The Role of the Autonomic Nervous System in the Mediation of the Resolution of Suicidal Ideation with Electroconvulsive Therapy: A Hypothesis and Review of Heart Rate Variability over a Course of Electroconvulsive Therapy

Longitudinal observational studies have shown a meaningful decrease in suicidal thinking and suicidal behavior after receipt of electroconvulsive therapy (ECT). The antisuicide effect of ECT may be related to success in the global relief of the presenting syndrome such as depressive or psychotic illness. However, it is possible that the antisuicide effect is specific to ECT per se, over and above the relief of the clinical syndrome. Electroconvulsive therapy is associated with many observable neurochemical and physiologic effects, and some of these may plausibly be specifically linked to an antisuicide effect. The phenomenon of physiologic hyperarousal has been named as a candidate mechanism driving the risk for suicide. Hyperarousal is associated with decreased neuropsychological executive function responsible for response inhibition and can lead to impulsive action. The level of arousal within the autonomic nervous system (ANS) can be assayed with the pupillary light reflex, electrodermal activity, or with heart rate variability (HRV). This article summarizes the literature on the effects of ECT on HRV 24 to 72 hours after a course of ECT and finds evidence for increases in HRV, which indicates lower levels of arousal in the ANS. This finding suggests that ECT-related reductions in ANS arousal, presumably with corresponding improvements in response inhibition, may be one mechanism whereby ECT reduces risk for suicide.