Blood tests can help accurately identify people suffering from depression, according to the latest research published in the journal Molecular Psychiatry.
Researchers from Massachusetts General Hospital have shown that by analyzing the level of 9 compounds in blood samples, it is possible to accurately distinguish patients suffering from severe (so-called) depression from people without the disease.
Traditionally, the diagnosis of major depression and other mental disorders is made on the basis of the symptoms described by the patient, but the accuracy of this procedure varies widely and is often dependent on the experience and capabilities of the attending physician. Including an objective bioassay could improve the accuracy of diagnosis and track individual patients ‘response to treatment,’ comments co-author George Papakostas.
Earlier attempts to develop depression tests based on a single chemical compound in blood or urine have not resulted in sufficiently sensitive and specific methods. The sensitivity of the test means its ability to recognize all sick people as sick, and the specificity – to exclude the disease in healthy people.
The new test measures 9 compounds in the blood, the so-called markers. These are substances related to, inter alia, with inflammatory process (e.g. soluble receptor for tumor necrosis factor alpha – TNF-R2), development and survival of neurons (e.g. brain derived neuron growth factor – BDNF), and interactions between key brain structures involved in stress response and other processes (e.g. the stress hormone cortisol). On this basis, the sum of points from 1 to 100 is calculated, which reflects the probability of depression in the subject, with depression being a score of 50 or more.
The initial phase of the study involved 36 patients diagnosed with major depression and 43 patients without this disease (the so-called control group). The average test result for people diagnosed with depression was 85, while for people in the control group – 33.
It turned out that in 33 out of 36 patients diagnosed with depression, the test result confirmed the disease, while in the control group, 8 people had an erroneous result indicating depression.
Subsequently, the study was repeated among 34 people.
Based on the results obtained in the two studies combined, the researchers calculated that the test has approximately 90% sensitivity and 80% specificity.
According to Papakostas, these results indicate that inflammation – which plays an important role in the development of many serious health conditions – also contributes to depression. However, the expert emphasizes that in order to verify the actual usefulness of the new test in the diagnosis of depression, it is necessary to conduct more extensive research.
The researcher hopes that in the future the test will also help predict patients’ response to therapy and choose the best treatment method for them.
“It can be difficult to convince patients of the need for treatment based on the results of something like a survey currently used to classify symptoms of depression that patients report themselves about,” says co-author Dr. John Libello of Ridge Diagnostics, which sponsored the study. According to the expert, the biological aspect of the new test may allow patients to view their disease as a treatable disease, not just a source of self-doubt and stigma.