Soluble urokinase plasminogen activator receptor – What are the clinical potentials in psychiatry?

Background: Mental disorders have been associated with systemic chronic inflammation, and conditions such as depression and schizophrenia are increasingly linked to inflammatory processes. Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker of chronic inflammation and has proven useful as a prognostic marker in various somatic diseases. This review examines the evidence for suPAR use in psychiatric populations and evaluates its potential role in clinical psychiatry. Method: A systematic search of Embase and PubMed was conducted using three concepts: biomarker, mental health–related terms, and psychotropics. Clinical and epidemiological studies investigating mental disorders with quantitatively measured suPAR were included. Screening was performed independently by two investigators. Results: Of 2781 identified studies, 32 met inclusion criteria. Elevated plasma suPAR levels were consistently observed in patients with psychosis and major depression, whereas findings for other psychiatric disorders were less conclusive. Evidence for predictive or prognostic applications remains sparse and inconclusive. Higher suPAR levels were associated with increased risk of subsequent antidepressant use and hospital admission for depression. Additionally, higher baseline suPAR levels were linked to a greater likelihood of antidepressant response and faster treatment effects. Discussion: It remains unclear whether elevated suPAR reflects immune activation intrinsic to psychiatric disorders or confounding factors such as lifestyle or psychotropic medication. Longitudinal data on suPAR and symptom development are lacking. Although suPAR is a potential biomarker within psychiatry, methodological inconsistencies persist, and its routine clinical use in psychiatry is premature.