Effects of Yohimbine on Heart Rate Variability in Panic Disorder Patients and Normal Controls: A Study of Power Spectral Analysis of Heart Rate

We studied the effects of yohimbine on heart rate (HR) variability in 13 normal controls and 13 patients with panic disorder. Yohimbine produced a significant increase in SD of HR in standing posture in both patients (p = 0.01) and normal controls (p = 0.025). Panic disorder patients had a significant increase in standing absolute midfrequency (MF) power (0.07–0.15 Hz) after administration of yohimbine (p = 0.002). The ratio of post- to preyohimbine standing MF power (0.07–0.15 Hz) during standing was significantly higher in patients as compared with controls (2.3 ± 1.08 vs. 1.33 ± 0.38; p = 0.01), which suggests an increased responsivity of panic disorder patients to the adrenergic effects of yohimbine