Plasma Lipidomic Profiles Investigating the Effects of Combined Therapy With Quetiapine and Magnesium Valproate in Emerging Adults With Bipolar <scp>II</scp> Disorder During Depressive Episodes: A Follow‐Up Study

Bipolar disorder (BD) is associated with alterations in plasma lipid profiles, which may contribute to its pathogenesis. However, the detailed plasma lipidomic composition of bipolar II disorder during depressive episodes (BPD-II) remains underexplored. This study investigates the temporal changes in plasma lipidomics in BPD-II patients at emerging adulthood undergoing treatment with quetiapine combined with magnesium valproate. We conducted a follow-up study involving individuals with BPD-II at emerging adulthood at baseline (BD-BL, n = 30), 3 weeks (BD-3w, n = 30), and 8 weeks (BD-8w, n = 30) after treatment initiation, as well as gender- and age-matched healthy controls (HC, n = 30). Plasma lipidomics were analyzed using a comprehensive lipidomic profiling approach to identify potential biomarkers. Significant differences in plasma lipid composition were observed between BPD-II patients and healthy controls. Treatment with quetiapine combined with magnesium valproate alleviated symptoms in a time-dependent manner, although residual symptoms persisted after 8 weeks. We identified 64 lipid species with diagnostic potential to distinguish BPD-II from HC and 42 lipid species that could predict treatment outcomes with high reliability. Our findings provide valuable insights into the therapeutic effects of quetiapine combined with magnesium valproate and highlight the potential role of plasma lipidomics in understanding the pathophysiology of BPD-II at emerging adulthood.