The literature on the relationship between marijuana use and psychosis has been best described by Time magazine in 2010: it’s complicated.
Various studies have attempted to investigate the connection between the two variables to rather confounding results, including “circumstantial evidence” that individuals afflicted by schizophrenia are more likely to abuse drugs including cannabis and that “only a very small proportion of the general population” using cannabis develop psychosis; all of which warrant further research.
It is through the media and public discourse that this already convoluted relationship becomes even more difficult to understand. A follower of the debate on cannabis and its association with non-affective psychotic disorders, I observe a disconnect in communication. It is as if many prohibitionists and reformists are talking about completely different topics: CAUSATION and EXACERBATION.
No, cannabis does not cause psychotic disorders such as schizophrenia. Numbers have shown that despite fluctuations in marijuana usage, there has not been a concurrent variation in the instances of schizophrenia, largely debunking claims of a causal relationship. There exists, however, an unsettling association between marijuana usage in existing patients of psychotic disorders and severity of symptoms and timing of onset. Several of the studies were conducted with relatively small sample sizes and so demand future investigation, yet are sufficient to recommend present caution.
One of my core principles is to share that which I appreciate – whether art or food or experiences – with those dear to me. One of the things I appreciate most in the world happens to be cannabis. From close friends, I ask that they at least try it, just as I’ll ask that they try oysters (a travesty, to miss out on the tender, slippery treat; like an intense and delightful shot of the ocean). If their experimentation leads to ultimate dislike, I never attempt to dissuade them; I will always respect individual preference or lack thereof. They simply need to try putting it in their mouth once.
The only exception to sharing my appreciation for cannabis is if the friend in question is genetically prone to schizophrenia.