In a pilot study, 10 men and women with an average age of 44 living in Los Angeles, California, and had general anxiety disorder (GAD) took 170 mg of Rhodiola rosea twice per day. After 10 weeks, anxiety was significantly lower with five of the 10 participants reporting half as many symptoms, a result doctors said was similar to clinical drug trials. Participants taking prescription anxiety drugs were allowed to combine the treatments.
In another Rhodiola rosea study, 89 men and women aged 18 to 70 with mild to moderate depression took 340 mg or 680 mg of Rhodiola rosea per day or a placebo for six weeks. Both Rhodiola rosea groups improved in overall depression symptoms, insomnia and emotional stability. The placebo group did not improve.
Reference: Journal of Alternative and Complementary Medicine; 2008, Vol. 14, No. 2, 175-80.