Mark may never learn how alcohol affects the brain. “Chug! Chug!” yells the chorus of freshmen crammed into Mark’s dorm. Mark rests against the wall. He feels the relaxation of a buzz take over his body. He feels confident, immune to pain, and slightly nauseous. But what is actually going on in Mark’s brain?
Alcohol is one of the most commonly used drugs, but few people understand the physiological effects. Alcohol affects the brain not only during drinking but also the next day and, for regular drinkers, over a lifetime. Below, we will look at the chemical effects that alcohol has on the brain and how these processes change behavior.
At the party When a person drinks, they digest alcohol into their bloodstream. The alcohol infused blood is pumped to the brain where it permeates different parts, including the cerebral cortex, cerebellum, and the limbic system. In the brain, alcohol latches onto the membrane (or skin) of cells. Here, it affects the neurotransmitters (or messages) sent between different cells. These messages control what a person thinks, does and feels. By inhibiting some messages, and encouraging others, alcohol changes behaviors and thoughts.
The largest part of the brain, the cerebral cortex, controls higher brain functions. When alcohol influences the neurotransmitters in the cerebral cortex, it can affect though processes, leading to potentially poor judgment, and depress inhibitions, often causing the drinker to become more confident and talkative. In addition, it can blunt the senses and increases the reveler’s threshold for pain. Alcohol also hampers function in the cerebellum, which controls fine muscle movements and balance, making the drinker commit what we commonly call party fouls.
The limbic system controls automatic processes of the brain like hunger, sexual arousal, emotion, and memory. The intake of alcohol can affect all of these processes. For example, as a person increases their consumption of alcohol over an evening it can cause short-term memory loss, or even blackouts. Another example is the increase in sexual arousal and simultaneous decrease in sexual performance. Alcohol is also a diuretic, it stops the release of a hormone that prevents constant urination. This explains why there is always such a long bathroom line at the bar.
The next day There are many causes for the different symptoms of a hangover. For example, because alcohol is a sedative, the brain counteracts the effect by releasing stimulants that cause a nausea, and light and sound sensitivity. As your blood alcohol levels decrease, these stimulants are left in your body without anything to balance them out.
The infamous hangover headache is caused primarily by a loss of water. The body’s organs compensate for this by stealing water from the brain, causing it to decrease in size. This change in pressure causes headaches.
Additionally, alcohol disrupts sleep patterns, by slowing down a neurotransmitter in the cortex. Although a drinker will feel very tired, the alcohol will initially suppress REM (or dream) sleep. When the effects of the alcohol wear away, the body compensates by producing a “REM backlash.” This means that in the later hours of sleep, the drinker has more dreams but gets less rest. As a result, besides the headache, many wake up the next morning feeling irritable.
Over a lifetime Alcoholics often suffer from severe permanent changes to the brain—especially the cerebellum. Diseases such as the Wernicke-Korsakoff syndrome or hepatic encephalopathy are caused when alcohol reduces the body's ability to absorb essential nutrients. These cause mental confusion, paralysis of nerves that move the eyes, and an impaired ability to coordinate movements. Often, patients go on to form lasting psychosis, behavioral abnormalities and memory impairments.
Additionally, alcohol damages the ability of the brain to create new brain cells and destroys existing ones. In a recent study, it was found that people that consumed alcohol had smaller brain sizes as they grew older.
"The Role of Thiamine Deficiency in Alcoholic Brian Disease." Martin, P.R., Singleton, C.K., & Hiller-Sturmhofel, S. (Spring, 2003)