Next to counteracting pain and stimulating appetite, managing mood disorders such as depression may be the most common self-medicating use of cannabis. Cannabis is, in fact, the most-widely used illicit drug among people who suffer from depression. The numbers are squishy, but, according to one report, as many as 60 percent of people with some form of depression will also use marijuana at some point.
According to another study, people with mental disorders were seven times more likely than the general public to use marijuana and 10 times more likely to have a cannabis use disorder. The trouble is what to make of these numbers. Are they merely coincidence, or do they show causality—and if there is a cause-and-effect relationship, which way does it go? The pro-pot camp argues that cannabis is a popular antidepressant because it works. But there are still fears that the very use of cannabis can trigger latent mental disorders.
Aside from the transitory intoxication and euphoria of the high, cannabis use may improve one’s mood simply because users feel that they are taking control over their illness.
The clinical evidence on the controversy is extraordinarily thin. A 2015 JAMA review, for instance, could find no studies specifically on cannabis and depression that met its criteria for consideration. Of five studies that coincidentally reported on cannabis’ effect on mood, three showed nothing significant and one showed a negative effect at large doses.
Anecdotal evidence, however, is more strongly positive—particularly with individuals whose depression is itself a symptom of a separate major illness. According to a 1996 survey of people with multiple sclerosis, for example, 90 percent who used cannabis found that it improved their depression. Although they haven’t been as conveniently quantified, similar positive effects have been documented by chemotherapy and AIDS patients.
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But popularity is no guarantee of clinical efficacy. We know, for example, that even moderate alcohol consumption can worsen anxiety and depression; nevertheless, it is a massively popular means of elevating mood and decompressing.
From a biochemical perspective, then, cannabis may not be “fixing” anything in an MS or a chemo patient, but that does not mean that it has no ameliorative effect. Aside from the transitory intoxication and euphoria of the high (which can itself have value), cannabis use may improve mood simply because users feel that they are taking control over their illness. The mere fact of doing something can itself be healing. That’s the placebo effect, and it’s a real thing.