News

Alcohol and the body: What it really does

Belinda Beresford

Within half an hour of having a drink, alcohol molecules spread into all tissues of a human body.

To make alcohol, take a couple of carbon atoms, some hydrogen and a bit of oxygen. Combine to the recipe C2H5OH, using microbes to do the work for you.

The result is ethanol, the least toxic form of alcohol and one of the planet’s most widely use drugs. It is a very small molecule, which accounts for its dramatic impact on humans. Ethanol is small enough to make its way through two of the most important lines of defence in a human being: the blood brain barrier, which protects our intellect, and the placenta, which protects the foetus.

Within half an hour of having a drink, alcohol molecules spread into all tissues of a human body. The levels of alcohol will rapidly become the same in blood, fat and the breath—which is why a breathalyser test can be used to check for the level of inebriation rather than needing to draw blood.

Alcohol interferes with neuropeptides, which are part of the signalling mechanism in the nervous system. The erratic sparking between neurones initially causes excitation—the buzz of that first drink. But in higher doses, as the interference with the neurones becomes greater, alcohol becomes depressive, hence the classic weeping drunks.

An obvious sign of the short-circuiting of electro-chemical functioning in the brain is the drunk’s unsteady gait. Sexual function may also be affected—the famed brewer’s droop—as alcohol drops the blood pressure, making it hard for a man to get an erection.

The neurobiology of alcohol in humans is still largely unknown, but it appears in particular to affect a ubiquitous neurotransmitter called Gaba (gama amino butyric acid) that acts on the so-called “pleasure centre” of the brain.

Professor Denis Viljoen, of the Foundation for Alcohol-Related Research, says alcohol smashes across a whole lot of functions and the effects follow a predictable order. “First it is excitatory, people get worked up. Then it is depressive, and then an anaesthetic.”

The old army trick of giving a slug of booze to reduce the pain before digging out the bullet does have a scientific basis, as long as the said dose of alcohol isn’t too high. When alcohol approaches 250mg/ml, people can stop breathing.

Viljoen says that violence is probably associated with alcohol consumption, but in some people it appears to be a direct effect. Some drinkers are low responders to alcohol—they need more alcohol to get the buzz. Such people, who appear able to drink a bottle of wine without being affected, are at much higher risk of alcoholism.

These low responders also appear to be more predisposed towards drunken violence. Viljoen, who has studied alcohol and particularly foetal alcohol syndrome in South Africa for decades, says that people with antisocial personalities, who are often highly aggressive, are often low responders to alcohol.

Like many drugs, alcohol has a good side to it as well. It can dampen the brain’s responses to anxiety and stress, making drinkers feel more relaxed and comfortable with themselves. People who regularly drink small mounts of alcohol appear to be protected from some forms of disease such as heart attacks and Alzheimer’s. This is probably because such low repeated doses of alcohol appear to reduce accumulation of certain fat deposits in the walls of arteries. The challenge is to keep the dose regular—and small.

Repeated use of alcohol causes the body to become resistant to it, so the body develops a need to satisfy that tolerance.

Some form of genetic interplay predisposes responses to alcohol. Alcoholism is probably 60% attributable to genes, says Viljoen. It is a disease of the brain and the body: “It’s a complex, multiple gene problem, and alcohol is just a trigger. But there are also lots of things that drive the need to drink. Peer pressure is very important, it becomes normal to drink.”

Topics In This Section

Comments

blog comments powered by Disqus