The brain is the body's control center. It enables you to run and play, learn new facts and ideas, and feel a wide range of emotions. The brain can process information gathered through the five senses—seeing, hearing, smelling, tasting, and touching. There is even a part of the brain that makes sure that vital life processes, such as breathing and maintaining a regular heartbeat, go on, even when you are asleep.
The brain is part of a body system called the Central Nervous System, or CNS. The CNS is made up of billions of neurons, or nerve cells, in the brain and the spinal cord. The peripheral nervous system, which includes neurons, forms a network that carries information to the neck and arms, trunk, legs, skeletal muscles, and internal organs.
What happens to the CNS after drinking? While all body systems feel the effects of alcohol, the CNS is particularly sensitive. That's because alcohol can pass through the blood-brain barrier, reaching neurons directly. Once alcohol touches these cells, they are changed, resulting in changes in behavior.
Let's find out more about the effect that alcohol has on the nervous system and the brain.
The Central Nervous System (CNS)
The CNS is responsible for taking in information through the senses, motor function, thinking, understanding, and reasoning. This system also controls emotion. The CNS includes the brain, the spinal cord, and the nerves that come from it. The most important parts of the CNS are protected by bones. The skull protects the brain, and the spine protects the spinal cord.
Alcohol is a depressant of the CNS. That means that alcohol makes nerve cells in the brain less excited, causing them to slow down. Does this surprise you? People often think that alcohol is a “pick-me-up” experience because it causes drinkers to become more animated and less reserved. That's because the first areas affected by small amounts of alcohol are those involved in inhibiting behaviors, which can cause an increase in animation, an increase in talkativeness, and greater sociability. But there are many indications that the brain is slowing down. Here are a few:
Exactly how much brain activity slows down depends on a variety of factors. How much, and how fast, a person drinks are important, as is whether other drugs, such as marijuana, have been taken. Your size, weight, and gender play a role, along with your genes. If alcohol abuse runs in your family, then you are at greater risk for having problems with it, too.
The brain is made up of more than 100 billion neurons. Each makes tens of thousands of connections. Alcohol can damage or even kill neurons, perhaps changing development of those parts of the teenage brain that are still developing.
Alcohol is able to penetrate the brain because it can cross the blood brain barrier. This means that it can move from circulation in the blood into the brain cells. Because it can touch brain cells directly, it is sometimes said that “alcohol kills brain cells.” Scientists used to think that once brain cells die, they can never come back, but new research says that this may not be true. Scientists now think that in some parts of the brain, cells can regenerate, or come back.
Another idea about the brain that is changing is the time it takes to develop. Researchers used to think that development only took place during the first few years of life. New findings, however, have shown that during the teen years and into a person’s twenties, important changes are taking place. For example, parts of the brain that help teens make decisions, regulate emotions, and control their impulses are still forming. In fact, many characteristics of adolescence, such as mood swings, may be, in part, a result of brain development.
This summary provides information about the role of different parts of the brain and how alcohol affects their functioning.
Ventral striatum and prefrontal cortex: These parts have connections that make up the brain’s reward system and regulate impulsive behavior. In a young person, drinking too much alcohol can affect those connections, which are not finished developing yet. As a result, teens may do impulsive things that they probably would not do under normal circumstances. This is also the part of the brain that is affected first, causing behavior to become looser and less guarded.
Hippocampus: This is the part of the brain that stores memory. It is still maturing during adolescence. Even a small amount of alcohol can make teens forget what they did or learned while they were drinking.
Cerebellum: This part works with the primary motor cortex to control movement, balance, and complex motor functions. Drinking alcohol can decrease motor function and slow reaction time. For example, when a person is drunk, he or she may not be able to stand or walk a straight line.
Frontal lobe: This section controls judgment, behavior, and emotion. Alcohol may affect emotions, leading to crying, fighting, or a desire to be close to another person.
Reticular activating system: This part is in the midbrain, and it controls sleeping and waking. Alcohol can depress these systems, causing a person to pass out.
Medulla: This part is in the hindbrain, and it controls heartbeats, breathing, and other functions. During heavy drinking, these may slow or stop working altogether, endangering an individual’s life.
Neurons: These are the nerve cells. Alcohol can reach and enter these cells and damage, or even, at high enough levels, kill them.
Blood vessels: At intoxicating levels, alcohol causes blood vessels to relax and widen. At even higher levels, it can shrink the vessels and increase blood pressure, exacerbating such conditions as migraine headaches.
Alcohol Can Be Dangerous
You can see that alcohol affects just about every part of the brain and the nervous system. As different parts of the brain "shut down" from alcohol abuse, teens may engage in behaviors that are not good for them. Here are some activities that young people may find themselves doing when “under the influence”:
Make bad decisions. Because the prefrontal cortex is not mature, alcohol can harm a teen’s ability to reason and weigh choices. Instead, teens may do something simply because it is fun or feels good.
Take risks they would not usually take. Because connections between the prefrontal cortex and the ventral striatum are still maturing, alcohol can affect those connections. As a result, teens may do impulsive things, such as drinking and driving or having unprotected sex. Both of these activities can have negative consequences.
Interfere with prescribed medications. Some teens take medication for conditions such as attention deficit disorder (Ritalin, for example); bipolar disorder (lithium); and depression (Prozac). Alcohol can increase the effects of some of these medications. For example, alcohol mixed with Ritalin may damage a teen’s ability to perform tasks that require total concentration. Large amounts of alcohol mixed with lithium may impair judgment, thinking, and motor skills.
Sometimes, too, people become so dependent on alcohol that they can't function properly unless they drink frequently. When this happens, a person has gone beyond heavy drinking into a new area. That person now suffers from a condition called alcoholism. If a person has alcoholism, he or she also can be considered to have an addiction to it.
Why do some people have more problems with alcohol than others? Research points to a relationship between early onset of drinking and later alcohol-related problems. There is evidence that young people are starting to drink earlier and earlier. In 2003, the average age of first use of alcohol was about 14, compared to about 17½ in 1965. Those individuals who reported starting to drink before the age of 15 were four times more likely to also report having signs of alcohol dependence at some point in their lives. New research shows that serious drinking problems (including what is called alcoholism) typically associated with middle age actually begin to appear much earlier, during young adulthood and even adolescence.
As people continue to drink heavily, their brains get used to alcohol, or develop a tolerance for it. This means that they require more alcohol to get the same effects as before. Throughout the nervous system, what is happening is that the alcohol is causing the nerve cells to slow down. To make up for this, the brain pushes these cells to go faster. The more used to alcohol the brain becomes, the more it pushes nerve cells. Over time, the brain pushes the nerve cells to such a point that they need alcohol in order to slow down and function properly. That's why some long-term alcoholics need a drink before they can even start their day.
The highest rates of alcohol abuse are reported among young people in their late teens and early twenties. The group with the second highest rates is young teens, between the ages of 12 and 17. High-school and college students may engage in binge drinking, which is defined as having 4-5 drinks over a two-hour period.
New research indicates that binge drinking may last beyond a couple of parties where teens may have indulged. Susan Tapert, a neuroscientist at the University of California, San Diego, studied the effect of binge drinking on developing adolescent brains. Comparing brain images from MRIs of binge drinkers with non-binge drinkers, she found that the white matter of the brain—the part responsible for fast relay of information—was not as well formed.
After observing these changes, Dr. Tapert wanted to find out how the changes to white matter affect functioning. She gave the group different kinds of tests measuring the ability to perform certain tasks. What was particularly interesting about her findings is that they were different for girls and boys. Girls performed less well on tests measuring spatial functioning, such as the ability to copy a difficult puzzle. Boys, on the other hand, tended to perform less well on tasks requiring attention. These are the kind of activities that are boring but have to be done. The difference was about 10 percent, which could translate into the difference between an A or a B.
Are these effects permanent? At this point, researchers don't know. But they are continuing to study the effect of binge drinking on teens, so they should know the answer soon.
Alcohol abuse can lead to major health problems—and can affect your ability to learn and function well. The best way to protect yourself from these problems is to never start drinking at all. It's a foolproof approach that works every time.