Free-Water Diffusion Magnetic Resonance Imaging Differentiates Suicidal Ideation From Suicide Attempt in Treatment-Resistant Depression.

BACKGROUND: Suicide attempt is highly prevalent in treatment-resistant depression (TRD); however, the neurobiological profile of suicidal ideation versus suicide attempt is unclear. Neuroimaging methods including diffusion magnetic resonance imaging-based free-water imaging may identify neural correlates underlying suicidal ideation and attempts in individuals with TRD. METHODS: Diffusion magnetic resonance imaging data were obtained from 64 male and female participants (mean age 44.5 ± 14.2 years), including 39 patients with TRD (n = 21 and lifetime history of suicidal ideation but no attempts [SI group]; n = 18 with lifetime history of suicide attempt [SA group]), and 25 age- and sex-matched healthy control participants. Depression and suicidal ideation severity were examined using clinician-rated and self-report measures. Whole-brain neuroimaging analysis was conducted using tract-based spatial statistics via FSL to identify differences in white matter microstructure in the SI versus SA groups and in patients versus control participants. RESULTS: Free-water imaging revealed elevated axial diffusivity and extracellular free water in fronto-thalamo-limbic white matter tracts of the SA group compared with the SI group. In a separate comparison, patients with TRD had widespread reductions in fractional anisotropy and axial diffusivity, as well as elevated radial diffusivity compared with control participants (thresholded p < .05, familywise error corrected). CONCLUSIONS: A unique neural signature consisting of elevated axial diffusivity and free water was identified in patients with TRD and suicide attempt history. Findings of reduced fractional anisotropy, axial diffusivity, and elevated radial diffusivity in patients versus control participants are consistent with previously published studies. Multimodal and prospective investigations are recommended to better understand biological correlates of suicide attempt in TRD.

Sex Differences in Determinants of Suicide Risk Preceding Psychiatric Admission: An Electronic Medical Record Study.

Background: Individuals requiring inpatient psychiatric care represent a group at higher risk of progressing toward suicide attempt. Using electronic medical record (EMR) data collected from psychiatric inpatient admissions, the objective of this study was to identify sex differences in risk factors for suicide plans and/or attempts within the 30 days preceding hospital admission. Methods: Resident Assessment Instrument for Mental Health (RAI-MH) intake data were obtained for patients admitted to a Canadian tertiary-care hospital deemed a "threat or danger to self" during a 10-year period (2008-2018). Data was extracted for individuals categorized into three groups: non-suicidal (N = 568), presence of suicide plan (N = 178), and presence of suspected suicide attempt (N = 124) in the 30 days prior to hospital admission. Multivariate logistic regression models were used to examine determinants of suicide risk. Results: Across all models, diagnosis of depression was the strongest predictor of suicide plan and/or attempt (OR = 5.54, 95% CI = 3.71-8.27, p < 0.001). Comparing clinical symptoms between suicidal and non-suicidal groups at the time of admission, the largest effect sizes were found for hopelessness (p < 0.001, η2 = 0.11), and guilt or shame (p < 0.001, η2 = 0.09). Female sex was identified as a significant factor for elevated suicidal risk (OR = 1.56, 95% CI = 1.01-2.21, p = 0.01), thus we stratified the regression model by sex to identify specific risk factors for suicide plan and/or attempt for males and females. Among males, having no confidant (OR = 2.13, 95% CI = 1.19-3.80, p = 0.01), presence of recent stressors (OR = 1.95, 95% CI = 1.16-3.29, p = 0.01), and participation in social activities (OR = 1.67, 95% CI = 1.02-2.71, p = 0.04) were important predictors, while among females, younger age (OR = 0.96, 95% CI = 0.94-0.97, p < 0.001) increased odds of suicide plan and/or attempt. Conclusion: EMR-derived findings highlight different psychosocial and clinical determinants for males and females associated with suicide plan or attempt prior to psychiatric admission. Identifying precipitating factors that elevate imminent suicide risk may inform suicide prevention efforts for psychiatric inpatients.