Genetic and environmental mediation of the associations between self-rated health and cognitive abilities.

This study examined the relationship between self-rated health and cognitive abilities. First, the authors investigated whether common complex diseases mediate the associations between self-rated health and cognitive abilities. Slight evidence was found that associations between self-rated health and cognitive test scores were mediated by chronic diseases. Second, the authors explored the genetic and environmental mediation of these relationships using bivariate quantitative genetic analyses. In the younger age group (<67 years), associations between self-rated health and spatial reasoning and perceptual speed were mediated by both genetic and nonshared environmental factors. In the oldest age group (>or=67 years), associations between self-rated health and spatial reasoning, perceptual speed, and visual memory were entirely due to genetic factors.