“Scientific research on how consumption of whole, natural Cannabis flower affects low mood and behavioral motivations more generally is largely nonexistent, and few studies to date have measured how common and commercially available Cannabis flower used in vivo may affect the experience of “depression” in real-time.
Results: On average, 95.8% of users experienced symptom relief following consumption with an average symptom intensity reduction of -3.76 points on a 0-10 visual analogue scale (SD = 2.64, d = 1.71, p <.001). Symptom relief did not differ by labeled plant phenotypes (“C. indica,” “C. sativa,” or “hybrid”) or combustion method. Across cannabinoid levels, tetrahydrocannabinol (THC) levels were the strongest independent predictors of symptom relief, while cannabidiol (CBD) levels, instead, were generally unrelated to real-time changes in symptom intensity levels. Cannabis use was associated with some negative side effects that correspond to increased depression (e.g. feeling unmotivated) in up to 20% of users, as well as positive side effects that correspond to decreased depression (e.g. feeling happy, optimistic, peaceful, or relaxed) in up to 64% of users.
Conclusions: The findings suggest that, at least in the short term, the vast majority of patients that use cannabis experience antidepressant effects, although the magnitude of the effect and extent of side effect experiences vary with chemotypic properties of the plant.”
https://pubmed.ncbi.nlm.nih.gov/32607086/
“In conclusion, almost all patients in our sample experienced symptom relief from using Cannabis to treat depression and with minimal evidence of serious side effects in the short run.”