The Effect of Small Changes in Hydration on Cognition

How do Small Changes in Hydration Influence Cognition: A Mechanistic Investigation

The aim of this study is to determine whether drinking plain water when mildly dehydrated benefits cognitive performance and mood. Volunteers undergo a dehydration protocol designed to result in minor dehydration. While some participants receive two 150ml drinks of water others do not. Differences in cognitive functioning are assessed.

Study Overview

• Status: Completed
• Conditions: Cognition; Hydration
• Intervention / Treatment: Dietary supplement: Water

Detailed Description

As an essential nutrient, an inadequate intake of water has negative consequences: without a source of water death will occur in days. When Benton and Young (2015) reviewed the topic they concluded that in healthy adults, mild dehydration (in the range of a loss of 2% body mass) had been found to adversely influence mood and cognition. However, it is unclear at what degree of hypohydration these effects begin to emerge.

This study was designed to determine whether small changes in hydration, of the level that might occur on a day to day basis, influence cognition and mood. During a dehydration protocol (sitting in a room heated to 30 degrees for four hours) young adult participants receive either drink two 150ml cups of water or nothing. Effects on memory, attention and mood are monitored.

• Study Type: Interventional
• Enrollment (Actual): 101
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • West Glamorgan
    • Swansea, West Glamorgan, United Kingdom, SA2 8PP
      • Swansea University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• In good general health i.e. no major health condition such as diabetes
• BMI < 30

Exclusion Criteria:

• Not on blood pressure medication or blood thinning medication such as aspirin - No learning difficulty such as dyslexia
• Diabetes
• Gastro-intestinal disease
• High BMI
• Cholesterol and BP
• Smoker
• Dyslexic/dyspraxic
• Depression or history of depression or other psychiatric disorder

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Drink water; Participants will receive two 150ml drinks of water during the dehydration protocol	Dietary supplement: Water; Participants will receive two cups of 150ml plain water
No Intervention: Drink nothing; Participants will drink nothing during the dehydration protocol

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Episodic memory - list of 30 words	Participants listen to a list of 30 words presented using a tape recorder. The words are of similar difficulty and matched for the number of syllables and frequency with which they occur in English. The subjects are asked to recall and write down as many words as possible. The difference in the total number of words remembered from baseline (before the intervention) is analysed.	change from 0 to 180 minutes after the start of the dehydration protocol
Focused attention - Eriksen Flanker Task	The Arrow Flankers test measures the ability to direct attention and ignore peripheral information. Participants are required to indicate whether the middle arrow is pointing to the right or left by pressing the corresponding arrow on the keyboard. Either side of the central arrow are distractors. Both the average reaction times (in milliseconds) and accuracy are recorded. The difference in performance from baseline (before the intervention) is analysed.	change from 0 to 180 minutes after the start of the dehydration protocol

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Thirst (Participants rate their thirst)	Participants rate their thirst	change from 0 to 180 minutes after the start of the dehydration protocol

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Amount of weight lost due to dehydration protocol	participants will be weighed at the start and end of the dehydration protocol and % weight loss calculated	180 minutes
Body temperature	Change in body temperature will be monitored throughout	180 minutes
Urine Osmolality	Urine samples will be collected at the start and end of the procedure so that changes in osmolality can be measured.	180 minutes

Collaborators and Investigators

• Sponsor: Swansea University

Publications and helpful links

General Publications

• Benton D, Young HA. Do small differences in hydration status affect mood and mental performance? Nutr Rev. 2015 Sep;73 Suppl 2:83-96. doi: 10.1093/nutrit/nuv045.
• Benton D, Jenkins KT, Watkins HT, Young HA. Minor degree of hypohydration adversely influences cognition: a mediator analysis. Am J Clin Nutr. 2016 Sep;104(3):603-12. doi: 10.3945/ajcn.116.132605. Epub 2016 Aug 10.

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2015
• Primary Completion (Actual): March 1, 2016
• Study Completion (Actual): March 1, 2016

Study Registration Dates

• First Submitted: September 22, 2015
• First Submitted That Met QC Criteria: February 1, 2016
• First Posted (Estimate): February 2, 2016

Study Record Updates

• Last Update Posted (Actual): April 6, 2020
• Last Update Submitted That Met QC Criteria: April 3, 2020
• Last Verified: April 1, 2020

More Information

Terms related to this study

• Other Study ID Numbers: HYD01