Hydration and Brain Fog: Is Dehydration Affecting Your Cognitive Function?
Can Poor Hydration Worsen Brain Fog?
Dehydration is a well-known cause of symptoms like headaches, fatigue, and dizziness, but did you know it can also impact your memory and cognitive abilities? Recent studies suggest a link between hydration status and brain function, raising the question: Could dehydration be contributing to the brain fog commonly experienced in fibromyalgia and chronic fatigue syndrome (ME/CFS)?
Drinking enough water throughout the day might be a simple and effective way to alleviate these symptoms.
The Science Behind Hydration and Cognitive Function
Evidence From Studies
As far back as 1980, researchers established a strong connection between dehydration and reduced cognitive performance. More recently, a 2019 study involving 2,506 participants aged 60 or older revealed:
Underhydrated participants performed worse on cognitive tests.
Overhydrated individuals also showed poor cognitive function, with the effect being strongest in women.
These findings highlight the importance of maintaining an optimal hydration balance—not too little and not too much.
How Much Water Do You Need to Optimize Cognitive Function?
Recommended Water Intake
U.S. Guidelines:
Women: 2.7 liters (91 ounces) daily.
Men: 3.7 liters (125 ounces) daily.
European Guidelines:
Women: 2.0 liters daily.
Men: 2.5 liters daily.
While there is no upper limit for water intake, excessive hydration can lead to hyponatremia, a dangerous condition caused by low sodium levels. A healthy kidney can process up to 0.7 liters (24 ounces) of water per hour. Exceeding this amount is not recommended, and salt intake should accompany increased water consumption.
Why Proper Hydration Matters for ME/CFS Patients
Dehydration and Blood Volume
Dehydration affects the blood directly, which can lead to cognitive issues. For ME/CFS patients, dehydration:
Reduces blood volume, causing low blood pressure, weak pulse, rapid heartbeat, and orthostatic intolerance.
Shrinks red blood cells, impairing their oxygen-carrying capacity.
Risks for Severe ME/CFS Patients
Bedridden ME/CFS patients face higher risks of dehydration due to muscle atrophy. Muscles store up to 70% of the body’s water, and as muscle mass decreases, fluid is lost. Adequate water intake—or in severe cases, intravenous or subcutaneous saline administration—is crucial for these individuals. Many patients report benefit from saline administration and it has long been used by ME/CFS physicians.
Hydration Challenges in Older Adults With Chronic Illness
Aging and Dehydration
As we age, our body's water content decreases from 70% to around 50%, while kidney efficiency declines. Additionally:
The brain’s thirst signals weaken, leading to reduced water intake.
Older adults with chronic illnesses, especially those over 60, are at a higher risk of underhydration.
Up to 28% of individuals over age 70 are underhydrated, according to long-term studies like the U.S. National Health and Nutrition Examination Survey. Mild dehydration can exacerbate symptoms like brain fog, fatigue, and dizziness in this population.
Recommendations for Optimal Hydration
To improve brain fog and support overall health:
Drink water in small, divided doses throughout the day.
Don’t rely solely on thirst cues to guide water intake.
Avoid consuming large amounts (like 1 liter) in a single sitting.
Ensure adequate salt intake in your diet.
Daily Water Intake Goals:
Women: At least 2 liters per day (increase to 2.7 liters for bedridden ME/CFS patients).
Men: At least 2.5 liters per day (increase to 3.7 liters for bedridden ME/CFS patients).
Adults over 60: Increase daily intake by at least 0.5 liters.
Final Thoughts: Stay Hydrated for Better Cognitive Health
Maintaining proper hydration is a simple yet powerful way to combat symptoms like brain fog, fatigue, and dizziness, especially for individuals with ME/CFS, fibromyalgia, or chronic illness. By drinking enough water, balancing electrolytes, and staying mindful of your hydration needs, you can support cognitive function and overall well-being.
References
D. G. SEYMOUR, P. J. HENSCHKE, R. D. T. CAPE, A. J. CAMPBELL, ACUTE CONFUSIONAL STATES AND DEMENTIA IN THE ELDERLY: THE ROLE OF DEHYDRATION/VOLUME DEPLETION, PHYSICAL ILLNESS AND AGE, Age and Ageing, Volume 9, Issue 3, August 1980, Pages 137–146.
Bethancourt HJ, Kenney WL, Almeida DM, Rosinger AY. (2019) Cognitive performance in relation to hydration status and water intake among older adults, NHANES 2011-2014. Eur J Nutr.
Hooper, L., Bunn, D., Jimoh, F. O., & Fairweather-Tait, S. J. (2014). Water-loss dehydration and aging. Mechanisms of Ageing and Development, 136-137, 50–58.
