Exposure to environmental occupational constraints and all-cause mortality: Results for men and women from a 20-year follow-up prospective cohort, the VISAT study. Be aware of shift-night workers!

Objective: To determine the predictive value of the large panel of occupational constraints (OC) on all-cause mortality with a 20-year follow-up, in general population of workers. Methods: In VISAT prospective cohort study, 3,138 workers (1,605 men; 1,533 women) were recruited during the periodic work health visits conducted by occupational physicians. OC (physical, organizational, psychological and employment categories) were collected through self-questionnaires. Exposure durations of each OC were divided by tertile distribution. Cox-regression models were performed to analyze the associations between all-cause mortality and each OC first separately and simultaneously in a single model. Results: The mortality rates were higher among exposed participants to most of OC compared to those unexposed. Being exposed and longer exposure increased the risks of all-cause mortality for exposures to carrying heavy loads, loud noise, working more than 48 h/week, starting its first job before 18 years old although these risks became non-significant after adjustments for cardiovascular risk factors. Shift work and night work confirmed a high risk of mortality whatever the adjustments and notably when the other occupational exposures were taking into account, with, respectively: HR: 1.38 (1.01-1.91) and 1.44 (1.06-1.95). After adjustments being exposed more than 13 years to a work requiring getting-up before 5:00 a.m. and more than 16 years in rotating shift work significantly increased the risk of mortality by one and a half. Conclusion: The links between each OC and all-cause mortality and the role of individual factors were stressed. For night-shift workers, it is urgent to implement preventive strategies at the workplace.

Blood pressure and cognitive performances in middle-aged adults: the Aging, Health and Work longitudinal study.

BACKGROUND: Our objective was to investigate the impact of both prevalent and incident hypertension on cognition in middle-aged individuals followed up for 10 years and to explore the extent to which blood pressure control by antihypertensive drugs could modify this relationship. METHOD: Three thousand, two hundred and one participants from the Vieillissement Santé Travail (Aging, Health and Work) (VISAT) cohort study, aged 32, 42, 52 and 62 years at baseline were followed up 5 and 10 years later. Blood pressure, antihypertensive medication use as well as memory and speed cognitive performances were assessed at baseline and follow-up. Linear mixed models were used for analyses. RESULTS: At 10-year follow-up, compared with nonhypertensive participants, prevalent hypertensive individuals showed poorer global cognitive performances (ß = -2.99 ±â€Š0.96, P = 0.002 for participants aged 32 or 42 years at baseline and ß = -5.94 ±â€Š1.00, P < 0.001 for those aged 52 or 62). Patients with incident hypertension had poorer global cognitive performances over time compared with patients without hypertension. When considering prevalent hypertension and blood pressure control status by antihypertensive therapy, untreated and uncontrolled hypertension were associated with poorer cognitive performances than controlled and no hypertension (untreated hypertension compared with no hypertension: ß = -5.51 ±â€Š0.75, P < 0.001; uncontrolled hypertension compared with no hypertension: ß = -6.13 ±â€Š1.40, P < 0.001). CONCLUSION: Our findings showed that both prevalent and incident hypertension are associated with poorer global cognitive function in middle-aged individuals and suggested a potential preventive effect of antihypertensive therapy on cognition. Thus, for brain functioning, heightened efforts to detect hypertension and adequately treat it are of critical importance.

Impact of occupational environmental stressors on blood pressure changes and on incident cases of hypertension: a 5-year follow-up from the VISAT study.

BACKGROUND: The role of occupational stressors (OS) on blood pressure (BP) is often suspected, but asserting its impact remains uncertain. Our goal was to evaluate their impact on BP increase and on incident cases of hypertension over a 5-year period. METHODS: One thousand, one hundred and fifty-six men and women from the French prospective VISAT study were followed up over five-years (T1 to T2). Exposures to a large panel of OS (physical, organizational, psychosocial and employment categories) were collected. Linear and logistic regressions were used to assess associations between OS and T2-T1 SBP difference and incident cases of hypertension. They were performed to determine the role of OS first considered separately, then in combination, in crude and adjusted models for main cardiovascular risk factors (gender, age, education, BMI, lifestyle habits and medical history). RESULTS: For initial SBP level < 130 mmHg, carrying loads, intense noise exposure, working more than 48 h/week, active and high strain tended to be associated with an SBP difference increase, while job recognition was associated with a decrease. After adjustment, only significant associations with job strain and job recognition persisted. For initial SBP level ≥ 130 mmHg, being exposed to an active job strain was positively associated with T2-T1 SBP difference only in unadjusted model. Considering all the OS, the recognition of completed tasks had a major protective role. No impact of OS on incident cases of hypertension was observed. CONCLUSION: Associations between OS and SBP were observed mainly when initial SBP is within the normal range, and are mainly explained by cardiovascular factors, requiring physician's particular attention to people exposed to these OS. VISAT study is registered in "LE PORTAIL EPIDEMIOLOGIE - FRANCE- AVIESAN -ID 3666".

Contribution of occupational factors to the incidence and persistence of chronic low back pain among workers: results from the longitudinal VISAT study.

OBJECTIVE: Among the aetiological factors of chronic low back pain (CLBP), occupational factors are often suspected, but their contribution remains to be ascertained. This study aimed to determine the impact of a wide range of occupational factors on the incidence and persistence of CLBP. METHOD: From the VISAT (VIeillissement SAnté Travail) study, 1560 workers were examined at baseline and 5 years later. CLBP was defined as having low back pain or specific treatment for at least 6 months. Participants newly affected with CLBP and those with persistent CLBP at follow-up were distinguished. In addition to individual factors, a broad panel of occupational factors were analysed, covering employment, physical, organisational and psychosocial factors. Multivariate analyses were used to determine predictive factors of incidence and persistence of CLBP. Receiver operating characteristic (ROC) curves were performed to analyse the contribution of occupational factors. RESULTS: 22.6% of participants without any CLBP initially presented with CLBP 5 years later, while 53.7% of participants with CLBP at baseline had CLBP at the second collection. Carrying heavy loads, the lack of recognition of completed work and productivity-related income predicted a higher risk of incidence of CLBP. However, no significant association between occupational factors and the risk for persistence of CLBP was observed, while the risk was multiplied by two for history of depression and rheumatological events. ROC curves confirmed the significant contribution of occupational factors to incidence of CLBP. CONCLUSIONS: Occupational factors played a pivotal role in the incidence of CLBP, while individual factors were the main determinants of persistence of CLBP.

Chronic effects of shift work on cognition: findings from the VISAT longitudinal study.

OBJECTIVES: Shift work, like chronic jet lag, is known to disrupt workers' normal circadian rhythms and social life, and to be associated with increased health problems (eg, ulcers, cardiovascular disease, metabolic syndrome, breast cancer, reproductive difficulties) and with acute effects on safety and productivity. However, very little is known about the long-term consequences of shift work on cognitive abilities. The aim of this study was to assess the chronicity and reversibility of the effects of shift work on cognition. METHODS: We conducted a prospective cohort study of 3232 employed and retired workers (participation rate: 76%) who were 32, 42, 52 and 62 years old at the time of the first measurement (t1, 1996), and who were seen again 5 (t2) and 10 (t3) years later. 1484 of them had shift work experience at baseline (current or past) and 1635 had not. The main outcome measures were tests of speed and memory, assessed at all three measurement times. RESULTS: Shift work was associated with impaired cognition. The association was stronger for exposure durations exceeding 10 years (dose effect; cognitive loss equivalent to 6.5 years of age-related decline in the current cohort). The recovery of cognitive functioning after having left shift work took at least 5 years (reversibility). CONCLUSIONS: Shift work chronically impairs cognition, with potentially important safety consequences not only for the individuals concerned, but also for society.

Relationship between markers of insulin resistance, markers of adiposity, HbA1c, and cognitive functions in a middle-aged population-based sample: the MONA LISA study.

OBJECTIVE: To determine the relationship between markers of insulin resistance (fasting insulin and homeostasis model assessment of insulin resistance), markers of adiposity (BMI, waist circumference, and body fat), HbA1c, and cognitive performances in a middle-aged population-based sample free of diabetes. RESEARCH DESIGN AND METHODS: Our study sample consisted of 1,172 people aged 35-64 years (49% women), free of diabetes, and recruited between 2005 and 2007 in the MONA LISA survey. Cognitive functions (memory, attention, and processing speed) were evaluated by neuropsychological tests: word-list learning test, digit symbol substitution test (DSST), word fluency test, and Stroop Test. Multiple logistic regressions were used to estimate the relationship between cognitive performance and metabolic markers. We serially adjusted for age, sex, education, and occupational status (model A), additionally for income, smoking, alcohol consumption, sedentarity, and psychotropic substance use (model B), and finally, included variables linked to the metabolic syndrome (hypertension, dyslipidemia, vascular disease, and C-reactive protein) and depression (model C). RESULTS: Elevated markers of adiposity were associated with poor cognitive performance in tests evaluating processing speed. The probability of being in the lowest quartile of each test was nearly doubled for participants in the upper quartile of BMI, compared with those in the lowest one [BMI, adjusted odds ratio (OR) 2.18, P = 0.003 (DSST), and OR 2.09, P = 0.005 (Stroop Test)]. High HbA1c was associated with poor cognitive performance in DSST (adjusted OR 1.75, P = 0.037). Waist circumference was linked to poor cognitive performance in men but not in women. CONCLUSIONS: Poor cognitive performance is associated with adiposity and hyperglycemia in healthy middle-aged people.

Shiftwork and metabolic dysfunction.

Many of the health problems that are more prevalent among shiftworkers are thought to be linked to their heightened susceptibility to metabolic syndrome, i.e., the association of even moderate degrees of visceral obesity, dyslipidemia, abnormal blood pressure, and serum glucose levels in the same individual. Although previous studies have identified associations between shiftwork and metabolic syndrome, there is relatively little evidence to date of how the risk of developing it varies as a function of exposure to shiftwork. The current study seeks to confirm earlier findings of an association between shiftwork exposure and metabolic dysfunction, and to examine the impact of exposure duration, while adjusting for a number of covariates in the analyses. The analyses were based on data from VISAT, a study involving the measurement of physiological, behavioral, and subjective outcomes from 1757 participants, 989 being current or former shiftworkers. The sample comprised employed and retired wage earners, male and female, who were 32, 42, 52, and 62 yrs old. The first analysis sought to confirm previous findings of an association between exposure to shiftwork and the risk of developing metabolic syndrome. It indicated that participants who were or who had previously been shiftworkers (i.e., working schedules that involved rotating shifts; not being able to go to bed before midnight; having to get up before 05:00 h; or being prevented from sleeping during the night) were more likely to exhibit symptoms of metabolic syndrome, after adjusting for age, sex, socioeconomic status, smoking, alcohol intake, perceived stress, and sleep difficulty (odds ratio [OR] 1.78; 95% confidence interval [CI] 1.03-3.08). The results suggest the association between shiftwork and metabolic syndrome cannot be fully accounted for by either higher levels of strain or increased sleep difficulty among shiftworkers, although it remains a possibility that either one or both of these factors may have played a contributing role. The second analysis addressed the issue of duration of exposure to shiftwork. Participants with >10 yrs' experience of working rotating shifts were more likely to exhibit symptoms of metabolic syndrome than participants without exposure to shiftwork, i.e., dayworkers, even after adjusting for age and sex (OR 1.96; 95% CI 1.03-3.75). Thus, the current study confirms the association between shiftwork exposure and metabolic syndrome. It also provides new information regarding the time course of the development of the illness as function of exposure duration, although this was only examined in relation to rotating shiftwork. It is concluded that those responsible for monitoring workers' health should pay particular attention to indices of metabolic dysfunction in workers who have been exposed to shiftwork for >10 yrs.

Advantages of shift changeovers with meetings: ergonomic analysis of shift supervisors' activity in aircraft building.

Good shift changeovers contribute to ensuring continuity and reliability in shift work. In situations where production is not maintained 24 h a day, changeovers with meetings (SCM) between the two work teams (written plus oral face-to-face handovers) alternate with changeovers without meetings (SCnM; written handovers only). An ergonomic work analysis on an aircraft assembly line showed that (1) incoming and outgoing operators met during the overlap time allotted by the company, and (2) the content of the exchanges was richer for SCMs than for SCnMs. SCMs enabled the operators to pass on and process more aspects of their work than SCnMs did. SCMs also allowed incoming operators to validate their predictions, and enabled both outgoing and incoming operators to update their mental models and work together on peripheral aspects of the technical process over a greater time span. The findings highlight the importance of allowing overlap time in shift work.

Shift work and cardiovascular risk factors: new knowledge from the past decade.

Cardiovascular diseases remain a major public health problem. The involvement of several occupational factors has recently been discussed, notably the organization of work schedules, e.g. shift work. To analyse the progress of knowledge on the relationship between cardiovascular risk factors and shift work. A review of English-language literature dealing with the link between cardiovascular factors and shift workers (published during 2000-2010) was conducted. Studies published in the past 10 years tend to document an impact of shift work on blood pressure, lipid profile (triglyceride levels), metabolic syndrome and, possibly, body mass index. However, the consequences on glucose metabolism are unclear. These results are not yet firmly established, but are supported by strong hypotheses. Some advice could reasonably be proposed to guide the clinical practitioner.

Impact of long-term benzodiazepine use on cognitive functioning in young adults: the VISAT cohort.

PURPOSE: Results from a number of studies have suggested a relationship between cognitive alteration and benzodiazepine use in the elderly. The aim of this study was to determine the impact of benzodiazepine use on cognitive functions in a young adult population. METHODS: This study included 1,019 French salaried workers from the VISAT (Aging, Health and Work) cohort whose objective was to determine the long-term impact of working conditions on health and aging. Data were collected during interviews by occupational physicians in 1996, 2001 and 2006. Cognitive function was assessed using five cognitive tests (immediate free recall test, delayed free recall test, recognition test, Digit Symbol Substitution Subtest and visual search speed test). Cognitive scores obtained after a 10-year follow-up were investigated among three categories of benzodiazepine users, namely, non-users, occasional users and long-term users, using analysis of covariance models adjusted for several potential confounders in men and women separately. RESULTS: In the course of the 10 year-follow-up, 3.9% of subjects were defined as occasional users of benzodiazepine and 7.5% as long-term users. The analysis revealed a significant alteration of long-term memory in women whereas there was no significant association in men. CONCLUSIONS: Long-term use of benzodiazepine leads to specific impairment in long-term memory only in women.

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

OBJECTIVES: With the workforces in industrialized countries getting older, this study sought to determine how shiftworking affects sleep in later life. METHOD: Longitudinal data were collected from a large sample in 1996, 2001, and 2006 from employees who were 32, 42, 52, and 62 years old in 1996. RESULTS: The effects of shift work were most apparent in the early and middle years of working life. Former shiftworkers reported more sleep problems than both current shiftworkers and those who had never worked shifts. Giving up shift work off-set the age-related accumulation of sleep problems, with the net result that former shiftworkers showed little or no change in sleep problems over the three measurement occasions. CONCLUSIONS: The effects of shift work on sleep may persist for a long time after giving up shift work but they are not permanent.

Analyzing feature distinctiveness in the processing of living and non-living concepts in Alzheimer's disease.

The conceptual structure account (CSA) is a model specifying the role of the living and non-living domain dichotomy in the structure of semantic memory. According to this model, feature distinctiveness and the perceptual-functional inter-correlation of concepts are assumed to play a major role in impairing the ability to discriminate between living and non-living concepts in Alzheimer's disease (AD). The hypothesis was tested in this study by using naming and sorting tasks traditionally considered as assessing distinctiveness, and a property verification task where distinctiveness and perceptual-functional inter-correlation were objectively controlled against norms especially created for this purpose. Alzheimer's patients (n=59) with minimal, mild or moderate dementia and normal elderly adults (n=31) participated in the study. Overall, the findings did not support the CSA predictions. They revealed a distinctiveness effect on response accuracy with shared features dominating distinctive features regardless of domain. They also revealed more difficulties in the tasks involving effortful processes. The results stress the need to consider both cognitive demands of tasks and structural aspects of knowledge in the evaluation of semantic memory in AD.

Shiftwork experience, age and cognitive performance.

Changes of alertness and cognitive efficiency has been suggested in people whose circadian rhythms are disrupted, e.g. night or shift-workers. Data from field and laboratory studies have demonstrated short-term cognitive disturbances related to circadian rhythm disruption. By contrast, little is known about the long-term consequences of chronic sleep deprivation, as can be observed with shift-work, on cognitive abilities. The present paper is aimed at evaluating, on a large cross-sectional sample of workers, the long-term influence of shift-work on verbal memory and speed performances. Participants were 3,237 workers aged 32, 42, 52, and 62 years of various occupational statuses included in the VISAT (Aging, Health and Work) cohort. Data collected by questionnaires included items on working hours and shift-work and sleep disorders. Cognitive abilities were assessed using neuropsychological tests. Current male shift-workers had lower cognitive performance than never exposed workers. In the same population, memory performance tended to decrease with increasing shift-work duration. Among former shift-workers, the cognitive performance of the participant having stopped shiftwork more than 4 years ago seemed to be increased, suggesting a possible reversibility of effects. In conclusion, this study demonstrated that cognitive functioning tends to be impaired by a long-term exposure to SW. As found by other authors, neuropsychological performance tends to decrease with the increases in the duration of exposure to SW.

Environmental factors associated with body mass index in a population of Southern France.

STUDY OBJECTIVE: Environmental-factor changes may largely be accountable for the dramatic increase of obesity prevalence in industrialized countries. This study investigated the relationships between body mass index (BMI) and various socio-economic, clinical, behavioural and reproductive factors in a population from Southern France. METHODS: Using a cross-sectional study, a sample of 3127 current and former salaried workers (1658 men and 1469 women) completed a questionnaire on personal and medical histories, and had a clinical examination including height and weight measurements. Age-adjusted and multiple linear regression analyses were performed. RESULTS: The overall prevalence of obesity (BMI> or =30 kg/m) was 9.8% and was higher in men than in women (11.1 versus 8.3%). Multivariate analyses showed that in both sexes, low educational level, television watching, low physical activity and ex-smoking habits, were independently associated with a higher BMI. Furthermore, in women, we found independent and positive associations between BMI and the number of naps per week, short sleep duration, daily alcohol consumption, the number of pregnancies, early age at menarche or the non-use of oral contraceptives. CONCLUSIONS: Our results reveal the complexity that exists between BMI and environmental factors and stress the need to analyse and to handle these factors simultaneously.

Age differences in learning maintenance skills: a field study.

The effects of age and previous relevant experience on learning anxiety, strategies, and performance were studied in 43 workers aged 25 to 49 during a 1-week maintenance vocational training course. The results showed that increased age was associated with higher training-related anxiety as measured at the beginning of the course. However, no age difference could be found in the level of knowledge assessed after 3 days of training. This was confirmed by another problem-solving-type test that took place on the last day. Previous experience had no effect on anxiety, and it did enable us to predict higher scores for the first test but not for the second one. Analysis of behavior strategies revealed that older trainees consulted and annotated the course material more often than the younger ones during the learning process. The results are discussed in relation to those obtained in previous laboratory and field studies on the same subject.