Pre-morbid intelligence, the metabolic syndrome and mortality: the Vietnam Experience Study

Abstract

Aims/hypothesis We examined the relationship between pre-morbid intelligence quotient (IQ) and the metabolic syndrome, and assessed the role of the metabolic syndrome as a mediating factor in the association of IQ with total and cardiovascular disease (CVD) mortality. Methods In this cohort study, 4,157 men with IQ test results from late adolescence or early adulthood [mean age (range) 20.4 (16-30) years] attended a clinical examination in middle-age [38.3 (31-46) years] at which the components of the metabolic syndrome were measured. They were then followed for 15 years to assess mortality. Results In age-adjusted analyses, IQ was significantly inversely related to four of the five individual components comprising the metabolic syndrome: hypertension, high BMI, high triglycerides and high blood glucose, but not low HDLcholesterol. After controlling for a range of covariates that included socioeconomic position, higher IQ scores were associated with a reduced prevalence of the metabolic syndrome itself (odds ratio 1 SD increase in IQ 0.87, 95% CI 0.78-0.98). Structural equation modelling revealed that education was not a mediator of the relationship between IQ and the metabolic syndrome. The metabolic syndrome partially mediated the relationship between IQ and CVD but not that between IQ and total mortality. Conclusions/interpretation In this cohort, higher scores on a pre-morbid IQ test were associated with a lower prevalence of the metabolic syndrome and most of its components. The metabolic syndrome was a mediating variable in the IQ-CVD relationship. Diabetologia (2008) 51:436-443

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“…In these analyses we adjusted first for age at telephone survey, and then additionally for variables that we conceptualised as potential confounding factors (place of service, ethnicity, marital status, smoking habit, alcohol consumption, IQ at enlistment, household income in midlife, body mass index, total cholesterol, systolic blood pressure, blood glucose, and somatic illness). These covariates were chosen a priori as they have all been associated with mortality in this dataset (23,36) and others (37). In the event that controlling for covariates attenuated the significance of relationships between the independent and dependent variables, we estimated the percentage effect of controlling for the covariates using the following formulae as we have elsewhere (38) .…”

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

“…This consists of two subtests, verbal and arithmetic reasoning, and compares well with components of the Wechsler Adult Intelligence Scale (31). Scores were standardised to z-scores for ease of interpretation.…”

Generalized Anxiety Disorder is Associated With Reduced Lung Function in the Vietnam Experience Study

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