B-29 Free Communication/Poster - Hydration and Performance: JUNE 2, 2010 1:00 PM - 6:00 PM: ROOM: Hall C
Adverse effects of dehydration on cognition appear to begin at 2% body mass loss, and may be present at a level of 1%. However, specific behavioral functions most likely to be affected by dehydration have not been established.
PURPOSE: To assess effects of mild dehydration on cognitive performance and mood of healthy young males.
METHODS: Twenty-six men (age, 20.0 ± 0.3 y; mean ± SD) participated in 3 placebo-controlled, randomized, single-blind, repeated measure trials (9.8 h each, separated by >4 d) designed to produce different hydration states: exercise-heat dehydration (D; three 40-min treadmill walks at 5.6 km/h, 5% grade, 28°C), D plus diuretic ingestion (D+F; 40 mg furosemide), and control (CON; exercise, body mass maintained by water intake). A comprehensive computerized 6-task cognitive test battery (CTB), Profile of Mood States (POMS) questionnaire, and visual analog scales (VAS; headache, concentration, task difficulty) were administered during each trail.
RESULTS: Paired t-tests compared all D and D+F trials that ended in >1% (1.59 ± 0.42%) body mass loss to CON (0.12 ± 0.06%). Dehydration degraded specific aspects of cognitive performance: visual working memory response latency was slowed (P=.021), and errors increased on visual vigilance (P=.048). Fatigue (POMS) increased (P=.026) due to dehydration. Resting gastrointestinal temperature (Tgi) was not altered by dehydration but plasma osmolality (Posm) increased (P=.001). In a similar study, we observed greater effects of mild dehydration (-1.39%) on mood in women as assessed by POMS and VAS than men. Fatigue (p<.001), tension (p<.023), vigor (p<.002), confusion (p<.003) (POMS) and concentration (VAS) deteriorated (p<.001), whereas headache (p<.002) as well as perceived task difficulty (p<.001) increased in women. These findings suggest that men are less able than women to detect the effects of mild dehydration on cognitive state. This may be due to the fact that men had smaller increases of Tgi and Posm than women, even though their level of dehydration was slightly greater.
CONCLUSION: Mild dehydration of 1.59% in men had subtle adverse effects on visual working memory, visual vigilance, and perception of fatigue. Other CTB variables were not affected. Funded by Danone Research, France.