Association of big-5 personality traits with cognitive impairment and dementia: a longitudinal study.

BACKGROUND: Personality traits have been liked to cognitive outcomes such as dementia, but whether these associations are robust to the effects of third variables remains the subject of debate. We examined the role of socioeconomic status, depression (history and depressive symptoms), health behaviours and chronic conditions in the association of the big-5 personality traits with cognitive performance, cognitive impairment and incidence of dementia. METHODS: Data on 6135 persons (30% women), aged 60-83 years in 2012/13, are drawn from the Whitehall II Study. Participants responded to the 26-item Midlife Development Inventory to assess personality traits (openness, conscientiousness, extraversion, agreeableness and neuroticism), underwent cognitive testing in 2012/13 and 2015/16 and were followed for incidence of dementia (N=231) until 2019. RESULTS: Logistic regression, adjusted for sociodemographic factors, suggested a cross-sectional association with cognitive impairment for four of the five traits but only neuroticism was associated with incident cognitive impairment. All associations were completely attenuated when the analyses were adjusted for depression. Cox regression (mean follow-up: 6.18 years) adjusted for sociodemographic variables showed higher conscientiousness (HR per SD increment=0.72; 95% CI 0.65 to 0.81) and extraversion (HR=0.85; 95% CI 0.75 to 0.97) to be associated with lower dementia risk; higher neuroticism (HR=1.32; 95% CI 1.17 to 1.49) was associated with increased risk. Further adjustment for depression led to only conscientiousness retaining an association with dementia (HR=0.81; 95% CI 0.69 to 0.96), which was robust to adjustment for all covariates (HR=0.84; 95% CI 0.71 to 0.91; P=0.001). CONCLUSION: Our results show that only conscientiousness has an association with incidence of dementia that is not attributable to socioeconomic status or depression. The association of neuroticism with dementia was explained by depression.

Estimating sleep parameters using an accelerometer without sleep diary.

Wrist worn raw-data accelerometers are used increasingly in large-scale population research. We examined whether sleep parameters can be estimated from these data in the absence of sleep diaries. Our heuristic algorithm uses the variance in estimated z-axis angle and makes basic assumptions about sleep interruptions. Detected sleep period time window (SPT-window) was compared against sleep diary in 3752 participants (range = 60-82 years) and polysomnography in sleep clinic patients (N = 28) and in healthy good sleepers (N = 22). The SPT-window derived from the algorithm was 10.9 and 2.9 minutes longer compared with sleep diary in men and women, respectively. Mean C-statistic to detect the SPT-window compared to polysomnography was 0.86 and 0.83 in clinic-based and healthy sleepers, respectively. We demonstrated the accuracy of our algorithm to detect the SPT-window. The value of this algorithm lies in studies such as UK Biobank where a sleep diary was not used.

Healthy obesity and risk of accelerated functional decline and disability.

BACKGROUND/OBJECTIVES: Some obese adults have a normal metabolic profile and are considered 'healthy', but whether they experience faster ageing than healthy normal-weight adults is unknown. We compared decline in physical function, worsening of bodily pain and likelihood of future mobility limitation and disability between these groups. SUBJECTS/METHODS: This was a population-based observational study using repeated measures over 2 decades (Whitehall II cohort data). Normal-weight (body mass index (BMI) 18.5-24.9 kg m-2), overweight (25.0-29.9 kg m-2) and obese (⩾30.0 kg m-2) adults were considered metabolically healthy if they had 0 or 1 of 5 risk factors (hypertension, low high-density lipoprotein cholesterol, high triacylglycerol, high blood glucose and insulin resistance) in 1991/1994. Decline in physical function and worsening of bodily pain based on change in Short Form Health Survey items using eight repeated measures over 18.8 years (1991/1994-2012/2013) were compared between metabolic-BMI groups using linear mixed models. Odds of mobility limitation based on objective walking speed (slowest tertile) and of disability based on limitations in ⩾1 of 6 basic activities of daily living, each using three repeated measures over 8.3 years (2002/2004-2012/2013), were compared using logistic mixed models. RESULTS: In multivariable-adjusted mixed models on up to 6635 adults (initial mean age 50 years; 70% male), healthy normal-weight adults experienced a decline in physical function of -3.68 (95% CI=-4.19, -3.16) score units per decade; healthy obese adults showed an additional -3.48 (-4.88, -2.08) units decline. Healthy normal-weight adults experienced a -0.49 (-1.11, 0.12) score unit worsening of bodily pain per decade; healthy obese adults had an additional -2.23 (-3.78, -0.69) units worsening. Healthy obesity versus healthy normal-weight conferred 3.39 (2.29, 5.02) times higher odds of mobility limitation and 3.75 (1.94, 7.24) times higher odds of disability. CONCLUSIONS: Our results suggest that obesity, even if metabolically healthy, accelerates age-related declines in functional ability and poses a threat to independence in older age.

Socioeconomic disparities in gait speed and associated characteristics in early old age.

BACKGROUND: A few studies have documented associations between socioeconomic position and gait speed, but the knowledge about factors from various domains (personal factors, lifestyle, occupation…) which contribute to these disparities is limited. Our objective was to assess socioeconomic disparities in usual gait speed in a general population in early old age in France, and to identify potential contributors to the observed disparities, including occupational factors. METHODS: The study population comprised 397 men and 339 women, aged 55 to 69, recruited throughout France for the field pilot of the CONSTANCES cohort. Gait speed was measured in meters/second. Socioeconomic position was based on self-reported occupational class. Information on personal characteristics, lifestyle, comorbidities and past or current occupational physical exposure came either from the health examination, from interview or from self-administered questionnaire. Four groups were considered according to sex-specific distributions of speed (the two slowest thirds versus the fastest third, for each gender). Logistic regression models adjusted for health screening center and age allowed to the study of cross-sectional associations between: 1- slower speed and occupational class; 2- slower speed and each potential contributor; 3- occupational class and selected potential contributors. The association between speed and occupational class was then further adjusted for the factors significantly associated both with speed and occupational class, in order to assess the potential contribution of these factors to disparities. RESULTS: With reference to managers/executives, gait speed was reduced in less skilled categories among men (OR 1.21 [0.72-2.05] for Intermediate/Tradesmen, 1.95 [0.80-4.76] for Clerks, Sale/service workers, 2.09 [1.14-3.82] for Blue collar/Craftsmen) and among women (OR 1.12 [0.55-2.28] for Intermediate/Tradesmen, 2.33 [1.09-4.97] for Clerks, 2.48 [1.18-5.24] for Sale/service workers/Blue collar/Craftsmen). Among men, occupational exposure to carrying heavy loads explained a large part of socioeconomic disparities. Among women, obesity and occupational exposure to repetitive work contributed independently to the disparities. CONCLUSIONS: This study suggests that some potentially modifiable occupational and personal factors explain at least part of the differences in gait speed between occupational classes, and that these factors differ between men and women. Longitudinal studies are needed to confirm and complement these findings.

Prevalence of educational inequalities in obesity between 1970 and 2003 in France.

This paper examines trends in obesity rates and education-related absolute and relative inequalities in obesity over the last 40 years in France. Data are drawn from the French Decennial Health Surveys of 1970, 1980, 1991 and 2003. The difference in obesity rates between the least- and most-educated, the Slope Index of Inequality, is used to estimate absolute inequalities in obesity. The ratio of the corresponding rates, the Relative Index of Inequality, reveals the relative inequalities in obesity. Obesity rates were similar in men and women, but educational inequalities were greater in women. Obesity rates were similar over the first three surveys but increased for all in the 2003 survey. This increase was accompanied by increases in absolute inequalities in men (P = 0.04) from a Slope Index of Inequality of 4.80% (95% confidence interval [CI] = 2.27, 7.32) to 8.64% (95% CI = 5.97, 11.32) and women (P = 0.004) from 8.90% (95% CI = 6.18, 11.63) to 14.57% (95% CI = 11.83, 17.32). Relative inequalities in obesity remained stable over the 40 years. Recent increase in obesity rates in France is accompanied by increases in absolute education-related inequalities, while relative inequalities have remained stable; this suggests that obesity rates have increased at a much faster rate in the low-education groups.