[Paleopsych] Discover Mag: We Find Out Why Stupid People Usually Die Young

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We Find Out Why Stupid People Usually Die Young
DISCOVER Vol. 27 No. 01 | January 2006 | Mind &  Brain

At Last: We Find Out Why Stupid People  Usually Die Young

In 2001 researchers in Great Britain were surprised to discover that 
people with low IQs live shorter lives. But a more startling finding came 
this year with a report that reaction time proved an even stronger 
predictor of life span than IQ.

Ian Deary, a psychologist at the University of Edinburgh, and Geoff Der, a 
statistician at the MRC Social and Public Health Sciences Unit in Glasgow, 
suspected that higher IQ might lead to healthier habits like not smoking 
or healthier environments like safer office jobs. So they looked at data 
on 898 people first tested at about age 56, and then tracked their 
survival until age 70. They found that the link between IQ and mortality 
held strong even after adjusting for education, occupation, social class, 
and smoking.

But the group had also taken button-pressing reaction-time tests, which 
measure how quickly and accurately a person repeatedly makes a simple 
decision. Deary and Der wanted to find out whether there was still a 
relationship between mental ability and survival once a person's reaction 
time was taken into account. "And there wasn't," Deary says. The upshot: 
"We could explain the association between mental ability and survival with 
reaction time."  In this study, the reaction times tested in subjects at 
age 56 appeared to have about as strong a link to chances of survival over 
the next 14 years as did being a smoker.

Why is still uncertain. One possibility is that reaction time slows 
because an undetected disease has begun to compromise performance. 
Another hypothesis is that the differences result from more fundamental, 
lifelong variations in the speed at which people process information. Both 
factors could be at work. For clues, Deary hopes to track a younger sample 
over several years.

The study has sparked interest in what its authors call "cognitive 
epidemiology," the study of associations between mental ability tests and 
health outcomes. "One of the indicators of whether mental ability tests 
are useful is whether they predict things about real life," Deary says, 
and these findings suggest they do.

Marina Krakovsky