International journal of epidemiology
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The association between socioeconomic circumstances and health in adulthood could come about through processes that may be divided into factors experienced early in life and those experienced in later adulthood. In order to disentangle the influences on health of the early genetic, prenatal and rearing environmental factors from environmental factor later in life, we compared the health status among male and female twin pairs who lived together during childhood and were discordant or concordant on adult socioeconomic position. ⋯ This study suggests that the relationship between adult social class and health outcomes in Denmark is due mainly to selection effects rather than a causal effect of social class exposures on health and behaviour.
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Several studies in older people have shown that grip strength predicts all-cause mortality. The mechanisms are unclear. Muscle strength declines with age, accompanied by a loss of muscle mass and an increase in fat, but the role that body composition plays in the association between grip strength and mortality has been little explored. We investigated the relation between grip strength, body composition, and cause-specific and total mortality in 800 men and women aged 65 and over. ⋯ Grip strength is a long-term predictor of mortality from all-causes, cardiovascular disease, and cancer in men. Muscle size and other indicators of body composition did not explain these associations.