Numbers don’t lie. And, it’s hard to argue with the numbers published in a new study examining the effects of cannabis on post-traumatic stress disorder (PTSD) and its associated symptoms.
A team of researchers led by Stephanie Lake of the University of British Columbia found that PTSD sufferers were significantly more likely to experience major depression and suicidal ideation unless they used marijuana.
“Post-traumatic stress disorder sharply increases the risk of depression and suicide,” state Lake and her research team. “We sought to investigate whether cannabis use modifies the association between post-traumatic stress disorder and experiencing a major depressive episode or suicidal ideation. […] Through the novel conceptual and methodological treatment of cannabis as an effect measure modifier, this study provides evidence that cannabis use may reduce the effect of PTSD on major depressive episodes and suicidal ideation.”
To arrive at this conclusion, Lake and her team examined data from Statistics Canada’s 2012 Canadian Community Health Survey. The sample included 25,113 Canadians aged 15 or older living in one of Canada’s 10 provinces. In the survey, people answered questions on a variety of health-related topics. The researchers, however, were interested in four questions in particular.
First, they wanted to know whether respondents had a PTSD diagnosis. Second, they wanted to know whether respondents experienced a major depressive episode in the past year. Third, they wanted to know how respondents answered the question, “In the past 12 months, did you seriously think about committing suicide or taking your own life?” And, fourth, they wanted to know whether respondents had used cannabis more than once in the past year.
Here’s what they found. The researchers reported that the prevalence of PTSD among the approximately 25,000 Canadian respondents was 1.7 percent. They also reported the prevalence of repeated cannabis use to be approximately 11.4 percent. That said, respondents with a PTSD diagnosis were significantly more likely to use cannabis. The researchers write, “Over one-quarter of Canadians with PTSD reported past-year cannabis use, which is remarkably high compared to the prevalence of recent use in the general Canadian population.”
Looking at the incidence of major depression and suicidal ideation, the researchers reported that 4.7 percent of respondents met the criteria for having experienced a major depressive episode in the past year and 3.3 percent of participants reported past-year suicidal ideation.
Of critical importance to the researchers’ hypothesis was whether PTSD sufferers who used cannabis were any less likely to experience major depressive episodes and suicidal ideation. They found strong support for their hypothesis. Specifically, they calculated that the odds of experiencing either major depressive episodes or suicidal ideation were about 20 times greater among non-cannabis users with a PTSD diagnosis. Among cannabis users, the odds of experiencing either major depressive episodes or suicidal ideation were only 6-7 times greater.
Even when accounting for socio-demographic factors and other health conditions that might influence the association between PTSD and its associated symptoms, the researchers still found a significant decrease in the co-occurrence of PTSD and depression/suicidal ideation among cannabis users. They write, “In sum, this study provides compelling preliminary evidence from a general population sample that cannabis use modifies the association between PTSD and depression and suicidality, such that the associations appear to be strengthened in the absence of cannabis use and tempered in the presence of lower-risk cannabis use.”
Source: Psychology Today