Resting-state functional MRI of abnormal baseline brain activity in young depressed patients with and without suicidal behavior

Suicide among youth is a major public health challenge, attracting increasing attention. However, the neurobiological mechanisms and the pathophysiology underlying suicidal behavior in depressed youths are still unclear. The fMRI enables a better understanding of functional changes in the brains of young suicide attempters with depressive disorder through detecting spontaneous neural activity. The purpose of this study was to identify the relationship between abnormalities involving local brain function and suicidal attempts in depressed youths using resting-state fMRI (RS-fMRI).Thirty-five depressed youths aged between 15 and 29 years with a history of suicidal attempts (SU group), 18 patients without suicidal attempts (NSU group) and 47 gender-, age- and education-matched healthy controls (HC) underwent psychological assessment and R-fMRI. The differences in fractional amplitude of low-frequency fluctuation (ALFF) among the three groups were compared. The clinical factors correlated with z-score ALFF in the regions displaying significant group differences were investigated. The ROC method was used to evaluate these clusters as markers to screen patients with suicidal behavior.Compared with the NSU and HC groups, the SU group showed increased zALFF in the right superior temporal gyrus (r-STG), left middle temporal gyrus (L-MTG) and left middle occipital gyrus (L-MOG). Additionally, significantly decreased zALFF values in the L-SFG and L-MFG were found in the SU group compared with the NSU group, which were negatively correlated with BIS scores in the SU group. Further ROC analysis revealed that the mean zALFF values in these two regions (sensitivity=83.3% and specificity=71.4%) served as markers to differentiate the two patient subtypes.The SU group had abnormal spontaneous neural activity during the resting state, and decreased activity in L-SFG and L-MFG was associated with increased impulsivity in SU group. Our results suggested that abnormal neural activity in these brain regions may represent a potential neurobiological diathesis or predisposition to suicidal behavior in youth depression.