At what stage in the drinking process does drinking water affect attention and memory? Effects of mouth rinsing and mouth drying in adults
Drinking water is important for health and there is an agreement that drinking water facilitates certain cognitive processes. However, the mechanism underlying the effect of drinking water on cognition is unknown. While attention performance is improved by even a very small drink, memory performance seems to require larger drinks for performance enhancement. This suggests that attention could be affected earlier in the drinking process than memory. We aimed to elucidate further the mechanism involved by investigating the stage during the drinking process influencing performance on cognitive tasks. To this end, we compared mouth rinsing and mouth drying. Mouth rinsing was expected to result in improved attention performance and would suggest that the mechanism responsible is located in the mouth and occurs early in the drinking process, before swallowing. Eighty-seven adults participated in either a treatment (mouth rinsing or mouth drying) or control (no intervention) condition. They were assessed at baseline and 20 min later after intervention on measures of visual attention, short-term memory, subjective thirst and mood. Our results showed that mouth rinsing improved visual attention, but not short-term memory, mood or subjective thirst. Mouth drying did not affect performance. Our results support the hypothesis that different mechanisms underlie the effect of drinking water on different cognitive processes. They suggest that merely sipping water, as opposed to having a large drink, can improve attention.
This research did not receive any specific grant from funding sources in the public, commercial or not-for-profit sectors. This work was part funded by money given to the first author by Nestec for an unrelated project—they had no influence in instigating, designing, analysing, interpreting or submitting the paper.
Compliance with ethical standards
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. All procedures were approved by the Department of Psychology ethics committee, University of Westminster (ETH1617-0099) and the University of East London ethics committee (UREC 1516 74).
Written informed consent was obtained from all participants prior to participation.
- Barker, M., Benefer, M. D., Russell, J. M., Lepicard, E. M., Constant, F., Hawili, N., & Friedlander, G. (2012). Hydration deficit after breakfast intake among British schoolchildren. Experimental Biology, 26, 10–11.Google Scholar
- Benton, D., Braun, H., Cobo, J. C., Edmonds, C. J., Elmadfa, I., El-Sharkawy, A., et al. (2015). Executive summary and conclusions from the European Hydration Institute Expert Conference on human hydration, health, and performance. Nutrition Reviews, 73, 148–150. https://doi.org/10.1093/nutrit/nuv056.CrossRefGoogle Scholar
- Booth, P., Taylor, B., & Edmonds, C. J. (2012). Water supplementation improves visual attention and fine motor skills in schoolchildren. Education and Health, 30(3), 75–79.Google Scholar
- Brunstrom, J. (2002). Effects of mouth dryness on drinking behavior and beverage acceptability. Physiology and Behavior, 76(3), 423–429. http://www.ncbi.nlm.nih.gov/pubmed/12117579. Accessed 28 Dec 2015
- Cohen, S. (1983). After effects of stress on human performance during a heat acclimatization regimen. Aviation, Space and Environmental Medicine, 54, 709–713.Google Scholar
- Edmonds, C. J., Booth, P., Carey, K., Stafford, A., Walker, A., & Gardner, M. R. (2019). Teachers’ attitudes to children drinking water in the classroom and strategies for increasing consumption : a pilot study a b c b. In Poster presented at the British Feeding and Drinking Group conference Swansea. https://doi.org/10.13140/rg.2.2.13883.67361
- Gandy, J. (2017). Fluid—food fact sheet. www.bda.uk.com/foodfacts. Accessed 30 April 2019
- Grandjean, A. C., & Campbell, S. M. (2004). Hydration: Fluids for life. Washington, DC: ILSI.Google Scholar
- Health and Safety Executive. (2013). Workplace health, safety and welfare : Workplace (health, safety and welfare) regulations 1992. http://www.hse.gov.uk/pUbns/priced/l24.pdf. Accessed 2 Apr 2019
- Health and Safety Executive. (2019). Case 187—employer refuses to allow employees bottles of water on retail floor due to health and safety. http://www.hse.gov.uk/myth/myth-busting/2013/case187-bottled-water.htm. Accessed 29 April 2019
- Jeukendrup, A., Rollo, I., & Carter, J. (2013). Carbohydrate mouth rinse: performance effects and mechanisms. Sports Science, 26(118), 1–8. https://secure.footprint.net/gatorade/prd/gssiweb/pdf/118_CarbohydrateMouthRinse-Jeukendrup_SSE.pdf. Accessed 16 May 2017
- Kaushik, A., Mullee, M. A., Bryant, T. N., & Hill, C. M. (2007). A study of the association between children’ s access to drinking water in primary schools and their fluid intake : Can water be ‘cool’ in school ? Child: Care, Health and Development, 33(4), 409–415. https://doi.org/10.1111/j.1365-2214.2006.00721.x.Google Scholar
- Kenney, E. L., Long, M. W., Cradock, A. L., & Gortmaker, S. L. (2015). Prevalence of inadequate hydration among US children and disparities by gender and race/ethnicity: National Health and Nutrition Examination Survey, 2009–2012. American Journal of Public Health, 105(8), e113–e118. https://doi.org/10.2105/AJPH.2015.302572.CrossRefGoogle Scholar
- Neave, N., Scholey, A. B., Emmett, J. R., Moss, M., Kennedy, D. O., & Wesnes, K. A. (2001). Water ingestion improves subjective alertness, but has no effect on cognitive performance in dehydrated healthy young volunteers. Appetite, 37, 255–256. https://doi.org/10.1006/appe.2001.0429.CrossRefGoogle Scholar
- Rolls, B. J., & Rolls, E. T. (1982). Thirst. Cambridge: Cambridge University Press.Google Scholar
- Sinclair, J., Bottoms, L., Flynn, C., Bradley, E., Alexander, G., McCullagh, S., et al. (2013). The effect of different durations of carbohydrate mouth rinse on cycling performance. Physiology and Nutrition, 14(3), 259–264.Google Scholar
- The Education (Nutritional Standards and Requirements for School Food) (England) Regulations. (2007). Statutory instrument. London: Nutritional Standards and Requirements for School Food.Google Scholar
- United States Department of Agriculture. (2016). Resources for making potable water available in schools and child care facilities. Washington: United States Department of Agriculture.Google Scholar