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Neurotrophins

What are neurotrophins in bipolar disorder?

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 bipolar disorder that is hypothesised to underpin signs and symptoms of the disorder.

What is the evidence for neurotrophins?

High quality evidence suggests a small increase in blood NGF levels in unmedicated people with bipolar disorder compared to controls.

Moderate quality evidence suggests a medium-sized increase in blood neurotrophin-3 and neurotrophin-4/5 levels in people with bipolar disorder (compared to controls) during a depressive state, but not during a manic or euthymia (normal mood) state.

Moderate quality evidence also suggests an overall small decrease in blood BDNF levels in people with bipolar disorder compared to controls. This effect is medium-sized when patients are in a manic state, and large in a depressive state, with no effect during euthymia. The effects increase with increased symptom severity and decrease with longer duration of illness.There was a small increase in blood BDNF levels with pharmacological treatment for mania but not for depression, and a medium-sized increase in blood BDNF levels after treatment with electroconvulsive therapy.

December 2021

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Last updated at: 6:41 pm, 9th December 2021
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