Medical cannabis use in Canada and its impact on anxiety and depression: A retrospective study

This was a retrospective study of patients utilizing medical cannabis who received their medical cannabis documentation and allotment from a Harvest Medicine clinic in Canada to determine the impact of medical cannabis on anxiety and depression outcomes. Patients included in the study were at least 18 years of age with completed validated questionnaires for anxiety (GAD-7) and depression (PHQ-9) at their initial evaluation and at least one follow-up visit. There were 7,362 patients included in the sample, of which the average age was 49.8 years, and 53.1% were female. There were statistically significant improvements between baseline and follow-up scores for both the GAD-7 and PHQ-9, with larger improvements seen for patients who were actively seeking medical cannabis to treat anxiety or depression. From 12 months on, those reporting anxiety had an average decrease in GAD-7 scores that was greater than the minimum clinically important difference of 4, and the same was seen for patients reporting depression from 18 months on, with the average decrease in PHQ-9 scores more than the MCID minimum clinically important difference of 5. This study provides some evidence to support the effectiveness of medical cannabis as a treatment for anxiety and depression.