- In the past, research has linked low levels of the protein brain-derived neurotrophic factor (BDNF) with severe depression.
- Now, researchers have developed a test that can accurately predict depression by measuring levels of the protein.
- Unlike other kits, this one could distinguish between the precursors of the protein; all of which have a different function in the brain.
Depression is one of the world’s leading cause of disability. According to the World Health Organization (WHO), an estimated 300 million people across the world suffer from depression. Diagnosis is based on the presence of symptoms for at least two weeks. Although the exact mechanism behind these symptoms is unclear, studies have suggested an imbalance of a brain protein as a possible cause. Now, researchers at the University of South Australia (UniSA) have developed the world’s first test for depression that measures the level of the specific brain protein.
The protein measured by the test is the brain-derived neurotrophic factor (BDNF). Previous studies have shown low levels of BDNF in people with mood disorders. However, there is little information about other forms of the protein. The mature BDNF (mBDNF) plays a role in supporting the growth of existing neurons in the brain. Thus, having a protective effect on the brain. However, proBDNF has an opposing effect; promoting cell death and inflammation. For the first time, researchers have developed a kit that can differentiate between these proteins in blood samples.
Growing evidence indicates that inflammation in brain cells is linked with depressive behaviors and proBDNF seems to activate the immune system. Therefore, we must separate it from mature BDNF to get an accurate reading.
Professor Xin-Fu Zhou, study author
New Test for Depression Has 83% Accuracy
Scientists at UniSA developed the new assay kit in collaboration with researchers from the University of Adelaide and Kunming Medical University in China. They aimed to investigate the change in levels of the two brain proteins in mood disorders. They published their findings in the Journal of Psychiatric Research.
Researchers tested the kit on 215 people in China. 90 patients had clinical depression, 15 had bipolar disorder, and 14 had a history of suicidal attempts. Around 96 patients were part of a control group and were not diagnosed with clinical depression.
Results showed a clear association between low levels of mBDNF and severe depression. Furthermore, those on antidepressants had higher levels of protein than those who did not. However, no difference was seen in the levels between the control group and the 14 patients with a history of suicide attempts.
The existing commercial BDNF ELISA (enzyme-linked immunosorbent assay) kits are not specific and can cross-react with each other. The kit we have developed has an accuracy rate of 80-83 percent.
Professor Xin-Fu Zhou, study author
According to Professor Zhou, stress likely decreases levels of mBDNF which in turn causes depression. Researchers suggest that a mBDNF level of 12.4ng/ml can likely be used as cut-off point for diagnosing bipolar disorders and depression.
Reference:
Lin L, Fu X, Zhou X, Liu D, Bobrovskaya L, Zhou L. Analysis of blood mature BDNF and proBDNF in mood disorders with specific ELISA assays. J Psychiatr Res. 2021;133:166-173. doi:10.1016/j.jpsychires.2020.12.021
