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BACKGROUND: Bipolar disorder (BD) carries a suicide risk 20 times higher than the general population, with up to 60% of patients attempting suicide. Current interventions have failed to reduce its incidence; static factors have shown limited predictive utility. Emerging evidence suggests dynamic monitoring approaches may offer complementary value. This study examined whether quantifiable differences in mood regulation patterns exist across the suicidality continuum among patients diagnosed with BD.

METHOD: We analyzed daily self-reported mood, anxiety, and energy levels from 164 participants recruited from two Canadian academic hospitals (April 2021-August 2024). Participants were stratified into six groups based on suicide attempt history, current polarity, and active suicidality status. Using time-series analysis, we computed autocorrelation and cross-correlation functions to examine temporal relationships within and between variables across 1-7 day lags. Data comprised 64,351 valid observations over 461.5 ± 236.6 days of follow-up.

RESULTS: Participants with the highest suicide risk (previous attempt, in a current depressive episode with active suicidality) demonstrated significantly higher day-to-day autocorrelation compared to the lowest-risk participants (no prior attempts and currently euthymic) for mood (0.53 vs. 0.29, p = 0.01), energy (0.52 vs. 0.23, p = 0.02), and anxiety series (0.55 vs. 0.32, p = 0.04). Cross-correlation analysis revealed mood-energy decoupling during active suicidality; as well as a stronger negative mood-anxiety correlation in those with a prior attempt, even during euthymia.

CONCLUSION: Higher autocorrelation patterns are indicative of a pathologically stable mood regulation in high-risk individuals, potentially serving as dynamic biomarkers for suicide risk stratification and targeted intervention development. Our findings demonstrate that a more aggressive approach to treating comorbid anxiety may be essential for reducing the risk of future attempts. They also challenge traditional conceptualizations equating euthymia with the absence of suicide risk, suggesting neurobiological vulnerability despite symptomatic remission.