Dehydration and Decreased Brain Function

Updated: Apr 4, 2020

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 drive through cell osmosis. The brain depends greatly on this cell-generated source of energy in order to maintain its complex processes and efficiency[1].

With lower than normal level of brain energy, you are unable to meet your physical, personal and social challenges and subsequently succumb to fear, anxiety, anger and other emotional tribulations. You may feel drained, lethargic, stressed and depressed.

Chronic fatigue syndrome is an example of this. It is often a symptom with a large contribution from 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.

Research shows that dehydration can actually lead to shrinkage of brain tissue and an associated increase in ventricular volume (ventricles are the "lakes" of cerebral spinal fluid filling in the spaces between brain tissue). Research shows that dehydration had 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 reaction[2]. Another study showed that alertness and attentiveness of participants increased, their fatigue decreased and their reaction ability improved after re-hydration [3].

The abuse of alcohol and depression are closely correlated. Many people who experience depression turn to alcohol in an attempt to "feel better" or to numb the pain. At least 30-40% of alcoholics suffer from a depressive disorder. 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 int he body. Neurotransmitters are chemical messengers that regulate emotions and other important bodily functions. These are affected by alcoholism and can lead to further depressive states. Alcohol also can increase dehydration in the body due to the high water molecule need in the chemical reactions that detoxify alcohol back out of the body [4].

So the moral of the story is, drink plenty of water daily. Don't let yourself get into a vicious cycle of depression and increased alcohol consumption that leads to more dehydration which furthers depressive states. Break the cycle. Care for your body, care for your brain, and your brain 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.


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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