It’s fewer than two weeks away from Christmas—time for get-togethers, holiday parties, and family gatherings. What’s a better way to warm up from the chill and snow than having a nice holiday drink?
It’s no surprise, then, that rates of drinking spike sharply around Christmas. This has been linked to more alcohol-related car crashes and violence around the holidays. So it’s a good idea to keep in mind how alcohol affects your body, and what a good limit for your drinking is.
We recently discussed in neurochemistry how alcohol affects the body, particularly the signaling processes in the brain. After alcohol is ingested, a chemical called gamma-aminobutyric acid GABA is released in the brain. The primary effect of GABA is to reduce the activity of cells in the brain. As the brain activity is reduced, a person feels more laid back, comfortable, and relaxed.
GABA “inhibits” the usual high activity of the brain by blocking the effect of another chemical called glutamate. Glutamate causes the neurons of the brain to fire and send signals. GABA inhibits the activity of these neurons, causing decreased activity in the brain. This is why some cognitive functions are impaired during alcohol use, specifically memory. GABA affects glutamate receptors, which are important for encoding memories. This leads to impaired memory ability and “gaps in memory.
This “relaxant” effect of alcohol is a large part of what causes people to continue using alcohol. For some people, it makes social interaction easier. For others, it makes socializing more enjoyable through the “buzz” created by alcohol. Many others just enjoy being able to relax after a hard week. However, as we know, past a certain level, the effects of alcohol become more negative and not as enjoyable. The impairment from GABA causes dizziness, slurred speech, and poor coordination. Nausea and vomiting may occur as well. This two-part effect of alcohol has been called the “biphasic effect,” since its positive results come before some its more negative aftereffects.
After continued use of alcohol, tolerance can develop. This means that the body has become accustomed to the alcohol in the system and now can counteract the impairment. Glutamate becomes more active, overpowering the inhibitory effect of GABA. How does this happen? There’s evidence that several different chemicals and molecules in the brain are involved in reversing glutamate receptors desensitivity caused by GABA. One molecule called Fyn is important for cellular structures in the brain and seems to be involved in this process. It interacts with glutamate receptors and change their shape so that they become more active. Increased activity of glutamate means less effects of alcohol on the brain.
When a person becomes more tolerant to alcohol, this can impact their drinking habits. First of all, when someone becomes “used” to alcohol, he or she will be more likely to drink more to get the same effect. Thus, they are at greater risk of inadvertently drinking a toxic amount of alcohol. 
Additionally, when a person becomes tolerant, there is evidence from animal studies showing that part of tolerance is due to the environment they are used to drinking in. For example, a person might develop alcohol tolerance from typically drinking with friends in a club on Friday night. In this case, being in the club will help produce their reduced response (high GABA activity) to alcohol, leading them to increase their alcohol intake. But if they try to drink a similar large amount of alcohol in a different environment, their tolerance may be reduced from being in a different environment. This dose may overpower their system, resulting in possible harm.
Alcohol’s effects, then, are more complicated than GABA’s relaxing effects on the body and inhibitory action on chemicals like glutamate. Instead, your drinking habits and experiences shape how your body and brain respond to alcohol. Keep those in mind as you celebrate this holiday season!
You Booze, You Lose
