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Thursday, February 13, 2014

Will a fast reaction time save your life?

Researchers led by Gareth Hagger-Johnson from University College London examined the relationship between reaction time and mortality. According to their results, you’d better hope you’re quick at the draw.

Over five thousand people aged 20-59 participated in a set of simple reaction tests. They were asked to press a button as soon as they saw a ‘0’ appear on the screen in front of them. Each person performed fifty trials. Educational level reached, smoking, drinking and physical activity were all self-reported. Body mass index, blood pressure and metabolic factors were assessed during clinical exams.

People with longer reaction times were significantly more likely to die during the fifteen year follow-up period.

Now for the caveats.

From the paper itself:

Adjusted for age, participants who died were more likely to be male, have lower socio-economic position, were physically inactive, and smoked cigarettes and drank alcohol more heavily.
You don’t say.

The authors claim that there was still a noticeable effect even after accounting for health and behavioral variables. However, they also point out that reaction time and cognition tends to be inversely related. That is, people who have a lower cognitive ability also have slower, more variable reaction times. It also turns out that lower cognitive ability by itself is associated with higher mortality.

Given that the authors lump all causes of death together, I don’t think this study says all that much. I wouldn’t rush to test my own reaction time as a harbinger of my coming demise.

Gareth Hagger-Johnson, Ian J. Deary, Carolyn A. Davies, Alexander Weiss, & G. David Batty (2014). Reaction Time and Mortality from the Major Causes of Death: The NHANES-III Study PLOS ONE DOI: 10.1371/journal.pone.0082959