Altered autonomic reactivity in Korean military soldiers with adjustment disorder.

Only few studies addressing the biological background of adjustment disorder (AD) exist. We examined the psychophysiological correlates indicative of autonomic regulation in AD. Heart rate variability (HRV), skin conductance, skin temperature, electromyography, and respiration were measured during serial stress tasks in 33 soldiers with AD and 60 healthy controls (HC). Patients with AD displayed lower relative power of high frequency (rHF) HRV and higher relative power of very low frequency (rVLF) HRV compared with HC at baseline. Inversely, the rHF of patients with AD remained higher and their rVLF remained lower compared with HC parameters after the single stress task, which suggests a reversed sympathovagal balance in AD. Mean heart rate and skin conductance increased during stress tasks in patients, although to a lesser extent than in HC. Skin temperature remained unchanged in all tasks in patients with AD. The tension of the frontalis muscle was higher in patients compared with HC from the second stress task onward. Thoracic breathing was more prevalent in patients with AD. Our study suggests altered autonomic reactivity in AD, which leads to a lack of sympathetic response to stress. We conclude that the distinctive biological mechanisms underlying AD are different from normal stress reactions.