Water for the brain

You might have a bottle or glass of water handy as you read this. We were designed to drink water, so it makes sense that we should make it our main beverage. Does it make you think better? There doesn’t appear to be many studies on water’s ability to improve brain function under our normal daily living conditions. Now, two research papers on kids hints that a water bottle on the school desk could improve cognition.

Very few studies are conducted on children for ethical reasons, so it’s no surprise that, until these two studies were done, only one other research paper had been done on kids, dehydration and thinking skills.

Water improves memory
Forty children aged 8-9 years were selected from two schools in Wales. The kids were tested mid-afternoon on two different days, one when they were given a 300 mL drink of water and one where they weren’t given water. Cognitive testing, lasting for about eight minutes, was scheduled for 30 mins later. The classroom temperature was around 20ºC (68ºF), quite pleasant, although chilly outside. Those that were given water, and observed to drink it, had a better memory (word recall) than those that weren’t given water.

A second study was of 58 children, aged 7-8 years, with half of them receiving 250 mL of additional water. Twenty minutes later they were given a range of cognitive tests. The water drinkers again did better in the tests, such as answering questions after a short story and “spot the difference” between similar cartoon pictures.

Drinks break
Water consumption during sport and hot weather has been encouraged for many decades. Coaches call for a drinks break during training because they know kids and adults function better physically when they are well hydrated. Adult cognitive function begins to decline when they are 1% or more dehydrated (that’s a 70kg adult losing 700 mL of sweat). Less is known about children because they are rarely subjects in dehydration studies. These two studies may be the trigger to start further research to find out how fluid affects young thinking.

What does it all mean?
Both studies were done in the UK when the ambient temperature was less than 10ºC (50ºC) so the kids weren’t likely to be dehydrated after playing outside as they might be during an Australian summer. As young children have an immature thirst mechanism they may become mildly dehydrated when distracted by play and classroom activities and “forget” to drink water. The studies do suggest that the practise of having water bottles in classrooms could well be having educational dividends. Just to think how much smarter I could have been with a water bottle by my side during the physics and chemistry classes. I might have at least remembered Boyle’s Law.

References: Appetite 2009; 52: 776-779; Appetite 2009; 53: 143-146