Impact of Hydration Status on Cognitive Performance

Abstract

Background: Adequate hydration is essential for maintaining physiological balance and optimal brain function. Even mild dehydration has been suggested to impair cognitive processes such as attention, memory, and executive function. Despite growing interest, findings across studies remain inconsistent due to variations in methodology, population characteristics, and definitions of hydration status. Understanding this relationship is particularly important in environments where dehydration risk is elevated, such as hot climates or during prolonged physical or mental activity.

Objective: This study aimed to evaluate the impact of hydration status on cognitive performance and to determine whether mild dehydration significantly affects specific cognitive domains in healthy adults.

Methodology: A cross-sectional study was conducted involving 120 healthy participants aged 18–35 years. Hydration status was assessed using urine specific gravity and self-reported fluid intake. Participants were categorized into euhydrated and mildly dehydrated groups. Cognitive performance was evaluated using a standardized battery of neuropsychological tests measuring attention, working memory, processing speed, and executive function. Statistical analyses, including independent t-tests and multiple regression models, were used to examine differences between groups and control for potential confounding factors such as age, sleep quality, and physical activity.

Results: The study included 120 participants, divided into euhydrated (n=62) and mildly dehydrated (n=58) groups. Findings showed that mildly dehydrated participants performed significantly worse in attention (p<0.001) and working memory (p<0.001) compared to the euhydrated group. No significant differences were observed in processing speed (p=0.12) and executive function (p=0.21). Urine specific gravity confirmed hydration classification, with higher values in the dehydrated group. Regression analysis identified hydration status as a significant predictor of attention even after adjusting for confounders. Overall, mild dehydration selectively impaired certain cognitive domains, particularly those related to attention and short-term memory performance.