The effects of age and shiftwork on perceived sleep problems: results from the VISAT combined longitudinal and cross-sectional study.

OBJECTIVE: With workforces in industrialized countries getting older, the study examined how shiftworking affects sleep in later life. METHOD: Longitudinal data were collected in 1996, 2001, and 2006 from a large sample of employees who were 32, 42, 52, and 62 years old in 1996. RESULTS: Effects of shiftwork were most apparent in middle-aged participants, becoming less apparent in later years when people tended to leave shiftwork. Nevertheless, a group of younger former shiftworkers reported more sleep problems than those who had never worked shifts. Giving up shiftwork offset a trend for sleep problems to accumulate over time, with the net result of no change in sleep problems after cessation of shiftwork. CONCLUSIONS: Poor sleep quality is a temporary consequence of shiftwork for some, whereas for others it is a cause of shiftwork intolerance.

Higher mental stimulation at work is associated with improved cognitive functioning in both young and older workers.

The study examined whether mental stimulation received in the workplace positively affects cognitive functioning and rate of cognitive change. Data taken from the VISAT (ageing, health and work) longitudinal study concerned 3237 workers who were seen three times (in 1996, 2001 and 2006) and who were aged between 32 and 62 years at baseline. Measures of cognitive stimulation both at work and outside work were available at baseline. Cognitive efficiency was assessed on the three occasions through episodic verbal memory, attention and processing speed tests. Greater cognitive stimulation (at work and outside work) was associated with higher levels of cognitive functioning and a more favourable change over the 10-year follow-up. These results were obtained after adjustment for age, education, sex and a variety of medical, physical and psychosocial confounders. The study thus supports the hypothesis that exposure to jobs that are mentally demanding and that offer learning opportunities increases the level of cognitive functioning and possibly attenuates age-related decline. STATEMENT OF RELEVANCE: The effect of occupational activity on cognitive functioning is under-researched. This paper reports results from a substantive longitudinal study, with findings indicating that exposure to jobs that are mentally demanding are beneficial in increasing levels of cognitive functioning and possibly attenuating age-related decline.

Factors associated with psychoactive drug initiation in a sample of workers in France: results of the VISAT cohort study.

PURPOSE: To identify which psychosocial factors at work are associated with the initiation of psychoactive drug use in a cohort of healthy French workers. METHOD: This study used data collected from the VISAT ('Vieillissement, Santé, Travail') cohort which included workers aged 32, 42, 52 and 62 years in 1996 with follow-ups conducted over the following 5 years. Data were collected through interviews and five standardized questionnaires in annual occupational medical examinations in 1996, 1999 and 2001. We defined new consumers of psychoactive drugs according to their answers during the follow-ups and compared their psychosocial and working characteristics to non-consumers. A multivariate logistic regression analysis was performed to investigate factors related to a psychoactive drug initiation. RESULTS: Among 1533 subjects, 5.4% began consuming psychoactive drugs during the follow-up with a twofold rate for women than for men. Factors related to psychoactive drug initiation were different according to gender. In men, initiation was mainly found in participants who were separated, showed high emotional reaction scores and were members of the white-collar working class. We did not find any other occupational factors associated to psychoactive drug initiation in men. By contrast, among women, drug initiation was more frequent in participants who were 52 years old and over, and whose job control-reward level was lower. CONCLUSIONS: Psychoactive drug initiation concerned 5.4% of workers within the 5-year interval in this study. The pressure of psychosocial environment was more important in men, whereas age and work-related psychosocial factors were the main factors associated with new consumption among women.

Effects of working conditions and sleep of the previous day on cognitive performance.

The study examined the consequences of working conditions on the previous day on cognitive performance the following day. It also addressed the issue of whether this relationship was mediated by sleep and whether it differed as a function of age. The data were taken from the VISAT study (aging, health and work) and concerned the participant's general work schedule, general sleep quality, working conditions on the previous day (content, duration, load and schedule), subsequent sleep length and quality, and cognitive performance. Results showed that both physical activity and working before 6 am or after 10 pm on the previous day were significantly associated with poorer cognitive performance. Significant effects of working conditions on the previous day were also observed on subsequent sleep, but these effects did not mediate the relationship between working conditions and cognitive performance. The observed effect on cognitive performance of atypical work hours on the previous day was similar for all ages, probably because of the healthy worker effect.

Relation between body mass index and cognitive function in healthy middle-aged men and women.

OBJECTIVE: To assess whether body mass index (BMI) is associated with cognitive function and cognitive decline in healthy men and women. METHODS: In this prospective cohort study, we analyzed data from 2,223 healthy workers aged 32 to 62 years at baseline. Medical, psychosocial, and environmental data were collected in 1996 and in 2001. We tested cognitive functions at baseline and at follow-up with word-list learning (four recalls), a Digit-Symbol Substitution Test, and a selective attention test. RESULTS: Cross-sectionally, a higher BMI was associated with lower cognitive scores after adjustment for age, sex, educational level, blood pressure, diabetes, and other psychosocial covariables. A higher BMI at baseline was also associated with a higher cognitive decline at follow-up, after adjustment for the above-cited confounding factors. This association was significant for word-list learning. For the changes in scores at word-list learning (delayed recall), regression coefficients were -0.008 +/- 0.13, -0.09 +/- 0.13, -0.17 +/- 0.14, and -0.35 +/- 0.14 (p for trend < 0.001) for the second, third, fourth, and fifth quintiles of BMI at baseline when compared with the first quintile. No significant association was found between changes in BMI and cognitive function. CONCLUSIONS: Body mass index was independently associated both with cognitive function (word-list learning and Digit-Symbol Substitution Test) and changes in word-list learning in healthy, nondemented, middle-aged men and women.

Job stress and occupational status in a French cohort.

BACKGROUND: The goal of this study was to examine a large, varied occupational French cohort for possible relationships between various dimensions of occupational stress, on the one hand, and the occupational status and socio-demographic characteristics of workers on the other. METHODS: Data was taken from the first, cross-sectional phase of the VISAT study (aging, health, and work), which took place in 1996. Participants were randomly drawn from the patient lists of about one hundred occupational physicians in three regions of southern France. The current study concerned 2,768 wage earners born in 1944, 1954, or 1964. The material consisted of 59 questions aimed at assessing a broad set of working conditions, some of which were proxy measures of the dimensions described in the Karasek and Siegrist models. RESULTS: From a principal component analysis, three main factors were extracted that accounted for 40% of the total variance. The first factor (a=0.79) included items that referred to the decision latitude in the Karasek model and items that referred to the reward dimension in the Siegrist model. The second factor (a=0.77) was made up of items tapping physical stressors, while the third factor (a=0.71) pooled items that corresponded fairly well to psychological demands in the Karasek model. Highly significant relationships (p<10(-4)) were found between the mean factor scores and both occupational status and educational level, with a lower occupational status and educational level being associated with greater lack of job control and rewards, higher physical stress, but lower psychological demands. Less job control and fewer rewards were also found to be greater in older workers (p<10(-3)) and females (p<10(-4)). CONCLUSION: Our results thus confirm the existence of a strong association, in a French cohort, between occupational status and dimensions of job stress known to be associated with adverse health outcomes.

Age differences in feeling-of-knowing and confidence judgements as a function of knowledge domain.

For two semantic knowledge domains, general and computer-related, feeling-of-knowing (FOK) and confidence level (CL) ratings and their relative accuracy were assessed in young, middle-aged, and older adults, after test difficulty was equated across age groups. Global memory self-efficacy beliefs were also assessed for each domain. As expected, greater age was associated with poorer memory self-efficacy beliefs only in the computer domain. The oldest two groups were found to be more underconfident than young adults when rating their FOK but not their CL, for computer items but not for general items. Statistical control of age differences in memory self-efficacy beliefs in the relevant domain greatly reduced this age effect on computer-related FOK ratings. This finding suggests that absolute FOK judgments are more closely related to memory self-efficacy beliefs than are CL judgments. Gamma correlations between judgments and recognition performance revealed that all age groups were equally accurate in FOK and in CL judgments, in both domains.

Effects of age, education, and sex on response bias in a recognition task.

This study examined age-related differences in decision criteria and the extent to which inconsistencies in earlier findings could be due to sampling artifacts, especially the underlying effects of educational level and sex. Male and female participants (N = 3,059) from 4 age groups (32, 42, 52, and 62 years) and a wide range of educational levels performed a word recognition task. Response bias was assessed with a nonparametric index derived from signal detection theory. The analyses revealed no age differences except for the most educated subjects, for whom increased age was associated with stricter decision criteria. Lower levels of education and men as compared with women were associated with a more conservative bias. Controlling for the level of sensitivity did not significantly change this pattern of results. This finding stresses the need for caution in generalizing age differences obtained from samples that are only partly representative or imbalanced with respect to education and sex.

Effects of age, working hours, and job content on sleep: a pilot study.

The effects of age, shiftwork with changing schedules, and job stress on self-reported sleep quality were studied in 2767 wage earners aged 32, 42, and 52, by means of a questionnaire. Greater age was associated with poorer sleep quality, as was shiftwork for the 32- and 42-year-olds but not for the 52-year-olds, suggesting a selection effect between the ages of 42 and 52. More than specific job demands, it was perceived job difficulty that was related to sleep dissatisfaction. No interactions between age, shiftwork, and job characteristics were found.

Sleep, age, and shiftwork experience.

The effects of age and shiftwork experience (never, past, present) on sleep were studied in a sample of 3236 wage earners and retired workers by means of a questionnaire. The sample was composed of 32-, 42-, 52-, and 62-year-old subjects, and included both sexes and various occupational statuses. Age resulted in a continuously increasing frequency of sleep disturbances and hypnotic use, except for difficulty getting back to sleep and early awakening, which peaked at 52 years and then decreased at 62 years, thus suggesting a 'retirement effect'. Current and past shiftworkers reported more problems with falling asleep and early awakening than subjects who had never worked on shifts. This is a likely explanation of why the effect of age was massive in the latter group and much less pronounced in the former groups. There were no clear effects of the length or recency of shiftwork experience. This finding does not support the hypothesized permanent effect of shiftwork experience on subsequent sleep. Females had higher complaint rates at every age. There was little interaction between age and sex, but women were affected more by shiftwork as they got older, particularly as to hypnotic consumption. Some of the results support the hypothesis that a selection process excludes workers who are no longer able to cope with the demands of shiftwork.

Age influence on attitudes of office workers faced with new computerized technologies: a questionnaire analysis.

The study of Bue and Gollac (1988) provided evidence that a significantly lower proportion of workers aged 45 years and over make use of computer technology compared with younger ones. The aim of the present survey was to explain this fact by a more intensive analysis of the older workers' attitude with respect to the computerization of work situations in relation to other individual and organizational factors. Six hundred and twenty office workers from 18 to 70 years old, either users or non-users of computerized devices, were asked to complete a questionnaire. The questions allowed the assessment of various aspects of the workers' current situation, such as the computer training they had received, the degree of consultation they were subjected to during the computerization process, their representation of the effects of these new technologies on working conditions and employment, the rate of use of new technologies outside the work context, and the perceived usefulness of computers for their own work. The analysis of the questionnaire revealed that as long as the step towards using computer tools, even minimally, has not been taken, then attitudes with respect to computerization are on the whole not very positive and are a source of anxiety for many workers. Age, and even more, seniority in the department, increase such negative representations. The effects of age and seniority were also found among users, as well as the effects of other factors such as qualification, education level, type and rate of computer use, and size of the firm. For the older workers, the expectation of less positive consequences for their career, or even the fear that computerization might be accompanied by threats to their own employment and the less clear knowledge of how computers operate, appeared to account for a significant part of the observed age and seniority differences in attitudes. Although the difference in the amount of computer training between age groups was smaller than expected, the study revealed that one third of the users never received any specific training, and that many of those who benefited from it were trained for only a few days. Consultation of the staff during the computerization process also appeared to be poor, to apply mostly to the best trained and qualified workers, and to be more highly developed in small companies. The results are discussed in the light of more qualitative data recorded during the survey. They suggest the need to increase information, training and involvement of all personnel from the very first stages of computerization (or other technical changes) in order to lessen fears and the feeling of disruption, which are particularly obvious among the oldest workers.

Age differences in sensitivity, response bias, and reaction time on a visual discrimination task.

Twelve young adults (age 21-25 years) and twelve older adults (age 57-65 years) performed a visual discrimination task (parallel lines) in which the following factors were manipulated: the difference in the length of the lines (3% and 9%), signal exposure duration (150, 750, and 2000 ms), and presentation modality (simultaneous and successive). The effect of repeating the task over three blocks was also controlled. Reaction time, sensitivity (d'), the decision criterion (beta), and the level of confidence the subjects had in their responses were measured and analyzed. The reaction time of the older subjects was longer than for younger ones. The difference remained constant across conditions. Signal detection analysis indicated that the ability to discriminate, as measured by d', was the same, on the whole, in the two age groups, but the sensitivity of the older was more affected by signal exposure duration than that of their younger counterparts. Contrary to what might have been expected, the older subjects used a more risky decision criterion than the younger subjects (preferring false alarms to omissions) and did not have significantly less confidence in their responses. Task repetition led to reduced reaction times and to a slightly higher level of confidence, but no age-related effects were found. The findings suggest that, in addition to a perceptual compensatory component, the longer reaction times of the older subjects include a decision-making component not necessary for their level of discrimination accuracy. The outcome of a lower criterion in the older group supports other findings according to which a more conservative decision strategy is not a general, systematic feature of the aged.