This intriguing double-blind, randomized, placebo-controlled trial appears to indicate that propolis as an adjunct to selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant medication, improves depressive symptoms over and above SSRIs alone.
Caveat: I have only been able to access the abstract of this study, so have not been able to assess the methodology. The abstract may be accessed here.
Varzaghani, V., Sharifi, M., Hajiaghaee, R., Bagheri, S., Momtaz, S., Tarassoli, Z., & Razmi, A. (2022). Propolis add-on therapy alleviates depressive symptoms; A randomized placebo-controlled clinical trial. Phytotherapy Research, 1– 10. https://doi.org/10.1002/ptr.7380.