Hydration and cognitive function are closely related
By Yanhong He, PhD student in the Food Science and Technology Department, College of Agriculture and Life Sciences, Virginia Tech
Dr. Benjamin Katz, assistant professor in the department of Human Development and Family Science at Virginia Tech, gave a wonderful presentation to students enrolled in the class of Water for Health: Interdisciplinary Seminar (GRAD 5414) this spring. The topic is that hydration and cognition are closely linked. Adequate hydration is necessary for human homeostasis and survival. Water acts as a transporter of nutrients and as the regulator of body temperature. Water balance is affected by dietary intake, physical activity, age, as well as environmental condition. Furthermore, euhydration is important for optimal cognitive function, while dehydration could negatively affect cognitive performance of human.
Major domains of cognition include intelligence, memory, attention, judgment, social cognition and executive functions. Executive functions are closely linked to many aspects of daily life, such as working memory, inhibitory control and cognitive flexibility. These functions can both impact and be impacted by our physical health. Healthy behaviors such as exercise can improve executive function. Hydration may be particularly important for maintaining executive function in specific populations, for instance, athletes, or older adults at risk for dementia.
The main water losses for humans occur via the respiratory system, skin and kidneys. Natural thirst sensations will send signals out to prompt fluid intake. Normally, the thirst sensation is a sufficient stimulus for adequate fluid intake to maintain water balance. However, under some stressful conditions, such as environmental temperature increase and physical exercise, thirst may not be enough to trigger fluid intake to compensate for body fluid losses.
Dehydration may produce negative effects on human beings. Mild dehydration, which refers to more than 1% of fluid loss of body weight, could decrease of exercise performance and the ability to control body temperature. Up to or more than 5% of fluid loss is considered severe dehydration. It makes people have difficulty with concentration and inhibitory control. And it introduces other negative effects, including headaches, irritability, sleeplessness and increase of respiratory rate. Still, too few studies about chronic eu- or dehydration exist to draw strong conclusions. A limited number of cross-sectional/long-term studies indicate a need for more work into the effects of chronic dehydration and euhydration.
It is important for us to maintain hydration status to sustain the normal cognitive functioning. It could be achieved by intake of fluids, drinking enough water daily, and eating water-rich fruits or vegetables. Further studies on hydration status and cognitive function are still needed.