Cognitive Epidemiology

Cognitive epidemiology is a field of research that examines the associations between intelligence test scores and health, more specifically morbidity (mental and physical) and mortality. Typically, test scores are obtained at an early age, and compared to later morbidity and mortality. In addition to exploring and establishing these associations, cognitive epidemiology seeks to understand causal relationships between intelligence and health outcomes. Researchers in the field argue that intelligence measured at an early age is an important predictor of later health and mortality differences.

Among the findings of cognitive epidemiology is that men with a higher IQ have less risk of dying from coronary heart disease. The association is attenuated, but not removed, when controlling for socio-economic variables, such as educational attainment or income. This suggests that IQ is an independent risk factor for mortality.

A strong inverse correlation between early life intelligence and mortality has been shown across different populations, in different countries, and in different epochs.” Various explanations for these findings have been proposed:

“First, …intelligence is associated with more education, and thereafter with more professional occupations that might place the person in healthier environments. …Second, people with higher intelligence might engage in more healthy behaviours. …Third, mental test scores from early life might act as a record of insults to the brain that have occurred before that date. …Fourth, mental test scores obtained in youth might be an indicator of a well-put-together system. It is hypothesized that a well-wired body is more able to respond effectively to environmental insults…”

A study of one million Swedish men found showed “a strong link between cognitive ability and the risk of death.”

People with higher IQ test scores tend to be less likely to smoke or drink alcohol heavily. They also eat better diets, and they are more physically active. So they have a range of better behaviours that may partly explain their lower mortality risk.
—-Dr. David Batty

A similar study of 4,289 former US soldiers showed a similar relationship between IQ and mortality.