Know the Facts

Helping you make informed decisions about your drinking

Alcohol and the Brain

Alcohol’s action in the brain

The noticeable effects of alcohol are due to its action on the central nervous system (CNS), which includes the brain and spinal cord. To understand exactly how alcohol acts on the brain, we must first learn a little bit about how the brain works.

Your brain is in control of telling your heart to beat, your lungs to breathe, your stomach to digest, as well as things like your mood, sleep and concentration. To do all this, the brain uses chemicals called neurotransmitters to send messages between the nerve cells in the body.

There are two kinds of neurotransmitters:

Excitatory

These neurotransmitters stimulate or excite the brain, increasing the response of the nerve cells. These responses activate various actions and reactions in the body.

Inhibitory

These neurotransmitters have a sedative or calming effect on the brain and body, decreasing the response of the nerve cells.

Alcohol is a nervous system depressant. It acts on the brain by reducing the effect of excitatory neurotransmitters, and increasing the effect of inhibitory neurotransmitters, altering the natural balance of the nervous system. All brain functions depend on a delicate balance between excitatory and inhibitory neurotransmission, so when the balance is disrupted, bodily functions controlled by the brain become disturbed. This disruption of the usual balance causes the noticeable side effects of drinking alcohol.

Effects of alcohol

Remember that excitatory neurotransmitters stimulate the brain and create actions. When these neurotransmitters are reduced you notice alcohol-induced effects like:

  • Problems with memory
  • Difficulty thinking and concentrating
  • Slowed reactions
  • ‘Blackouts’, where you don’t remember what happened
  • Lowered inhibitions
  • Mood swings and extreme emotions

Remember that inhibitory neurotransmitters sedate and calm the brain. When these neurotransmitters are increased you notice alcohol-induced effects like:

  • Loss of coordination and balance
  • Slurred speech
  • Relief of anxiety
  • Sleepiness
  • Numbing of senses
  • Slower heart rate and breathing

These effects will disappear as the alcohol is processed and removed by your body. However, if alcohol is drunk often and over long periods of time, some of the effects will become worse, and may become permanent. You will also develop tolerance to alcohol, which means you will need to drink more and more to get the same effect as before, even though drinking more and more increases your risk of alcohol-related illnesses and injuries.

Sources

  • Chin, S.B. & Pisoni, D.B. (1997). Alcohol and Speech. (Chapter 2: The nature and pharmacology of alcohol.) San Diego: Academic Press. doi: 10.1016/B978-012172775-8/50002-X
  • Lingford-Hughes, A. & Nutt, D.J. (2001). Neuropharmacology of ethanol and alcohol dependence. In N. Heather, T.J. Peters & T. Stockwell (Eds.). International Handbook of Alcohol Dependence and Problems. (pp. 103-127). West Sussex: John Wiley & Sons Ltd.
  • Neurogistics Corporation. (2010). What Are Neurotransmitters? Austin, TX. Accessed online on 09/02/2012 at: http://www.neurogistics.com/TheScience/WhatareNeurotransmi09CE.asp
  • Valenzuela, C.F. (1997). Alcohol and neurotransmitter interactions. Alcohol Health and Research World, 21, 144-148.