Exploring white matter integrity in major depressive disorder with and without suicidal attempts: a diffusion tensor imaging study

The study investigates the neurobiological basis of suicidality in patients with Major Depressive Disorder with suicidal attempts (MDD + SA) by examining differences in white matter integrity among three groups: MDD + SA, MDD–SA without suicide attempts, and healthy controls (HC). Sixty-one participants—17 with MDD + SA, 19 MDD–SA, and 25 HC—underwent diffusion MRI scans to assess white matter microstructure using measures such as fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD). Correlational tractography was then performed to identify white matter pathways affected in suicidality. Compared to patients with MDD–SA, patients with MDD + SA exhibited distinct bilateral white matter microstructural changes. They showed greater FA and AD in the cingulum tracts, including the bilateral Cingulum Frontal Parietal, bilateral Cingulum Frontal Parahippocampal, and right Cingulum Parolfactory, as well as higher FA in the left Cingulum Parolfactory. Furthermore, patients with MDD + SA showed lower MD and RD in the right Cingulum Frontal Parietal and right Cingulum Parolfactory, and lower RD in the bilateral Cingulum Frontal Parahippocampal and left Cingulum Parolfactory, compared to patients with MDD–SA. In contrast, patients with MDD + SA demonstrated lower FA in the right Frontal Corticopontine tract compared to MDD–SA. Relative to HC, patients with MDD + SA showed higher FA and lower RD across the cingulum bundle, including the bilateral Cingulum Frontal Parietal, bilateral Cingulum Parolfactory, and left Cingulum Frontal Parahippocampal. They also exhibited higher AD in the left Cingulum Frontal Parietal, left Cingulum Parolfactory, and left Cingulum Frontal Parahippocampal, as well as lower MD in the right Cingulum Frontal Parietal and right Cingulum Parolfactory compared to HC. In addition, patients with MDD + SA showed an interesting pattern of elevated FA with reduced MD, RD, and AD in the Corpus Callosum Forceps Major and lower FA in the Corpus Callosum Forceps Minor, compared to HC. These findings highlight specific white matter microstructural differences in MDD + SA, particularly in the cingulum bundle, which may serve as neurobiological markers of suicidality, potentially enabling more effective assessment and intervention techniques. Not applicable.