BACKGROUND: Bereavement following suicide and fatal overdose is associated with posttraumatic stress disorder (PTSD) and prolonged grief (PG). However, information about plausible explanations for these associated symptoms is scarce. Leveraging data from two assessment points, we examine the prospective roles of stigmatization, guilt, shame, and avoidant coping on PTSD and PG symptom severity and whether these relations are similar across groups. METHODS: We analyzed data (N = 212) from suicide- and overdose-bereaved adults who completed two waves of data collection (T1 and T2
six months apart) as part of a larger study of traumatic loss. Multigroup path analysis with serial mediation was used to estimate models of PTSD and PG symptomatology. Stigmatization (T1) and guilt (T1) were modeled as predictors, while shame (T1) and avoidant coping (T2) were modeled as mediators explaining PTSD (T2) and PG symptoms (T2). RESULTS: Prospective relations between T1 stigma, T1 guilt, T2 PTSD and T2 PG symptoms were mediated by T1 shame and serially mediated by T2 avoidant coping. Multigroup analyses indicated similar relations across suicide and overdose-bereaved adults, but a stronger effect from T2 avoidant coping on outcomes for overdose bereaved adults. LIMITATIONS: Online self-report and use of a convenience sample are limitations. CONCLUSION: Our results suggest shame and avoidance may help explain elevated symptoms of PTSD and PG in the context of suicide and overdose bereavement. Accordingly, transdiagnostic interventions that concurrently target shame-related cognitions and behavioral avoidance may be promising and warrant further attention.