Abstract
Suicidality is a significant public health concern, with neuroimaging studies revealing abnormalities in the brains of suicidal individuals and post-mortem samples. However, the genetic architecture between suicidality and subcortical brain volumes remains poorly characterized. Using genome-wide association studies (GWAS), we investigated the genetic overlap between suicidality and subcortical brain volume. GWAS summary statistics for suicidal behaviours, including Suicide Attempts, Ever Self-Harmed, and Thoughts of Life Not Worth Living, from the UK Biobank, Suicide from the FinnGen Biobank, and data on seven subcortical brain volumes and Intracranial Volume from the ENIGMA2 study, were used to investigate the genetic correlation between phenotypes as well as potential genetic factors. A common genetic factor was identified, comprising two categories: Suicide Attempt, Ever Self-Harmed, and Thoughts of Life Not Worth Living from the UK Biobank, and Suicide from FinnGen, Intracranial Volume, and subcortical brain volumes. Cross-phenotype GWAS meta-analysis of each category at variant, gene and subnetwork levels unveils a list of significant variants (P-value <5 × 10(-8)), and potential hub genes (P-value <0.05) of consideration. Network, pathway, and Gene Ontology analyses of these joint categories highlighted enriched pathways and biological processes related to blood-brain barrier permeability suggesting that the presence and severity of suicidality are associated with an inflammatory signature detectable in both blood and brain tissues. This study underscores the role of brain and peripheral blood inflammation in suicide risk and holds promise for developing targeted interventions and personalized treatment strategies to reduce suicidality in at-risk populations.