Diabetologia. 2008 Mar;51(3):436-43. doi: 10.1007/s00125-007-0908-5. Epub 2008 Jan 18.

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

Batty GD¹, Gale CR, Mortensen LH, Langenberg C, Shipley MJ, Deary IJ.

Author information

¹MRC Social and Public Health Sciences Unit, University of Glasgow, 4 Lilybank Gardens, Glasgow G12 8RZ, UK. david-b@sphsu.mrc.ac.uk

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 HDL-cholesterol. 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.