Hydration may be a problem in adults suffering from poor cognitive health, according to a new study published in the European Journal of Nutrition. Not getting enough water has been shown to cause many problems such as fatigue and headache, but this new research shows it may be harming cognitive function as well.
The study from Penn State suggests that among women, lower hydration levels could be associated with slow motor speed, poor working memory, and a lack of sustained attention. The same results were not found in men.
“The study gives us clues about how hydration and related drinking habits relate to cognition in older adults,” said Hilary Bethancourt, a postdoctoral scholar in biobehavioral health and first author on the study. “This is important because older adults already face an increased risk of cognitive decline with advancing age and are often less likely than younger adults to meet daily recommendations on water intake.”
With the results found in dehydration, researchers looked at those who showed overhydration and found similar results. Senior author of the study, Asher Rosinger. who also directs the Water, Health, and Nutrition Laboratory spoke about water intake.
“We found a trend suggesting overhydration may be just as detrimental to cognitive performance as dehydration for older adults. Because of this, being in the ‘sweet spot’ of hydration seems to be best for cognitive function, especially for tasks requiring sustained attention.”
Total Water Intake
For the study, researchers used data from a national sample of 1,271 women and 1,235 men who were over the age of 60. Participants provided blood samples and were asked about all foods and drinks consumed the previous day. Hydration status was calculated based on concentrations of sodium, potassium, glucose, and urea nitrogen in a participant’s blood. Total water intake was measured as the combined liquid and moisture from all beverages and foods.
To test cognitive health, participants were required to complete tasks designed to measure verbal fluency and verbal recall. A test to measure processing speed, working memory, and sustained attention was also given. Participants were given a list of symbols, each matched with a number between one and nine. They were then supplied with a list of numbers one through nine in random order and asked to draw the corresponding symbol for as many numbers as possible within two minutes.
Hilary Bethancourt commented, “Once we accounted for age, education, hours of sleep, physical activity level, and diabetes status and analyzed the data separately for men and women, the associations with hydration status and water intake were diminished. A trend toward lower scores on the number-symbol test among women who were categorized as either underhydrated or overhydrated was the most prominent finding that remained after we accounted for other influential factors.”
Researchers have long suspected that dehydration may have an effect on cognitive performance, but all previous studies have largely focused on young, healthy people who are dehydrated after exercise or after being subjected to heat. Exercise and elevated body temperatures can have effects on cognition, apart from dehydration. This is why researchers were interested in focusing on the effects of day-to-day hydration status in the absence of exercise or heat stress.
“As we age, our water reserves decline due to reductions in muscle mass, our kidneys become less effective at retaining water, and hormonal signals that trigger thirst and motivate water intake become blunted,” Bethancourt said. “Therefore, we felt like it was particularly important to look at cognitive performance in relation to hydration status and water intake among older adults, who may be underhydrated on a regular basis.”
There are many preventative measures for cognitive impairment, but this shows one that may have been previously overlooked. Older adults must make it a priority to ensure they are staying properly hydrated throughout the day.