Aging and Chronic Disease
Objectives : Previous work in adults has shown that dehydration has negative effects on cognitive function. However, the effect of changes in hydration on cognitive function remain understudied in children. This is relevant since epidemiological data suggests that a large proportion of children in the United States exhibit highly concentrated urine, suggestive of insufficient hydration. This study aimed to determine the effects of changes in daily water intake on urinary markers of hydration and cognitive control among school-aged children.
Methods : 9-11-year-old children (N=82) completed a three-intervention crossover water intake intervention where they were asked to either maintain their regular water intake (ad libitum) or consume High [2.5L/d] or Low [0.5L/d]) water for 4 consecutive days. Following the interventions, cognitive control tasks requiring inhibition, working memory, and cognitive flexibility were assessed using a modified flanker, Go/NoGo, and color-shape switch tasks. During day 4 of each intervention, children collected their urine over a 24-hour period for urine color, urine specific gravity (USG), and osmolality assessment.
Hydration differed significantly between interventions. Urine color during the Low intervention was significantly higher than ad libitum and both were significantly greater than High intervention (Low: 6 [median] and 2 [iqr], ad libitum: 5 [median] and 2 [iqr], High: 3 [median] and 0 [iqr], all P ≤0.01). Similar intervention effects were observed for osmolality (Low: 912± 199, ad libitum: 790±257.0, High: 260±115 mOsmol/kg, all P < 0.001) and USG (Low: 1.023± 0.005, ad libitum: 1.020±0.007, High: 1.005±0.004, all P < 0.001). Ad libitum hydration was positively related to switch task performance. Benefits of the High intervention were observed during the switch task whereby participants exhibited lower working memory cost relative to the Low intervention. No significant changes in cognition were observed for the flanker and Go/NoGo tasks.
Conclusions : Children with better habitual hydration exhibited superior performance during the cognitive flexibility task. Additionally, the 4d water intervention resulted in significant changes in urinary markers of hydration and had selective benefits during task switching.
Funding Sources : Danone Research, Palaiseau, France