Neurostructural differences associated with self-harm in youth bipolar disorder

Background Youth with bipolar disorder (BD) are at greatly elevated risk for suicide. Self-harm, encompassing all self-injurious behaviors regardless of suicidal intent, is among one of the greatest risk factors for death by suicide. This study aims to extend the sparse literature regarding the neurostructural correlates of self-harm in youth with BD. Methods Participants included 156 youth (17.14 +/- 1.61 years): 38 BD with lifetime history of self-harm (BDSH+), 43 BD without history of self-harm (BDSH-), and 75 healthy controls (HC). Measures of cortical thickness, surface area (SA), and volume were obtained using 3 T magnetic resonance imaging. Orbitofrontal and ventrolateral prefrontal cortices were examined in region-of-interest (ROI) analyses, complemented by exploratory vertex-wise analyses using a general linear model controlling for age, sex, and intracranial volume. Results In ROI analyses, there were no between-group differences after correction for multiple comparisons. Vertex-wise analysis revealed three significant clusters in precentral gyrus SA, inferior temporal gyrus SA, and caudal middle frontal gyrus volume. Post-hoc vertex-wise analyses showed BDSH+ had lower cortical SA and volume compared with both BDSH- and HC for all clusters. Conclusions Significant vertex-wise findings were observed in frontotemporal regions relevant to BD and self-harm, with smaller neurostructural measures among BDSH+ compared with both BDSH- and HC. Future studies are needed to evaluate the temporal nature of the relationship of these neurostructural differences (i.e., potential risk indicators) to self-harm and to identify mechanisms underlying these findings.