Antoinette Gibbs, age 14, of Galveston, Texas, for her question:

WHAT IS A DEPRESSANT?

A depressant is any drug that slows the activity of the nervous system. Doctors sometimes prescribe them to ease pain, cause sleep or reduce tension.

A most important thing for everyone to understand is that a depressant should never be taken unless it is prescribed by a doctor.

Many depressants are either habit forming or addictive. If a person takes such a depressant daily for several weeks, he may very well develop a physical or psychological dependence on it. Also, an overdose of a depressant can often result in death.

Major types of depressants include alcohol, anesthetics, sedatives and tranquilizers.

Alcohol decreases most brain functions. Anesthetics, the most powerful painkillers, are used during surgery. Sedatives calm a patient or put him to sleep. Such sedatives as barbiturates depress the central nervous system. Tranquilizers lessen tension without decreasing mental or physical ability.

Many doctors say that people use tranquilizers too often. These medical people believe anxiety is normal and that tranquilizers should be used only if the anxiety produces severe mental or physical strain.