Proper hydration of only 4 days increases the cognitive flexibility in preadolescents (9-12 years old)
More and more evidence suggests that there is insufficient hydration among children, on a global scale. Epidemiological examination of urine osmolality, an important hydration marker, suggested that more than half of the children in the United States have highly concentrated urine (≥800 mOsmol/kg), indicating insufficient hydration.
Information on hydration in children from other countries is not very extensive, but we found out from a large survey conducted in 13 countries that more than 60% of children did not have an adequate fluid intake. Moreover, it has been reported that in some countries, up to 50% of children have limited or no free access to water while at school. This situation is all the more alarming as the implications of hydration on children’s health are not very well known.
Dehydration is defined as the process of water loss, below the basic value, which is necessary to maintain the body’s functions. In adults, dehydration was mainly correlated with decreased attention, short-term memory impairment and psychomotor function. Children may be at a higher risk for insufficient hydration because they depend on adults for regular access to water and have a higher daily need for water, relative to body weight.
Previous research in this area has suggested that increased hydration markers, such as urine osmolality, are associated with poorer short-term memory performance in children. Better hydration can have benefits for memory and visual attention. For example, in the study by Perry et al., they examined the changes in working memory and attention in children aged 9 to 12, by providing them with 500 ml to 750 ml of water throughout the morning, compared to the situation in which they were not hydrated during working hours. The study indicated that hydration had a positive impact on their school performance. Specifically, cognitive function was moderately influenced by normal hydration. This was an immediate effect analysed, but they wanted information regarding the prolonged effects on cognitive function, depending on the water intake analysed over several days.
Cognitive control, often referred to as executive function, comprises a set of interrelated but also dissociable, higher-order cognitive processes, including inhibition (the ability to resist distractions and maintain concentration and the ability to inhibit a dominant response in favour of a less learned response), working memory (the ability to keep information in our minds and manipulate it for later use) and cognitive flexibility (the ability to dynamically change attention and change response). These processes are extremely important for performance in many daily activities. Higher performance of the cognitive control function is predictive of higher-level studies, which allow for higher education, higher incomes, and higher socioeconomic status.
In this study, the children received additional hydration that began at 8:00, when participants received a 500 ml bottle, and were instructed to drink water during regular school breaks (four breaks between lessons).
Children who consumed the extra amount of water performed better after drinking more than 0.5 L of water during the morning, compared to the group that did not consume this extra amount. We remind you that for children, the recommended values of daily water intake are 44 ml/kg for boys and 39 ml/kg for girls.