Do Suicidal Behaviors Increase the Capability for Suicide? A Longitudinal Pretest–Posttest Study of More Than 1,000 High-Risk Individuals

Abstract

Despite the prominence of the capability-for-suicide construct in suicide research, fundamental hypotheses about its nature and development remain largely untested. In this study, we tested the primary mechanism proposed to account for its development: habituation to painful or provocative events. More than a thousand adults were recruited worldwide from online suicide, self-injury, and mental health web forums and subsequently followed for 28 days. Analyses examined the experiences purported to have the strongest effects: suicidal and nonsuicidal-self-injurious behaviors. Capability was measured explicitly and implicitly. Multiple mediation was used to test whether changes in capability between baseline and 28-day follow-up were accounted for by exposure to self-injurious behaviors that occurred over the intervening time interval. Results failed to support the habituation hypothesis, at least as studied within the methodological constraints of this study. Post hoc power analyses indicated ample power to detect small effects. Results raise questions about the validity of the habituation hypothesis.