Brain Activation During Suicide-Specific Cognition in Trauma-Exposed Veterans.

Introduction: The suicide Implicit Association Test (S-IAT) captures the strength of the implicit identification between self and death and is one of the few suicide-specific behavioral tasks that uniquely predicts future suicide risk. Thus, identifying brain regions associated with the S-IAT provides insights into the neural mechanisms underlying suicidality.

Methods: This study measured brain activation during the S-IAT with concurrent fMRI in a post-9/11 trauma-exposed veteran sample. In total, 37 post-9/11 veterans at low risk for suicide participated in this study as part of an ongoing longitudinal study.

Results: Behaviorally, participants were slower to categorize words during incongruent (death-me) contexts relative to congruent (life-me) contexts (p < 0.001). Whole-brain voxelwise fMRI contrasts revealed a brain network that was significantly more active during incongruent trials than congruent trials that included the bilateral occipital, posterior parietal, and cerebellum (corrected p < 0.05). This increased brain activation corresponded with task performance, suggesting that more brain resources are needed to complete death-me identifications.

Conclusions: These results suggest that death-me implicit identifications involve resolving conflict between self and death representations in the brain and mark an important step towards characterizing neural mechanisms contributing to suicidality.