The Effects of Alcohol on the Brain

Though it is a legal substance, alcohol significantly impacts the body, particularly the brain, and excessive use can cause substantial damage. It reaches your brain in only 5 minutes after you start drinking, and short- and long-term heavy use affects neurons (brain cells) throughout the entire brain.1 Before you start drinking, either regularly or for social occasions, it’s important to be aware of the effects of alcohol on the brain.

In this article:

Short-Term Effects of Alcohol on the Brain

It may seem surprising, but alcohol is a depressant, not a stimulant. A stimulant increases certain chemicals in the brain leading to an increase in energy, alertness, and attention, whereas a depressant increases chemicals in the brain that inhibit or slow down brain activity.

At the point of feeling “tipsy,” alcohol is having a significant impact on your brain’s functioning. Your cognitive judgment becomes impaired and your brain releases more dopamine, the chemical associated with pleasure.

Being “tipsy” may feel like alcohol is increasing energy and alertness, but at that level of intoxication, alcohol simply mimics a stimulant. Tipsiness is the result of your brain waking up in a way, recognizing that something has crossed the blood-brain barrier that normally isn’t there.

The blood alcohol content (BAC) when you feel tipsy is about .04-.06 (that is, 0.04 – 0.06% of your blood volume is alcohol). The number of alcoholic drinks you need to consume to reach this BAC depends on your sex and weight. For a 150-pound male, drinking 2 standard drinks in about 1 hour leads to a BAC of about .05, while a 120-pound female would need to drink about 2 standard drinks in about 2 hours. A standard drink is defined as:

  • 12 ounces of beer or wine cooler
  • 8 ounces of malt liquor
  • 4-5 ounces of wine
  • 1-1.5 ounce of 80-proof distilled spirits or liquor (e.g., gin, rum, vodka, whiskey)

Once you get to a higher level of intoxication, you lose the “tipsy” feeling because your brain has gotten used to the presence of alcohol. At that point, you start to solely feel the depressant effects of alcohol. Furthermore, the more frequently you drink, the less intense “tipsy” feeling you experience because your body has become more tolerant of alcohol. These two phases of how alcohol affects the brain, from mimicking a stimulant to causing depressant effects, are why the process is called bi-phasic.

Once you reach a BAC of .08—the legal limit in many states—alcohol affects even more areas of your brain, and you start to feel those effects in your functioning. The affected areas of your brain and some effects are:

  • Occipital lobe: Blurred vision
  • Temporal lobe: Slurred speech and difficulty hearing
  • Frontal lobe: Lack of control
  • Parietal lobe: Slower reaction time

If you or someone you know is in need of alcohol addiction treatment, call 800-839-1686Who Answers? to speak with a rehab specialist today.

Effects of Binge Drinking on the Brain

For men, binge drinking is defined as having more than 5 drinks on one occasion, and for women, more than 4 drinks per occasion. Binge drinking causes a BAC of about .11-.15. At this stage, your brain loses the ability to formulate memories because the hippocampus, the part of the brain involved in memory, is no longer working well. This period of time is known as a “blackout,” where you might appear to others as though you are functioning normally, but you don’t recall what you said or did during the blackout.

Once you reach a BAC of about .17, your cerebellum, the part of the brain that helps with coordination, is affected. This leads to problems with walking or standing.

At BACs between .17-.30, all mental, physical, and sensory functions are severely impaired. At BACs higher than .30, you are at risk for coma or death because the brain can no longer control the body’s vital functions at this stage.

Heavy Alcohol Use and the Brain

Heavy alcohol use also interferes with sleep. One possibility for this is that alcohol suppresses the brain’s ability to produce melatonin, which regulates the sleep-wake cycle.

Though drinking alcohol may seem to make it easier to fall asleep, you do not get quality sleep after heavy drinking. This is because you spend less time in the rapid eye movement (REM) sleep, the phase during which you dream. You need to spend enough time in the REM phase to have normal cognitive function while awake.

Long-Term Effects of Alcohol on the Brain

When you drink more (and more frequently), you’ll develop a tolerance to the intoxicating effects of alcohol. Having a high tolerance for alcohol means that you can reach high BAC levels and still appear to others as functioning normally.

You might think that tolerance is a good thing because it means your body can handle more alcohol. However, all tolerance does is give you no warning before you’ve reached a severe level of alcohol poisoning. In other words, with tolerance, you might at one point appear to function normally and then the next second, suddenly crash and possibly go into a coma.

Long-Term Alcohol Abuse and Addiction

Moreover, chronic alcohol use and withdrawal lead to affecting certain areas of the brain—the amygdala and nucleus accumbens—such that alcohol-seeking behavior increases, perpetuating alcohol abuse. In addition, chronic alcohol use and withdrawal lead to a decrease in dopamine transmission.1 Dopamine is a neurotransmitter, a chemical that your body makes and the nervous system uses to send messages between nerve cells. It is involved in how we experience pleasure, think, and plan. In turn, chronic alcohol abuse can lead to a depressive disorder and/or decreased cognition and planning ability.

Wernicke Encephalopathy

Wernicke encephalopathy is a life-threatening disease caused by a thiamine deficiency and requires immediate medical attention. Various conditions can cause this disease, alcohol dependence being one. Thiamine, or vitamin B1, plays a part in turning food into energy to keep the CNS and PNS healthy.

Symptoms of this disease are:

  • Confusion
  • Ataxia (loss of coordination of extremities)
  • Nystagmus (rapid, involuntary movement of the eyeball from side to side)

Wernicke-Korsakoff Syndrome

If not treated promptly, Wernicke encephalopathy can become Korsakoff syndrome. Korsakoff syndrome symptoms include:

  • Confusion
  • Loss of mental activity that could progress to coma and death
  • Loss of muscle coordination that can cause leg tremors
  • Vision changes including abnormal eye movements, double vision, drooping eyelids
  • Alcohol withdrawal

Surprisingly, in some heavy and chronic drinkers, the brain is the first organ to show damage, not the liver. In fact, it is estimated that about 25% of the patients in nursing homes have alcohol-related dementia, such as Wernicke Korsakoff syndrome.3

Alcohol Effects on Adolescent Brains

Your brain continues to grow and develop through your mid-20s. Therefore, binge drinking in adolescence and early adulthood can significantly impair brain development and function, and cause alterations in brain structure.

Adolescents aged 12-18 who drink heavily have shown a greater rate of grey matter reduction in the brain and weakened white matter growth compared to non-drinkers.4 This can lead to issues with your:5,6

  • Sensory organs, including the eyes, ears, nose, tongue, and skin
  • Balance and motor coordination
  • Decision-making abilities
  • Planning abilities
  • Self-control

Can Brain Damage be Reversed?

Contrary to the common message you may have heard, alcohol does not kill brain cells. However, it damages the neurons’ dendrites, making it difficult for them to send messages to one another. Unlike the cells in various other parts of your body, neurons do not divide or renew themselves, with only a few exceptions.7

However, the central nervous system (CNS) has a strategy for repairing itself that is completely different from other organs in the body. Though damaged neurons cannot repair and rebuild themselves the way the skin can, they make new connections to compensate for the losses due to the damages.7

Some people with a severe alcohol use disorder (AUD) can improve their cognitive functioning if they abstain from alcohol for about 1 year.8 The brain appears to reorganize to compensate for the behavioral problems.9

In most severe AUD cases, however, limited recovery is possible. In about 20% of those with a severe AUD, virtually no improvement in cognitive functioning is made even after abstaining from alcohol for a long time.

It is important to note that alcohol’s impact on your brain, specifically, depends on individual factors such as your family health history and history of substance use, your age, sex, and mental and physical health.9

Reversing Wernicke Encephalopathy

Wernicke encephalopathy can be reversible if treated with thiamine within the first 48-72 hours of the onset of symptoms. Failure to treat Wernicke encephalopathy could lead to death or progression to Korsakoff syndrome, which is irreversible.

Short-term memory loss and anterograde amnesia, the decreased ability to retain new information, is associated with Korsakoff syndrome.10 This could significantly affect your work and social activities because you would have trouble creating new memories.

Education and Treatment for Alcoholism

If you are new to using alcohol or a high school or college student who is heavily using alcohol, you will want to seek out education on safer drinking practices to reduce the risks of developing an AUD and damage to your brain health.

Your school or college may have alcohol education classes. Information covered in such classes usually includes:

  • A description of the alcohol bi-phasic curve
  • Male and female BAC charts for different body weights
  • Healthier and safer drinking strategies

If you are struggling with excessive alcohol use or a dependency on alcohol, getting treatment as soon as possible is very important to lower the risks of damage to your brain that could lead to permanent memory loss, paralysis, coma, or even death.

For 24/7 help with your AUD or that of a loved one, call 800-839-1686Who Answers?.

References

  1. Abrahao, K.P., Salinas, A.G., & Lovinger, D.M. (2017). Alcohol and the brain: Neuronal molecular targets, synapses and circuits. Neuron Review, 96, 1223-1238.
  2. Daneman, R., & Prat, A. (2015). The blood-brain barrier. Cold Spring Harbor Perspectives in Biology, 7(1).
  3. Cheng, C., Huang, C., Tsai, C., Chou, P., Lin, C., & Chang, C. (2017). Alcohol-related dementia: A systemic review of epidemiological studies. Psychosomatics, 58(4), 331-342.
  4. Squeglia, L.M., Tapert, S.F., Sullivan, E.V., Jacobus, J., Meloy, M.J., Rohlfing, T., & Pfefferbaum, A. (2015). Brain development in heavy-drinking adolescents. American Journal of Psychiatry, 172(6), 531-542.
  5. Smith, K.W., Gierski, F., Andre, J., Dowell, N.G., Cercignani, M., Naassila, M., & Duka, T. (2015). Altered white matter integrity in whole brain and segments of corpus callosum, in young social drinkers with binge drinking pattern. Addiction Biology, 22(2), 490-501.
  6. Cservenka, A. & Brumback, T. (2017). The burden of binge and heavy drinking on the brain: Effects on adolescent and young adult neural structure and function. Frontiers in Psychology, 8.
  7. Weishaupt, N. & Zhang, A. (2016). Why doesn’t your brain heal like your skin?
  8. Northwestern Medicine. (2021. How alcohol impacts the brain.
  9. Oscar-Berman, M., Valmas,M., Sawyer, K.S., Ruiz, S.M., Luhar, R.B., & Gravitz, Z.R. (2014). Chapter 12 – Profiles of impaired, spared, and recovered neuropsychologic processes in alcoholism. Handbook of Clinical Neurology, 125, 183-210.
  10. Latt, N., & Dore, G. (2014). Thiamine in the treatment of Wernicke encephalopathy in patients with alcohol use disorders. Internal Medicine Journal, 44, 911-915.

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