The Science and Policy of Marijuana

Science and policy are often in tension with one another, but in the case of cannabis, as medicinal or recreational marijuana, science seems to be playing catch-up.

“Cannabis was scheduled [made illegal] in the absence of science,” and now is being legalized in some areas, still in the near-absence of science, said J. Michael Bostwick, a practicing psychiatrist and a senior associate dean at Mayo Medical School. In 1970, when Congress classified cannabis as Schedule 1 (“drugs with no currently accepted medical use and a high potential for abuse”), scientists did not know which neuronal receptors it activated or what exactly in the substance was causing which effects.

aaas nida

NIDA’s Nora Volkow and DC council member David Grosso listen to psychiatrist J. Michael Bostwick answer a question from the audience at AAAS.

More than four decades later (and 5,000 years since people first started using it as pain reliever), we still don’t know much more of the botanical substance’s potential as a medicine, because its Schedule 1 status means US researchers have to jump through hoops at several different agencies to get access to the legal federal supply. That’s just the start, science-wise: As with any plant, cannabis varies widely in quality, strength, and in what other compounds are bound within the plant, so research—and comparing previous studies in the US and elsewhere—can be tricky.

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Antidepressant may offer hope for stroke victims

It's probably not too reassuring to learn that scientists don't really understand how antidepressants work. Despite their almost ubiquitous presence in television advertisements and doctor's offices, the drugs remain a cipher, with researchers still unsure whether they work by simply altering concentrations of the neurotransmitters that influence communication between brain cells or by some type of long-term change in the brain.

One popular theory, for instance, is that antidepressants induce neurogenesis, or the growth of new brain cells; this is why, the argument goes, the drugs need two to four weeks to take effect. So far, the evidence for this theory has been inconclusive and even contradictory; studies have shown that antidepressants do seem to lead to neurogenesis but also that this seems irrelevant to their effectiveness, which may have to do more with changes in connections between brain regions.

But there is a benefit to drugs that remain somewhat mysterious—they sometimes end up offering unexpected but useful treatments for seemingly unrelated conditions. A new study, has found that the antidepressant escitalopram seems to help stroke victims recover more of their cognitive function than other treatments.

The study, conducted by Ricardo Jorge and his colleagues at the University of Iowa, Iowa City, involved 129 people treated within three months of their strokes. After 12 weeks of therapy, the 43 patients given escitalopram showed better overall scores on tests of thinking, learning, and visual and verbal memory than 45 patients taking a placebo pill and 41 participating in a problem-solving therapy program designed for patients with depression. Many people who have strokes become depressed after their attack, but further analysis of the data showed that the benefits of the antidepressant were independent of its effect on depression symptoms; it was doing something beyond simply treating depression.

The findings are particularly promising, since they offer treatment options for nearly all newly diagnosed stroke victims. Many other cutting-edge stroke therapies in testing or research can prevent much of the damage from occurring in the first place, but only if applied within a few hours of the stroke. Escitalopram offers hope for modest improvements even for the many people who miss that crucial window. According to the researchers, the drug also was effective regardless of the type of stroke suffered.

The situation is likely to come full circle: Just as the Iowa researchers speculate that structural brain changes attributed to antidepressants may contribute to the stroke recovery, scientists studying drug function may one day point to the stroke results to support their theories about antidepressants. If the stroke findings make anything clear, it's that the debate over the drugs is far from over—and that that's not necessarily a bad thing.

—Aalok Mehta
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