Cognitive Science

Drink Up!

Your head starts to throb, your throat feels scratchy and you just can’t quite think straight. You’re starting to feel the signs of dehydration.

You probably know already that you need to drink lots of water when you’re outdoors on a hot day or exercising at the gym. But did you know you can easily begin to feel the effects of dehydration even if you’re not exerting yourself?

Most older adults don’t meet the daily recommendations of water intake. And, believe it or not, water and your hydration status can greatly impact your cognition.

Dehydration is believed to impact cognitive abilities including math ability, short-term memory, reaction time and motor skills.

In one study of older adults, the effects of hydration and adequate water intake on cognition were examined. Evidence from this study suggested a relationship between cognitive test performance and hydration status for men and women, with women who were more hydrated performing better on cognitive tests than their counterparts. Dehydration is believed to impact cognitive abilities including math ability, short-term memory, reaction time and motor skills.

It’s harder to stay hydrated as you age. With less muscle mass, there’s less water reserve (another good reason to keep up your exercise routine). Hormonal drivers that influence thirst might also not work as well as they used to.

So, how can you stay hydrated to keep your brain firing as quickly as it can? First, just drink water. Ditch the sodas, juices and sweet teas that have added sugar. Their sugar content isn’t good for your cognitive function, and they don’t hydrate as well as water. Limit tea and coffee to one or two cups a day—caffeine can be dehydrating. Finally, carry water with you everywhere you go. Never leave home without a bottle of water.

Recommended water intake for women is 2.7 liters/91 ounces of total water and 3.7 liters/125 ounces daily for men. Total intake includes water from food, so you can get by drinking less than the total recommendation. To give you a mental picture, 3 liters is the size of a giant bottle of soda or about 12-13 drinking glasses worth of liquid. Bottoms up!


  • Bethancourt, H. J., Kenney, W. L., Almeida, D. M., & Rosinger, A. Y. (2019). Cognitive performance in relation to hydration status and water intake among older adults, NHANES 2011-2014. European Journal of Nutrition. doi: [10.1007/s00394-019-02152-9](
  • Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate. (2004). Institute of Medicine. Retrieved February 5, 2020, from https://www.nationalacademies....
  • Wilson, M.-M. G., & Morley, J. E. (2003). Impaired cognitive function and mental performance in mild dehydration. European Journal of Clinical Nutrition, 57 Suppl 2, S24-29. doi:

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