Dehydration may impair thinking ability

July 9, 2018 in Brain Health, Nutrition Topics in the News, Sports Nutrition and Exercise

Dehydration may impair thinking ability

Dehydration can impair your ability to think clearly, a new study from the Georgia Institute of Technology suggests. 

Among athletes,  losing fluid equal to 2 percent body weight, impacted cognition. Even this mild to moderate level of dehydration (e.g., the loss of 2 pounds for a person who weighs 100 pounds and four pounds for someone weighing 200) led to attention problems and impaired decision making. 

In particular, dehydration impaired tasks that required attention, motor skills and executive function, which includes things like map recognition, grammatical reasoning, mental math, and proofreading. 

It’s already known that physical performance suffers when 2 percent of body mass is lost from dehydration, especially when it’s caused by exercising in a warm environment. 

The researchers addressed the question: What happens in the brain with the same amount of water loss, which is common with people who are active or work outside in the heat?

While the effects weren’t huge at 2 percent, they increased with increasing dehydration.

The new study isn’t the first to look at the impact of dehydration on cognition. However, earlier research has turned up mixed findings, possibly because studies were based on small numbers of subjects.

About the study

The researchers decided to get around that pitfall by performing a meta-analysis, an approach that combines data from many smaller studies. With a bigger pool of participants, you can get more robust information.

The researchers found 33 studies involving a total of 413 adults. Participants lost fluids amounting to 1 to 6 percent of their body mass either through exercise alone, exercise coupled with heat, heat alone or fluid restriction. 

These findings should also remind weekend warriors as well as more dedicated athletes of the importance of staying hydrated. The more dehydrated you are, the less sharp you are.

It’s important for athletes to keep track of how much fluid they’re taking in and how much they’ve lost. Still, certain symptoms should be reminders that it’s time to take in more fluid: Fatigue, loss of appetite, flushed skin, light-headedness, muscle cramps, headache and dry mouth.

How much water?

Adults should drink 125 to 175 ml of water every 10 to 15 minutes of exercise. And, as a first step, it’s important to make sure that you are properly hydrated before commencing exercise or sports.

Weighing yourself before and after exercise can give you more information about your rehydration needs. For every pound lost during activity, drink 500 to 750 ml of water. Drink water with your post-workout snacks and meals to achieve this.

It’s also recommended that on especially hot days, athletes make a plan before working out so potentially clouded judgment won’t steer them wrong. 

Experts warn against drinking too much water, which can lead to a dangerous condition known as hyponatremia. That condition occurs when there’s too much water compared to the amount of sodium in the body. 

The color of your urine is a simple way of monitoring your fluid levels. If it’s very, very clear, then you are probably drinking far more water than necessary. On the flip side, if it’s dark gold that may mean you are not drinking enough.

Source: Medicine & Science in Sports & Exercise, online June 21, 2018.

All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.