The Medical View

It is used as an aphrodisiac, but Indian monks take it to repress physical desires. Caribbean laborers use it by day as an "energizer," but by night as a sedative. Marijuana is a paradox.

It has been around since at least the 15th century B.C., when it was used in China as an anesthetic, a ritual potion, a condiment and an intoxicant. As it moved on to India and beyond, it was applied to all manner of miseries: allergies, rheumatism, falling hair, tapeworm, leprosy, gonorrhea, failing memory and dandruff. Today marijuana is being considered as a treatment to reduce eyeball pressure in glaucoma patients and to reduce vomiting by cancer patients receiving drug therapy.

Systematic scientific studies of marijuana's benefits or dangers began with the isolation and synthesis in 1965 of the plant's principal psychoactive ingredient--delta-9-tetrahydrocannabinol. But that is only one of more than 100 chemical substances in marijuana, some of which exert their own characteristic effects. Further hampering marijuana studies is the difficulty of screening out such other factors as environmental or genetic influences, and deciding what constitutes long-term use or heavy use. To date, most results have been based on studies of laboratory animals or small groups of healthy young men. Thus little is known about marijuana's effects on the elderly, on pregnant women, and on developing youngsters, an area of particular concern. In addition, the greater strength of the marijuana now being imported from Colombia adds a new dimension to the question.

About the only findings so far that have widespread support are the drug's effects on the heart and the lungs. Marijuana accelerates the rate at which the heart contracts and may temporarily weaken the strength of the contractions, making it potentially dangerous for people with certain cardiac conditions. Smoking pot irritates the lungs and throat and can result in "joint cough." Long-term use may impair the lungs. Other tentative findings:

Immunity. Some studies have shown a marked reduction in white blood cell response, the body's prime defense against infection, in marijuana smokers.

Chromosomes, Human cell cultures from pot users have shown breaks in the chromosomes carrying genetic information, or reduced numbers of chromosomes.

Endocrine Function. Levels of testosterone, the male sex hormone, have been reported to drop with long-term pot intake. While the levels remained within normal range, the drop might reduce potency and fertility.

A number of psychological problems have also been associated with marijuana use. The most common is described as "acute panic anxiety reaction." It is seen most frequently in inexperienced users,, but can also follow an unexpectedly high dose. Transient feelings of mild paranoia are fairly common in users, especially those who are anxious about the experience to start with.

Prolonged or long-term effects of marijuana use are an area of much dispute. There have been reports of psychotic reactions, personality change, impaired learning ability and development of a chronic lethargy. By no means all doctors are convinced, however, that marijuana is the real cause of these reactions.

If the scientific studies of marijuana are uncertain, the studies on cocaine are even more mysterious. When the drug's active ingredient was chemically isolated in the 1860s, doctors soon found that cocaine was valuable as a local anesthetic. They also found that it acted as a very pleasant stimulant. Young Sigmund Freud used it and advocated it: "The psychic effect consists of exhilaration and lasting euphoria."

Scientists still do not know how it produces its psychic effects, but they believe it somehow causes a buildup of "neuro-transmitters." substances that make possible the movement of impulses across nerve endings. It also causes an increase in heart rate and blood pressure, and some of its other consequences are distinctly unpleasant. Prolonged use sometimes causes the nasal tissues to wear away so that the nose itself collapses. Chronic use may lead to a psychosis most resembling alcoholic DTs. Overdoses, particularly when injected, can lead to convulsions, heart and respiratory failure and death.

Neither cocaine nor marijuana in commonly used dosages causes withdrawal symptoms when use is stopped. Many doctors believe, however, that some people can easily become psychologically dependent on the two drugs and the effects they produce.

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