Scientists create first test to accurately predict depression, bipolar disorder

ADELAIDE, Australia — When it comes to mood disorders and mental health, medical professionals are constantly forced to play catch-up. After all, it’s impossible to treat a condition like depression before symptoms appear, right? That may have been true not so long ago, but a new innovation out of Australia may change all that. Scientists at the University of South Australia have developed the first ever predicative test for mood disorders like depression and bipolar disorder.

How is this possible? It all comes down to the levels of a certain protein in the brain. Scientists say that low levels of mature brain-derived neurotrophic factor (mBDNF) have a connection to a greater risk of depression. Up until now, it had been impossible to differentiate between three distinct forms of the BDNF protein in blood samples.

The most mature version of the protein promotes neuron growth and protects the mind. The other two forms, however, tend to do more harm than good. These other two versions bind to different receptors, which incites inflammation and nerve degeneration.

The link between proteins and depression

Luckily, an assay kit created by the team at UniSA is capable of precisely identifying these three protein variations in ways that just weren’t possible before.

Researchers from Kunming Medical University in China collaborated on this project. One of the study’s co-authors, UniSA Professor Xin-Fu Zhou, says they’ve collected “strong evidence” indicating that stress leads to drops in overall mBDNF levels and lower mBDNF leads to depression.

Researchers studied a total of 215 Chinese residents during this project. That group included 90 people being treated clinically for depression and 15 with bipolar disorder. Among those sub-groups specifically, study authors noted a clear trend: low blood levels of mBDNF. Moreover, the more depressed a person reported feeling, the lower their mBDNF reading.

Similarly, mBDNF levels in patients not taking an antidepressant were also lower in comparison to those receiving an antidepressant.

However, researchers did not note any connection between gender differences and mBDNF levels. Also, low mBDNF levels don’t appear to correlate with suicidal behavior or thoughts.

“As mature BDNF and proBDNF have different biological activities, working in opposition to each other, it is essential that we can distinguish between these two proteins and detect changes in their levels,” Prof. Zhou says in a university release. “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.”

A new treatment for mental health disorders?

According to the findings, serum mBDNF levels lower than 12.4 ng/ml may justify a preemptive depression or bipolar disorder diagnosis.

“This could be an objective biomarker in addition to a clinical assessment by a doctor,” Zhou explains. “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.”

“Interestingly, our recent studies in animals showed that proBDNF injected in both the brain and muscle can directly trigger depressive behaviors,” he adds.

Moving forward, researchers want to investigate if electric convulsion therapy can help restore proper mBDNF levels.

Mood disorders affect millions of people worldwide. However, about one third of people with depression and bipolar disorder are resistant to antidepressants or alternative therapies. 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,” Prof. Zhou concludes.

The study is published in the Journal of Psychiatric Research.

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