In a newly published study by Jane Metrik and colleagues, marijuana use was found to exacerbate symptoms of post-traumatic stress disorder (PTSD) in veterans with cannabis use disorder (CUD). This confirms the results of previous studies in veterans that found an association between marijuana use and worsening symtpoms of PTSD. A common issue with many studies on the effect of marijuana use on mental health outcomes is the bi-directionality of the relationship. In other words, it is difficult to definitively say whether it is marijuana use that leads to mental illness or if those susceptible to mental illness tend to use marijuana more. This is still a subject of considerable debate in the research community, especially with respect to development of psychotic disorders.
In the present study, the authors prospectively followed 361 veterans deployed post-9/11. This prospective design–in which subjects are followed as they move forward in time–enabled the authors to examine the direction of the relationship between CUD and the development and worsening of PTSD with more clarity than previous studies. Although the authors found evidence of a bi-directional relationship between CUD and PSTD, they found that the magnitude of the relationship was much greater between CUD and later development and worsening of PTSD. In other words, it was much more likely that CUD resulted in worsening PTSD symptoms rather than the other way around. This is important from a causal standpoint because it indicates a possible biological mechanism between marijuana use and worsening PTSD symptoms. Previous research established the presence of significant withdrawal symptoms, including anxiety and depression, associated with the heavy use that typifies CUD. Veterans using marijuana to relieve PTSD likely fall into a vicious cycle of escalating marijuana use and worsening PTSD symptoms as they attempt to avoid withdrawal.
PTSD is a qualifying condition for a medical marijuana recommendation in many states despite there being no evidence that marijuana is a safe, effective treatment for PTSD. And as the present study indicates, there is a growing body of research suggesting that it may actually worsen PTSD symptoms. Thus, sadly, many veterans still believe that marijuana is beneficial for PTSD when in fact the opposite is probably true. Our veterans have risked life, limb, and mental-well being by doing the job that they were ordered to do. It is imperative that we protect them and other vulnerable populations from a predatory marijuana industry that willfully misleads by promoting marijuana as medicine despite the evidence to the contrary.