What are neurotrophins? 

Neurotrophins, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), regulate neuronal survival and growth during development. Effects of neurotrophins on neuronal transmission in the hippocampus, cortex, cerebellum and basal forebrain are important for learning and memory processes. Reduced neurotrophins may affect synaptic efficiency and connectivity in schizophrenia that is hypothesised to underpin signs and symptoms of the disorder.

What is the evidence for neurotrophins?

Moderate to high quality evidence suggests reduced blood BDNF levels in people with schizophrenia compared to people without schizophrenia. This result remains regardless of symptom severity, medication dose, age, BMI, or study quality. First-episode or drug-free patients showed a larger reduction in BDNF levels than other patients. This may be explained by medication status, as blood BDNF levels increased after treatment with antipsychotics, although this effect was found only in plasma and not serum studies. There is also a small association between increased BDNF levels and increased performance on reasoning and problem solving, verbal memory, working memory, processing speed and verbal fluency tasks, and after non-pharmaceutical, non-exercise interventions.

Moderate to high quality evidence finds a medium-sized reduction in blood NGF levels in people with schizophrenia, regardless of medication status. More severe symptoms were related to greater NGF reductions.

October 2020

Last updated at: 4:41 am, 27th October 2020
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