Suhr JA., Hall J., Patterson SM., Niinistö RT.
The relation of hydration status to cognitive performance in healthy older adults.
Int J Psychophysiol 2004; 53 (2): 121-125.
In the United States, data suggest that individuals do not drink enough water and thus may
be exposed to chronic mild dehydration. In young healthy adults, mild dehydration can
impair attention, psychomotor processing speed and memory. However, the relationship
between hydration status and cognitive performance among older adults had never been
investigated, even if they are at higher risk of dehydration and cognitive impairment.
Therefore, this study examined whether hydration status was related to cognitive
functioning in 28 healthy adults (22 females; 6 males) aged between 50 and 82 years.
Subjects were randomly allocated to two groups. In one group (n=14), they were asked to
abstain from drinking and eating after their evening meal the night before their participation
to the trial. In the other group (n=14), participants were allowed to eat and drink normally
the day before the study. Moreover, they received an extra 16 oz of noncaffeinated and
nonalcoholic beverage (preferably water) throughout the day before the day of testing. In
the morning, people from both groups were given a large set of cognitive tests in order to
assess attention, memory and psychomotor processing speed.
Subjects assigned to the overnight fast condition were slightly less hydrated than
participants under normal dietary intake condition. Analysis showed that lower hydration
status was related to slower psychomotor processing speed and poorer attention/memory
performance. Higher age was also significantly associated with slower psychomotor
processing speed. Higher systolic blood pressure showed a trend for relation to worse
memory performance.
Consistently with former studies performed in younger adults, these findings emphasize the
importance of considering poor hydration as a contributor to impairment in cognition in
older adults, even at relatively mild levels. Those findings should now be replicated with
larger and more diverse sample of older adults. Further studies might also determine
whether hydration status enhancement leads to improvement in cognitive performance in
older adults.
Key messages: Low hydration status is related to a slow psychomotor processing speed, poor
attention and memory performance in older adults.