Recent research: six lifestyle & health studies - two on sleep, two on smoking, one on diet & one on weight
Last updated on 28th January 2011
Here are half a dozen recent research papers on lifestyle and health - fuller details, abstracts & links to all studies mentioned are listed further down this post. The first couple are on sleep. I live a pretty healthy life, but I do "short change" myself a bit on sleep (otherwise you probably wouldn't get this blog). Every now and again I question myself on the health sense of this personal lifestyle choice. A recent paper by Chandola & colleagues reassures me a bit. In their paper "The effect of short sleep duration on coronary heart disease risk is greatest among those with sleep disturbance", they found that "Short sleep duration and sleep disturbance were both associated with increased hazards for CHD (coronary heart disease) in women as well as in men, although, after we adjusted for confounders, only those reporting sleep disturbance had a raised risk." In another recent study on sleep, Salo et al underline significant risks associated with sleep disturbance (not 'undisturbed' short sleeping). Concerningly - in their large scale prospective study - they conclude "Sleep disturbances are associated with increased risk for subsequent disabling mental disorders and various physical illnesses. They also predict the outcome of work disability due to musculoskeletal disorders." This is useful information for mental health professionals - it is likely to be worth helping people to develop better sleeping patterns when trying to reduce risk of future psychological illness. It is also useful for individuals wanting to understand how to live more healthily. In either case, reading Colin Espie's fine self-help book "Overcoming insomnia and sleep problems" is often a good place to start. See too the various relevant handouts & questionnaires on this website's "Sleep, ADHD & fatigue" page.
The next two papers I mention are on the continuing vast damage produced by smoking. And this disease burden is not only caused by smokers to themselves but also to those around them. Oberg et al review this in their publication "Worldwide burden of disease from exposure to second-hand smoke: a retrospective analysis of data from 192 countries." Soberingly and shockingly they conclude "Worldwide, 40% of children, 33% of male non-smokers, and 35% of female non-smokers were exposed to second-hand smoke in 2004. This exposure was estimated to have caused 379,000 deaths from ischaemic heart disease, 165,000 from lower respiratory infections, 36,900 from asthma, and 21,400 from lung cancer. 603,000 deaths were attributable to second-hand smoke in 2004, which was about 1.0% of worldwide mortality. 47% of deaths from second-hand smoke occurred in women, 28% in children, and 26% in men." Probably legislation and other community-wide initiatives are the most helpful response to this situation (as they would probably be for the parallel pattern of damage caused to both self and others by excessive alcohol use). But Hettema & Hendricks in their paper "Motivational interviewing for smoking cessation: a meta-analytic review" highlight the importance of focusing on supporting individual choice as well.
Staying with this post's overall look at recent research on lifestyle & health, Sofi & colleagues have put together a major review of diet in "Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis." Increasingly the food we eat is proving to be relevant to our mental health as well as our physical health - see, for example, an earlier blog post on this site "New research shows diet's importance for preventing depression". The sixth and last study that I mention in this post is on weight. Berrington de Gonzalez et al write on "Body-mass index and mortality among 1.46 million white adults." They comment "A high body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) is associated with increased mortality from cardiovascular disease and certain cancers, but the precise relationship between BMI and all-cause mortality remains uncertain." They quantify the increased death rate found at different BMI's and report "All-cause mortality is generally lowest with a BMI of 20.0 to 24.9." There are lots of BMI calculators easily accessible on the web, for example the NIH provide a useful one.
Chandola, T., J. E. Ferrie, et al. (2010). "The effect of short sleep duration on coronary heart disease risk is greatest among those with sleep disturbance: a prospective study from the Whitehall II cohort." Sleep 33(6): 739-744. [PubMed]
STUDY OBJECTIVES: Short sleep duration is associated with increased CHD (coronary heart disease) mortality and morbidity, although some evidence suggests that sleep disturbance is just as important. We investigated whether a combination of short sleep duration and sleep disturbance is associated with a higher risk of CHD than their additive effects. SETTING: The Whitehall II study. PATIENTS OR PARTICIPANTS: The Whitehall II study recruited 10,308 participants from 20 civil service departments in London, England. Participants were between the ages of 35 and 55 years at baseline (1985-1988) and were followed up for an average of 15 years. INTERVENTIONS: N/A. MEASUREMENTS: Sleep hours and sleep disturbance (from the General Heath Questionnaire-30) were obtained from the baseline survey. CHD events included fatal CHD deaths or incident nonfatal myocardial infarction or angina (ICD-9 codes 410-414 or ICD-10 120-25). RESULTS: Short sleep duration and sleep disturbance were both associated with increased hazards for CHD in women as well as in men, although, after we adjusted for confounders, only those reporting sleep disturbance had a raised risk. There was some evidence for an interaction between sleep duration and sleep disturbance. Participants with short sleep duration and restless disturbed nights had the highest hazard ratios (HR) of CHD (relative risk:1.55, 95% confidence interval:1.33-1.81). Among participants who did not report any sleep disturbance, there was little evidence that short sleep hours increased CHD risk. CONCLUSION: The effect of short sleep (< or = 6 hours) on increasing CHD risk is greatest among those who reported some sleep disturbance. However, among participants who did not report any sleep disturbance, there was little evidence that short sleep hours increased CHD risk.
Salo, P., T. Oksanen, et al. (2010). "Sleep disturbances as a predictor of cause-specific work disability and delayed return to work." Sleep 33(10): 1323-1331. [PubMed]
STUDY OBJECTIVE: To examine sleep disturbances as a predictor of cause-specific work disability and delayed return to work. DESIGN: Prospective observational cohort study linking survey data on sleep disturbances with records of work disability (> or = 90 days sickness absence, disability pension, or death) obtained from national registers. SETTING: Public sector employees in Finland. PARTICIPANTS: 56,732 participants (mean age 44.4 years, 80% female), who were at work and free of work disability at the study inception. MEASUREMENTS AND RESULTS: During a mean follow-up of 3.3 years, incident diagnosis-specific work disability was observed in 4,028 (7%) employees. Of those, 2,347 (60%) returned to work. Sleep disturbances 5-7 nights per week predicted work disability due to mental disorders (hazard ratio [HR] 1.6, 95% confidence interval [CI] 1.3-1.9) and diseases of the circulatory system (HR = 1.6, 95% CI 1.2-2.1), musculoskeletal system (HR = 1.6, 95% CI 1.4-1.8) and nervous system (HR = 1.5, 95% CI 1.0-2.2), and injuries and poisonings (HR = 1.6, 95% CI 1.2-2.1) after controlling for baseline age, sex, socioeconomic status, night/shift work, health behaviors (e.g., smoking, exercise), diagnosed somatic diseases, use of pain killers, depression, and anxiety. In addition, sleep disturbances prior to disability were associated with higher likelihood of not returning to work after work disability from musculoskeletal diseases (HR = 1.2, 95% CI 1.1-1.7) and, in men, after work disability due to mental disorders (HR = 4.4, 95% CI 1.7-11.1). CONCLUSIONS: Sleep disturbances are associated with increased risk for subsequent disabling mental disorders and various physical illnesses. They also predict the outcome of work disability due to musculoskeletal disorders.
Oberg, M., M. S. Jaakkola, et al. (2011). "Worldwide burden of disease from exposure to second-hand smoke: a retrospective analysis of data from 192 countries." Lancet 377(9760): 139-146. [PubMed]
BACKGROUND: Exposure to second-hand smoke is common in many countries but the magnitude of the problem worldwide is poorly described. We aimed to estimate the worldwide exposure to second-hand smoke and its burden of disease in children and adult non-smokers in 2004. METHODS: The burden of disease from second-hand smoke was estimated as deaths and disability-adjusted life-years (DALYs) for children and adult non-smokers. The calculations were based on disease-specific relative risk estimates and area-specific estimates of the proportion of people exposed to second-hand smoke, by comparative risk assessment methods, with data from 192 countries during 2004. FINDINGS: Worldwide, 40% of children, 33% of male non-smokers, and 35% of female non-smokers were exposed to second-hand smoke in 2004. This exposure was estimated to have caused 379,000 deaths from ischaemic heart disease, 165,000 from lower respiratory infections, 36,900 from asthma, and 21,400 from lung cancer. 603,000 deaths were attributable to second-hand smoke in 2004, which was about 1.0% of worldwide mortality. 47% of deaths from second-hand smoke occurred in women, 28% in children, and 26% in men. DALYs lost because of exposure to second-hand smoke amounted to 10.9 million, which was about 0.7% of total worldwide burden of diseases in DALYs in 2004. 61% of DALYs were in children. The largest disease burdens were from lower respiratory infections in children younger than 5 years (5,939,000), ischaemic heart disease in adults (2,836,000), and asthma in adults (1,246,000) and children (651,000). INTERPRETATION: These estimates of worldwide burden of disease attributable to second-hand smoke suggest that substantial health gains could be made by extending effective public health and clinical interventions to reduce passive smoking worldwide.
Hettema, J. E. and P. S. Hendricks (2010). "Motivational interviewing for smoking cessation: a meta-analytic review." Journal of consulting and clinical psychology 78(6): 868-884. [PubMed]
OBJECTIVE: Motivational interviewing (MI) is a treatment approach that has been widely examined as an intervention for tobacco dependence and is recommended in clinical practice guidelines. Previous reviews evaluating the efficacy of MI for smoking cessation noted effects that were modest in magnitude but included few studies. The current study is a comprehensive meta-analysis of MI for smoking cessation. METHOD: The meta-analysis included 31 controlled trials with an abstinence outcome variable. Studies with nonpregnant (N = 23) and pregnant samples (N = 8) were analyzed separately. RESULTS: For nonpregnant samples, combined results suggest that MI significantly outperformed comparison conditions at long-term follow-up points (dc = .17). The magnitudes of this result represented a 2.3% difference in abstinence rates between MI and comparison groups. All analyses investigating the impact of moderating participant, intervention, and study design characteristics on outcome were nonsignificant, with the exception of studies including international, non-U.S. samples, which had larger effects overall. Several subgroups of studies had significant combined effect sizes, pointing to potentially promising applications of MI, including studies that had participants with young age, medical comorbidities, low tobacco dependence, and, consistent with clinical practice guidelines, low motivation or intent to quit. Effects were smaller among pregnant samples. In addition, significant combined effect sizes were observed among subgroups of studies that administered less than 1 hr of MI and among studies that reported high levels of treatment fidelity. CONCLUSIONS: The results are interpreted in light of other behavioral approaches to smoking cessation, and the public health implications of the findings are discussed.
Sofi, F., R. Abbate, et al. (2010). "Accruing evidence on benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis." American Journal of Clinical Nutrition 92(5): 1189-1196. [PubMed]
BACKGROUND: The Mediterranean diet has long been reported to be protective against the occurrence of several different health outcomes. OBJECTIVE: We aimed to update our previous meta-analysis of published cohort prospective studies that investigated the effects of adherence to the Mediterranean diet on health status. DESIGN: We conducted a comprehensive literature search through electronic databases up to June 2010. RESULTS: The updated review process showed 7 prospective studies published in the past 2 y that were not included in the previous meta-analysis (1 study for overall mortality, 3 studies for cardiovascular incidence or mortality, 1 study for cancer incidence or mortality, and 2 studies for neurodegenerative diseases). These recent studies included 2 health outcomes not previously investigated (ie, mild cognitive impairment and stroke). The meta-analysis for all studies with a random-effects model that was conducted after the inclusion of these recent studies showed that a 2-point increase in adherence to the Mediterranean diet was associated with a significant reduction of overall mortality [relative risk (RR) = 0.92; 95% CI: 0.90, 0.94], cardiovascular incidence or mortality (RR = 0.90; 95% CI: 0.87, 0.93), cancer incidence or mortality (RR = 0.94; 95% CI: 0.92, 0.96), and neurodegenerative diseases (RR = 0.87; 95% CI: 0.81, 0.94). The meta-regression analysis showed that sample size was the most significant contributor to the model because it significantly influenced the estimate of the association for overall mortality. CONCLUSION: This updated meta-analysis confirms, in a larger number of subjects and studies, the significant and consistent protection provided by adherence to the Mediterranean diet in relation to the occurrence of major chronic degenerative diseases.
Berrington de Gonzalez, A., P. Hartge, et al. (2010). "Body-mass index and mortality among 1.46 million white adults." New England Journal of Medicine 363(23): 2211-2219. [PubMed]
BACKGROUND: A high body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) is associated with increased mortality from cardiovascular disease and certain cancers, but the precise relationship between BMI and all-cause mortality remains uncertain. METHODS: We used Cox regression to estimate hazard ratios and 95% confidence intervals for an association between BMI and all-cause mortality, adjusting for age, study, physical activity, alcohol consumption, education, and marital status in pooled data from 19 prospective studies encompassing 1.46 million white adults, 19 to 84 years of age (median, 58). RESULTS: The median baseline BMI was 26.2. During a median follow-up period of 10 years (range, 5 to 28), 160,087 deaths were identified. Among healthy participants who never smoked, there was a J-shaped relationship between BMI and all-cause mortality. With a BMI of 22.5 to 24.9 as the reference category, hazard ratios among women were 1.47 (95 percent confidence interval [CI], 1.33 to 1.62) for a BMI of 15.0 to 18.4; 1.14 (95% CI, 1.07 to 1.22) for a BMI of 18.5 to 19.9; 1.00 (95% CI, 0.96 to 1.04) for a BMI of 20.0 to 22.4; 1.13 (95% CI, 1.09 to 1.17) for a BMI of 25.0 to 29.9; 1.44 (95% CI, 1.38 to 1.50) for a BMI of 30.0 to 34.9; 1.88 (95% CI, 1.77 to 2.00) for a BMI of 35.0 to 39.9; and 2.51 (95% CI, 2.30 to 2.73) for a BMI of 40.0 to 49.9. In general, the hazard ratios for the men were similar. Hazard ratios for a BMI below 20.0 were attenuated with longer-term follow-up. CONCLUSIONS: In white adults, overweight and obesity (and possibly underweight) are associated with increased all-cause mortality. All-cause mortality is generally lowest with a BMI of 20.0 to 24.9.