The goal of this interventional clinical trial is to assess the diagnostic performance of a composite diagnostic medical devise based on blood-based in vitro diagnostic device and Mood Disorder Questionnaire (MDQ) in identifying bipolar disorder among adult patients presenting with a current major depressive episode in primary care. The study will compare the results of the medical device diagnostic test to those of standardized psychiatric clinical evaluation, to evaluate its sensitivity, specificity, and overall clinical utility. The main research questions are : * Can the investigational medical device accurately distinguish bipolar disorder from unipolar depression ? * How does its diagnostic accuracy compare with validated psychiatric questionnaires commonly used in clinical practice ? Participants will : * Provide a blood sample for biomarker analysis using the investigational diagnostic device. * Complete a few validated psychiatric assessment tools (e.g., MDQ, MINI). * Share sociodemographic and clinical data relevant to psychiatric evaluation.