 μg/m³; 95% CI: 3.35; 12.4%), SHS (4.38% per increase of 1 of 5 categories; 95% CI: 2.22; 6.54%) and use of kerosene (13.8%; 95% CI: 2.51; 25.1%), whereas the associations with use of wood stove and candles were inverse. PM_2.5 and NO₂ showed positive associations with IFN-γ and TNF-α, while PM_2.5 further associated with IL-10 and IL-18. Hs-CRP was inversely associated with use of candles. These results suggest that the levels of exposure to ambient air pollution and SHS are more harmful than are the levels of exposure to indoor combustion sources from candles and wood stoves in a high-income setting.

Longitudinal associations of self-reported satisfaction with life and vitality with risk of mortality

OBJECTIVE

The aims of the current study were to investigate the associations between two aspects of well-being - satisfaction with life and vitality - and all-cause mortality, and examine the impact of potential confounding factors on the associations.

METHODS

Baseline satisfaction with life was assessed using the Satisfaction With Life Scale (n = 7058) and vitality was assessed using the Short-Form 36 vitality subscale (n = 6987). The study sample consisted of midlife participants from the Copenhagen Aging and Midlife Biobank (CAMB) study conducted from 2009 to 2011. Deaths (n = 312) in the study sample in the follow-up period (mean of 8.6 years) were assessed using Danish register data. The hazard ratios of all-cause mortality according to satisfaction with life and vitality scores adjusted for potential covariates were examined with proportional hazard regression.

RESULTS

A one standard deviation increase on the SWLS and the SF-36 vitality scale was associated with a 39% (HR = 0.61, 95% CI = 0.55-0.67) and 40% (HR = 0.60, 95% CI = 0.54-0.66) decreased risk of mortality respectively, after adjustment for baseline sociodemographic factors. The associations remained significant after separate adjustment for lifestyle (SWLS: HR = 0.67, SF-36 vitality: HR = 0.67), health (SWLS: HR = 0.65, SF-36 vitality: HR = 0.64), depressive symptoms (SWLS: HR = 0.72, SF-36 vitality: HR = 0.71) and social factors (SWLS: HR = 0.76, SF-36 vitality: HR = 0.69).

CONCLUSIONS

Satisfaction with life and vitality are of predictive value for mortality, independently of sociodemographics, lifestyle, health, depressive symptoms, and social factors.

Satisfaction with life and SF-36 vitality predict risk of ischemic heart disease: a prospective cohort study

The main objective of the current study was to investigate associations between two aspects of well-being - satisfaction with life and vitality - and incidence of and mortality from ischemic heart disease. Study design. The Copenhagen Aging and Midlife Biobank (CAMB) was conducted from 2009 to 2011 and was used as baseline data with 6750 individuals having complete information on The Satisfaction with Life Scale (SWLS) and 6652 individuals with complete information on the Short Form Health Survey (SF-36) vitality scale. Incidence of and mortality from ischemic heart disease were assessed using Danish register data and a total of 349 CAMB individuals were registered with either a diagnosis (n = 337) or had died (n = 12) from ischemic heart disease before the end of follow-up (31 December 2017). The hazard ratios of ischemic heart disease according to satisfaction with life and vitality scores were investigated using Cox proportional hazard regression adjusted for potential covariates. Results. A one standard deviation increase on the SWLS was associated with an 18% reduced risk of ischemic heart disease while a one standard deviation increase on the SF-36 vitality scale was associated with a 24% reduced risk of ischemic heart disease after adjustment for baseline socio-demographic factors. These associations remained when separately adjusting for lifestyle, objective health, and social factors, but became non-significant when adjusting for self-reported health. Conclusion. Our study indicates that both psychological and health-related components of wellbeing are important in relation to ischemic heart disease.

Labour market affiliation among non-bullied colleagues at work units with reported bullying

AIM

This study investigates if non-bullied employees in Work units (WUs) where bullying occur, are more prone to leave the WUs than employees in WUs with no bullying, and if the prevalence of workplace bullying had an impact on leaving the WUs. Leaving the workplace was defined by unemployment or change of workplace at follow-up.

METHODS

We had data from 8326 Danish public health invited employees from 302 WUs. Of these 3036 responded to a questionnaire on working conditions and health in 2007. WUs were classified into three categories of WUs: (1) no bullying (0% bullied), (2) moderate prevalence of bullying (< 10% bullied), and (3) high prevalence of bullying (≥ 10% bullied). Bullied respondents were used to classify the WUs and excluded in the analyses.

RESULTS

We found odds ratios (ORs) for unemployment 1 year later of 1.27 [95% CI 0.69-2.37] in WUs with moderate prevalence of bullying and 1.38 [95% CI 0.85-2.23] among employed in WUs with high prevalence of bullying, adjusted for size of WUs, age, sex, and job category. For turnover 1 year later the ORs were 1.27 [95% CI 0.78-2.15] and 1.46 [95% CI 0.99-2.15] in WUs with moderate and high prevalence of bullying, respectively.

CONCLUSION

We did not find that non-bullied employees leave the WUs with moderate and high prevalence of bullying more than employees in WUs with no bullying behaviour 1 year later. Leaving the workplace tended to be higher among employees in WUs with high prevalence of bullying compared to no and moderate bullying.

Who will go the extra mile? Selecting organizational citizens with a personality-based structured job interview

Employees' organizational citizenship behaviors (OCB) are important drivers of organizational effectiveness. Yet, there exist no established tools for selecting employees with a propensity to engage in OCB. Given that personality traits describe typical behavioral tendencies and are established OCB predictors, we propose that personality assessment is a useful approach for selecting employees who are likely to exhibit OCB. To test this proposition, we developed a structured job interview measuring the Big Five traits and then compared this interview to a personality self-report measure to determine which method of personality assessment works best for selecting organizational citizens. Employees (N = 223) from various occupations participated in the structured job interview and completed the personality self-report in a simulated selection setting. We then obtained supervisor ratings of employees' OCB. Results supported the assumption that structured job interviews can be specifically designed to assess the Big Five personality traits and, most importantly, to predict OCB. Interview ratings of specific personality traits differentially predicted different types of OCB (i.e., OCB-compliance, OCB-helping, and OCB-initiative) and explained incremental variance in OCB over and above personality self-reports and verbal cognitive ability. Taken together, these findings expand our knowledge about dispositional predictors of OCBs, personality assessment in selection, and the design of job interviews.

Cognitive Ability in Midlife and Labor Market Participation Among Older Workers: Prospective Cohort Study With Register Follow-up

Background

The study aimed to determine the association of individual cognitive ability in late midlife with labor market participation among older workers.

Methods

This prospective cohort study estimates the risk of long-term sickness absence, disability pension, early retirement, and unemployment from scores on the Intelligenz-Struktur-Test 2000R by combining data from 5076 workers from the Copenhagen Aging and Midlife Biobank with a register on social transfer payments. Analyses were stepwise adjusted for age, gender, physical and psychosocial work environment, health behaviors, occupational social class, education, and chronic diseases.

Results

In the fully adjusted model, low cognitive ability (≥1 standard deviation below the mean for each gender) and high cognitive ability (≥1 standard deviation above the mean for each gender) were not associated with risk of any of the four labor market outcomes.

Conclusion

Individual cognitive ability in late midlife was not associated with risk of long-term sickness absence, disability pension, early retirement, and unemployment in the fully adjusted model. Thus, no direct effect of individual cognitive ability in late midlife was observed on the risk of permanently or temporarily leaving the labor market.

Early life predictors of intelligence in young adulthood and middle age

BACKGROUND

Studies on early predictors of intelligence often focus on single or few predictors and often on childhood intelligence. This study compared the contributions of a broad selection of potential early predictors of intelligence at different adult ages.

METHODS

Information on predictors was recorded prospectively in the Copenhagen Perinatal Cohort during pregnancy, at delivery, and at 1- and 3-year examinations for children born between 1959-61. Adult intelligence was assessed at three independent follow-ups using three different tests of intelligence: Børge Priens Prøve, Wechsler Adult Intelligence Scale, and Intelligenz-Struktur-Test 2000R. From a total of 4697 cohort members, three non-overlapping samples were derived.

RESULTS

The included predictors explained between 22.2-24.3% of the variance in adult IQ, with parental socioeconomic status and sex explaining 16.2-17.0%. Other consistent predictors were head circumference at birth, increase in head circumference head during the first three years, and 3-year milestones. Head circumference was the most important anthropometric measure compared to measures of weight and length.

CONCLUSION

Besides social status and sex, the strongest and most consistent early predictors of adult intelligence were physical or behavioural characteristics that to some extent reflect brain-and cognitive development.

Midlife Forgetfulness and Risk of Dementia in Old Age: Results from the Danish Working Environment Cohort Study

BACKGROUND

Despite the current evidence of a high prevalence of forgetfulness in middle-aged individuals, and the evidence of a link between midlife memory complaints and biological changes in the brain, no previous study has yet investigated midlife forgetfulness in relation to risk of dementia in old age.

AIMS

We investigated whether midlife forgetfulness was an indicator of an increased risk of dementia in old age.

METHODS

We used data from 3,136 employed men and women who participated in the Danish Work Environment Cohort Study in 1990. These data were linked to Danish national registers. Participants were asked whether their closest relative had ever told them that they were forgetful. Incidence rate ratios (IRR) were estimated using Poisson regression analysis.

RESULTS

At baseline, 749 (24%) study participants were categorized as forgetful, and 86 (2.7%) participants were diagnosed with dementia during a total of 31,724 person-years at risk. After adjusting for sociodemographic factors, comorbidities, and work-related factors, midlife forgetfulness was associated with a higher risk of dementia (IRR = 1.82; 95% CI: 1.12-2.97).

CONCLUSIONS

This study is the first to investigate midlife forgetfulness and dementia, and the results suggest that midlife forgetfulness is an early indicator of an increased risk of dementia in old age.

Social Relations at Work and Incident Dementia: 29-Years' Follow-Up of the Copenhagen Male Study

Objective:

We investigated whether social relations at work were associated with incident dementia in old age.

Methods:

One thousand five hundred seventy-two occupationally active men from the Copenhagen Male Study Cohort were followed from 1986 to 2014. Participants underwent a clinical examination at baseline and answered questionnaires on whether they (1) had possibilities to be in contact with coworkers, (2) could get along with coworkers, and (3) were satisfied with supervisor. Poisson regression was used to estimate incidence rate ratios (IRR).

Results:

Two hundred forty five (15.6%) men were diagnosed with dementia during an average of 15.8 years of follow-up. After adjusting for potential confounders, limited contact with coworkers was associated with a higher risk of dementia (IRR = 2.49, 95% confidence interval [CI] 1.14 to 5.44), but the other two measures were not.

Conclusions:

Our data partially support that social relations at work are associated with incident dementia.

Brain Responses to Passive Sensory Stimulation Correlate With Intelligence

This study investigates the association between intelligence and brain power responses to a passive audiovisual stimulation. We measure the power of gamma-range steady-state responses (SSRs) as well as intelligence and other aspects of neurocognitive function in 40 healthy males born in 1953. The participants are a part of a Danish birth cohort study and the data therefore include additional information measured earlier in life. Our main power measure is the difference in power between a visual stimulation and a combined audiovisual stimulation. We hypothesize and establish empirically that the power measure is associated with intelligence. In particular, we find a highly significant correlation between the power measure and present intelligence scores. The association is robust to controlling for size-at-birth measures, length of education, speed of processing as well as a range of other potentially confounding factors. Interestingly, we find that intelligence scores measured earlier in life (childhood, youth, late midlife), are also correlated with the present-day power measure, suggesting a deep connection between intelligence and the power measure. Finally, we find that the power measure has a high sensitivity for detection of an intelligence score below the average.

Economic hardship over twenty-two consecutive years of adult life and markers of early ageing: physical capability, cognitive function and inflammation

This study assesses the associations between annual measures of economic hardship (EH) across 22 years of adulthood and objective measures of early ageing in a Danish late-middle-aged population (N = 5575). EH (years < 60% of the National median equivalized household disposable income) was experienced by 18% during 1987-2008. Four or more years in EH (reference = null years in EH) was related to poorer physical capability (chair rise: - 1.49 counts/30 s [95% confidence interval (CI) - 2.36, - 0.61], hand grip strength: - 1.22 kg [95% CI - 2.38, - 0.07], jump height: - 1.67 cm [95% CI - 2.44, - 0.91] and balance: 18% [95% CI 9, 28]), poorer cognitive function (Intelligenz-Struktur-Test: - 1.50 points [95% CI - 2.89, - 0.12]) and higher inflammatory levels (C-reactive protein: 22% [95% CI 4, 44], and Interleukin-6: 23% [95% CI 10, 39]). Comparing four EH trajectories, people with a high versus low probability of EH over time had poorer physical capability (chair rise: - 1.70 counts/30 s [95% CI - 3.38, - 0.01], grip: - 4.33 kg [95% CI - 6.50, - 2.16], jump: - 1.68 cm [95% CI - 3.12, - 0.25] and balance: 31% [95% CI 12, 52]). No associations were observed with tumour necrosis factor-α. Results were adjusted for sex, age, long-term parental unemployment/financial problems, education, baseline income and cohort. This study suggested EH for four or more years to be associated with poorer physical capability, cognitive function and increased inflammatory levels in midlife. High probability of EH across adulthood was similarly related to poorer physical capability and CRP, but not cognitive function and the remaining inflammatory markers. In conclusion, preventive initiatives focusing on reducing the burden of sustained economic hardship may lead to increased healthy ageing.

Prolonged or serious conflicts at work and incident dementia: a 23-year follow-up of the Copenhagen City Heart Study

PURPOSE

Only a few studies have investigated the impact of negative aspects of social relations on cognitive function, and they have shown mixed results. Conflicts at work are part of the negative aspects of social relations, but the impact of experiencing conflicts at work has not yet been investigated as a risk factor for dementia. Therefore, we investigated whether experiencing prolonged or serious conflicts with a supervisor or colleagues at work was associated with incident dementia in old age.

METHODS

We analyzed data of 6,436 men and women from the third survey of the Copenhagen City Heart Study. At baseline in 1991-1994, the participants reported whether they had ever had a prolonged or serious conflict at work. The participants were followed until 2014. We used Poisson regression to estimate incidence rate ratios (IRR) and their 95% confidence intervals (CI).

RESULTS

After adjusting for potential confounders, the IRR for dementia was 1.53 (95% CI 0.77-3.03) among participants who had reported having prolonged or serious conflicts both with a supervisor and colleagues compared with participants who had never had such conflicts. In separate analyses stratified by sex, the IRRs were 2.14 (95% Cl 0.97-4.71) for men and 0.98 (95% Cl 0.29-3.32) for women.

CONCLUSIONS

Our findings did not support an overall association between experiencing prolonged or serious conflicts at work and incident dementia. However, because of the large differences in the point estimates for men and women, future research could aim at investigating potential sex differences regarding the association between conflicts at work and dementia.

Attained SES as a moderator of adult cognitive performance: Testing gene-environment interaction in various cognitive domains

We examined whether attained socioeconomic status (SES) moderated genetic and environmental sources of individual differences in cognitive performance using pooled data from 9 adult twin studies. Prior work concerning SES moderation of cognitive performance has focused on rearing SES. The current adult sample of 12,196 individuals (aged 27-98 years) allowed for the examination of common sources of individual differences between attained SES and cognitive performance (signaling potential gene-environment correlation mechanisms, rGE), as well as sources of individual differences unique to cognitive performance (signaling potential gene-environment interaction mechanisms, G × E). Attained SES moderated sources of individual differences in 4 cognitive domains, assessed via performance on 5 cognitive tests ranging 2,149 to 8,722 participants. Attained SES moderated common sources of influences for 3 domains and influences unique to cognition in all 4 domains. The net effect was that genetic influences on the common pathway tended to be relatively more important at the upper end of attained SES indicating possible active rGE, whereas, genetic influences for the unique pathway were proportionally stable or less important at the upper end of attained SES. As a noted exception, at the upper end of attained SES, genetic influences unique to perceptual speed were amplified and genetic influences on the common pathway were dampened. Accounting for rearing SES did not alter attained SES moderation effects on cognitive performance, suggesting mechanisms germane to adulthood. Our findings suggest the importance of gene-environment mechanisms through which attained SES moderates sources of individual differences in cognitive performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Language development and intelligence in midlife

Individual differences in early language skills have been found to be associated with other cognitive outcomes in childhood and adolescence. However, research is limited on whether these associations persist into adulthood. In this study, we examined potential associations of the timing of early language milestones with cognitive ability in a prospective cohort study of 938 singletons from the Copenhagen Perinatal Cohort (CPC), who participated in a 50-year follow-up examination in 2009-2011. Later attainment of a number of milestones was associated with lower midlife IQ with the strongest associations found for 'Naming objects/animals in pictures', 'Forming a sentence', and 'Sharing experiences'. Milestones related to language explained 6.7% of the variance in midlife IQ, while milestones related to social interaction explained 3.1%. The study provides evidence that individual differences in language development during the first years of life are associated with intelligence in midlife. Statement of contribution What is already known on this subject? Differences in early language skills are associated with other cognitive skills in childhood and adolescence. No study has examined this association from childhood through midlife in a large community-based sample. What does this study add? Early language development is associated with intelligence in midlife. A total of 6.7% of the variance in midlife IQ is explained by milestones related to language. Adjustment for potentially confounding factors did not change the associations.

Hyposalivation and Poor Dental Health Status Are Potential Correlates of Age-Related Cognitive Decline in Late Midlife in Danish Men

Introduction: Peripheral correlates of age-associated cognitive decline are important tools in the screening for potentially abnormal courses of cognitive aging. Since salivary gland function is controlled by the autonomic and central nervous system, associations between cognitive changes and salivary gland hypofunction were tested in two groups of middle-aged men in late midlife, who differed substantially with respect to their midlife performance in verbal intelligence when compared with their performance in young adulthood.

Materials and Methods: Participants (n = 193) were recruited from the Danish Metropolit Cohort of men born in 1953. Based on their individual change in performance in two previously administered intelligence tests, they were allocated to one group of positive and one group of negative outliers in midlife cognition scores, indicating no decline versus decline in test performance. All participants underwent a clinical oral examination including assessments of their dental, periodontal, and mucosal conditions. Whole and parotid saliva flow rates were measured, and the number of systemic diseases and medication intake as well as daytime and nocturnal xerostomia were registered.

Results: Participants with decline in cognitive test performance in midlife had significantly lower unstimulated whole saliva flow rates, higher prevalence of hyposalivation and daytime xerostomia and a higher caries experience than participants with no decline in midlife performance. Daytime and nocturnal xerostomia were associated with daily intake of medication and alcohol.

Discussion: Overall, hyposalivation, xerostomia and poor dental status distinguished a group of men displaying relative decline in cognitive performance from a group of men without evidence of cognitive decline. Thus, hyposalivation and poor dental health status may represent potential correlates of age-related cognitive decline in late midlife, provided that other causes can be excluded.

Associations of Personality with Body Mass Index and Obesity in a Large Late Midlife Community Sample

OBJECTIVE

The study examined cross-sectional associations of personality with BMI and obesity among men and women in a large late midlife community sample.

METHODS

The sample comprised 5,286 Danish individuals aged 49-63 years from the Copenhagen Ageing and Midlife Biobank (CAMB) with complete information on measured BMI, personality assessed by the NEO Five Factor Inventory (NEO FFI), and sociodemographic factors including sex, age and educational length. Analysis of variance and logistic regression models were used to investigate associations between personality and BMI as well as obesity. Personality traits were analyzed separately and combined in the same model.

RESULTS

All personality traits except for neuroticism were significantly associated with BMI, with extraversion (p value ranged from <0.001 to 0.012) and agreeableness (p value ranged from 0.001 to 0.002) being the most consistent predictors of BMI among men and women, respectively. Furthermore, extraversion among men (high scores) (p = 0.016) and agreeableness among women (low scores) (p = 0.026) were the only personality traits significantly associated with obesity when adjusting for duration of education.

CONCLUSION

Personality was significantly associated with BMI and to a lesser extent with obesity, and these associations differed between men and women. Also, it was suggested that the interrelations of the five personality traits should be considered in future research of personality and health outcomes.

Is there a relationship between accelerometer-assessed physical activity and sedentary behavior and cognitive function in US Hispanic/Latino adults? The Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

Normative changes in cognitive function are expected with increasing age. Research on the relationship between normative cognitive decline and moderate-to-vigorous physical activity (MVPA) and sedentary behavior (SED) needs further investigation in Hispanic/Latinos adults. We assessed the cross-sectional association between accelerometer assessed MVPA and SED with cognitive function in 7,478 adults aged 45-74years from the Hispanic Community Health Study/Study of Latinos. At baseline, cognitive tests included two executive function tests (Digit Symbol Substitution Test (DSST), a test of language (Word Fluency), and a test of memory (Spanish English Verbal Learning Test). Multiple regression models were used to examine associations of time spent in MVPA and SED with cognitive function by age groups, adjusted for age, education, sex, acculturation, and field center. Mean time spent in sedentary behaviors was 12.3h/day in females and 11.9 h/day in males (75% and 77% of accelerometer wear time, respectively). Higher SED, but not MVPA, was associated with lower DSST raw scores (β -0.03 with each 10-min increment in SED; P<0.05), indicating lower performance in executive function in all age groups. No associations were observed for MVPA and SED with tests of language or memory tests. Our findings suggest a distinct association of SED but not MVPA on executive functioning in middle-aged and older Latino adults. Longitudinal studies are needed to more conclusively determine causal links.

Birth Weight and Intelligence in Young Adulthood and Midlife

OBJECTIVES

We examined the associations between birth weight and intelligence at 3 different adult ages.

METHODS

The Copenhagen Perinatal Cohort is comprised of children born in Copenhagen from 1959 to 1961. Information on birth weight and ≥1 tests of intelligence was available for 4696 members of the cohort. Intelligence was assessed at a mean age of 19 years with the Børge Priens Prøve test, at age 28 years with the Wechsler Adult Intelligence Scale, and at age 50 years with the Intelligenz-Struktur-Test 2000 R.

RESULTS

Birth weight was significantly associated with intelligence at all 3 follow-up assessments, with intelligence scores increasing across 4 birth weight categories and declining for the highest birth weight category. The adjusted differences between those in the <2.5kg birth weight group and those in the 3.5 to 4.00kg group were >5 IQ points at all 3 follow-up assessments, corresponding to one-third of a SD. The association was stable from young adulthood into midlife,and not weaker at age 50 years. Adjustment for potential confounding factors, including infant socioeconomic status and gestational age, did not dilute the associations, and associations with intelligence were evident across the normal birth weight range and so were not accounted for by low birth weight only.

CONCLUSIONS

The association between birth weight and intelligence is stable from young adulthood into midlife. These long-term cognitive consequences may imply that even small shifts in the distribution of birth size, in normal-sized infants as well, may have a large impact at the population level.

Associations between obesity and mental distress in late midlife: results from a large Danish community sample

BACKGROUND

To examine associations of Body mass Index (BMI) and mental distress in late midlife in a large Danish community sample and to investigate the effect of socio-demographic factors.

METHODS

The study sample comprised 3613 Danish men and 1673 women aged 49-63 years from the Copenhagen Ageing and Midlife Biobank (CAMB) with complete information on measured BMI, severity of mental symptoms assessed by the Symptom Check-List' (SCL-90), and socio-demographic factors including sex, age, occupational social class, and educational duration. Linear and logistic regression were used to evaluate associations between BMI category and SCL-90.

RESULTS

Unadjusted SCL-90 subscale scores differed significantly across BMI categories (p < 0.001) among both men and women with more mental distress in the underweight, obese and severely obese BMI categories except for the anxiety scale which was not associated with BMI category in women. In the adjusted analyses, all symptom scales remained significantly associated with BMI among men after adjusting for socio-demographic factors while only associations with somatization and depression scales remained significant for women.. When SCL-90 case status was applied as an outcome, significant unadjusted associations with BMI category were observed for somatization (p < 0.001), depression (p = 0.026) and the General Severity Index (p = 0.002) among men and somatization (p = 0.002) among women. Furthermore, somatization case-status was significantly predicted by BMI category (p < 0.001) in men after adjusting for socio-demographic factors.

CONCLUSION

Results indicate more mental distress among underweight, obese and severely obese men and women after adjusting for socio-demographic factors. Furthermore, obese men have higher risk of reporting clinically relevant symptoms of somatization independently of socio-demographic factors.

Cognitive Change during the Life Course and Leukocyte Telomere Length in Late Middle-Aged Men

Importance: Cognitive skills are known to decline through the lifespan with large individual differences. The molecular mechanisms for this decline are incompletely understood. Although leukocyte telomere length provides an index of cellular age that predicts the incidence of age-related diseases, it is unclear whether there is an association between cognitive decline and leukocyte telomere length.

Objective: To examine the association between changes in cognitive function during adult life and leukocyte telomere length after adjusting for confounding factors such as education, mental health and life style.

Design, Setting, and Participants: Two groups of men with negative (n = 97) and positive (n = 93) change in cognitive performance were selected from a birth cohort of 1985 Danish men born in 1953. Cognitive performance of each individual was assessed at age ~20 and 56 years. Leukocyte telomere length at age ~58 was measured using qPCR. Linear regression models were used to investigate the association between cognitive function and leukocyte telomere length.

Results: Men with negative change in cognitive performance during adult life had significantly shorter mean leukocyte telomere length than men with positive change in cognitive performance (unadjusted difference β = −0.09, 95% CI −0.16 to −0.02, p = 0.02). This association remained significant after adjusting for smoking, alcohol consumption, leisure time activity, body mass index (BMI) and cholesterol (adjusted difference β = −0.09, 95% CI −0.17 to −0.01, p = 0.02) but was non-significant after adjusting for smoking, alcohol consumption, leisure time activity, BMI, cholesterol, current cognitive function, depression and education (adjusted difference β = −0.07, 95% CI −0.16 to −0.01, p = 0.08).

Conclusion and Relevance: Preclinical cognitive changes may be associated with leukocyte telomere length.

Influence of physical and psychosocial work environment throughout life and physical and cognitive capacity in midlife on labor market attachment among older workers: study protocol for a prospective cohort study

Background

As average life span increases, elderly will account for an increasing proportion of the total population in most parts of the world. Thus, initiatives to retain older workers at the labor market are becoming increasingly important. This study will investigate the influence of physical and psychosocial work environment throughout working life and physical and cognitive capacity in midlife on labor market attachment among older workers.

Methods/Design

Approximately 5000 participants (aged 50–60 years) from the Copenhagen Aging and Midlife Biobank (CAMB) will be followed prospectively in a national register (DREAM), containing information on a week-to-week basis about social transfer payments for about 5 million Danish residents. Using Cox regression, we will model the risk of long-term sickness absence, disability pension, early retirement and unemployment within a 4 to 6 year period from the baseline measurement as a function of the following predictors: 1) physical work demands throughout working life, 2) psychosocial working conditions throughout working life, 3) physical capacity in midlife, 4) cognitive capacity in midlife. Estimates will be adjusted for age, sex, lifestyle, socioeconomic position, chronic disease and long-term sickness absence prior to baseline.

Discussion

The project will generate new knowledge on risk factors for loss of labor market attachment. The results will potentially contribute in identifying factors that could be targeted in future interventions for maintaining a longer and healthier working life among older workers.

Elevated p16ink4a Expression in Human Labial Salivary Glands as a Potential Correlate of Cognitive Aging in Late Midlife

BACKGROUND

The cell-cycle inhibitor and tumor suppressor cyclin dependent kinase inhibitor, p16ink4a, is one of the two gene products of the ink4a/ARF (cdkn2a) locus on chromosome 9q21. Up-regulation of p16ink4a has been linked to cellular senescence, and findings from studies on different mammalian tissues suggest that p16ink4a may be a biomarker of organismal versus chronological age.

OBJECTIVE

The aim of this study was to examine the immunolocalization pattern of p16ink4a in human labial salivary gland (LSG) tissue, and to analyze whether its expression level in LSGs is a peripheral correlate of cognitive decline in late midlife.

METHODS

The present study was a part of a study of causes and predictors of cognitive decline in middle-aged men in a Danish birth cohort. It is based on data from 181 male participants from the Danish Metropolit birth cohort, born in 1953, who were examined for age-associated alterations in cognition, dental health, and morphological and autonomic innervation characteristics of the LSGs. The participants were allocated to two groups based on the relative change in cognitive performance from young adulthood to late midlife. LSG biopsies were analyzed by qRT-PCR for the expression level of p16ink4a. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections of LSGs.

RESULTS

p16ink4a immunoreactivity was observed in LSG ductal, myoepithelial, and stromal cells, but not in acinar cells. The mean relative expression of p16ink4a in LSGs was higher in the group of participants with decline in cognitive performance. A logistic regression analysis revealed that the relative p16 expression was predictive of the participant's group assignment. A negative correlation was found between relative p16ink4a expression and the participant's standardized regression residuals from early adulthood to late midlife cognitive performance scores.

CONCLUSIONS

p16ink4a expression in human LSGs may constitute a potential peripheral correlate of cognitive decline. Human labial salivary glands seem suitable for studies on organismal as opposed to chronological age.

Social gradient in allostatic load among Danish men and women in late midlife

OBJECTIVE

The objective of the present study is to describe the prevalence of allostatic load (AL) among Danish men and women in late midlife, and if there is a social gradient in AL.

METHOD

A total of 5,420 participants from the Copenhagen Aging and Midlife Biobank (CAMB) aged 48 to 63 years (68.5% men, 31.5% women) underwent a health examination including standardized measures of height, weight, body fat, and blood pressure in 2009-2011. AL (range 0-14) was established by summing the scores of the poorest quartile for each of 14 biological variables related to the metabolic and immune systems.

RESULTS

We found a social gradient in AL in late midlife among men and women living in Denmark.

DISCUSSION

AL may be a potential biomarker for early aging in countries with a strong social welfare system. It is important for intervention studies to be aware of this type of biological vulnerability already present in late midlife.

Addressing social inequality in aging by the Danish occupational social class measurement

OBJECTIVE

To present the Danish Occupational Social Class (DOSC) measurement as a measure of socioeconomic position (SEP) applicable in a late midlife population, and to analyze associations of this measure with three aging-related outcomes in midlife, adjusting for education.

METHOD

Systematic coding procedures of the DOSC measurement were applied to 7,084 participants from the Copenhagen Aging and Midlife Biobank (CAMB) survey. We examined the association of this measure of SEP with chronic conditions, self-rated health, and mobility in logistic regression analyses, adjusting for school education in the final analysis.

RESULTS

The measure of SEP showed a strong social gradient along the social classes in terms of prevalence of chronic conditions, poor self-rated health, and mobility limitations. Adjusting for school education attenuated the association only to a minor degree.

DISCUSSION

The DOSC measure was associated with aging-related outcomes in a midlife Danish population, and is, thus, well suited for future epidemiological research on social inequalities in health and aging.

Smoking and Drinking as Risk Indicators for Tooth Loss in Middle-Aged Danes

Objectives: To investigate tobacco and alcohol consumption as risk indicators for missing teeth in late middle-aged Danes. Method: In all, 1,517 Copenhagen Aging and Midlife Biobank (CAMB) participants received a clinical oral examination that included number of teeth. Information on smoking, drinking, and various covariates was obtained using self-administered, structured questionnaires. Descriptive statistics and logistic regression (dependent variable: 6+ vs. <6 missing teeth) were used to investigate smoking and drinking in relation to missing teeth. Results: Current smokers, persons who currently or previously smoked >15 tobacco units/day, and persons who had smoked for 27+ years had elevated mean scores of missing teeth and associated odds ratios (OR) compared with never smokers. Relative to nondrinkers, alcohol consumption was associated with reduced odds of missing 6+ teeth. Discussion: Our findings suggest that smoking is positively associated, while alcoholic beverage consumption is inversely related to tooth loss in middle-aged Danes.

Personality in Late Midlife

Objectives: To analyze associations in late midlife between sex, age, education and social class, and the Big Five personality traits; to analyze associations between personality traits and cognitive ability in late midlife; and to evaluate how these associations are influenced by demographic factors. Methods: The study sample comprised 5,397 late midlife participants from three cohorts who had completed the NEO Five-Factor Inventory (NEO-FFI) and a measure of cognitive ability. Results: Associations were demonstrated between the five NEO-FFI personality traits, and all included demographic factors. Cognitive ability and years of education correlated with several NEO-FFI personality traits in analyses adjusting for demographic variables. Cohort differences were observed for Extraversion and Openness. Discussion: Robust sex, educational, and social class differences in personality may contribute to late midlife social gradients in health and early aging. Demographic factors did not fully explain correlations between personality and cognitive ability or cohort differences in personality.