Examining the Neural Basis of Pain Tolerance and Fearlessness About Death in Suicide Risk: A Research Protocol

Introduction: Suicide is a global health concern that takes the lives of over 700,000 people each year. Suicide capability – including heightened pain tolerance and fearlessness about death – may explain the progression from suicidal ideation to a suicide attempt. Thus, investigating the neural circuitry associated with pain, fear, and suicide risk presents a unique opportunity to identify biomarkers of suicide capability and contribute to our understanding of the transition from suicidal ideation to suicide attempt. Methods: A total of 90 adults aged 18 to 65 will be recruited from Toronto, Canada. Participants will either be patients with current suicidal ideation but no previous suicide attempt (n=30), patients with current suicidal ideation and a suicide attempt within the past six months (n=30), or healthy controls (n=30). Participants will complete self-report measures and magnetic resonance imaging tasks measuring pain tolerance and fearlessness about death. Results: We expect that suicide attempters will exhibit significantly higher pain tolerance and fearlessness about death than suicide ideators or healthy controls. We also predict negative associations between self-reported suicide capability and pain- and fear-related neural activation. Discussion: Findings of the present study may contribute to the validation of ideation-to-action models of suicide by providing neurobiological evidence supporting the distinction between suicide ideators and attempters. Conclusion: By examining the neural underpinnings of suicide capability, our work contributes to the understanding of biomarkers indicating those at greatest risk of suicide.