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Dehydration and Decreased Brain Function Correlation

Updated: Apr 25, 2023

The human brain requires more water than any other part of the body. It is estimated that brain cells consist of 70 - 80% water. Their energy requirements are not only met by metabolizing glucose (from a healthy diet), but also by generating hydroelectric energy from the water absorption process through cell osmosis. The brain depends greatly on this cell-generated source of energy in order to maintain its complex processes and efficiency [1].

Dehydration occurs when the body loses more fluids than it takes in, leading to a decrease in the amount of water available to the body. This can occur due to various factors such as high temperatures, physical activity, and illness. When the body becomes dehydrated, the blood becomes thicker, and the heart has to work harder to pump blood to the brain, leading to a decrease in the amount of oxygen and nutrients available to the brain.

Hydration provides the brain with its ultimate energy. When we aren't providing our bodies and brains with enough H2O, we have decreased neurological energy. This means we would be unable to meet standard, daily physical, mental and social challenges; subsequently making you more prone to experiencing fear, anxiety, anger and other emotional tribulations. You may feel drained, lethargic, stressed and depressed. These are just the psychological symptoms of dehydration, not to mention the physical reaction correlated.

Chronic fatigue syndrome is one of the biggest symptoms of progressive brain dehydration that results from the inability to readily remove all metabolic waste matter and cellular debris from the brain and other vital parts of the body. This waste builds up in the body's cells, creating toxicity and sluggishness of organs.

Research shows that dehydration can actually lead to shrinkage of brain tissue called atrophy, and an associated decrease in ventricular volume (ventricles are the "lakes" of cerebral spinal fluid filling in the spaces between brain tissue). Research shows that dehydration has negative effects on mood, vigor, esteem-related affect, short-term memory, and attention. Re-hydration after water supplementation improved fatigue, short-term memory, attention, mood and reflexes by over 80% [2]. Another study showed that alertness and attentiveness of participants increased, their fatigue decreased and their reflexes/reaction time improved after re-hydration [3].

The effects of dehydration on brain function can be subtle but significant. Studies have shown that even mild dehydration, which can occur with a fluid loss of just 1-2% of body weight, can lead to a decline in cognitive function, including:

  1. Poor concentration and focus - Dehydration can lead to a decrease in the ability to concentrate and focus on tasks, leading to decreased productivity and performance.

  2. Memory problems - Dehydration can affect the ability to recall information and can lead to memory problems.

  3. Slower reaction time - Dehydration can slow down reaction time, leading to decreased performance in activities that require quick thinking and response times, such as sports or driving.

  4. Mood changes - Dehydration can lead to changes in mood, including increased irritability and decreased motivation.

  5. Headaches - Dehydration can lead to headaches and migraines, which can further impair cognitive function and performance.

In addition to the above effects, severe dehydration can lead to more serious and life-threatening complications such as seizures, coma, and even death. Therefore, it is crucial to maintain adequate hydration levels by drinking enough fluids throughout the day.

The recommended daily water intake varies depending on factors such as age, sex, and physical activity levels, but a general guideline is to drink at least eight glasses of water per day. Other sources of fluids such as fruits and vegetables, soups, and broths can also contribute to hydration levels.

The abuse of alcohol and depression are closely correlated. Many people who experience depression turn to alcohol in an attempt to "feel better" or numb the pain. At least 30-40% of alcoholics suffer from a depressive disorder, and at least 60% of alcoholics are severely dehydrated (the alcohol counteracts hydration because of the cellular toxicity). Unfortunately, alcohol is a depressant to the central nervous system and reduces activity in the brain and body. Studies show that alcohol increases both the duration and the intensity of depressive episodes. Prolonged alcohol abuse can dramatically alter and rewire the brain, as well as affect other chemical balances in the body. Neurotransmitters are chemical messengers in the brain that regulate emotions and other important bodily functions. These are affected by alcohol and when damaged, can lead the psyche further into depressive states. Alcohol also can increase dehydration in the body; detoxifying alcohol (a chemical reaction) from the body requires high amounts of water molecules [4].

Overall, it is vital in the health and well-being of all living things to consume H2O. Try not to let yourself get into a vicious cycle of depression from increased alcohol consumption-- which leads to more dehydration which furthers unhealthy and unstable mental and psychological states. Break the cycle. Care for your body, care for your brain, and you will stay healthy long into old age!

*** I recommend to all my patients that they drink at least half of their body weight in ounces of water every single day, and add 10-20 ounces during summer months or days when they workout or go to a sauna. Sweating can decrease our body's supply of water as well.

Dr. Leila Doolittle Dallas, TX

Resonance Wellness Clinic SCORP


1. Tang C., Zelenak C., Völkl J., Eichenmüller M., Regel I., Fröhlich H., Kempe D., Jimenez L., Le B.L., Vergne S. Hydration-sensitive gene expression in brain. Cell. Physiol. Biochem. 2011;27:757–768. doi: 10.1159/000330084. [PubMed] [CrossRef] [Google Scholar]

2. Kempton M.J., Ettinger U., Schmechtig A., Winter E.M., Smith L., Mcmorris T., Wilkinson I.D., Williams S.C., Smith M.S. Effects of acute dehydration on brain morphology in healthy humans. Hum. Brain Mapp. 2009;30:291–298. doi: 10.1002/hbm.20500. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

3. Masento N.A., John A., Wilton V., Benzesin V., Field D.T., Butler L.T., Reekum C.M.V. Investigating the effects of acute water supplementation on cognitive performance and mood in young and older adults. Appetite. 2014;83:355. doi: 10.1016/j.appet.2014.06.076. [CrossRef] [Google Scholar]

4. Irwin C., Leveritt M., Shum D., Desbrow B. The effects of dehydration, moderate alcohol consumption, and rehydration on cognitive functions. Alcohol. 2013;47:203–213. doi: 10.1016/j.alcohol.2012.12.016. [PubMed] [CrossRef] [Google Scholar]

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