Psychological theories of suicide suggest that certain traits may reduce aversion to physical threat and increase the probability of transitioning from suicidal ideation to action. Here, we investigated whether blunted sensitivity to bodily signals is associated with suicidal action by comparing individuals with a history of attempted suicide to a matched psychiatric reference sample without suicide attempts. We examined interoceptive processing across a panel of tasks: breath-hold challenge, cold-pressor challenge, and heartbeat perception during and outside of functional magnetic resonance imaging. Suicide attempters tolerated the breath-hold and cold-pressor challenges for significantly longer and displayed lower heartbeat perception accuracy than non-attempters. These differences were mirrored by reduced activation of the mid/posterior insula during attention to heartbeat sensations. Our findings suggest that suicide attempters exhibit an ‘interoceptive numbing’ characterized by increased tolerance for aversive sensations and decreased awareness of non-aversive sensations. We conclude that blunted interoception may be implicated in suicidal behavior.
Bibliographical noteFunding Information:
The authors thank W Kyle Simmons, PhD, for helpful discussions that motivated the initial work on this project, Rachel Lapidus, MA, for helpful comments offered on the manuscript, Maria Puhl, PhD, and Wesley Thompson, PhD, for providing statistical consultation, the Tulsa-1000 clinical assessment team for participant recruitment and data collection, and the MRI technologists at the Laureate Institute for Brain Research for MRI data acquisition. The authors acknowledge Austin Lignieres, BS, James Hale, and Max Paulus for assisting with physiological data inspection and correction. This work has been supported in part by The William K Warren Foundation, by NIH/National Institute of Mental Health grant K23MH112949 (to SSK), and the National Institute of General Medical Sciences Center Grant Award Number 1P20GM121312 (JLS, MPP, SSK). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Results presented in part at the Anxiety and Depression Association of America 39th Annual Scientific Meeting, March 2019, and at the Society of Biological Psychiatry 74th Annual Meeting, May 2019, in Chicago, IL.