Neutrophil/lymphocyte ratio: Can a non-specific marker of inflammation helps to confirm the inflammatory hypothesis of the serious mental diseases? A case-control study

Abstract Background The hypotheses of autoimmune, allergic or infectious etiology of severe mental illness have been reported in the scientific literature repeatedly. The main objective of this work is to study the relationship of inflammatory, autoimmunity or recent infection markers with the fact of suffering Severe Mental Disorders (SMD). Methods In the present case-control study, adult patients with a diagnosis of SMD were compared with controls who underwent routine health checks that included analytical control. Cases with psychosis substance-induced and controls with diagnosis of any psychiatric illness were excluded. In both groups, patients with chronic inflammatory diseases or intercurrent infectious disease were also excluded. A set of common analytical parameters, markers of infectious diseases and inflammatory markers were retrieved for both groups, as well as demographic and clinical data. Results A total of 212 subjects (81 cases and 131 controls) were recruited. From cases, 70 (86.4%) have a diagnosis of Schizophrenia Disease (SD) and 11 (13.6%) of Schizoaffective Disorder (SAD). In the multivariate model the female sex (OR 0.24, 95% CI 0.12–0.46) and the neutrophil-lymphocyte ratio (OR 3.00, 95% CI 1.91–4.70) were associated with the fact of being case. Conclusions Patients with SMD seem to have higher inflammatory markers compared to the general population, being the neutrophil-lymphocyte ratio, the marker associated with more strength. The role of inflammatory processes in the etiology of this type of disorders, if confirmed, opens interesting and innovative therapeutic possibilities.