The six large groups of mood-altering drugs are alcohol (beer, wine, distilled spirits), depressants (barbiturates, tranquilizers, sedatives, sleeping pills), stimulants (cocaine, amphetamines, caffeine, nicotine), opiates (heroin, opium, morphine, synthetic morphine compounds), hallucinogens (marijuana, LSD, PCP), and inhalants (nitrous oxide, toluene, gasoline).

Alcohol
Alcohol has been around for centuries. It probably first appeared in skins full of grape juice that had been left out too long in the heat of the desert. Fruit syrup plus heat (and a few other ingredients) eventually produce ethanol, which is the active ingredient in all types of intoxicating beverages.

Alcohol is found in beer, wine, and distilled spirits. The active ingredient is the same - ethanol. The differences among these beverages is in the concentration of the alcohol. Beer is the most dilute, and the alcohol content varies from state to state. Wine is a little less dilute, and alcohol contents vary according to the type of wine. Less dilute are the distilled spirits, such as vodka or whiskey. Pure grain alcohol is the least dilute and is the substance known as “moonshine” or “corn squeezings.”

Alcohol dissolves fat. The cells in our bodies are encased in membranes, which are complicated multilayered structures composed of specialized fats and proteins. They contain channels for various ions, such as calcium and potassium, and for messenger proteins that communicate with other cell structures which regulate the activity of the cell. Alcohol not only dissolves into the fats of the cell membrane but also disrupts many of these delicate structures.

But because it dissolves fat, alcohol crosses easily into all types of cells. This is one reason that drinking on an empty stomach makes a person drunk quickly. If there is nothing in the stomach, the alcohol crosses easily through the stomach lining and into the bloodstream, then through the blood-brain barrier, which is a specialized fatty membrane that protects the brain from many of the substances that get into the bloodstream. While it is exerting its intoxicating effects on the brain, it is also passing into the cells of various other organs in the body. This results in a variety of toxic effects.

What happens when you drink? In the short term, alcohol causes mild stimulation at first. It causes an easing of tension, a mild sense of euphoria, and a slight drop in inhibitions. It is for these effects that alcohol is used in social settings. But these occur only at low blood levels of alcohol.

As blood levels increase, the depressant effects become more obvious. Since alcohol affects the balance center of the brain, you become uncoordinated. Another part of the brain that becomes less functional is the frontal lobe area, which is the one that exercises social judgment. You might begin to make remarks that are inappropriate or do things that will seem embarrassing later. You might become irritable and easily provoked. Speech becomes slurred, and fine motor coordination is lost. Your ability to perform complex tasks such as driving is lost. And your ability to judge whether or not it’s appropriate to drive is also lost.

As blood levels rise further, you may become stuporous and eventually lose consciousness. This is not quite the same as going to sleep, since it is a drug-induced state. The normal patterns of sleep, such as alternating periods of deep sleep and dreaming, are disrupted. At this point, the danger exists of an alcohol-induced coma with total depression of life functions such as the breathing reflex. Far too often we hear about teenagers or young adults who have intentionally drunk to a point of extreme intoxication and have ended up dead from respiratory arrest due to the alcohol.

Because the chemical structure of alcohol is fairly simple, one would expect it to have a number of diverse effects on the brain, and it does. Unlike some other addictive substances, alcohol does not interact directly with specific neurotransmitter systems. But it does interfere with the activity of a number of substances important in the regulation of mood and excitability of the brain. Alcohol also has a cascading effect on several systems in the brain, probably produced in part by the effects that it has on the fats within the membranes of nerve cells. Each of these intoxicating effects reflects alcohol’s interaction with and disruption of a different brain system. We can break down the intoxicating effect of alcohol on the brain into four basic categories: mood-altering effects, motor impairment, interference with memory, reasoning, and judgment, and addictive potential.

The research literature on the molecular effects of alcohol is very complicated, so we’ll just touch the high points.