In a retrospective study of over 7000 adults, cannabis use improved depression and anxiety at 12 and 18 months in adults diagnosed with these conditions. The Canadian researchers who conducted the study published their findings in Psychiatry Research.

Compared with its use for chronic pain, the researchers stated that reliable evidence to support the use of cannabis to treat anxiety is lacking and available data are “conflicting.” To bring clarity to the issue, the researchers conducted a retrospective database study of Canadian medical cannabis patients. Patients received their cannabis from Harvest Medicine clinic, a network of specialty medical cannabis clinics across Canada.

Of the 7362 patients, 43.9% reported anxiety as the reason for using cannabis and 25.9% reported depression. The average age of the sample was 49.8. The group was fairly evenly divided between men (46.9) and women (53.1%).


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The mean General Anxiety Disorder-7 (GAD-7) score for patients with anxiety was 11.1 compared with 5.3 without anxiety. The scores for patients with anxiety went down over time with the most notable decreases taking place between 1 and 3 months after treatment and 2 years later.

Patients with depression reported a mean Patient Health Questionnaire (PHQ-9) score of 13.7 compared with 7.4 for those without depression. The most notable drop for patients with depression took place within the first 3 months of treatment.

The researchers also reported that men with the highest scores at baseline showed the most significant improvement over time.

While the researchers had a large sample size to work with, they noted that some of the demographic data was missing and they didn’t have information on prescription medications, psychiatric therapy, or any diagnostic information other than the PHQ-9 and GAD-7 scores.

The researchers conclude, however, that this real-world data analysis provides evidence of the effectiveness of cannabis on depression and anxiety. They conclude, “this study offers reasonable justification for the completion of large clinical trials to further the understanding of medical cannabis as a treatment for anxiety and depression.”

Disclosure: Some study authors declared affiliations with Harvest Medicine. Please see the original reference for a full list of authors’ disclosures. 

Reference

Sachedina F, Chan C, Damji RS, de Sanctis OJ. Medical cannabis use in Canada and its impact on anxiety and depression: a retrospective study. Psychiatry Res. Published online April 25, 2022. doi:10.1016/j.psychres.2022.114573