Genetic and Environmental Mediation of the Associations Between Self-rated Health and Cognitive Abilities

Abstract

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 (≥67 years), associations between self-rated health and spatial reasoning, perceptual speed, and visual memory were entirely due to genetic factors.

The Swedish Adoption/Twin Study of Aging (SATSA) is supported by the John D. and Catherine T. MacArthur Foundation Research Network on Successful Aging, the U.S. National Institute on Aging (grants AG-04563, AG-10175), and the Swedish Council for Social Research (97:0147:1B).

Notes

^a Self-rated health is summed over four questions (1. How would you rate your general health status? 2. How would you rate your general health status compared to 5 years ago? 3. How would you rate your health status compared to others in your age group? 4. Do you think your health prevents you from doing things you would like to do?) The items were standardized to a mean of 0 and a standard deviation of 1 before summing.

Note. All individuals with data available regardless of pair status. ^a Controlling for age and sex within age group. ∗∗p < .01; ∗p < .05.

Note. Number of twin pairs in parentheses. ∗∗p < .01; ∗p < .05.

Note. All variables are adjusted for age and sex within age group. ^a Most parsimonious model according to AIC is the AE—a₂₁ models (no E(e₂₁) covariance); hence, genetic and environmental components of the phenotypic correlations (r_p ) are calculated from best-fitting models. a₂₁-e₂₁ denotes cross-paths included.