Thank you, Mr. Chair.
Dr. Grant, I want to probe the state of the research on this to separate what we believe and what we know. We've already heard from a number of witnesses the challenges of conducting research in a criminalized environment, wherein there are all sorts of difficulties with doing research. It's hard to have control studies, where we have a group of 15-year-olds smoking cannabis and a group who are not and chart their paths. You have ethical considerations, of course, and the fundamental issue of causation versus correlation.
A recent study from Harvard Medical School and the VA Boston Healthcare System found that:
While cannabis may have an effect on the age of onset of schizophrenia it is unlikely to be the cause of illness....
It also reported:
In general, we found a tendency for depression and bipolar disorder to be increased in the relatives of cannabis users in both the patient and control samples. This might suggest that cannabis users are more prone to affective disorders than their non-using samples or vice versa.
Although intuitively I share the concern that cannabis use in young people is not a good thing and can't be positive—I absolutely believe that—I think it's important that as a health committee we distinguish what we believe from what we know.
Is there, then, a causative element established in literature with respect to cannabis causing mental illness, or is it correlated?