Neuroticism, cognitive ability, and the metabolic syndrome: The Vietnam Experience Study.

OBJECTIVES The purpose of this study is to explore the association of neuroticism with the metabolic syndrome, separate components of the metabolic syndrome, and the number of components of metabolic syndrome an individual possesses. The purpose of this study is to examine also the extent to which any associations are accounted for by sociodemographic factors, health behaviors, and cognitive ability. METHOD Participants were 4208 men drawn from the Vietnam Experience Study. From military archives, and a later telephone interview and psychological and medical examination, sociodemographic, health behavior, cognitive ability, neuroticism, and health data were collected. Neuroticism and cognitive ability were assessed with standardized tests during the medical examination. Presence of the metabolic syndrome was based on body mass index, fasting blood glucose or a diagnosis of diabetes, high blood pressure or taking antihypertensive medication, high-density lipoprotein cholesterol, and triglyceride levels. RESULTS Neuroticism was positively associated with the occurrence of the metabolic syndrome and several of its components in both age-, and sociodemographic- and health behavior-adjusted analyses. Many associations were accounted for by individual difference in cognitive ability. Neuroticism was robustly associated with the number of components of the metabolic syndrome after adjustment. CONCLUSIONS Individuals with higher neuroticism scores had a higher prevalence of the metabolic syndrome and a larger number of its components. On the whole, differences in cognitive ability appeared to partially mediate the relationship between neuroticism and the metabolic syndrome.