Aberrant resting-state functional connectivity of major depressive disorder with higher risk of suicide

Aim: Suicide prevention for depressive patients is an important clinical issue in psychiatry. However, not all depressive patients plan or attempt suicide. In this study, we investigated the differences of functional brain networks between a high-risk group and a low-risk group for suicide by comparing resting-state functional connectivity (rsFC). Methods: The subjects were 29 patients with major depressive disorder, nine of whom had attempted suicide. The suicidal ideation of all subjects was assessed with the Columbia-Suicide Severity Rating Scale, then the subjects were divided into two groups based on the most severe suicidal ideation (MSI) in their lifetime. We compared rsFC between the two groups. Results: Of the 29 subjects, 16 were in the severe MSI group. We found that the severe MSI group members had significantly smaller rsFC in two networks: one comprised the right dorsolateral prefrontal cortex and the default-mode network, and the other comprised the left rostrolateral prefrontal cortex and the striatum, amygdala, and hippocampus. These regions are reported to be associated with rumination, retrieval suppression, and delay discounting (DD). Conclusion: Our results suggest that functional networks related to rumination, retrieval suppression, and DD might be impaired in depressive patients with severe suicidal ideation. It might be beneficial for psychiatrists to assess these characteristics in terms of suicide prevention for depressive patients.