The influence of depressive and manic symptoms on suicidal ideation in mixed mood states

Background: While bipolar disorder is strongly linked to an increased risk of suicide, recent evidence has challenged the assumption that mixed symptoms play a distinct role in suicidal ideation beyond depressive severity. This study examines how depressive, hypo/manic, and mixed features influence suicidal ideation in individuals with bipolar disorder. Data from 903 participants in the Stanley Foundation Bipolar Network (1995–2002) were analyzed to assess associations between mood states, classified by the Inventory of Depressive Symptomatology–Clinician-Rated (IDS-C) and the Young Mania Rating Scale (YMRS), and suicidal ideation, measured using IDS-C item 18, using generalized estimating equations. 

Results: Depressive symptoms were strongly associated with suicidal ideation (OR = 21.98, 95% CI: 15.31–31.54). Moderate hypo/manic symptoms also conferred risk (OR = 3.11, 95% CI: 1.51–6.49), and milder hypo/mania showed a weaker but significant association (OR = 1.74, 95% CI: 1.05–2.89). The highest suicidal ideation was observed in individuals with hypo/mania featuring mixed symptoms (OR = 29.43), exceeding that of depression or depression with mixed features (OR = 21.98). However, findings diverged based on modeling approach: in continuous predictor models, SI was driven solely by depressive symptom severity, with no significant association observed for hypo/mania or its interaction with depression. In contrast, when mood states were categorized using clinically meaningful thresholds, hypo/mania with mixed features emerged as a distinct contributor to suicidal ideation risk. 

Conclusion: These findings underscore the need for integrating both dimensional and categorical approaches to mood state classification in research on suicidality in bipolar disorder.