Impact of Lifestyle on Allostatic Load of the Hong Kong Population

Abstract

Background: Allostatic load measures the overall physiological ‘wear-and-tear’ from chronic life stress on one’s body and the Allostatic-Load-Index (ALI), a composite index of biological markers, has been shown to predict disease in later life. Identifying protective factors which reduce ALI potentially allow prevention of chronic diseases arising from cumulative stress earlier in disease trajectories when conditions are still reversible. However, the impact of modifiable lifestyle factors on allostatic load remains unknown. Objectives: To evaluate the relative importance of protective lifestyle on allostatic load Methods: A cross-sectional study of 1,732 people aged 15-84 without hypertension, diabetes, cardiovascular disease or dementia was conducted on data from the governmental Hong Kong Population Health Survey 2014/15. Biomarkers of allostatic load collected and respective increased-risk cutoffs were: systolic blood pressure≥130mmHg, diastolic blood pressure≥80mmHg, waist-to-hip ratio≥0.9(male)/0.8(female), haemoglobin-A1c≥5.7%, total-cholesterol to high-density-lipoprotein-cholesterol ratio≥4.5(male)/4.0(female) and triglyceride≥1.7mmol/L. ALI was calculated by the sum of biomarkers that fall above increased-risk cutoffs, ranging from 0-6. Protective lifestyle included not-smoking, not-drinking, adequate physical activity(PA) defined by ≥150minutes moderate-intensity or ≥75minutes vigorous PA/week, fruit and vegetable consumption ≥5portions/week and sleep≥6hours/night. Associations between ALI and protective lifestyle were evaluated by multivariable linear regression, adjusted by age, gender, education level and employment status. Results: 48% subjects were men; mean age was 38.6 years (standard deviation(SD)=15.7). The mean ALI was 1.65 (SD=1.55). Increasing age, male gender, currently employed and secondary education or below were associated with increased ALI. Among the protective lifestyle, not-smoking(-0.247, p=0.017), adequate PA(-0.146, p=0.024) and adequate sleep(-0.457, p<0.001) had significant impact on ALI after adjusting for confounding socio-demographics. Conclusion: For the healthy general Hong Kong population, not-smoking, exercising and sleeping enough may reduce allostatic load. While smoking cessation and PA promotion are well-known and popular health promotion strategies, the importance of adequate sleep, an easily overlooked but important modifiable factor, should also be advocated.