BDNF and schizophrenia: Chen da et al. (2009) also found significantly lower BDNF levels in first-episode patients with schizophrenia in comparison to healthy control subjects (9.0 ± 4.2 ng/ml vs. 12.1 ± 2.2 ng/ml), and observed a significant positive correlation between BDNF levels and PANSS positive subscore.