Structural connectivity abnormalities in suicidal thoughts and behaviours: a meta-analysis

Suicidal thoughts and behaviours (STBs) are major public health concerns. Despite much research focus on grey matter abnormalities in STBs, the study of white matter tracts that connect the brain regions implicated in STBs has received relatively less attention. Hence, we conducted the first meta-analysis of whole-brain voxel-based diffusion tensor imaging studies in STBs to elucidate the most robust white matter microstructure abnormalities relative to controls. Fourteen DTI datasets were included, comprising 289 individuals with a history of STBs and 506 controls. Anisotropic effect-size signed differential mapping, a voxel-based meta-analytic method, was used to examine regions of altered fractional anisotropy (FA) in individuals with STBs compared to controls. Individuals with a history of STBs had significantly lower FA in bilateral inferior longitudinal fasciculus, inferior frontal-occipital fasciculus, uncinate fasciculus, fornix, cingulum bundle and corpus callosum body than controls. There were no regions with increased FA. Findings remained in subgroup analyses of adult and drug-free samples. Decreased FA in the right fronto-limbic-occipital cluster was more severe in younger individuals and females with STBs than controls. STBs are associated with microstructural abnormalities particularly evident in the ventral fronto-limbic, visual-limbic-OFC and callosal body pathways, suggesting that the neural pathways involved in emotion and sensory processing are specifically compromised in this population. Insights into the neurobiological abnormalities associated with STBs are important as they encourage greater efforts to examine treatments to normalise these morphological alterations and reduce suicide deaths.