Effect of kava extract on vagal cardiac control in generalized anxiety disorder: preliminary findings

Anxiety disorders are associated with low vagal control of heart rate and increased risk of cardiac mortality and sudden cardiac death. This study examined whether the herbal anxiolytic, kava, produces improvement in vagal control in generalized anxiety disorder. Before and after treatment with placebo (n = 7) or kava (n = 6), two indices of vagal control were measured under supine conditions using power spectral analysis: baroreflex control of heart rate (BRC) and respiratory sinus arrhythmia (RSA). Significantly more patients treated with kava showed improved BRC compared to the placebo group (p < 0.05). Furthermore, the magnitude of improvement in BRC was significantly correlated with the degree of clinical improvement (p < 0.05). RSA did not respond to treatment. These preliminary findings suggest that kava might exert a favourable effect on reflex vagal control of heart rate in generalized anxiety disorder patients. The parallel clinical and BRC responses may reflect an underlying common effect of this herbal anxiolytic.