Alcohol can make you laugh, or it can make you cry, it can make you live or make you sleep, it can increase your confidence or make you act like a fool. How can alcohol have it all on people? If we want to know how alcohol affects our moods and behavior, we must first understand a little how the brain works.
The human brain consists of about 100 billion nerve cells (also known as neurons). Everything we think, feel or do is the result of electrical signals passing between neurons. These electrical signals require the help of chemicals, called neurotransmitters, to go from neuron to neuron. Scientists have identified about 60 different neurotransmitters so far and tell us that there is probably a lot more to be identified.
Different neurotransmitters have different effects in the brain. For example, serotonin is associated with mood. People suffering from clinical depression tend to experience a serotonin deficiency in their brains, and drugs such as Prozac can help relieve depression by increasing the availability of serotonin in the brain. Endorphins are a class of neurotransmitters that act as natural painkillers of the brain.
Electrical signals in the brain are transmitted as follows: a neuron that sends an electrical signal releases a neurotransmitter, and a neuron that receives an electrical signal receives a neurotransmitter at a site called the receptor. When the neurotransmitter from the first neuron is chemically bound to the receptor of the second neuron, an electrical signal is transmitted. Neurotransmitters and receptors work like locks and keys: there is at least one different receptor for every other neurotransmitter. For example, the endorphin receptor can only be caused by endorphin, the serotonin receptor can be caused only by serotonin, and so on. Different neurons have different receptors. Some neurons will be caused only by serotonin, some by endorphin, etc. For all different neurotransmitters.
Good. Is it all about alcohol now?
Every mood changing substance from heroin to coffee affects the neurotransmitter system of the brain. Some psychoactive drugs affect only one specific neurotransmitter system, while others affect many. Morphine, for example, mimics the neurotransmitter beta-endorphin, a natural painkiller found in the brain. Morphine is in the form of beta-endorphin and binds to receptors for beta-endorphins, acting as a painkiller, and also causes a feeling of pleasure. Caffeine has the form of adenosine and acts on adenosine receptors. On the other hand, alcohol affects many different neurotransmitters, not just one, why is that?
Morphine and caffeine are large molecules. Neurotransmitters are also large molecules. Morphine and caffeine have an impact that they have due to their similarity in form to neurotransmitters, which occur naturally in the brain. Alcohol, on the other hand, is a rather small molecule. Alcohol does not imitate the neurotransmitter. So how does alcohol affect neurotransmitters?
Alcohol is a fat soluble molecule. Fats (called lipids) are the main component of all cell membranes, including neuronal cell membranes. Alcohol penetrates the cell membranes of neurons and changes their properties. The receptors are located on the cell membranes, and this means that the properties of the receptor change in the presence of alcohol. Cell membranes also control the release of neurotransmitters, and this means that the release of neurotransmitters also depends on the presence of alcohol.
The effects of alcohol on receptors and neurotransmitters are well documented for several neurotransmitters and their respective receptors. These effects are shown in Table 1.
Table 1: Effects of alcohol on neurotransmitters and receptors
- glutamate
- Alcohol inhibits glutamate receptor function
- It causes muscle relaxation, dissociation, slurred speech, stunning memory impairment and darkening.
- Ether and chloroform have a similar effect on the glutamate system.
- GABA (gamma-aminobutyric acid)
- Alcohol enhances the function of the GABA receptor
- It causes a feeling of calm, anxiety and recession.
- Valium has a similar effect on the GABA system
- dopamine
- Alcohol increases dopamine levels
- This leads to arousal and stimulation.
- Cocaine and amphetamine have a similar effect on the dopamine system.
- Endorphins
- Alcohol increases endorphin levels
- It kills pain and leads to “high” endorphin,
- Morphine and heroin have a similar effect on the endorphin system.
Drugs such as morphine or cocaine are called “chemical scalpels” because of their very precise effects on only one neurotransmitter system. On the other hand, alcohol is much more like a chemical hand grenade, because it affects almost all parts of the brain and all neurotransmitter systems. Alcohol affects all of these systems simultaneously. When people drink alcohol, they become alive and agitated because alcohol increases the level of dopamine, as cocaine does, although alcohol does not increase the level of dopamine anywhere near cocaine. When people drink alcohol, they feel relaxed and lose their anxiety, because alcohol makes GABA receptors more effective like Valium. The reason people tend to fall asleep after drinking or taking Valium is also due to this effect on the GABA receptor. And alcohol has an analgesic effect, such as morphine, and produces the same amount as morphine, because it causes the release of endorphins in the brain, increasing the levels of endorphins. (Note that the effect of morphine is different from alcohol in its mechanism — morphine mimics endorphins and binds to endorphins, while alcohol increases the amount of endorphins in the brain.) Finally, we come to glutamate. Alcohol significantly inhibits the functioning of the glutamate receptor. Glutamate is responsible for the formation of new memories, as well as for the coordination of muscles. The effect of alcohol on the glutamate receptor leads to slurred speech and stuns people who consume alcohol, as well as the inability to remember what was done that night when morning came. Perhaps the only positive effect of this effect on the glutamate receptor is a feeling of muscle relaxation. Many of the negative effects of alcohol, such as deaths in cars due to drunk driving, are the result of a loss of coordination caused by the effects of alcohol on the glutamate receptor. Even a small amount of alcohol has a great influence on coordination, so never, never drink or eat.
You may have noticed that alcohol seems to have different effects on different people. Some people quickly become sleepy after drinking alcohol, while others become lively and want to just go, leave, leave. Studies in mice show that this difference is genetic. Scientists were able to propagate the strains of mice, which quickly fell asleep after drinking alcohol. They were also able to propagate the strains of mice, which become very active after drinking alcohol. This suggests that genetics determines which neurotransmitter system is most exposed to the effects of alcohol in which a person. Persons who become sleepy soon after drinking probably have a stronger effect on their GABA system. And people who become alive and agitated after drinking alcohol are likely to have the most exposed dopamine.
The effect of alcohol on the brain does not end when alcohol is completely metabolized and leaves the system - what happens next is something like the recovery of the neurotransmitter. This rebound effect is most easily illustrated if we look at what happens to many people when they use a drink or two as an aid for sleep. These people often wait to wake up in the middle of the night and cannot sleep. What happens is that alcohol improved the functioning of the GABA system and made these people feel relaxed and sleepy. Whenever alcohol is present, the GABA system struggles to overcome the effects of alcohol and return to normal functioning. When all the alcohol finally leaves the body, the GABA system over-fulfills the mark and leaves people restless and vigorous. This is why alcohol is not a good sleep aid. Large amounts of alcohol can hold a person longer, but drinking large amounts of alcohol has its negative consequences. The neurotransmitter rebound can also be implicated in hangover symptoms, such as hypersensitivity to light and alcohol withdrawal syndrome, causing anxiety and panic and other symptoms.
Some drugs used to treat alcohol abuse, such as campral and naltrexone, affect neurotransmitter systems. Naltrexone (also called revia) is an opioid receptor antagonist. Naltrexone works by binding to endorphin receptors (which are sometimes also called opioid receptors) and blocks them, so that opiates cannot bind to these receptors. Unlike opiates or endorphins, naltrexone does not have analgesic effects and does not cause pleasant effects. Naltrexone simply blocks endorphin receptors, so either opiates or endorphins can have their own analgesic or pleasant effects. Naltrexone is very effective with people who use opiates, such as morphine or heroin, because these drugs do not work at all when the receptors are blocked by naltrexone. Naltrexone has a definite effect on helping people to abstain from alcohol or to soften their use, but it is not as effective with alcohol as it is with opiates, because alcohol affects many different neurotransmitters. The disadvantage of naltrexone is that the body's natural painkillers, endorphins, cannot do their work when they are present. People taking naltrexone are advised to wear drug bracelets so that doctors know that pain killers are not effective for these people.
Campral (also known as acamprosate) is a glutamate receptor modulator. Campral helps eliminate long-term alcohol cravings. It is assumed that prolonged use of alcohol disrupts the glutamate neurotransmitter system and that campral helps restore it to normal.
No discussion of alcohol and the brain would be complete without mentioning possible brain damage caused by alcohol abuse. It is likely that we all heard that drinking kills brain cells. However, do scientific data confirm this common popular statement? In 1993, a study by Jensen and Pakkenberg published in the Lancet, entitled “Do Alcoholics Drink Their Neurons?” Compared the brains of alcoholics with non-alcoholic brains. This study showed that the white matter of the brain of alcoholics was significantly depleted. The gray matter, however, was the same in both alcoholics and non-alcoholics. This is interesting since this gray matter makes thinking. Gray matter was compared with a network of computers, and white - with cables connecting them together. The brain does not produce a new gray matter to replace the lost. The brain can, however, produce a new white substance to replace the white substance that has been lost. The researchers concluded that the loss of white matter for heavy use of alcohol may not cause irreparable damage.
There is, however, a form of irreparable brain damage that can be caused by prolonged use of alcohol. This is the Wernicke-Korsakov Syndrome, also known as the wet brain. Wernicke-Korsakov syndrome is not caused by the loss of brain cells - it is caused by a deficiency in vitamin B1 (also known as thiamine). Wernicke-Korsakov syndrome can have several causes, including excessive malnutrition, long periods of vomiting due to morning tiredness or eating disorders, kidney dialysis, gastric stitching, or alcohol abuse. The vast majority of cases of Wernicke-Korsakov syndrome, which occurs in the United States, are caused by heavy, prolonged, heavy use of alcohol. Alcohol can lead to Wernicke-Korsakov syndrome, as it blocks the absorption of thiamine. Symptoms of Wernicke-Korsakov syndrome include amnesia, inability to form new memories, confusion, hallucinations and confusion. Some of the more severe symptoms of Wernicke-Korsakov syndrome can be treated with thiamine, but in most cases many of the symptoms persist throughout life.
Have scientists learned everything you need to know about the effects of alcohol on the brain? It seems that this is clearly not the case. Scientists believe that alcohol probably affects many other neurotransmitters than those discussed in this article. There are ongoing and ongoing research to find out how alcohol can affect other neurotransmitters. The future is likely to bring us a lot of new knowledge about alcohol and the brain.
