Integrating Scientific Realism and the Biopsychosocial Model in Biomarker Research for Depression

Major Depressive Disorder (MDD) is a complex and debilitating condition influenced by biological, psychological, and social determinants. The biopsychosocial model has long guided mental health research and practice, yet it is often criticized for being conceptually broad and insufficiently operationalized. At the same time, interest in biomarkers, particularly hematological indices such as complete blood count (CBC) parameters, has grown, with the goal of providing objective tools to complement subjective assessments. This paper argues that integrating scientific realism with the biopsychosocial model offers a stronger conceptual and methodological foundation for biomarker research in depression. Scientific realism emphasizes the existence of causal mechanisms that can be approximated through measurable indicators, thereby addressing the limitations of the biopsychosocial model's vagueness. Using depression as an exemplar, this paper demonstrates how a scientifically realist approach can guide the operationalization of biological, psychological, and social constructs into testable models. Implications for nursing research, education, and clinical practice are discussed, with recommendations for developing rigorous biomarker studies and embedding biomarker literacy into mental health nursing curricula. This integration advances a more evidence-based, holistic, and clinically relevant understanding of depression.