- Structural and microstructural abnormalities: reduced prefrontal-limbic grey matter, corpus callosum alterations, and decreased fractional anisotropy in fronto-limbic tracts linked to impulsivity and suicidal intent.
- Functional dysregulation: limbic and paralimbic hyperactivity with prefrontal hypoactivity; default mode hyperconnectivity and salience/executive network hypoconnectivity; altered amygdala-prefrontal connectivity.
- Integrated model: structural and functional vulnerabilities impair emotion regulation and behavioural control, facilitating transition from ideation to attempt; neuroimaging biomarkers require prospective validation.
Alpha Psychiatry. 2026 Sep 10;27(5):50801. doi: 10.31083/AP50801. eCollection 2026 Oct.
ABSTRACT
BACKGROUND: Suicide attempts (SA) represent a high-risk indicator for subsequent suicidal behavior in patients with bipolar disorder (BD). However their underlying neurobiological mechanisms remain incompletely understood.
METHOD: This systematic review synthesized neuroimaging findings from the PubMed and Web of Science databases (January 1990 to April 2026) to elucidate the structural and functional brain alterations associated with SA in BD.
RESULTS: Structural magnetic resonance imaging (MRI) studies revealed reductions in prefrontal-limbic gray matter, alterations in the corpus callosum, and inconsistent findings regarding cerebellar volume. Diffusion tensor imaging (DTI) demonstrated microstructural disconnection in the uncinate fasciculus, inferior fronto-occipital fasciculus, cingulum bundle, forceps minor, and the corpus callosum, with reduced fractional anisotropy correlating with impulsivity and suicidal intent. Functional MRI identified a multilevel pattern of dysfunction, characterized by limbic and paralimbic hyperactivity (including the anterior cingulate cortex, insula, and temporal regions) alongside prefrontal hypoactivity. Network dysregulation was characterized by hyperconnectivity within the default mode network and hypoconnectivity within the salience and executive control networks, as well as altered amygdala-prefrontal and frontotemporal connectivity. Whole-brain dynamic analyses further demonstrated prolonged dwell time in a maladaptive brain state.
CONCLUSIONS: Convergent multimodal evidence supports an integrated model in which structural and functional vulnerabilities disrupt emotion regulation and behavioral control, thereby facilitating the transition from suicidal ideation to suicidal behavior. Neuroimaging findings may represent potential candidate biomarkers; however, prospective validation is required before these markers can inform risk stratification or targeted interventions for suicide prevention in BD.
PMID:42985191 | PMC:PMC13732002 | DOI:10.31083/AP50801
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