A PRELIMINARY INVESTIGATION OF RESTING STATE FUNCTIONAL CONNECTIVITY NETWORKS IN PATIENTS WITH TREATMENT-RESISTANT DEPRESSION AND A HISTORY OF SUICIDE ATTEMPT

Abstract Background Suicidal ideation (SI) and history of previous suicide attempt (SA) remain the most prominent prognostic factors for completed suicides. Understanding suicide is a nuanced multifaceted issue, and a mounting body of literature has used neuroimaging to enhance our understanding of suicide. Resting state functional magnetic resonance imaging (fMRI) strategies may reveal unique neuroimaging phenotypes related to suicide. Aims & Objectives This study examined resting-state functional connectivity (FC) differences between SI and SA in patients with treatment-resistant major depressive disorder (MDD). Method Resting-state FC data was obtained from N=40 patients with treatment-resistant MDD (n=21 with lifetime history of suicidal ideation and no attempts [SI-group]; n=19 with lifetime history of suicide ideation and attempts [SA-group]. Functional MRI data were acquired at 3T and pre-processed using the default CONN Functional Connectivity pipeline. A region of interest (ROI)-to-ROI approach was used to evaluate FC with the Harvard-Oxford and the resting-state network atlases. SI and SA history were examined using the Columbia Suicide Severity Rating Scale (C-SSRS). Findings were thresholded to p <0.005, false-discovery rate corrected. Results Resting-state FC analyses revealed that compared to the SA-group, the SI-group had higher FC between the right hippocampus and the DMN (lateral-parietal lobe) bilaterally (right hemisphere, t(38) = 3.8, pFDR = 0.02; left hemisphere, t(38) = 3.6, pFDR = 0.02) and decreased FC between the right DMN and regions of the salience network (bilateral supramarginal gyrus: t(38) = - 3.3, pFDR = 0.03 and bilateral anterior cingulate gyrus (t(38) = -3.2, pFDR = 0.03). A within group analysis revealed a negative correlation between current SI severity and FC between the caudate and the hippocampus/posterior para-hippocampus in the full sample (N = 40; pFDR = 0.05) and in the attempter grouper group specifically (n = 19; pFDR=0.008). Discussion & Conclusion Conceptualizing suicide is complex, and neuroimaging can identify neurobiological markers that reflect the underlying pathophysiology of depression and suicide. Our preliminary resting state functional MRI analyses shows significant differences in DMN FC in patients with SI and a lifetime history of SA compared to those with SI only. There were significant associations between limbic network FC and current SI severity. Our work contributes to a growing field highlighting the complex biosignatures involved in SI and SA in patients with treatment-resistant MDD.