Prefrontal responses to negative emotional cognitive stimuli are associated with future suicide attempts in patients with mood disorders: a near-infrared spectroscopy study.

Abstract

Early identification of suicide risk remains a critical challenge in psychiatry. Longitudinal evidence linking baseline brain responses to subsequent suicide attempts remains limited. In this exploratory prospective follow-up study, 29 patients with major depressive disorder or bipolar disorder underwent near-infrared spectroscopy (NIRS) during an emotional Stroop task at baseline; 22 completed the 6-month follow-up and were included in the analysis, five of whom attempted suicide. Baseline oxygenated hemoglobin (Oxy-Hb) responses during the threat-word condition were compared between patients with and without suicide attempts using Mann-Whitney U tests. The main exploratory NIRS measure was the mean normalized Oxy-Hb response across 15-45 s (periods b + c) in the left dorsolateral prefrontal cortex (DLPFC); the corresponding left orbitofrontal cortex (OFC) measure was also examined. The follow-up attempt group showed higher baseline Oxy-Hb responses in the left DLPFC (U = 7.00, Holm-adjusted p = 0.022) and left OFC (U = 5.00, Holm-adjusted p = 0.020). Exploratory Spearman's rank correlations showed that baseline Quick Inventory of Depressive Symptomatology scores were associated with the periods b + c NIRS measures in both regions, suggesting that baseline depressive symptom severity may have contributed to the observed group differences. These preliminary findings suggest that altered prefrontal hemodynamic responses during threat-related emotional interference may be associated with subsequent suicidal behavior. Larger prospective studies are required to replicate these findings and clarify their clinical relevance.

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