The Cogstate Blog

Expert perspectives on improving cognitive measures from clinical trials to clinical practice.

Stay Hydrated Throughout The Day For Better Cognitive Performance

January 10, 2018

Right up there with taking ten thousand daily steps, drinking enough water is another recommended health goal to include in your New Year’s resolutions. While many of us try to maintain our weekly average hydration through the foods and beverages we consume, there can be fluctuations throughout each day, caused by our work or exercise schedules. If we get to the end of a day without adequately fueling our water-based cells, it can affect not only our physiological well-being but also, according to a new study, our cognitive performance.

According to the CDC, adults in the U.S. drink an average of 39 ounces of water per day, well below the Institute of Medicine’s recommendation of 91 ounces for women and 125 ounces for men. This doesn’t necessarily mean you have to drink 12-15 glasses of water, as we can get as much as 20% of our hydration needs from the food we eat.

In a new study, the effects of mild dehydration on changes in mood and cognition were measured against normal and rehydration states. Twelve healthy, adult women volunteers visited a lab on three consecutive days. At 5pm on Day 1, the control day, their hydration was measured along with their cognition, emotion and sensory perception. At 7am, noon and 5pm of Days 2 and 3, these tests were repeated. For half of the group, Day 2 was a dehydration day where their water intake was restricted while Day 3 was a euhydration day where water intake was back up to recommended levels. The other half of the population sample had Days 2 and 3 reversed.

“We hypothesized that mild dehydration would adversely impact executive function tasks, with no effects on simple tasks, and that these changes in cognitive performance are independent of changes in emotion,” summarized the researchers. “We further hypothesized that controlled fluid intake based on Recommended Daily Standards would improve or restore cognitive performance.”

A battery of computerized tests from Cogstate were used to test simple to complex cognitive tasks, including reaction time, visual attention, memory and executive function.

“The Cogstate battery used in our experiments is of value in assessing changes in cognitive function due to a specific intervention, and relied on tasks used commonly in cognitive neuroscience,” wrote the researchers. “We chose specific tests from the Cogstate battery because these have been designed to assess both simple cognitive change as well as neurophysiological changes in executive function, acquisition, storage, and use of new knowledge. We therefore consider these tests to be objective and reliable to detect small changes that might occur in response to mild changes in hydration in free living adults.”

The results confirmed the hypotheses with significant changes seen in the more complex cognitive tasks, even after the short period of dehydration with results rebounding back to normal after rehydration.

“Our primary findings were that while healthy, active women maintained body water during activities of daily living, when we induced mild dehydration these subjects increased errors on complex cognitive tasks that measure memory and learning during these same activities,” concluded the study authors. “Importantly, when we controlled hydration to meet IOM standards, women restored performance on these same cognitive tests compared to dehydration, and even improved performance on the test that measured cognitive flexibility.”

Bottom line for all adults is to try to get your daily ounces of water in just as you try to get your steps in. It will boost your end of day cognitive performance and recharge you for a better tomorrow.