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Drinking water boosts your brain's performance

Teresa Tanoos's picture
Drinking 3 cups of water before test boosts brain's performance

Drinking water is known to be healthy for your body, but it also boosts your brain’s performance in mental tests, according to a new study published in the journal Frontiers in Human Neuroscience.

The study, conducted by researchers from the University of East London and the University of Westminster in the UK, analyzed the potential effects of water on cognitive performance and mood among 34 participants with an average age of 29 years.

For the study, the 34 participants took part in a "water" and a "no water" experiment one week apart as follows:

1. The "water" experiment required participants to complete a number of mental tests after eating a cereal bar and drinking some water.

2. The "no water" experiment meant the participants consumed just the cereal bar alone. The amount of water drunk by the participants in the "water" test depended on their level of thirst.

"Our study found that reaction times were faster after people drank water, particularly if they were thirsty before drinking," said lead study author, Dr. Caroline Edmonds of the University of East London School of Psychology.

For both of the experiments, participants were asked to fast overnight, not consuming any food or drink after 9pm the night before testing.

They were assessed via three measurements: 1) a thirst scale; 2) a mood scale; and 3) with a computer-administered variety of tasks called the Cambridge Neuropsychological Test Automated Battery (CANTAB).

The researchers then analyzed particular areas of the participants' brain, including reaction time, verbal recognition memory, visual memory and learning.

What they found was that the participants who drank about three cups of water just prior to completing the tests had a 14% increased reaction time compared with those who did not drink any water.

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The finding, according to the study authors, shows that water consumption can increase cognitive performance, based on the participants' subjective feelings of thirst.

"The present study revealed water consumption to have contrasting effects on different cognitive processes. Water consumption was found both to impair 'set shifting' performance, and to facilitate speed of responding, but in a manner that was dependent upon subjective thirst,” they said.

“More specifically, water consumption appeared to have a corrective effect on the response times for thirsty individuals, bringing their speed of responding up to the level of non-thirsty individuals," the study authors added.

As this pertains to mood, the results showed that when participants were dehydrated, they were more tense, sad and confused.

On the flip side of the coin, Dr. Edmonds pointed out that the study also showed that drinking water can have negative effects on cognitive performance, as the study "also showed that people performed worse on a complex rule-learning task after drinking."

For example, in an experiment called the Intra-Extra Dimensional Set Shift (IED) test, the participants were monitored for "attention flexibility" and then tested on how many mistakes they made in discriminating a series of visual images. Depending on how the researchers ran the test, participants who drank water before the test, performed worse than those who did not drink any water.

Further research is needed to examine how the brain effects of water are mediated by thirst mechanisms, as well as determining why water consumption can also have negative effects on cognitive performance, according to the study authors.

"This study shows that water can be helpful for cognitive performance, and sometimes it can be helpful to be thirsty - we need to do more studies to find out why," said Edmonds.

So what is the ideal amount of water you should drink for strong mental performance?

"We don't really know the answer to that question at the moment,” said Edmonds. “This study is part of a program of research that is investigating how much water we should consume to affect cognitive performance.”

Edmonds added that there is also “a whole host of other research questions, such as what cognitive tasks are affected, and how far in advance of performance on these tasks is optimal for improving performance."

SOURCE: Frontiers in Human Neuroscience, “Subjective thirst moderates changes in speed of responding associated with water consumption”, Whiteman, H. (July 16, 2013).