Rhodiola rosea versus sertraline for major depressive disorder: A randomized placebo-controlled trial. 

This 2015 head to head study between Rhodiola rosea extract and the pharmaceutically prescribed antidepressant sertraline was observed in a phase II randomized placebo controlled clinical trial. Authors monitored the improvements by measuring the HAM-D scores over 12 weeks of treatment. The results for both treatment groups were clinically meaningful reductions over time in HAM-D scores though these results were not statistically significant compared to placebo.  

References:

Mao JJ, Xie SX, Zee J, Soeller I, Li QS, Rockwell K, Amsterdam JD. Rhodiola rosea versus sertraline for major depressive disorder: A randomized placebo-controlled trial. Phytomedicine. 2015 Mar 15;22(3):394-9. doi: 10.1016/j.phymed.2015.01.010. Epub 2015 Feb 23. PMID: 25837277; PMCID: PMC4385215.