How Does Drinking Alcohol Affect the Brain and Body? Detailed Breakdown

Alcohol use is pervasive in today’s culture. Even though most people drink frequently, very few people know the specifics of what alcohol does to the mind and body. These effects are far reaching and can sometimes be very dangerous. In this article we take a look at how alcohol affects the brain and the various systems of the body.

How Alcohol Affects The Brain

The most direct and immediate impact of alcohol is on the GABA and glutamate pathways in the brain. Both GABA and glutamate are neurotransmitters used in the regulation of excitation and produce cascade effects all throughout the body. GABA is an inhibitory neurotransmitter which dampens and moderates signals, while glutamate is an excitatory neurotransmitter which helps stimulate activity. Alcohol directly causes a flood of GABA and a sharp drop in glutamate which produces the depressant effects. Dopamine and serotonin are also affected but not as strongly. Interactions with these neurotransmitters is responsible for the mood and anxiety reduction (serotonin) and the pleasure and good memories associated with alcohol use (dopamine).

Continued alcohol use causes the brain to undergo a process called downregulation (or upregulation in the case of glutamate), which is the brains response to the consistently elevated levels of GABA, glutamate, serotonin, and dopamine. This occurs when the levels of neurotransmitters are too high for too long, and the brain will make changes to protect itself from excitotoxicity. These changes will either lower or increase the brain’s sensitivity to these chemicals. This has the effect of a drinker needing more alcohol to produce the same effect, as well as someone feeling progressively worse and worse when they are not drinking. Once someone has drank consistently for long enough, the changes may be so strong as to make someone physically ill and shake when they do not have alcohol. This is the beginning of alcohol withdrawal.

The interactions alcohol has with these powerful neurotransmitter can produce a variety of effects on the perception of a drinker. Lets take a look at some different areas affected to get a closer look at the results:

Sensory Effects

The increase in GABA levels coupled with the decrease in glutamate produces a very powerful sedative effect. A drinker will begin to feel relaxed and calm and will be less aware of their environment. With the addition of impaired coordination and motor control and a slower reaction time, this can make someone very clumsy and contributes to the danger of someone driving a car under the influence of alcohol. A drinker will also have a reduced ability to reason and make sound judgments. This is attributed to the anti anxiety effect of increased GABA levels making someone feel like things are less important of less risky than they really are.

Memory is also greatly impaired when drinking alcohol. This can be mild at low amounts, but when a person drinks more their memory becomes more and more impaired, potentially to the point of blackout. A blackout is when the brain is so slowed down that it does not effectively create and store memories. The memories may be present, but the person affected is unable to consciously bring them to mind. Vision is impaired as well, with enough alcohol making someone see double. This is both because the muscles of the eye can’t tighten enough to properly align the eyes, as well as the brain being unable to properly combine input from the optic nerves.

Emotional Effects

The emotional effects of alcohol use are complicated and paradoxical. In the short term alcohol can make someone feel happy, calm, and have more fun doing normal, mundane things. In the long term the effects are the opposite. When someone comes down from alcohol, typically the next morning, a hangover is the result. This is not only the physical symptoms including headache and stomach trouble, but an increase in anxiety and mild feelings of depression. Now with decreased GABA and increased glutamate, someone will begin to feel on edge and tense. This will only worsen the longer alcohol is used, since downregulation will make this more pronounced over time.

Someone who is drinking is likely to feel more open and connected since their inhibitions are down. They don’t have the normal hesitance to be totally open with anyone around them, and this can promote feelings of solidarity and fellowship. Additionally, the effect alcohol has on dopamine means that positive memories are strongly linked to alcohol use. This can contribute to addictive or alcoholic behavior, but first and foremost it means that someone associates alcohol with good times and this produces a desire to drink to recapture those times. This is one of the most subtle, but dangerous effects that alcohol produces.

Behavioral Effects

As mentioned, alcohol decreases a drinkers ability to perform “big picture” thinking. This means that short term fun will take priority over long term risk. This often includes driving drunk, fighting, stealing, and anonymous sex. Thrills and excitement seem much more attractive since the potential risks can’t be weighed properly. Coupled with the risks of lowered reasoning, sex drive is also increased through alcohol use. With more sexual desire, someone who is drunk is much more likely to give in to more base instincts since they lack the ability to properly think through the implications. This can result in unsafe sex, unwanted sex, or sex with people that the drinker would never sleep with if they were sober.

Due to the effects of alcohol, people tend to be much more boisterous and rowdy when they are drunk. This can, in turn, increase risks of all sorts since there is a large increase in risk taking behavior in general among active drinkers. This could be in the form of normal activities, but commonly includes someone doing drugs they normally would not do. Mixing drugs with alcohol can be extremely dangerous, and depending on the drug, a drug interaction could easily be fatal.

How Alcohol Affects The Body

Alcohol has a very heavy impact on the body as well as the brain. The physical effects of alcohol are mostly depressive but it can also affect other systems, interrupting normal function. The symptoms vary depending on the system affected, so we have broken down these effects as follows:

Cardiovascular Effects

While alcohol is a central nervous system depressant, it has the opposite effect when it comes to the heart. Alcohol acts as a vasodilator, causing the blood vessels to relax. This lets more blood reach the tissues and skin and is responsible for the flushing of the face when drinking. This also lowers blood pressure, meaning that the heart has to work harder to circulate blood resulting in a higher heart rate. This can lead to an increased risk of stroke, as blood pressure fluctuations happen more frequently. Oxidative stress is also a factor in the cardiovascular system as alcohol metabolism and the toxic byproducts it produces must travel through the blood to be filtered. These byproducts can cause damage to blood vessels, as well as potentially damage other organ systems through transit exposure. This is known to play a role in damage to the myocardium (heart muscle tissue). Finally, alcohol makes it more difficult for blood to clot which increases the risk of blood loss through injury¹.

Pulmonary Effects

When drinking alcohol, the breathing rate usually increases. This is because the body needs more oxygen due to a higher heart rate. Alcohol use also changes the structure of the lungs making it more susceptible to infection and injury. When drinking alcohol, the interior surface of the lungs (specifically the alveolar epithelium) become more permeable. This will encourage fluids to leak from cells into the airways which can cause a wide range of issues, the most serious of which is pulmonary edema. Aside from compromising lung immune function, this reduces the overall efficiency of the lungs and will worsen any other lung issues that may be encountered¹².

Gastrointestinal Effects

Alcohol use takes a heavy toll on the GI tract. This can begin in the stomach, where alcohol is corrosive to protective mucus increasing the risk of a stomach ulcer or esophageal issues. Once in the small intestine, alcohol really begins to do more major damage. Being a disinfectant, alcohol can kill many of the healthy gut flora which help us digest food. The liver and the intestines are the major centers for alcohol metabolism. Alcohol metabolism is the process which the body rids itself of alcohol, which is technically a toxin. This first requires alcohol being metabolized into acetaldehyde, which is extremely toxic and a known carcinogen in humans. It can also damage mucous membranes, which are prevalent in the gut. The general effect alcohol has in the digestive system is to prohibit the normal absorption of nutrients such as fats, proteins, and vitamins. This can result in brain damage through alcohol induced thiamine deficiency, as well as chronic diarrhea and poor nutrition in general. Again, since alcohol is a toxin, the body will prioritize alcohol metabolism over normal food metabolism. This means that even though a person may eat while they are drinking, they are getting much less nutrition from this food while alcohol is present¹². It also appears that the type of alcoholic beverage consumed plays a role; with beer producing greater GI disturbances, and hard liquor producing less.

Reproductive Effects

Alcohol can have a massive impact on reproduction and fertility in both men and women. Additionally, drinking alcohol while pregnant can lead to a wide range of very serious complications and birth defects. Some of the ways this can manifest may include:

  • Male Reproduction: The most direct effect of alcohol on the male reproductive system is on the quality of sperm. High levels of alcohol use (binge or heavy drinking) is directly correlated to sperm count, sperm motility (ability to swim), and physical sperm defects. Alcohol use is also known to increase levels of testosterone in the blood¹².
  • Female Reproduction: Alcohol has a powerful impact on the female reproductive system. This can vary in expression depending on age and sexual maturity. Alcohol use during puberty is known to disrupt  many sex hormones such as estrogen and may delay the onset of puberty. Post puberty alcohol use can drastically disrupt the normal reproductive cycles resulting in many issues such as menstrual irregularities, ovarian failure or anovulation, and infertility to name just a few. The effects of alcohol on post menopausal women are not well defined, but alcohol is known to increase the risk of osteoporosis. It is unclear if this is caused directly, or through the attendant nutritional deficits resulting from alcohol induced GI disruption¹².
  • During Pregnancy: Alcohol is a known cause of a large number of birth defects, collectively known as Fetal Alcohol Spectrum Disorders. The most serious FADS disorder is Fetal Alcohol Syndrome which causes mental disabilities and physical deformities. Further, alcohol use before and during pregnancy increases the risk of the newborn dying by Sudden Infant Death Syndrome. While the amounts that are drank can increase these risks, it is becoming clear that there is no safe level of alcohol use during pregnancy¹²³.


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Michael Smeth
Michael Smeth
Michael Smeth is the Director of Online Marketing at The Summit Wellness Group. He has been involved in the addiction recovery community for over 18 years and has a passion for spreading the message of hope that recovery has brought him and countless others.
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