Nerve growth factor and brain-derived neurotrophic factor concentrations in schizophrenia: a review

There is growing interest in the role of neurotrophins in the pathophysiology of schizophrenia. Neurotrophins are a large family of dimeric polypeptides that promote the growth and the differentiation of developing neurons in the central and peripheral nervous systems as well as the survival of neuronal cells in response to stress. Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) concentrations are here reviewed in relation to medication-naive early psychotic patients and in medicated chronic schizophrenic patients. Most data point to decreased plasma and serum NGF and BDNF concentrations in naive drug and in medicated schizophrenic patients compared to healthy controls. Higher BDNF levels were observed in patients with the paranoid subtype of schizophrenia. Low serum BDNF levels were associated with reduction in hippocampal volume (HV) at the onset of schizophrenia. Evidence on the correlation between BDNF levels and positive and negative schizophrenic symptoms were ambiguous. There are contrasting results on a possible correlation between increase in BDNF concentrations and treatment with antipsychotics. Antipsychotic treatment can elevate NGF values, specifically atypical. Growth factors might be good candidates as prognostically and diagnostically useful markers in schizophrenia.