World’s First Biomarker Test for Depression, Bipolar Disorder Is in the Works
The tool is the first of its kind; currently, clinicians rely on subjective self-reports of mood and other symptoms to diagnose depressive disorders.
Published in the Journal of Psychiatric Research, the study focused on using a specific brain protein, called brain-derived neurotrophic factor (BDNF), to predict mental health disorders. The protein is present in different forms: mature BDNF (mBDNF), the precursor of BDNF (proBDNF), and the prodomain of BDNF, all of which have different biological functions. While mBDNF is understood to promote the growth of neurons and to protect the brain, the other two BDNF forms bind to different receptors and cause nerve degeneration and inflammation.
Low levels of mBDNF are linked to depression, while higher levels of the other forms of BDNF seem to trigger depressive behaviors. However, lab tests couldn’t distinguish between the different forms of the protein in blood samples. Until now — the researchers have developed a blood testing kit that can measure the different levels of each BDNF form, and from them, diagnose depression and bipolar disorder, they say.
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“As mBDNF 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,” Professor Xin-Fu Zhou, from the University of South Australia, who was involved in the study, said in a statement. “The [existing kits] are not specific and can cross-react with each other. The kit we have developed has an accuracy rate of 80 to 83%.”
In the study of 215 blood samples from participants in China, researchers discovered that low levels of mBDNF correlated with both clinical depression and bipolar disorder. And in samples where the levels dropped lowest, more severe depression was found in the participants — suggesting that an individual’s mBDNF level was directly proportional to the severity of the depression they experienced.
Interestingly, the study noted high levels of mBDNF in participants with depressive disorders who were taking anti-depressants — the opposite result of those who weren’t on medication. This suggests that not only can the new biomarker test be useful to diagnose depressive disorders, but also gauge how well (and if at all) a patient is responding to prescribed antidepressants.