Neurotrophins have been proposed to be involved in biological mechanisms which might underlie different clinical outcomes in schizophrenia. The aims of the present study were to examine the BDNF/NGF plasma levels in a cohort of first-episode schizophrenia (FES) patients in remission as potential biological predictors of relapse; to study the associations between these neurotrophins and the symptomatology severity through different stages after a FES in two independent cohorts. 2EPs-Cohort: 69 first-episode in clinical remission were included. BDNF/NGF plasma levels and symptom severity were measured at enrollment and at 3-year or at the time of the second episode/relapse. FLAMM-PEPs-Cohort: 65 first-episodes were also included. BDNF/NGF and symptom severity were obtained at enrollment and 2-year follow-up. Symptomatology was assessed with the Marder-PANSS-Factor scores. Plasma neurotrophins did not differ significantly over time and neither BDNF/NGF were predictors of relapse. Besides, in remission stages, baseline BDNF levels showed significant correlations with both positive and negative symptoms (p<0.05); NGF, with negative symptomatology (p<0.01). Similarly, in the FLAMM-PEPs-Cohort, baseline BDNF/NGF levels showed significant correlations with negative symptoms (and not positive symptomatology) at follow-up (p<0.05). In both cohorts, lower levels correlated with higher symptom severity. Findings did not support a role for BDNF/NGF plasma levels as biomarkers of relapse in FES patients. Nevertheless, baseline BDNF/NGF may lead to be considered potentially useful biomarkers of long-term severity in schizophrenia and of the underlying illness traits, specially of negative symptomatology severity. More longitudinal studies in FES samples and adding a control group are warranted to replicate these findings.
Keywords: Brain-derived neurotrophic factor (BDNF); First-episode schizophrenia; Nerve growth factor (NGF); Peripheral biomarker; Prevention; Relapse.
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