Researchers here investigate another easy measure that correlates with mortality rates, confirming results seen in earlier studies. Insofar as reaction time is a function of rising levels of damage in brain and nervous system tissue the correlation seems plausible, but as the researchers point out there is no good understanding of the exact mechanisms involved.
In a representative sample of adults, slower and more variable performance on a simple reaction time task was associated with increased rates of both all-cause and cardiovascular disease mortality over a follow-up period of approximately 15 years. The association between reaction time variability and mortality remained after adjustment for reaction time mean, and was therefore not accounted for by the tendency for people with more variable reaction times to have slower responses.
Mechanisms underlying the association between slower and more variable reaction times and mortality risk are not known. One hypothesis concerns 'system integrity', which suggests that since bodily systems deteriorate with age, slower and more variable reaction times reflect a central nervous system that is deteriorating in parallel with other bodily systems. Given the correlated heterogeneity in the aging of these systems, slower and more variable reaction times in adulthood might indicate poor physiological functioning across several bodily systems, any of which might increase risk of death in turn.
Our results demonstrate that slower and more variable reaction times are predictors of mortality risk in a representative population sample. Priorities for future research should include identifying the mechanisms underlying these associations. Since reaction time can be measured at low cost relatively quickly, it should be measured routinely in epidemiological studies.