Abstract
Major depressive disorder (MDD) and suicidal behavior have been associated with structural and functional changes in the brain. However, little is known regarding alterations of brain networks in MDD patients with suicidal ideation. We investigated whether or not MDD patients with suicidal ideation have different topological organizations of white matter networks compared with MDD patients without suicidal ideation. Participants consisted of 24 patients with MDD and suicidal ideation, 25 age- and gender-matched MDD patients without suicidal ideation and 31 healthy subjects. A network-based statistics (NBS) and a graph theoretical analysis were performed to assess differences in the inter-regional connectivity. Diffusion tensor imaging (DTI) was performed to assess topological changes according to suicidal ideation in MDD patients. The Scale for Suicide Ideation (SSI) and the Korean version of the Barrett Impulsiveness Scale (BIS) were used to assess the severity of suicidal ideation and impulsivity, respectively. Reduced structural connectivity in a characterized subnetwork was found in patients with MDD and suicidal ideation by utilizing NBS analysis. The subnetwork included the regions of the frontosubcortical circuits and the regions involved in executive function in the left hemisphere (rostral middle frontal, pallidum, superior parietal, frontal pole, caudate, putamen and thalamus). The graph theoretical analysis demonstrated that network measures of the left rostral middle frontal had a significant positive correlation with severity of SSI (r=0.59, P=0.02) and BIS (r=0.59, P=0.01). The total edge strength that was significantly associated with suicidal ideation did not differ between MDD patients without suicidal ideation and healthy subjects. Our findings suggest that the reduced frontosubcortical circuit of structural connectivity, which includes regions associated with executive function and impulsivity, appears to have a role in the emergence of suicidal ideation in MDD patients.
Highlights
Suicide is one of the major causes of death
No significant differences in gender, age, education, number of episode, duration of current episode, Barrett Impulsiveness Scale (BIS) scores, Hamilton Depression Rating Scale (HAM-D) score and Mood Disorder Questionnaire (MDQ) score were present between two patient groups
We demonstrated that a distinct brain network characterizes the structural connectivity differences that are present in patients with suicide ideation
Summary
Suicide is one of the major causes of death. Over 800 000 people die from suicide every year, and many more attempt suicide worldwide.[1] Patients with major depressive disorder (MDD). Represent a population with high suicide risk, with 16% reporting at least one suicide attempt during their lifetime. The risk of completed suicide in patients with MDD is estimated at 3.4–6.8% Many studies have investigated factors associated with completed suicide or attempts in MDD patients, such as psychiatric comorbidities,[4] biomarkers,[5,6] environmental factors[7] and traumatic experience.[8,9] In addition, impulsivity has been reported to be associated with suicidal behavior across numerous studies.[10] MDD patients with suicidal ideation have a higher rate of previous suicide attempts,[11] have a lower treatment response rate and take longer to respond to treatment.[12] previous studies have suggested that MDD patients with suicidal ideation differ biologically from those without suicidal ideation,[13,14] few studies have focused on the differences in brain networks between MDD patients with and without suicidal ideation
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