Research into specific levels of a brain protein has led Australian scientists to develop the world’s first blood test to accurately predict mood disorders in people.
University of South Australia researchers have developed a kit that can precisely distinguish between three different brain-derived neurotrophic factor (BDNF) proteins.
While a link between mature BDNF (mBDNF) proteins and depression had been well documented, it had not yet been possible to differentiate the three forms of proteins in blood samples — until now.
Researchers say there is strong evidence to suggest psychological stress decreases mBDNF and that a lack of the protein causes depression.
A study was conducted with 215 people in China, including 90 patients with clinical depression and 15 with bipolar disorder.
Its findings revealed clear links between low levels of the protein in blood and severe depression.
The more severe a person’s depression, the lower their mBDNF level, the study found.
There were also lower levels in patients who were not on antidepressants, compared to those who were taking them.
UniSA Professor Xin-Fu Zhou said existing commercial kits were not specific, but the one developed by the university had an accuracy rate of 80-83 per cent.
“As mBDNF and (another of the three proteins) proBDNF have different biological activities, working in opposition to each other, it is essential that we distinguish between these two proteins and detect changes in their levels,” he said.
The researchers believe proportionate mBDNF levels could be used as a cut off point to diagnose depression and bipolar disorder.
“This could be an objective biomarker in addition to a clinical assessment by a doctor,” Prof Zhou said.
“Growing evidence indicates that inflammation in brain cells is linked with depressive behaviours and proBDNF seems to activate the immune system. Therefore, we must separate it from mature BDNF to get an accurate reading.
Prof Zhou said mood disorders affect millions of people worldwide, but about one third of people with depression and bipolar disorder are resistent to antidepressants.
“The reasons are not understood but it could have something to do with the imbalances between the different forms of BDNF, which we hope to investigate next,” he said.
The findings, which were in collaboration with University of Adelaide and Kunming Medical University in China, are published in the Journal of Psychiatric Research.