An Investigation into the Bidirectional Relationship Between Post-Traumatic Stress Disorder and Suicidal Ideation: A Nine Year Study

Abstract Suicide is the second leading cause of death in adolescents; a frequent precursor of suicide is suicidal ideation (SI). Literature indicates that Post-Traumatic Stress Disorder (PTSD) and SI are robust cross-sectional correlates of one another, with PTSD often being conceptualized as a risk factor (i.e., conferring risk) for SI. Indeed, PTSD is a well-established risk factor for SI; however, SI is an understudied risk factor for PTSD. It is possible that, yet unknown if, PTSD and SI promote each other over time in a bidirectional fashion. We investigated the bidirectional longitudinal associations between PTSD and SI in a large, diverse sample, who at baseline were adolescents. Participants were interviewed between 1995-1998 and again between 2004-2008. We hypothesized that PTSD and SI would be cross-sectionally, longitudinally, and bidirectionally related and that the number of traumas endorsed at baseline would be positively associated with PTSD and SI at baseline and follow-up. Indeed, PTSD and SI were cross-sectionally correlated at baseline, but not follow-up. PTSD predicted SI over nine years; however, SI during adolescence did not predict PTSD in adulthood. Finally, poly-trauma endorsed at baseline was associated with increased risk of SI, but not PTSD, over nine years.