Abstract
Despite recent developments in neuroimaging, alterations of brain functional connectivity in major depressive disorder (MDD) patients with suicidal ideation are poorly understood. This study investigated specific changes of suicidal ideation in functional connectivity of MDD patients. Whole brain functional connectivity in 46 patients with MDD (23 with suicidal ideation and 23 without) and 36 age- and gender- matched healthy controls were compared using resting-state functional Magnetic Resonance Imaging (fMRI) analyzed with network-based statistics (NBS) and graph-theoretical methods. Decreased functional connectivity in a characterized sub-network was observed in patients with MDD and suicidal ideation (FDR-adjusted p < 0.05). The sub-network included the regions of the fronto-thalamic circuits in the left hemisphere. The network measures of the left superior frontal gyrus, pars orbitalis (r = −0.40, p = 0.009), left thalamus (r = −0.41, p = 0.009), and right thalamus (r = −0.51, p = −0.002) were shown, through graph theoretical analysis, to be significantly negatively correlated with severity of suicidal ideation. The reduced functional connectivity in left orbitofrontal-both thalamic regions with suicidal ideation in MDD were inversely proportional to the severity of suicidality independent from depression severity. These findings suggest problems with decision-making and information integration in MDD patients with suicidal ideation.
Highlights
Every 40 seconds, one individual dies from suicide[1] while suicide accounts for 1.4% of all deaths, making it the 15th leading cause of death globally[2]
We focused on the comparison between major depressive disorder (MDD) patients with suicidal ideation and patients without suicidal ideation, but we compared healthy control to rule out the pathologic functional connectivity change coming from depression itself, which can find clear associative functional connectivity in suicidal ideation
There were no significant differences in gender, age, education, number of episodes, duration of current episode, the Korean version of the Barrett Impulsiveness Scale (BIS) score, Hamilton Depression Scale (HAM-D) score, and the Mood Disorder Questionnaire (MDQ) score between the patient groups
Summary
Every 40 seconds, one individual dies from suicide[1] while suicide accounts for 1.4% of all deaths, making it the 15th leading cause of death globally[2]. Suicidal ideation is a distinct phenomenon that is not equivalent to depression severity indicators, other dimensions with underlying biology, impact on disability, and risk factors[8,9]. MDD accompanying suicidal ideation is related to a higher rate of previous suicide attempts[10], poorer treatment response[11], and is thought to have different neuropsychological correlates that discriminate it from MDD without suicidal ideation[12]. Measuring severity of both depression and suicidal ideation in MDD patients with suicidal ideation may help determine whether severe depression status predicts depression with suicidal ideation. Considering that severity and intensity of suicidal ideation can fluctuate over time, vary according to biological, psychological, and environmental factors[13,14], suicidal ideation should be assessed as a continuous measurement, and real-time neuroimaging could be a promising approach to examine neural network alterations as correlates of the degree and intensity of suicidal ideation[15]
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