Cannabis can have antidepressant effects — in the short term, study finds

A young woman plays a game of jenga. (yanukit/123rf)

Countless people turn to cannabis to help relieve stress, ease anxiety, or just put a smile on their face in good times and bad. But does it actually have a quantifiable antidepressive effect? According to an observational study published in late June, it does — at least in the short term.

In the study published in the Yale Journal of Biology and Medicine in late June, researchers stated that their findings indicate “at least in the short term, the vast majority of patients that use cannabis experience antidepressant effects,” although they added that the strength and duration of the effect depends on the chemical profile of the cannabis used.

The study design did not include a control group, and the participants were already using cannabis to treat depression.

The researchers also found that cannabis flower “is an effective and fast acting antidepressant medication,” and that the THC levels “are the strongest independent predictors of symptoms relief among the product characteristics that are generally available to the public.”

The study used data compiled through the mobile phone app ReleafApp, which helps cannabis users “anonymously track real-time and historic experiences with specific cannabis & CBD products,” according to the company. Users send their input to the platform which then sends back reports to help inform their next purchase or treatment decision.

The parameters examined by the app include cannabis usage during each session, product types used, routes of administration, phenotypes, cannabinoid contents, and the users symptoms and changes in symptoms. The researchers said that the company provided them with confidential, anonymous user-level data.

The central parameter measured in the study was “symptom relief,” gauged by the difference between the symptom intensity at the beginning and ending of the session. On average, they found that 95.8% of users reported symptoms relief, 2.1% reported worsening systems, and 2.1% reported no changes.

The symptoms were rated on a scale of 0 to 10. On average, users suffering from depression reported a starting symptom intensity of 5.85 and an ending symptom of 2.08, resulting in a decrease in symptom intensity of 3.76, according to the study. The results show no statistical difference when the users reported using indica, sativa, or hybrid varieties of cannabis flower.

Out of a total of 5,182 sessions, hybrid strains were used 50% of the time and indica and sativa varieties were used 26% and 24% of the time, respectively. The most popular method of smoking was with a pipe (51%), followed by vape (33%), and joint (15%).

The testing showed a dramatic preference for higher THC products, with 48% of the sessions involving cannabis with 20-35% THC, and 35% using between 10-19% cannabis. Only 17% used below 10% THC products, and the average percentage in all sessions was 18.61%.

While the researchers concluded that THC potency levels are the strongest predictor of symptom relief, “the benefit of higher THC appears to plateau to some extent such that products with THC ranges of 10-19% and 20-35% offer greater relief than products with THC less than 10%, but increasing from 10-19% to 20-35% does not convey additional benefits in terms of symptom relief.”

The researchers noted that the study is not without its shortcomings, namely, that did not include a control placebo group. In addition, they posit that people who choose to use cannabis to treat depression may be those most likely to benefit from it or people for whom other forms of treatment are less effective. There is also the question of who is more likely to use the app. They also note that because the study focused on short-term effects, it should not be used to assess long term-effects of using cannabis for depression.

Regardless, they state that the study did establish the clinically relevant finding that there is “widely experienced relief from depression within two hours or less,” with cannabis use, and that because traditional antidepressants take weeks to take effect “short-term cannabis use might be a solution to these delays in treatment or could be used to treat acute episodes associated with suicidal behavior and other forms of violence.”

The study joins a number of previous reports that have asserted the effectiveness of cannabis in treating depression. At the same time, a number of other studies have found that cannabis can actually worsen the symptoms of depression, including a systematic review of research from 2013 which stated that “cannabis use, and particularly heavy cannabis use, may be associated with an increased risk for developing depressive disorders.” In addition, a clinical study published in 2017 recommended cannabis use reduction as a part of treatment for anxiety, depression, or sleep problems.