The Economist: Marijuana as a medicine A subtle syllogism

Washington, DC, August 16, 1997

Cannabis is a drug. Drugs are supposed to make you better. Therefore cannabis can make you better. Discuss

"There is not a shred of scientific evidence . . . that smoked marijuana is useful or needed." Thus spake Barry McCaffrey, a retired army general and Gulf-war hero, in his new role as commander-in-chief of the Clinton administration’s War on Drugs. The National Institutes of Health (NIH) begs cautiously to differ. An NIH report issued on August 8th said that eight experts whom it had convened earlier this year expressed "varying degrees of enthusiasm" about whether the dreaded weed had true medical value and, if it had, whether it did things that other drugs, less frowned upon by officialdom, could not. William Beaver of Georgetown University, who chaired the original workshop, said that "for at least some potential indications marijuana looks promising enough to recommend that there be new controlled studies." Those who advocate marijuana as a medicine usually have four potential uses in mind: to control glaucoma, to suppress the nausea induced by anti-cancer drugs, to relieve the pain of multiple sclerosis, and to stimulate the appetites of those with AIDS.

Smoking can be good for you

In the case of glaucoma it is widely accepted that the elevated pressure in the eyeball that damages the optic nerve falls when marijuana is smoked. That is why, until 1991, America’s Food and Drug Administration (FDA) permitted ophthalmologists to prescribe the weed to patients for whom other treatments had failed. Since then, new glaucoma drugs have been produced. These act at different points in the biochemical pathway that causes eyes to produce too much fluid. However, no approved drug actually makes the eyes’ drainage system more efficient. If marijuana improves the outflow (which is possible, but not yet known) it would be a valuable addition to current therapies.

Marijuana is also of undoubted benefit in suppressing the nausea suffered by many people on anti-cancer chemotherapy. The argument here is whether it is necessary to smoke the stuff for the full benefits to emerge. This is because a capsule version of marijuana’s active ingredient, delta-9-tetrahydrocannabinol, or THC, has been passed through the regulatory process for use in these circumstances.

Despite that, none of the NIH's experts deemed smoked marijuana to be by definition a superfluous adjunct to chemotherapy. Unlike oral THC, its vapour is easily absorbed and acts quickly. It may also contain as yet unidentified substances that help THC's action. And, unlike both the THC capsules and other legal nausea suppressors which work in different ways, reefers allow users to fine-tune the dose for themselves. Chemotherapy powerfully reminds cancer patients of their life-threatening illness. Because marijuana cigarettes are under their control, they tend to ease their feelings of helplessness.

In the case of multiple sclerosis (MS), marijuana brings relief that other painkillers do not seem to manage. Many of those who suffer from this disease have burning sensations in their limbs, particularly at night. These sensations are probably caused both by the disorder’s destruction of the protective fatty coating around nerve cells and the damage it does to the brain.

Conventional analgesics can do little to ease this burning sensation—which seems to be similar to the phantom pain often suffered by amputees—but some sufferers say that a joint at bedtime makes the difference between their sleeping and not doing so. What study there has been of marijuana for MS -- and it is not much—suggests they could be right.

The fourth use—marijuana’s well-known ability to stimulate the appetite—is particularly significant in the treatment of AIDS. Again, smoking appears to be better than taking THC in capsule form. The pure form of the drug is poorly absorbed by many of the afflicted and, besides, often makes people so high that they never get around to eating. The loss of lean-muscle mass that occurs as patients waste away to shadows of their former selves is an ominous predictor of their impending deaths.

The best alternative to smoked pot for appetite stimulation is human growth hormone, which has been found both to restore lean tissue to emaciated AIDS patients and to improve their chances of survival. The catch is that—at $36,000 for a year’s supply—it is prohibitively expensive (marijuana treatment for the same period costs a mere $500). The other readily available option is megestrol acetate, a synthetic female hormone which is somewhat cheaper. Unfortunately, studies have shown that it does not improve survival—probably because the weight gain it produces, instead of being muscle, is mainly fat.

All this would seem to make smoked marijuana the medicine of choice for helping the HIV-positive to gain the right kind of weight. Indeed, AIDS one patient testified to the workshop that it had enabled him to regain 40lbs (around 20kg), and that by using it only at night he had been able to keep that weight on for four years while working full-time as a newsletter editor.

Some studies done before the AIDS epidemic found, however, that marijuana dampens the immune system. Something that depresses their immune systems is the last thing that patients need. But these studies were only preliminary (others came to the opposite conclusion) and they were done without the benefit of modern techniques for assessing immune-system damage. Unfortunately, they have not been repeated—which outlines one of the greatest difficulties in the effort to assess marijuana’s value as a medical drug: doing trials to find out the truth.

Don’t ask, don’t Tell

A team of AIDS researchers, led by Donald Abrams of the University of California, San Francisco, planned a patient study aimed at resolving the immunity issue in 1992, but it was unable to get the marijuana that would have made the trial possible. The federal government is the only legal source of the drug for research purposes in America, and scientists cannot obtain it without the blessing of the NIH. In this case, the NIH stipulated that the proposal would first have to be given a sufficiently high score by an independent panel of scientific reviewers. But when the panelists received it, they refused to review it.