Genetic and environmental contributions to the associations between midlife personality and late-life metabolic health.

Objective: Personality traits such as conscientiousness and emotional stability are consistently linked with better metabolic health, but there is limited evidence on the etiology of these associations and their robustness across the life-span.

Methods: Therefore, we estimated phenotypic, genetic, and unique environmental associations of traits indexed by the Multidimensional Personality Questionnaire in early-to-middle adulthood (mean age = 38.3 years) with BMI, waist circumference, high-density lipoprotein cholesterol, C-reactive protein, triglycerides, and glycated hemoglobin in older adulthood (mean age = 70.4 years) using the Minnesota Twin Registry sample (n = 950).

Results: Traits that indexed emotional instability in midlife, such as alienation and stress reactivity, were significant predictors of several metabolic outcomes late in life (bivariate |r| ≤ 0.22), whereas negative associations with traits related to conscientiousness (e.g., control, constraint, achievement) tended to be more modest. For most traits that were phenotypically associated, we observed significant genetic correlations. Additionally, alienation and stress reactivity had weak-to-moderate unique environmental correlations with BMI, waist circumference, and C-reactive protein (r_e = 0.10-0.29).

Conclusions: These results are consistent with an etiology of declining metabolic health into old age involving the propensity toward negative affective experiences decades prior, further validating the health relevance of individual differences in personality.