A Critical Review to Identify the Domains Used to Measure the Effect and Outcome of Adaptogenic Herbal Medicines

Background: Phytoadaptogens are considered to be herbal medicines with a multi-target effect that strengthen organ systems compromised by stress. Although animal and laboratory studies have identified numerous molecular targets associated with adaptogenic activity, the non-specific characteristic of these herbal medicines has meant there is no known methods to accurately determine efficacy of adaptogens in humans. This critical review of the evidence aims to identify domains which have been used to measure the effect of adaptogens in humans, in order to create pathways for translating laboratory, animal, and clinical studies on adaptogens into practical applications in the future. Methods: EMBASE, AMED, PubMed, Cochrane Library, and WHO ICTRP databases were searched for randomized trials which examined known physiological actions of adaptogens. Results: Twenty-four studies were identified and critically appraised using the Jadad scale. The findings identified three broad categories of outcome measures, including cognitive, mood and biological measures. Conclusions: There was a great heterogeneity in data making it difficult to draw conclusions as to the most effective measurement tools to capture the holistic activity in humans. Cognitive measures hold promise as a reliable measurement tool when used in conjunction with other relevant tools. Further investigation is necessary to determine the most appropriate and diverse tools to measure the complex multi-target action of adaptogens.