School of Exercise Science, Sport & Health, Charles Sturt University, Bathurst, Australia.
School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology, Melbourne, Australia.
Physiol Behav. 2019 May 15;204:297-308. doi: 10.1016/j.physbeh.2019.03.008. Epub 2019 Mar 12.
Hypohydration is generally considered to have a negative effect on cognitive function, despite several studies reporting comparable findings between hydration states. Recommendations to avoid moderate dehydration (≥ 2% loss in body mass) are commonly made to athletes, on the provision that this deficit may impair optimal cognitive performance. To determine whether cognitive function is impaired by hypohydration, and investigate the existence of the proposed critical water deficit of ≥2% loss in body mass purported to diminish cognitive performance, we conducted a systematic search of the literature and examined appropriate studies by meta-analysis. Overall, cognitive performance was not found to be impaired by hypohydration (g = -0.177; 95% CI = -0.532-0.179; P = .331). Nor were the underlying cognitive domains (complex attention, executive function, learning and memory) impaired (all P > .236), independent of the incurred fluid loss (less than or >2% loss in body mass), although results were not always homogenous (I ranging between 0% and 93%). Collectively, these results suggest that hypohydration may not compromise cognitive function, nor any of the investigated subdomains to a greater extent than if euhydration had been maintained. Furthermore, recommendations to avoid moderate hypohydration on the basis of maintaining optimal cognitive function are not substantiated by this meta-analysis.
脱水通常被认为对认知功能有负面影响，尽管有几项研究报告称在水合状态下有类似的发现。建议运动员避免中度脱水（体重损失≥2%），因为这种不足可能会损害最佳认知表现。为了确定脱水是否会损害认知功能，并研究拟议的≥2%体重损失的临界水缺失是否会降低认知表现，我们系统地搜索了文献，并通过荟萃分析检查了适当的研究。总的来说，脱水并没有导致认知功能受损（g= -0.177；95%CI= -0.532-0.179；P= 0.331）。基础认知领域（复杂注意力、执行功能、学习和记忆）也没有受损（所有 P>0.236），与所发生的液体损失无关（体重损失小于或大于 2%），尽管结果并不总是一致（I 值在 0%到 93%之间）。总的来说，这些结果表明，脱水可能不会损害认知功能，也不会比保持水合状态更严重地影响任何被调查的子领域。此外，本荟萃分析并没有证实基于保持最佳认知功能而避免中度脱水的建议。
