Dehydration Impairs Cognitive Performance: A Meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of experimental trials
PubMed 29933347 · doi:10.1249/MSS.0000000000001682
What was done
The authors conducted a systematic literature review and multivariate meta-analysis of 33 studies (providing 280 effect size estimates from 413 subjects) to examine the impact of dehydration (ranging from 1% to 6% body mass loss) across various cognitive domains, outcome measures (accuracy, reaction time), and dehydration induction methods.
What was found
Dehydration resulted in a small but significant overall impairment across all cognitive domains and outcomes (ES = -0.21; 95% CI: -0.31 to -0.11; P < 0.0001) with significant heterogeneity (Q(279) = 696.0, P < 0.0001; I² = 37.6%). Significant impairments were observed in attention (ES = -0.52; 95% CI: -0.66 to -0.37), motor coordination (ES = -0.40; 95% CI: -0.63 to -0.17), and executive function (ES = -0.24; 95% CI: -0.37 to -0.12) (all P ≤ 0.01), which differed from reaction time tasks (ES = -0.10; 95% CI: -0.23 to 0.02; P < 0.001). Impairment increased with greater body mass loss (P = 0.04), showing larger effects for >2% loss (ES = -0.28; 95% CI: -0.41 to -0.16) versus ≤2% loss (ES = -0.14; 95% CI: -0.27 to 0.00).
Why it matters
This review establishes that acute dehydration causes domain-specific cognitive deficits—most prominently affecting attention, motor coordination, and executive function—with impairment escalating significantly when fluid deficits exceed 2% of body mass.
Limits
The total pooled sample was modest (413 participants across 33 trials), reflecting small individual study sizes. Substantial heterogeneity was present across trials due to varying dehydration protocols, cognitive testing batteries, and outcome measures.
Cited by
- supports Mild dehydration can impair cognitive and physical performance.
- partial Even mild dehydration causes measurable reductions in cognitive and physical performance.
- partial Even a slight degree of dehydration diminishes cognitive and physical performance.
- context Even a slight degree of dehydration can impair cognitive and physical performance.
- supports Mild dehydration can diminish both cognitive and physical performance.
- partial Even mild dehydration diminishes cognitive and physical performance.
- supports Even a slight degree of dehydration can impair cognitive and physical performance.
- context Even slight dehydration impairs cognitive and physical performance.