The Effects of Echinacea (EP107^TM) on Anxiety: A Comparison of Anxiety Measures in a Randomized, Double Blind, Placebo-Controlled Study

Background/Objectives: Echinacea extracts with unique alkamide profiles (EP107™) have been shown to affect upper respiratory tract infections and reduce anxiety in both animals and humans. However, a recent study found that a similar extract did not reduce anxiety more than a placebo, although it did enhance well-being and produced antidepressant-like effects. We hypothesized that the discrepancy arose from the differences in the anxiety assessment methods used. The study that observed no effects used the Clinically Useful Anxiety Outcome Scale, which focuses on physical symptoms, while earlier studies used the State-Trait Anxiety Inventory, which focuses on psychic symptoms. Methods: To investigate the influence of the anxiety measure on the detectability of anxiolytic effects, we examined the effects of Echinacea EP107^TM using the Hospital Anxiety and Depression Scale-anxiety subscale (HADS-A), which focuses on psychic symptoms, and the Hamilton Anxiety Rating Scale (HAM-A), most items of which involve physical symptoms. The study was placebo-controlled, double-blind, and multicenter. Results: The extract significantly alleviated anxiety compared to placebo when measured with HADS-A. HAM-A total scores did not show significant treatment effects. However, Echinacea was superior to placebo in three psychic anxiety items on the HAM-A. Conclusions: These findings suggest that Echinacea EP107TM reduces psychic anxiety without affecting somatic symptoms. This indicates that the extract may be useful in mild or early-phase anxiety when somatic symptoms are not prominent.