Inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P): State or trait?

Background: Studies linking neuro-inflammation to psychotic episodes has been rapidly expanding. Assessments of changes in inflammatory biomarkers in prodromal patients who subsequently convert to psychosis may help in predicting those likely to transition to psychosis. Methods: We reviewed the literature for original studies that measured inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P), and compared pro-inflammatory biomarker data between converters and non-converters to psychosis as well as in healthy controls. Results: Our search yielded 15 studies. Our findings suggest a possible role of plasma levels of Interleukins-1 beta, 7, 8, matrix metalloproteinase (MMP)-8, cortisol, albumin and salivary cortisol, measured at baseline, as predictors of psychotic transition. Both baseline C-reactive protein (CRP) and Interleukin-6 levels were not shown to discriminate between converters and non-converters to psychosis. The dearth of longitudinal biomarker measures, before and after treating the psychotic episodes, was a limitation for assessing inflammatory biomarkers as trait vs state marker properties of biomarkers. Discussion: Gaps of data in published studies prevent confirming whether inflammatory biomarkers are state or trait indicators of transition to psychosis in the CHR-P populations. Future investigations should be designed to longitudinally measure inflammatory biomarkers in order to navigate the extensive heterogeneity of the schizophrenia syndrome and its prodrome. (c) 2018 Elsevier B.V. All rights reserved.