Can Marijuana Be Medicine?

SUSAN NELSON SPENT most of 1978 watching her husband, Don, retch almost constantly. His body fought so hard to expel the chemicals used to treat his testicular cancer that, after 18 months, his battered esophagus ripped, causing tissue damage that has plagued him ever since. A decade later, it was Susan's turn. She developed lymphoma in 1989, and she, too, underwent chemotherapy. But in four months of treatment, she vomited only once. Instead of heading for the bathroom when she felt a surge of nausea, she took matters into her own hands: she fired up a joint.

Susan Nelson is no dopehead. She grew up in a military family, and never even experimented with pot as a '60s teenager. But she wasn't about to relive her husband's experience. The anti-nausea drug her doctor prescribed did wonders for her digestion, but it also lowered her inhibitions, causing inexplicable urges to throw plates and roll burning logs on the living-room floor. Smoking marijuana may have broken the law (she bought it from fellow patients), but it didn't break her dishes. ""When I smoked it,'' she recalls, ""you could still trust me.''

Americans may frown on recreational pot smoking, but as recent votes in California and Arizona make clear, a lot of people favor leaving folks like the Nelsons alone. The states' initiatives won't have much practical effect (they free doctors to recommend marijuana without creating legal supplies of the drug). Still, the measures have revived an important and long-neglected question: does pot ever make good medicine? Federal drug-enforcement officials say the drug is both useless and dangerous. They're challenging the new initiatives in court and vow to punish doctors who prescribe pot to their patients. But proponents claim marijuana can help control glaucoma, forestall AIDS-related wasting, ease the nausea brought on by cancer chemotherapy and counter the symptoms of epilepsy and multiple sclerosis. The claims are largely unproven, but they warrant some serious attention.

Marijuana's basic mode of action is well known. Several years ago, researchers discovered that the body makes a chemical closely resembling THC, the main active ingredient in cannabis, and that the brain has receptors designed specifically to receive it. The receptors are concentrated in the brain regions responsible for motor activity, concentration and short-term memory. As anyone who ever inhaled will attest, marijuana can disrupt all those functions.

The question is whether it can do anything else. For nearly three decades the government has listed marijuana as a ""schedule I'' drug, a designation reserved for substances with no apparent medical value and a high potential for abuse. Barry McCaffrey, director of the Office of National Drug Control Policy, stoutly defends that ruling, saying there is ""no convincing scientific evidence'' that marijuana offers benefits that a person can't get from approved prescription drugs.

Where glaucoma is concerned, McCaffrey has a point. It's well known that smoking marijuana can reduce pressure within the eye, a hallmark of the disease. But the drug may also reduce the blood supply to the optic nerve--the last thing a glaucoma sufferer needs--and it doesn't seem to prevent blindness. Even if marijuana could save eyes, smoking it enough would take extraordinary effort. ""In order to substantially reduce eye pressure,'' says Dr. Harry Quigley of Johns Hopkins University's Wilmer Eye Institute, ""you'd have to be stoned all the time.'' When researchers tried dissolving THC in eye drops, they succeeded only in irritating people's eyes, but other compounds proved more useful. As a result, glaucoma patients can now choose from a number of potent topical treatments. The latest, a once-a-day eye drop called Xalatan, is virtually free of major side effects.