Coming soon: blood test for depression?

The quest for biomarkers for certain disorders and diseased has kept biomedical scientists busy in recent years. Their efforts have borne fruit in the discovery of biomarkers in the blood that help in the screening and diagnosis of medical conditions such as cardiovascular diseases and cancer. However, when it comes to neurological and psychiatric disorders, the search of biomarkers has been very slow. Recent research results however, seem to show promise.

In general, the search for diagnostic markers can be approached in many different ways. The field of genomics is focusing on identifying variations in the genes (DNA) which can be detected in blood cells. In the field of proteomics, the measurement of the levels of specific proteins in the blood is being explored. Another field of research is the so-called gene expression profiling, “which measures the levels of RNA produced from DNA as an indication of the level of the “activity” of particular genes.”

With the third approach (gene expression profiling), Dutch researchers report promising results in screening patients for major depressive disorder, or MDD. The researchers were able to identify a set of 7 genes whose expression in the blood differs between patients with MDD and those without MDD.

According to study author Dr. Sabine Spijker:

“This is a first, but major step in providing a molecular diagnostic tool for depression. Although psychiatry already has specific criteria for diagnosing mental health disorders, this type of diagnosis would be unbiased and particularly valuable for those with whom it is more difficult to have a conversation. It may also eventually assist in reducing the stigma associated with mental health problems.”

Indeed, current methods of diagnosis of depression are still mainly based on patient-reported symptoms and evaluation by a mental health professional. The use of diagnostic markers, especially those detectable in the blood  

However, further research needs to be done to validate the sensitivity and specificity of the described blood test.

According to Dr. John Krystal, Editor of Biological Psychiatry.

“It is far too early to be confident that gene expression profiling will lead us to diagnostic or prognostic tests for depression. However, the objective of this line of research is extremely important. In the past, many types of tests have been explored as potential diagnostic markers, but they all have failed to have sufficient sensitivity and specificity to guide doctors in making psychiatric diagnoses or choosing between treatments. I look forward to seeing whether the patterns of gene expression profiling are replicable and diagnostically specific as multiple groups report their findings.”