Nerve Growth Factor in Psychiatric Disorders: A Scoping Review.

Background: Neurotrophins have been implicated in multiple psychiatric disorders. Nerve Growth Factor (NGF) is one of the major neurotrophins that has attracted much research interest. Therefore, we undertook, to the best of our knowledge, the first scoping review encompassing all major psychiatric disorders and their relation to NGF. This review aimed to identify the current position of NGF in psychiatric research and to outline present gaps in knowledge, which can be answered with a more detailed systematic review in the future. Methods: Suitable studies were identified using PubMed. A total of 20 studies were included in the review: two on bipolar affective disorder (BPAD), three on schizophrenia, seven on depression, and eight on alcohol use disorder. Results: NGF levels are definitively reduced in BPAD and depression, while NGF levels in schizophrenia decreased further after treatment than in the drug-naïve state. The effect of treatment on NGF levels in depression varied based on treatment modalities and severity of depression. In patients with depression, raised NGF was a predictor of conversion to bipolar disorder (BD). NGF levels were raised in acute alcohol intoxication and withdrawal but normalized slowly as abstinence was maintained. NGF may play a protective role in preventing the toxic ill effect of acute alcohol intoxication on the central nervous system. Conclusion: Based on current knowledge, NGF levels may be a useful biomarker of a chronic mental stress condition. However, further research is needed before it can be used to identify a specific psychiatric illness or predict treatment response.