Levels of serum brain-derived neurotropic factor in individuals at ultra-high risk for psychosis - Findings from the Longitudinal Youth at Risk Study (LYRIKS).

Background: Identifying biomarkers to enrich prognostication and risk predictions in individuals at high risk of developing psychosis will enable stratified early intervention efforts. Brain-derived neurotrophic factor (BDNF) has been widely studied in schizophrenia and in first-episode psychosis with promising results. The aim of this study was to examine the levels of serum BDNF between healthy controls and individuals with ultra-high risk of psychosis (UHR).

Methods: A sample of 106 healthy controls and 105 UHR individuals from the Longitudinal Youth at Risk Study was included in this study. UHR status was determined using the Comprehensive Assessment of At-Risk Mental State (CAARMS) at recruitment. Calgary Depression Scale for Schizophrenia (CDSS) was used to assess the severity of depression. All participants were followed up over 2 years and UHR remitters were defined by UHR individuals who no longer fulfilled CAARMS criteria at the end of the study period. Levels of BDNF were measured in the serum by enzyme-linked immunosorbent assay method (ELISA).

Results: The UHR group had significantly higher baseline levels of serum BDNF compared with control group (3.7 vs. 3.3 ng/ml, p=0.018). However, baseline levels of serum BDNF did not predict the development of psychosis (OR=0.64, CI = 0.40 - 1.02) or remission (OR=0.83, CI = 0.60 - 1.15) from UHR status.

Conclusion: Findings from our study did not support a role for serum BDNF in predicting outcomes in UHR individuals. However, the finding of higher levels of serum BDNF in UHR individuals deserves further study.