The Effect of Mild Dehydration Induced by Heat and Exercise on Cognitive Function

Abstract

Background: Past studies have demonstrated cognitive impairment after dehydration, though results are not always consistent. Methodological differences may account for these discrepancies. Therefore, the purpose of the present study was to determine the effects of mild dehydration on various domains of cognitive function.
Methods: Twenty-seven men (n=14; 26.9±4.6 years; 176.3±6.6 cm; 79.1±9.0 kg) and women (n=13; 27.3±4.3 years; 171.0±6.5 cm; 66.5±4.5 kg) participated in the study. Subjects were dehydrated to approximately 2% body mass loss via treadmill running and sauna. Measurements were collected prior to and after dehydration. Cognitive function tests included: Finger tapping, symbol digit coding, Stroop, and shifting attention tests.
Results: Reaction time during the shifting attention test was significantly lower from pre-testing to post-testing (PRE: 882.67±126.59 ms; POST: 830.00±105.83 ms; p=0.0012). The Stroop reaction time was significantly lower from pre-testing to post-testing (PRE: 712.56±97.52 ms; POST: 671.63±97.21 ms; p=0.02). No significant changes were observed in any other measurements.
Conclusion: Dehydration may enhance cognitive functioning in the areas of Stroop reaction time and reaction time during the shifting attention test.