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While alcohol does damage the brain, it does not kill brain cells. Drinking is associated with a variety of adverse cognitive effects both in the short- and long-term.
In the short-term, this includes loss of muscle coordination, slurred speech, memory loss, and possible loss of consciousness.
In the long-term, alcohol damages the brain in several ways, from deforming brain cells to brain shrinkage.
Alcohol is a neurotoxin that damages cognitive function in multiple ways. Research indicates heavy drinking can damage neurons by altering the structure, development, and function of dendrites. Dendrites are responsible for problem-solving, memory, and focus and are essential for the communication between neurons.15
Researchers point to thiamine (vitamin B1) deficiency as the culprit. Many of those suffering from alcohol use disorder (AUD), commonly known as alcoholism, end up malnourished, leading to thiamine deficiency. Thiamine is an essential vitamin for the metabolism of dendrites. Alcohol also inhibits the absorption of thiamine.
Alcohol use also leads to loss of brain volume — literally shrinking the brain. This does not just apply to heavy drinking. Some studies suggest this is also true for moderate alcohol consumption.2
According to the National Institute on Alcohol Abuse and Alcoholism, heavy drinking is defined as four or more drinks on a given day for men or more than fourteen drinks in a week. For women, this is three or more drinks on a given day or more than seven drinks in a week.
A recent British study showed that moderate drinkers tripled their risk of brain damage over thirty years.
Specifically, moderate drinking is associated with a reduction in brain volume. According to the study, moderate drinkers had a three times greater risk of brain shrinkage over thirty years.12
Heavy drinkers had six times the risk, showing that more drinking leads to more damage.12 However, this shrinkage does not appear to be due to brain cell death but from other forms of damage.
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When a person drinks alcohol, several brain areas are affected, causing short-term emotional and behavioral changes.
One area of the brain alcohol affects is the cerebral cortex, responsible for thinking and making decisions. As a person drinks, their inhibitions gradually reduce, and they become less shy and more impulsive.
As drinking continues, it affects the limbic system of the brain, which controls emotions. The person may become sad, angry, or aggressive. Intoxicated people often are uncoordinated and lose their balance. This is because of alcohol's effect on the cerebellum.
When alcohol reaches the hypothalamus, it interferes with hormones and can cause excessive urination and sexual impairment.
The medulla is the brain area that controls the most basic functions, such as consciousness, breathing, and heart rate. Therefore, drinking may cause the person to feel sleepy and slow down their heart and breathing.
Research has shown that the brain damage caused by alcohol can be at least partially reversed. According to MRI studies, the brain does recover to some extent after a significant period of abstinence from a period of one month to a year.2
Some long-term effects of alcohol on the brain include:
Long term alcohol use causes a persistent form of memory impairment, which affects short-term or "working memory." Short-term memories therefore never get stored as new long term memories.
MRI studies allow scientists to see and measure the brain. These studies show that alcohol use causes parts of the brain to shrink or become less dense. This is called atrophy. Certain parts of the brain appear to be especially vulnerable.
The frontal lobes are important for voluntary movement, language, and higher-level thinking. One study showed shrinkage of 11% in this area in heavy drinkers.15
Shrinkage of the cerebellum, which controls balance and movement, can happen in long-term drinkers. This is also true of the corpus callosum, an area that links the right and left sides of the brain, allowing communication between them.2
Another vulnerable area is the hippocampus, which is vital for learning and memory. Atrophy of this area is also strongly linked to Alzheimer's Disease.1
Neurogenesis means the creation of new brain cells. It was once thought that the body was unable to create new brain cells, but it is now known that new brain cells (neurons) can be generated.
Scientists also know that alcohol interferes with this process, which some think may explain brain atrophy.6 However, it has been shown that neurogenesis does begin again if a person stops drinking, though it takes months for the new neurons to be put in place.2
WKS is a devastating disorder of brain function associated with a lack of thiamine. This happens because heavy drinkers eat poorly and are often malnourished. It is actually two disorders — Wernicke syndrome and Korsakoff syndrome — but they often occur one after the other.
Wernicke syndrome develops first and has the following symptoms: confusion, lack of physical coordination, involuntary movements, and abnormal involuntary eye movements or eye paralysis.
Without medical intervention, about 80% of affected people develop Korsakoff syndrome. In this phase, the person shows significant short-term memory impairment — they are unable to create new memories and retain new information. Sometimes long-term memories are lost as well.
The ability to pay attention and have a conversation is not affected, so this person may seem normal to a casual observer. The person may not even be aware of the problem. WKS may cause permanent nerve damage and weakness of the arms and legs.
Many heavy drinkers find it hard to quit even if they want to do so. If they stop drinking, they may experience withdrawal symptoms ranging from mild to severe. These include tremors, irritability, and anxiety, or sleep disruptions. If you have an alcohol use disorder and a mental health problem, it is essential to seek help for both conditions.
More severe symptoms include hallucinations, seizures, sweating, fever, fast heart rate, and high blood pressure.
Research indicates alcohol exposure over a significant period of time will lower IQ. A study of just under 50,000 Swedish military conscripts between 1969 and 1970 found that IQ was inversely correlated with heavy alcohol consumption.11 A study in neighboring Norway found similar results.9
Women who drink while pregnant put their children at higher risk of developing fetal alcohol spectrum disorder (FASD). Children born with Fetal Alcohol Syndrome have IQ's well below average.9
Damage to dendrites caused by alcohol can be reversed after a period of abstinence.2
Brain scans have also shown that some brain atrophy can be reversed. Some improvement has been seen in just one month of abstinence, with mild improvements after six months.
The degree of recovery depends on the duration and quantity of alcohol use, though most published studies indicate that complete recovery is rare.13
The level of alcohol-related brain damage depends on the severity of alcohol use, the age at which it began, and how long it continued.
It takes months for the brain to generate new cells and put them in place.
The reversal of brain volume loss has been seen as soon as a month after the drinking stopped, and some mental faculties begin to improve about 6 months afterward. However, this process is uneven and full recovery is unlikely.
One study showed no regrowth at all of the prefrontal lobes after 6 months.13
Symptoms of alcohol use disorder include:
Treatment options include:
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