British Journal of Nutrition

Human and Clinical Nutrition

Mild dehydration impairs cognitive performance and mood of men

Matthew S. Ganioa1a2, Lawrence E. Armstronga2 c1, Douglas J. Casaa2, Brendon P. McDermotta2, Elaine C. Leea2, Linda M. Yamamotoa2, Stefania Marzanoa2, Rebecca M. Lopeza2, Liliana Jimeneza3, Laurent Le Bellegoa3, Emmanuel Chevillottea3 and Harris R. Liebermana4

a1 Texas Health Presbyterian Hospital, Institute for Exercise and Environmental Medicine, Dallas, TX 75231, USA

a2 Human Performance Laboratory, University of Connecticut, Unit 1110, Storrs, CT 06269-1110, USA

a3 Danone Research, R&D Waters, Palaiseau 91767, France

a4 US Army Research Institute of Environmental Medicine, Military Nutrition Division, Natick, MA 01760, USA


The present study assessed the effects of mild dehydration on cognitive performance and mood of young males. A total of twenty-six men (age 20·0 (sd 0·3) years) participated in three randomised, single-blind, repeated-measures trials: exercise-induced dehydration plus a diuretic (DD; 40 mg furosemide); exercise-induced dehydration plus placebo containing no diuretic (DN); exercise while maintaining euhydration plus placebo (EU; control condition). Each trial included three 40 min treadmill walks at 5·6 km/h, 5 % grade in a 27·7°C environment. A comprehensive computerised six-task cognitive test battery, the profile of mood states questionnaire and the symptom questionnaire (headache, concentration and task difficulty) were administered during each trial. Paired t tests compared the DD and DN trials resulting in >1 % body mass loss (mean 1·59 (sd 0·42) %) with the volunteer's EU trial (0·01 (sd 0·03) %). Dehydration degraded specific aspects of cognitive performance: errors increased on visual vigilance (P = 0·048) and visual working memory response latency slowed (P = 0·021). Fatigue and tension/anxiety increased due to dehydration at rest (P = 0·040 and 0·029) and fatigue during exercise (P = 0·026). Plasma osmolality increased due to dehydration (P < 0·001) but resting gastrointestinal temperature was not altered (P = 0·238). In conclusion, mild dehydration without hyperthermia in men induced adverse changes in vigilance and working memory, and increased tension/anxiety and fatigue.

(Received September 06 2010)

(Revised March 17 2011)

(Accepted March 17 2011)

(Online publication June 07 2011)


c1 Corresponding author: Dr L. E. Armstrong, fax +1 860 486 1123, email


Abbreviations: DD, exercise-induced dehydration plus a diuretic; DN, exercise-induced dehydration plus placebo containing no diuretic; EU, euhydration plus placebo