Association between factors in life course and physiological disorders among the middle-aged and older population in Zhoushan city of Zhejiang province.

Objective: To analyze the associations between factors in life course and physiological dysregulation in the middle-aged and elderly population in Zhoushan city of Zhejiang province, and the mediating roles of lifestyle and mental health.

Methods: A total of 1553 island residents aged ≥45 years were enrolled from the Zhejiang Metabolic Syndrome Cohort Zhoushan Liuheng Sub-cohort. The demographic information, life course information, lifestyle, and mental health information of participants were documented, and blood samples were collected. The status of aging was evaluated by physiological dysregulation calculation model developed by authors previously. The Shapley value decomposition method was used to assess the cumulative and relative contribution of multiple factors in life course to the aging. Principal component analysis and hierarchical cluster analysis were used to classify subgroups. General linear regression model was used to assess the associations between the life course subgroups and physiological dysregulation, and the key factors associated with aging were finally identified. Logistic regression model, general linear regression model, and mediation analysis model were used to assess the complex associations between life course subgroups, key factors, unhealthy lifestyle, mental health, and aging.

Results: Shapley value decomposition method indicated that eight types of life course factors explained 6.63%(SE=0.0008) of the individual physiological dysregulation variance, with the greatest relative contribution (2.78%) from adversity experiences in adulthood. The study participants were clustered into 4 subgroups, and subgroups experiencing more adversity in adulthood and having low educational attainment or experiencing more trauma and having poorer relationships in childhood had significantly higher levels of physiological dysregulation. Life course subgroups and key factors childhood trauma and health, adversity experience in adulthood, and lower education were positively associated with unhealthy lifestyles (β=0.12-0.41, P<0.05). In addition, life-course subgroups and key factor adversity experience in adulthood were positively associated with psychological problems (OR=2.14-4.68, P<0.05). Unhealthy lifestyle scores showed a marginal significant association with physiological dysregulation (β=0.03, P=0.055). However, no significant association was found between psychological problems and physiological dysregulation (β=0.03, P=0.748). The results of the mediation analysis model suggested that unhealthy lifestyles partially mediated the associations between life course subgroups, adversity experience in adulthood and physiological dysregulation, with the proportions mediated ranged from 3.9%-6.8%.

Conclusion: Multiple life course factors contribute about 6.63% of the variance in physiological dysregulation in the middle aged and elderly population of the study area; subgroups with adverse life course experiences have higher levels of aging; and the association may be partially mediated by unhealthy lifestyles.