A randomised, double-blind, placebo controlled, parallel group study of the standardised extract SHR-5 of the roots of Rhodiola rosea in the treatment of subjects with stress-related fatigue
The aim of the study was to assess the efficacy of the standardised extract SHR-5 of roots of Rhodiola rosea L. in the treatment of individuals suffering from stress-related fatigue. The phase III clinical trial took the form of a randomised, double-blind, placebo-controlled study with parallel groups. Participants, males and females aged between 20 and 55, were selected according to the Swedish National Board of Health and Welfare diagnostic criteria for fatigue syndrome. A total of 60 individuals were randomised into two groups, one (n=30) of which received four tablets daily of SHR-5 extract (576mg extract/day), while a second (n=30) received four placebo tablets daily. The effects of the extract with respect to quality of life (SF-36 questionnaire), symptoms of fatigue (Pines' burnout scale), depression (Montgomery Asberg depression rating scale – MADRS), attention (Conners' computerised continuous performance test II – CCPT II) and saliva cortisol response to awakening, were assessed on day 1 and after 28 days of medication. Data were analysed by between-within analyses of variance. Repeated treatment with SHR-5 seems to have a positive effect on fatigue level, attention (as measured by a computerised performance test, p<0.05) and saliva cortisol response to awakening stress (p<0.05). It is suggested that the inhibitory effect of Rhodiola on the increased basal level of cortisol is associated with improvement in cognitive function. This is in line with other studies demonstrating that optimal corticosteroid level is a requirement for efficient cognitive function since significant changes (up or down) in circulating levels of corticosteroids results in cognitive impairment. Modulation of cortisol content is considered to be a key mechanism of action of phytoadaptogens. It may be concluded that Rhodiola, acting as an adaptogen, increases attention and endurance in situations of decreased performance caused by fatigue and sensation of weakness, and reduces stress-induced impairments related to the function of neuro-endocrine and immune systems.