A systematic review of studies on the association between physiological parameters and self-harm

Background: Self-harm is common in people with intellectual disabilities and is associated with multiple adverse consequences for the client engaging in self-harm, other clients and caregivers. Self-harm is related to emotional dysregulation according to both observational and self-report data. Measures of the autonomic nervous system might provide additional insight in this relationship. Methods: The current systematic review systematically summarized a broad spectrum of studies on the association between self-harm and physiological parameters. The search identified 2400 articles, 46 were included. Results: In most studies, which compared electrodermal activity and heart rate in people with and without self-harm, no clear indications for a relation between physiology and self-harm was found. Studies on heart rate variability showed indications for lower heart rate variability during recovery, which could imply emotion dysregulation, findings which were supported by results from imagery studies (heart rate and skin conductance). No consistent findings were found when self-harm was studied before, during or after actual occurrences of self-harm, although this was examined by very few studies. Conclusions: Although wearable technology has improved, the majority of studies to date are lab-studies. Future research should focus on measuring physiology in daily life before, during and after self-harm, in people with intellectual disabilities, study different types and functions of self-harm separately, and test multimodal prediction models. This knowledge could improve the understanding, prevention and assessment of this debilitating behaviour.