|The complex neuronal clockwork in your brain needs water to run smoothly. But how much water does it need?|
Fully convincing experimental evidence for the efficacy and, more importantly, optimal amount(s) of water as a 'nootropic supplement' in non-dehydrated individuals, as it has just been provided by a recent study from the University of East London and the University of Westminster (Edmonds. 2016), however, has not been available...
Not available, yet?! That is, obviously, before Edmonds and colleagues set out to investigate the dose-response characteristics of the effects of acute water supplementation on cognitive performance and mood.
And the scientists did not stop with a classic 'proof of concept study' in which they tested the generality of the phenomenon by assessing both adults (Study 1) and children (Study 2), but they also explored this phenomenon systematically in adults and children, using visual attention (letter cancellation) and memory (digit span) tasks that have been employed in previous studies.
In all experiments, the subjects (3x32 adults, mean age of participants was 21.0 years in
"All participants completed the thirst and mood scale, followed by baseline cognitive tests. They were then offered either 25 ml, 300 ml, or no water and were encouraged to drink the full amount, which all of them did. After water consumption there was an interval of approximately 20 min, which is the interval commonly reported in the literature reviewed above, during which the participants spent time quietly. Following the interval, participants completed the second set of scales and cognitive tests." (Edmonds. 2016).
Figure 1: Overview of the study design (Edmonds. 2017).
114 each group (300 ml, SD = 2.5 years; 25 ml, SD = 3.6 years; no water, SD = 2.8 years in Study 1 | 60 children aged 7 to 10 years in Study 2) were offered either no water, 25 ml or 300 ml water to drink. In both studies, performance was assessed at baseline and 20 min after drinking (or no drink); on thirst and mood scales, letter cancellation and a digit span test.
|Figure 2: Relative changes in cognitive performance (vs. baseline test) in all three conditions (Edmonds. 2016)|
|Figure 3: Rel. change in thirst and mood in adults and kids according to treatment condition (Edmonds. 2016).|
- in adults, a large drink improved digit span, but there was no such effect in children,
- in children, but not adults, a small drink resulted in increased thirst ratings,
- both children and adults show dose-response effects of drinking on visual attention.
- Edmonds, Caroline J., et al. "Dose-response effects of water supplementation on cognitive performance and mood in children and adults." Appetite 108 (2017): 464-470.
- Sanders, Matthew A., et al. "The gargle effect rinsing the mouth with glucose enhances self-control." Psychological Science 23.12 (2012): 1470-1472.
- Turner, Clare E., et al. "Carbohydrate in the mouth enhances activation of brain circuitry involved in motor performance and sensory perception." Appetite 80 (2014): 212-219.