Posttraumatic Stress Disorder and Impaired Autonomic Modulation in Male Twins

Background Posttraumatic stress disorder (PTSD) has been linked to increased morbidity. An inflexibility of the autonomic nervous system might be the underlying mechanism. We aimed to assess whether PTSD and combat trauma exposure are associated with lower heart rate variability (HRV), a measure of autonomic function and a predictor of death. Methods We measured HRV by power spectral analysis on 24-hour ambulatory electrocardiogram in 459 middle-aged veteran male twins. Combat trauma was assessed with the combat exposure scale, and current and remitted PTSD was assessed with the Structured Clinical Interview for Psychiatry Disorders. Mixed-effects regression models were used to test associations of PTSD and HRV between and within twin pairs. Results Of all twins, 211 had combat exposure, 31 had current PTSD, and 43 had remitted PTSD. Current PTSD was inversely associated with very-low-frequency and low-frequency HRV both in individual twins and within 20 pairs discordant for current PTSD. Twins with current PTSD had a 49% lower low-frequency HRV than their brothers without PTSD ( p