Since we practice in San Francisco, which was at the forefront of the move to decriminalize marijuana, we find that many of the people with depression or bipolar have smoked, or are smoking, marijuana as a way of treating their depression.
Over the years we have developed a general impression of marijuana as a psychotropic (mood affecting) agent.It has been our clinical experience that marijuana is perhaps an antidepressant, but like many antidepressants, has a tendency to destabilize mood (more rapid cycling, more mixed episodes of mania and depression). The people who seem to have clearly benefited from marijuana have almost all been people with no bipolar tendencies, and with a significant amount of anxiety.
In that respect, marijuana acts like gabapentin (Neurontin), it reduces anxiety and improves (in the short run) depression, but it can lead to more extreme mood swings.
Recently we were challenged to reconsider this assessment by one of our patients who feels that marijuana has been very helpful for her bipolar depression.
So, we delved into the research literature.
There are surprisingly few good studies on this topic.
However we found some articles that were intriguing.
A number of articles from the past ten years have shown that people with bipolar who smoke marijuana are more likely to be rehospitalized and seem to have more rapid cycling, more psychosis, and more mixed and unstable moods.
An article in the Journal of Neuroscience (The Journal of Neuroscience, October 24, 2007 • 27(43):11700 –11711) provides evidence that cannabinoids have antidepressant effects on neurotranmitters. Which could explain this effect.
One of the few articles on the topic of cannabinoids for bipolar moods that was positive was a review and somewhat speculative article in the Journal of Clinical Psychopharmacology (Cannabinoids in bipolar affective disorder: a review and discussion of their therapeutic potential. C. H. Ashton, P. B. Moore, P. Gallagher and A. H. Young. J Psychopharmacol 2005 19: 293)
The authors speculated that cannabinoids might be useful and suggested that more research be done. But there was very little positive evidence cited.
A more recent article, in the same journal, found that cannabinoids were ineffective as mood stabilizers. (Cannabidiol was ineffective for manic episode of bipolar affective disorder AW Zuardi, JAS Crippa,
SM Dursun, SL Morais, JAA Vilela, RF Sanches and JEC Hallak J Psychopharmacol 2010 24: 135
originally published online 18 September 2008).
Finally, an interesting article in Pharmacological Review (The Endocannabinoid System as an Emerging Target of Pharmacotherapy. Pal Pacher, Sandor Batkai and George Kunos. Pharmacol Rev 58:389–462, 2006) notes that all cannabinoids are not the same and suggests that more research be done on the various psychoactive molecules present in marijuana.
Which seems like a good idea.
In summary, my review of the literature seems generally supportive of my clinical experience that marijuana can be helpful for anxiety, but can have mood destabilizing effects. With the addition of information pointing to the need to study different psychoactive components separately in order to understand the pharmacology of this natural agent… especially since growers are now breeding different strains of marijuana to increase or decrease the levels of certain psychoactive compounds in the plant…