Could hydration levels influence cognitive function?
One segment of the population is particularly susceptible to dehydration: older adults.
ISLAMABAD (Online) - Dehydration can cause headaches and several physiological issues, and older adults are most at risk of experiencing it. Does it also affect cognitive function, however? And might overhydration also affect mental performance?
Studies have tended to focus on the effects of dehydration in younger populations — especially in the context of sports and fitness, where overexertion and abundant sweating can cause people to lose more fluids than they than ingest.
However, one segment of the population is particularly susceptible to dehydration: older adults.
"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," explains Hilary Bethancourt, Ph.D., from the Pennsylvania State University College of Health and Human Development in State College.
Under and overhydration are both nonideal
All the participants involved in the study were able to give blood samples. They also provided information about what they had consumed throughout the day preceding the blood sample collection.
To measure each participant’s hydration levels, the investigators looked at the concentration of different substances and compounds — including sodium, potassium, glucose, and urea nitrogen — in their blood.
All participants also undertook cognitive function tests, including tasks designed to assess verbal recall and fluency, and exercises focused on attention levels and working memory.
At first glance, the researchers found an association between appropriate hydration and good scores in the cognitive function tests. However, the results became less clear when the researchers adjusted their analysis for confounding factors.
"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," says Bethancourt.
"A trend toward lower scores on [one of the cognitive function tests] among women who were categorized as either underhydrated or overhydrated was the most prominent finding that remained after we accounted for other influential factors," explains Bethancourt.
The test that those who were overhydrated or underhydrated performed the worst in was "the test of attention, processing speed, and working memory," she says.
