Alcohol has two principle actions in the brain. First, it enhances the widespread inhibitory effects of the neurotransmitter GABA and acts as a depressant on the entire central nervous system. For this reason, in the 19th century, alcohol was widely used as a general anesthetic. Unfortunately, the duration of its depressant action on the brain was too long and could not be controlled easily or safely. The effective dose for surgical analgesia using alcohol is very close to its lethal dose. Therefore, it was possible to induce sufficient anesthesia for a cowboy to remove an arrow from his leg, but it was unlikely that the unfortunate cowboy would survive the operation. Thus, if the arrow does not kill him, the operation certainly might; of course, prior to the 20th century, this was generally true of most medicines. Now you understand why Hippocrates requested in his oath that physicians, at the very least, do no harm. Drug therapies in ancient times often produced more harm than benefit to the patient.
In ancient times, there is ample evidence that alcohol was tested for its potential benefits beyond being a source of nutrition. Unfortunately, the side effects usually greatly outweighed the benefits. What are some of these side effects and what's happening in the brain; first, the staggering and "wall-banging." Alcohol alters the activity of neurons that project into the cerebellum, a structure that is critical for the timing and execution of smooth movements. This leads to the incoordination that is seen in people after drinking alcoholic beverages.
Second, alcohol inhibits the brain's principle excitatory neurotransmitter called glutamate. Alcohol impairs the function of this neurotransmitter in brain areas that are critical for memory formation. The combined action upon these two critical neurotransmitter systems underlies the amnesia that occurs for events that can take place during intoxication, for example the classic blackout regarding ones inappropriate behavior at the office holiday party.
The impairment in the function by GABA and glutamate also explains why our most complex behaviors are lost first. Many of my students complain about the behavior of their friends following consumption of only modest amounts of alcohol. Which behaviors are released from control first? Usually, alcohol consumption initially releases what are called "punished behaviors," such as not drinking and driving, not dancing on picnic tables naked in the park at midnight, etc. You get the idea: these are behaviors that we are warned against undertaking by our mom, the police or God.
As the alcohol concentration in the brain increases, more and more neural systems are turned off. Ultimately, when blood levels become too high the neurons critical to controlling breathing and heart rate are inactivated. Death due to alcohol intoxication occurs because of respiratory failure due to depressed function of neurons in the brainstem. Usually, the brain's vomiting control center will become activated at blood alcohol levels of about 0.12%. However, if a person drinks slowly and steadily, they can sneak up on these vital protective circuits and gradually inactivate them with alcohol. Once this happens, the body makes no effort to rid itself of alcohol in the stomach by vomiting and the levels of alcohol can continue to rise to lethal levels. Thus, vomiting at the end of the party is a good thing, really. Your body is trying to protect you!
Finally, our drinking behavior is greatly influenced by our environment. The people who make a profit on the sale of alcoholic beverages are well aware of this fact and clearly take advantage of the knowledge in designing their environments. When studies were made of the behavior of people in bars, time is a big predictor of alcohol abuse; for example, the shorter the stay in the bar the faster the rate of consumption. People drinking alone stay the shortest time and drank the most; thus there are always plenty of single (usually uncomfortable) barstools available. One study compared drinking behavior in two different settings, a Rock & Roll bar and a Country & Western bar. The study found a correlation between the sipping rate and the beats per minute of the music. Fast paced music was associated with the slowest drinking rate. Music that was closest to a person's resting heart rate produced the fastest drinking. Lyrics of slow songs also contributed to drinking behavior. Tear-jerk lonesome Country & Western lyrics involving losing, hurting and cheating, or working, dying and drinking, or wailing and self-pitying were associated with increased drinking - who's not surprised?! Live bands and action photography flashing on the walls also increase drinking rates. Next time you find yourself in such an environment take notice of how carefully and subtly your behavior is being controlled so that you'll spend the most amount of money in the shortest period of time.
See also: Marijuana and Coffee are good for the brain. http://www.youtube.com/watch?v=2uVXs6CY2ps
© Gary L.Wenk, Ph.D. author of Your Brain on Food (Oxford, 2010); http://faculty.psy.ohio-state.edu/wenk/
