Despite decades of research on the relationship between socioeconomic status (SES) and health, key questions remain unresolved. First, studies seldom examine mechanisms underlying the SES-health gradient. Second,... [ view full abstract ]
Despite decades of research on the relationship between socioeconomic status (SES) and health, key questions remain unresolved. First, studies seldom examine mechanisms underlying the SES-health gradient. Second, operationalization of SES continues to be problematic. Measures of SES (i.e., education, occupation, income, and their composites) tend to be used and interpreted interchangeably in twin studies. We analyzed the extent to which childhood and adult SES moderate genetic and environmental influences on health in an attempt to better understand mechanisms by which inequality contributes to health. We also evaluated the effects of different SES measures on health outcomes.
Method. Participants were ~1000 monozygotic and dizygotic male twins ages 51-60 (“age 56”) and 56-67 (“age 62”) from the Vietnam Era Twin Study of Aging (VETSA). Objective health (OH) was a count of 15 major chronic health conditions elicited by the question “have you ever been told by a physician that you had any of the following conditions or illnesses.” Subjective health (SH) was assessed with the question: “In general, how would you rate your health?” (excellent to poor) from the SF-36v1. OH and SH were correlated 0.30. Measures of SES included own, spouse, maternal and paternal occupation and education, own income, and the Hollingshead-Redlich social status index (HR-Index) which combines occupation with education across spouses using a weighted formula. Separate childhood and adult HR-Indices were created.
Results. Both OH and SH were significantly heritable and consistent over time (h2=0.37; 0.31 OH56, OH62 respectively; h2-=0.33, 0.30; SH56, SH62 respectively). Remaining variance was primarily explained by unique environmental influences with very small effects for common environment. There was evidence for significant new genetic and environmental influences specific to OH62 and SH62. Moderator effects varied according to SES measure and outcome. For instance, the current—but not maximum—adult HR-Index moderated means and variance for SH62. Unique environmental variance for SH62 was significantly higher for lower SES men.
We discuss the impact of different SES measures, reasons for the differential effects of SES on genetic and environmental influences on health, and we consider the challenge of such characteristics as age, gender, cohort, culture and time.
Ageing , Health (e.g., BMI, Exercise) , Other
