Water intake reverses dehydration associated impaired executive function in healthy young women.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 29277553 · doi:10.1016/j.physbeh.2017.12.028
What was done
Twelve healthy young women (age 26 ± 5 years, BMI 22.5 ± 2.6 kg/m²) completed three experimental conditions. Session 1 was a control session with ad libitum intake and activity tracking. Sessions 2 and 3 were completed in balanced order: a dehydration session with minimized fluid intake and a euhydration session with fluid intake set to recommended daily levels (2500 ml/24 h). Subjective state and cognitive performance (Cogstate battery) were measured at baseline (5:00 PM the evening prior) and at 7:00 AM, 12:00 PM, and 5:00 PM during each test day. Urine specific gravity was tracked as a marker of hydration status.
What was found
Baseline urine specific gravity was similar across conditions (1.013 to 1.015), but by 5:00 PM on the test day it rose to 1.021 ± 0.002 in the dehydration condition versus 1.011 ± 0.003 in control and 1.010 ± 0.002 in euhydration (P < 0.05). Fluid manipulation did not affect Detection, Identification, or One-Card Learning tasks. Euhydration significantly reduced errors on the Groton Maze Learning Test of visual and working memory (33.9 ± 10.9) compared to control (40.1 ± 11.1) and dehydration (40.5 ± 10.1, P < 0.05). Executive function errors on the Set Shifting task were also lower under euhydration at 5:00 PM (17.8 ± 6.2) compared to baseline (22.5 ± 12.7, P < 0.05).
Why it matters
This study provides experimental evidence that consuming recommended daily fluid intake (2.5 L/day) can restore visual working memory and executive function in young women experiencing mild daytime dehydration.
Limits
The sample size was very small (n = 12) and exclusively composed of healthy young women, limiting generalizability to men, older individuals, or clinical groups. Participants could not be blinded to fluid intake interventions.
Cited by
- supports Mild dehydration can impair both cognitive and physical performance.