Another difference between sons of alcoholics and sons of nonalcoholics is seen when we measure body sway after a dose of alcohol. To do this, a person is given a dose of alcohol and then told to stand still, feet together and hands at the side. The number of degrees off the vertical that the person’s body sways is then measured. If the family history is negative for alcoholism, there is much more body sway than if the family history is positive. What this means is that people with a genetic risk for alcoholism don’t seem to have as much impairment in motor functioning when they drink the same amount of alcohol.

Again, this is probably important in the development of alcoholism because it affects how the person feels and functions while drinking. It’s as though people who have alcoholism in the family are somehow better suited - at first - to tolerate the short-term effects of drinking. They are less likely to have a negative experience early on and probably more likely to continue drinking, which will lead eventually to alcohol dependence.

Some other traits that sons of alcoholic fathers have include differences found on a brain wave test (electroencephalogram, or EEG) and a blunting of the brain’s electrical response to a specific stimulus (event-related potential, or ERP).

A genetic trait that appears to actually protect people from developing alcoholism involves a metabolizing enzyme.

When alcohol is consumed, the body breaks it down into a compound called acetaldehyde, which is then further broken down and eliminated from the body. The enzyme called alcohol dehydrogenase is necessary to break down the acetaldehyde. However, many people lack a certain form of the enzyme. They build up large amounts of acetaldehyde in their system, which causes them to feel ill, with flushing, rapid heartbeat, and burning in the stomach. Asians commonly have this trait. For those people, drinking alcohol is a very unpleasant experience and not likely to be repeated. A similar phenomenon is exploited when we use the drug disulfiram (Antabuse), which disables the enzyme. Someone who drinks while taking disulfiram will become physically ill, so that the drug can be used as a deterrent.

So we can see that there are measurable differences between people with family histories of alcoholism and those without. But what is the mechanism that causes people with such histories to become addicted?

As we will learn in “The Addicted Brain” section, all addictive drugs interact in one way or another with a certain part of the brain commonly referred to as the “pleasure center.” Many researchers are focusing on this part of the brain in alcoholics and in nonalcoholics, trying to find some type of clearly inherited differences. This is, of course, a daunting task. It sometimes seems as though the more we learn, the more we realize how complicated the brain is. But we do know a few things.