Prevalence and incidence of memory complaints in employed compared to non-employed aged 55-64 years and the role of employment characteristics.

OBJECTIVES: To examine the association of employment status and characteristics with prevalent and incident memory complaints (MC) in 55-64-year-olds. METHODS: Subjects were participants of the Longitudinal Aging Study Amsterdam (LASA). Respondents with baseline data were selected to examine the association of employment status (n = 1525) and employment characteristics (n = 1071) with prevalent MC (i.e., MC at baseline). Respondents without MC at baseline were selected to examine the association of employment (n = 526) and employment characteristics (n = 379; working hours, job prestige, job level, psychological job demands, iso-strain) with incident MC (i.e., no MC at baseline and MC at three-year follow-up). Associations were adjusted for relevant covariates (demographics, memory performance, physical health, mental health, personality traits). Logistic regression was applied. Data were weighed according to gender and age of the Dutch population. RESULTS: At baseline 20.5% reported MC. At three-year follow-up, 15.4% had incident MC. No associations were found between employment status and MC. Adjusted analysis revealed that individuals with high occupational cognitive demands were more likely to have prevalent MC. CONCLUSIONS: Middle-aged workers are equally as likely to experience MC as non-working age-peers. Among workers, those with cognitively demanding work were more likely to experience MC, independent of memory performance. Memory decline due to ageing may be noticed sooner in 55-64-year-olds performing cognitively demanding work.

Development and validation of a physical and psychosocial job-exposure matrix in older and retired workers.

OBJECTIVES: A general population job-exposure matrix (GPJEM) including physical and psychosocial demands as well as psychosocial resources applicable to older and retired workers was developed. Its validity was evaluated by examining associations of physical demands and iso-strain (combination of high psychosocial demands and low resources) with health. METHODS: Physical and psychosocial work exposures reported by 55-64 year olds were derived from the Netherlands Working Conditions Survey and linked to the Netherlands Standard Classification of Occupations 1992. A GPJEM with low, moderate, and high probability of exposure to demands and resources was developed. To examine associations with health, two groups of the Longitudinal Aging Study Amsterdam were selected: current (i.e. at the time of the interview, 55-64 years) and former workers (55-84 years). Linear and logistic regression models were applied. RESULTS: Use of force and work in uncomfortable positions were significantly associated with functional limitations and self-perceived health (SPH), but not hip or knee osteoarthritis (OA), in current and former workers. A moderate probability of repetitive movements was associated with functional limitations in former workers. A high probability of repetitive movements was associated with functional limitations in current and former workers as well as with SPH and hip and knee OA in former workers. Respondents formerly exposed to iso-strain had significantly higher diastolic blood pressure and more often hypertension. No such associations were found in current workers. No association was found with cardiovascular disease. CONCLUSIONS: The results suggest that our GPJEM accurately classifies jobs according to physical demands and, although less clearly, iso-strain.

Predictors of having paid work in older workers with and without chronic disease: a 3-year prospective cohort study.

BACKGROUND: As the prevalence of chronic disease amongst older workers is high and increasing, it is important to know if the large subgroup of older workers with chronic disease has specific needs when it comes to prolonging participation in paid work. OBJECTIVES: To investigate differences and similarities in predictors of having paid work in workers aged 55+ with and without chronic disease. METHODS: Workers aged 55-62 years were selected from the 2002-2003 cohort of the Longitudinal Aging Study Amsterdam (n = 333). Potential predictors were: health, personality, work characteristics, and demographics. Per potential predictor, a logistic regression coefficient for 'having paid work in 2005-2006' was calculated for workers with and without chronic disease. A pooled estimate was computed and differences between the pooled estimate and the coefficients were tested. Results Follow-up data were available for 95 %, of whom 67 % still had paid work. Predictors of having paid work were similar for workers with and without chronic diseases, except for physical workload (χ(2) = 5.37; DF = 1) and psychosocial resources at work (χ(2) = 5.94; DF = 1). Having more psychosocial resources (OR = 3.57; 95 %CI 1.33-10.0) was predictive for having paid work in workers with chronic disease and not in workers without chronic disease. Lower age, more weekly working hours, no functional limitations, fewer depressive symptoms, lower neuroticism scores, and more sense of mastery were significantly associated with having paid work in all workers. CONCLUSIONS: Differences between predictors of having paid work between workers with and without chronic disease should be taken into account when aiming to prevent exit from the workforce. In particular the vulnerable subgroup of older workers with chronic disease and low psychosocial resources at work is more likely to quit working.

Classification models for identification of at-risk groups for incident memory complaints.

BACKGROUND: Memory complaints in older adults may be a precursor of measurable cognitive decline. Causes for these complaints may vary across age groups. The goal of this study was to develop classification models for the early identification of persons at risk for memory complaints using a broad range of characteristics. METHODS: Two age groups were studied, 55-65 years old (N = 1,416.8) and 65-75 years old (N = 471) using data from the Longitudinal Aging Study Amsterdam. Participants reporting memory complaints at baseline were excluded. Data on predictors of memory complaints were collected at baseline and analyzed using logistic regression analyses. Multiple imputation was applied to handle the missing data; missing data due to mortality were not imputed. RESULTS: In persons aged 55-65 years, 14.4% reported memory complaints after three years of follow-up. Persons using medication, who were former smokers and had insufficient/poor hearing, were at the highest risk of developing memory complaints, i.e., a predictive value of 33.3%. In persons 65-75 years old, the incidence of memory complaints was 22.5%. Persons with a low sense of mastery, who reported having pain, were at the highest risk of memory complaints resulting in a final predictive value of 56.9%. In the subsample of persons without a low sense of mastery who (almost) never visited organizations and had a low level of memory performance, 46.8% reported memory complaints at follow-up. CONCLUSIONS: The classification models led to the identification of specific target groups at risk for memory complaints. Suggestions for person-tailored interventions may be based on these risk profiles.

Do employed and not employed 55 to 64-year-olds' memory complaints relate to memory performance? A longitudinal cohort study.

BACKGROUND: Whether middle-aged individuals are capable of employment continuation may be limited by poor memory. Subjective memory complaints may be used to identify those at risk of poor memory. Research questions, therefore, were (i) are prevalent memory complaints associated with relevantly poor memory performance and decline in 55 to 64-year-olds; (ii) are incident memory complaints associated with relevant memory decline; and (iii) do these associations differ between employed and not employed individuals? METHODS: Participants of the Longitudinal Aging Study Amsterdam (LASA) were examined. Data were weighted by sex, age and region. To examine the association of prevalent memory complaints with relevantly poor learning ability (n=903) and delayed recall (n=897; both assessed with the Auditory Verbal Learning Test), subnormal (≤ mean-1 SD) and impaired (≤ mean-1.5 SD) memory performance were defined. To examine the association of prevalent and incident memory complaints with relevant decline after 3 years in learning ability (n=774 and 611, respectively) and delayed recall (n=768 and 603, respectively), above normal (≤ mean-1 SD) and clinically relevant (≤ mean-1.5 SD) memory decline were investigated. Logistic regression analyses were applied. RESULTS: Adjusted for gender, education and age, individuals with memory complaints more often had impaired delayed recall and clinically relevant decline in learning ability. Incident memory complaints were borderline significantly associated with clinically relevant decline in learning in continuously employed individuals (paid job ≥ 1 h weekly), but not in continuously not employed individuals. CONCLUSION: Memory complaints may identify 55 to 64-year-olds at risk of memory impairment and decline. Our results provide hypotheses about the association between memory complaints and decline in employed 55 to 64-year-olds.

Endogenous subclinical thyroid disorders, physical and cognitive function, depression, and mortality in older individuals.

OBJECTIVE: To what extent endogenous subclinical thyroid disorders contribute to impaired physical and cognitive function, depression, and mortality in older individuals remains a matter of debate. DESIGN: A population-based, prospective cohort of the Longitudinal Aging Study Amsterdam. METHODS: TSH and, if necessary, thyroxine and triiodothyronine levels were measured in individuals aged 65 years or older. Participants were classified according to clinical categories of thyroid function. Participants with overt thyroid disease or use of thyroid medication were excluded, leaving 1219 participants for analyses. Outcome measures were physical and cognitive function, depressive symptoms (cross-sectional), and mortality (longitudinal) RESULTS: Sixty-four (5.3%) individuals had subclinical hypothyroidism and 34 (2.8%) individuals had subclinical hyperthyroidism. Compared with euthyroidism (n=1121), subclinical hypo-, and hyper-thyroidism were not significantly associated with impairment of physical or cognitive function, or depression. On the contrary, participants with subclinical hypothyroidism did less often report more than one activity limitation (odds ratio 0.44, 95% confidence interval (CI) 0.22-0.86). After a median follow-up of 10.7 years, 601 participants were deceased. Subclinical hypo- and hyper-thyroidism were not associated with increased overall mortality risk (hazard ratio 0.89, 95% CI 0.59-1.35 and 0.69, 95% CI 0.40-1.20 respectively). CONCLUSIONS: This study does not support disadvantageous effects of subclinical thyroid disorders on physical or cognitive function, depression, or mortality in an older population.

Associations between vitamin D receptor genotypes and mortality in a cohort of older Dutch individuals.

CONTEXT: Vitamin D receptor (VDR) polymorphisms are associated with a variety of diseases, which may translate into an effect on mortality. OBJECTIVE: To investigate the associations between VDR gene variants and mortality among older people. DESIGN: The analyses were conducted in a population-based, prospective cohort of the Longitudinal Aging Study Amsterdam. Adequate DNA analysis was performed in 923 men and women (≥65 years). We aimed to assess the associations between mortality and the VDR polymorphism FokI, three haplotypes of the Cdx2 and GATA polymorphisms, and three haplotypes of the BsmI, ApaI, and TaqI polymorphisms. RESULTS: During the median follow-up of 10.7 years, 480 participants deceased (51%). Homozygosity for the Cdx2-GATA haplotype 1 allele was associated with a 30% higher mortality risk compared to the absence of alleles (hazard ratios (HR) 1.30, 95% confidence intervals (CI) 1.01-1.68). Adjustment for cardiovascular risk factors and 25-hydroxyvitamin D levels did not affect this HR. The number of copies of the Cdx2-GATA haplotype 1 allele was associated, although not significantly, with an increased risk of osteoporotic fractures (0 copies=reference, HR, 95% CI: 1 copy 2.01, 0.99-4.07 and 2 copies 1.81, 0.87-4.18). After adjustment for osteoporotic fractures, homozygosity for the Cdx2-GATA haplotype 1 allele was no longer associated with higher mortality risk (HR 1.08, 95% CI 0.83-1.41). CONCLUSIONS: The Cdx2-GATA haplotype 1 allele was related to increased mortality risk, which may be partly explained by osteoporotic fractures. As the biological mechanism is uncertain and this study size is limited, our results should be interpreted as hypothesis generating.