Association Between Abnormal Default Mode Network Activity And Suicidality In Young Depression

Object: Suicide is the second leading cause of death among 15- to 29-year-olds in China, and 60% of all suicidal patients have a history of depression. Previous brain imaging studies have shown that depression and suicide may be associated with abnormal activity in default mode network(DMN) regions, and to date, no study has specifically investigated the relationship between DMN functional activity and suicide behavior in depressed individuals. In the present study, we directly investigated features of DMN brain activity in young patients with histories of depression and attempted suic ide.Methods: A total of 35 sex- and age-matched suicidal depressed patients were compared with 18 non-suicidal depressed patients and 47 healthy controls. We explored functional activity differences of DMN regions in three groups using independent component analysis(ICA) after collecting resting-state functional magnetic resonance imaging(rs-f MRI) signals and extracting DMN. We chose the left cerebellum and right precuneus that may have a close relationship with suic ide attempts as the regions of interest(ROIs), seed-based functional connectivity was used to further explore ROIs change in functional connectivity in SD and NSD groups. Six clinical scales about depression or suicide traits were assessed and were analyzed for the correlation with values of connectivity in the two groups.Results: 1. One-way ANOVA and chi-squared tests showed that the scores on all six clinical scales significantly differed among the three groups(all P<0.001). There were no differences in gender, age or educational level. Post hoc analys is showed that the scores on all six scales significantly differed between the HCs and the depressed patients with and without suicide history(P<0.001), no difference was found between the depressed patients with and without suicide history.2. Compared with the healthy controls, all of the evaluated depressed patients showed increased functional connectivity in select DMN regions. The suicidal depressed patients showed increased connectivity in the left cerebellum(BA18) and decreased connectivity in the right posterior cingulate cortex(PCC)(BA29), whereas the non-suicidal depressed patients showed increased connectivity in the left superior frontal gyrus(BA32), left lingual gyrus(BA18) and right precuneus(BA23) and decreased connectivity in the left cerebellum(BA19). Compared to the non-suicidal depressed patients, the suicidal patients showed increased connectivity in the left cerebellum(BA18)and the left lingual gyrus(BA18)and decreased connectivity in the right precuneus(BA23).3. Seed-based functional connectivity analysis found that, compared with NSD group, SD group showed increased functional connectivity between precuneus and right cerebellum( t=4.15, P<0.01), anterior cingulate cortex(ACC)(t=3.5, P<0.01),posterior cingulate cortex(PCC)(t=2.94, P<0.01) and right lingual gyrus(t=3.22, P<0.01), and between left cerebellum and the right angular gyrus(t=3.06, P<0.01).4. In SD group, values of functional connectivity between the precuneus and anterior cingulate cortex had a positively correlated with BHS total scores(r=-0.534,P=0.001).Conclusions: Collectively, our results highlight the importance of the DMN in the pathophysiology of depression and suggest that suicidal behavior in young depression may be related to abnormal functional connectivity in the DMN. Abnormal connectivity in left cerebellum and precuneus might be a predictor of suicidal behavior in young depressed patients.