Heightened reactivity to uncertain threat as a neurobehavioral marker of suicidal ideation in individuals with depression and anxiety

Identifying neurobehavioral correlates of suicidal ideation can help detect those most vulnerable for suicide among high-risk groups, such as those with internalizing psychopathology. Individuals with elevated sensitivity to uncertain threat (U-threat) have a strong preference for known outcomes relative to unknown outcomes and often experience high levels of chronic distress. We therefore hypothesized that among individuals with internalizing psychopathology, those with heightened reactivity to U-threat would be especially prone to suicidal ideation as a means to escape uncertainty. The present study examined whether in two independent samples suicidal ideation was associated with heightened startle response to U-threat, and whether the effects were specific to responses U-threat relative to predictable threat (P-threat). Study 1 was a sample of treatment-seeking patients (N = 99) and Study 2 was a community sample (N = 102). Participants in both samples met current DSM-5 criteria for an anxiety and/or depressive disorder. In Study 1, current suicidal ideation was positively associated with startle potentiation to U-threat. Similarly, in Study 2, a lifetime history of suicidal ideation was positively associated with startle potentiation to U-threat. The relation between suicidal ideation and startle potentiation to U-threat remained when adjusting for number of internalizing diagnoses. Heightened reactivity to U-threat may therefore characterize those with a propensity for suicidal ideation among individuals with internalizing psychopathology.