Thinking about marijuana


A writer asked me to respond to some questions about marijuana. Here’s what I wrote

1. Is there any evidence that cannabis has mental health benefits?

There is one high-quality paper (multi-center, randomized, double-blind, placebo controlled; American Journal of Psychiatry, March, 2018) that suggests cannabidiol (not cannabis) 1000 mg/day may be helpful as an augmenting agent (i.e. added to a patient’s antipsychotic medication) in schizophrenia.

The evidence that cannabis has mental health benefits is largely anecdotal at this point.

The evidence that it causes harm, especially in the young, greatly outweighs the reports of benefits. See, for example, Terrie Moffitt’s Dunedin study, which followed over a thousand New Zealand kids for 38 years, and saw cognitive decline in adolescent onset users not reversed by cessation of use and suggested a neurotoxic effect of cannabis on the adolescent brain. (PNAS 10/2/2012)

2. Some argue that “Big Pharma” is afraid of the medical benefits of cannabis. Is there any truth to that?

Since at present there are few demonstrated medical benefits of cannabis, big pharma has nothing to be afraid of, and, I suspect, would be happy to develop patented products if anything interesting emerges, much as Johnson and Johnson has developed esketamine nasal spray after ketamine’s  benefits became apparent.

The cannabis industry, on the other hand, has reason to be afraid of (and attempt to discount, ignore, minimize, and denigrate) the increasing reports of harm associated with cannabis use, following the tobacco, alcohol, and sugar industries’ playbooks.

See, for example, the recent review in JAMA Psychiatry of 11 studies covering about 23,000 patients, showing an odds ratio for suicide attempt of 3.54 in the cannabis users, and linking adolescent cannabis use with the development of depression and suicidality in later life (but, surprisingly, not anxiety).

3. Would you ever recommend someone use cannabis for mental health treatment? If so, why? If not, why?

No, because a doctor’s goal is to help his or her patients. Everyday life provides enough harm and pain without any need for help from the doctor.  The evidence for harm from cannabis is pretty overwhelming today, on March 2, 2019.

That being said, since cannabis is easily available in California, my patients use it on their own quite frequently. When I ask them what they observe, those who observe benefit seem to find it helpful for relaxing in the evening. One patient, for example, found that 2-3 puffs of a largely indica blend helped him unwind  and reduce the amount of Seroquel he needed to sleep.

4. Furthermore, would you ever recommend someone replace their mental health medication with cannabis?

Based on our present knowledge base, that would constitute malpractice, or an extreme deviation from the standard of care, since the evidence of benefit from cannabis rests on anecdote, the lowest level of scientific evidence. FDA approved medications need to demonstrate efficacy in at least 2 randomized, double-blind, placebo-controlled trials. Granted, the negative trials are usually not published, but that’s another story.

5.  In a perfect world, how should cannabis be used medically, if at all?

Cannabis has moved rather quickly in the public’s perception from a schedule 1 controlled substance (defined as a drug with no currently accepted medical use and a high potential for abuse) to a putative medicine. But before it can be taken seriously as a medicine, we need high-quality data ( like randomized, double-blind, placebo-controlled trials) that show what it can do.  At present, in my opinion it is similar to alcohol and tobacco, and best avoided.

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