Historically, research has suggested a direct relationship between cannabis use and higher risk of suicidal behavior. However, few studies have examined whether or not this is true of populations already “at risk”, such as in individuals who have a psychiatric disorder diagnosis.

In the first study of its kind (published in the journal Biology of Sex Differences), a team of researchers in Canada examined what effect cannabis use might have in a population of individuals with a psychiatric disorder diagnosis and found somewhat surprising results: the risk of suicidal behavior is not increased with moderate cannabis use.

However, other known risk factors for suicidal behavior affected the study population just as one might expect based on previous research with non-psychiatric populations; those with mood disorders, those who are unemployed, and men with heavy cannabis use remain at a higher risk of suicidal behavior. How can this be?

The authors posit a few theories to explain their findings—it could be that the participants in this study, many of whom also had other substance abuse disorders, are already in an “altered neurological state”, and therefore, it’s difficult to ascertain the contribution of cannabis use to suicidal behavior in this population, whereas the effect is more obvious in individuals without concurrent substance abuse.

While there were admittedly limitations to their results given the sample size and concurrent variables that could also be influencing suicidal behavior, this study is the first to suggest that marijuana use might not be as reliable an indicator of increased risk of suicide as it might have been thought especially in individuals with known psychiatric disorders.

An additional interesting finding of the study that could warrant additional consideration is that the traditional sex differences observed with suicidal behavior in the general population are nearly eliminated in this study cohort. Whereas research has traditionally shown that women are more likely to engage in suicidal behavior (whereas men are less suicidal but are more likely to be successful in their suicide attempts), this trend is not observed in the population with psychiatric diagnosis.

This study will hopefully encourage further research and inform medical professionals who are working within these high-risk populations to assess suicide risk, taking into consideration that concurrent mood disorders and other social factors may actually play a larger role in suicidal behavior than the use of marijuana.