Background: Nonsuicidal self-injury (NSSI) is associated with reduced pain sensitivity and alterations in top-down processing of nociceptive information. The experience of acute pain is characterized by reactivity of the autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis, which to our knowledge has not been systematically investigated in the context of NSSI.
Methods: Adolescents fulfilling DSM-5 diagnostic criteria for NSSI and matched healthy controls received cold pain stimulation. We obtained self-reports on psychological distress and measured blood pressure, heart rate variability (HRV) and saliva cortisol. Regression analyses were used to investigate group differences on observed difference scores, adjusting for confounding variables.
Results: We included 30 adolescents engaging in NSSI and 30 controls in our study. Adolescents in the NSSI group showed a greater pain threshold. Groups significantly differed in their psychological response to pain. In patients with NSSI, mood and body awareness increased after painful stimulation; in controls it decreased. Tension increased in controls only. The HPA axis response to painful stimulation was increased in the NSSI compared with the control group. Analysis of ultra-short-term recordings of HRV revealed significant group differences during the anticipation of pain and recovery.
Limitations: Future studies should incorporate multiple measures of saliva cortisol and replicate the present findings in a naturalistic setting.
Conclusion: Compared with controls, individuals engaging in NSSI show psychological benefits in response to pain. Biological findings highlight decreased physiologic arousal before and prolonged arousal (ANS and HPA axis response) after painful stimulation in adolescents engaging in NSSI. Greater pain-inflicted autonomic arousal and cortisol secretion may counteract dissociative states, reduce negative affect and increase body awareness in adolescents engaging in NSSI, lending support for a neurobiological pathomechanism underlying the intraindividual and antisuicide functions of NSSI.