When you’re feeling unwell, a simple blood test can help find the cause of illness in many cases. Blood tests can help doctors diagnose many conditions, such as heart disease, anemia and diabetes.
But what if doctors could use a blood test to diagnose mental illnesses as well, such as depression?
Researchers at the Medical University of Vienna have found that a blood test could actually be used to help diagnose depression.
Although this research is still in the beginning stages, researchers found an association between depression and the length of time that it takes serotonin to enter blood platelets through use of the serotonin transporter (SERT), according to an article on the university’s website.
Serotonin is a neurotransmitter that is commonly linked to happiness, and low levels tend to indicate depression.
Researchers were able to determine the above association by using “pharmacological investigations” and functional magnetic resonance imaging (fMRI) of the brain.
Although this study only involves the potential diagnosis of depression through a blood test, it brings up the thought that other mental disorders could be diagnosed in a similar way.
Nicole Beurkens, a licensed psychologist as well as the founder and executive director of Horizons Developmental Resource Center, said in an email that there are too many different causes for depression and other mental disorders to be able to use a single blood test to diagnose each type of disorder.
“While research on definitive blood tests for disorders like depression is interesting, the reality is that there are far too many factors that play into symptoms of conditions like depression to ever have a definitive blood test to diagnose the disorder,” Beurkens said.
She added that there can be a variety of underlying environmental or biological causes of depression.
There is some possible concern that if a depression blood test did come out, insurance companies could base their mental health coverage on “passing” the blood test.
“People can suffer from depression symptoms for many different reasons,” Beurkens said. “It would be unethical to say that someone is not depressed because they don't show a positive result on one specific measure of neurotransmitter levels in the body.”
People could also be incorrectly treated for depression or misdiagnosed as a result of a single blood test, she said. And blood tests could move treatment away from a holistic approach to more medication-based treatment, which doesn’t work for all patients.
Beurkens doesn’t believe researchers understand the brain enough to ever be able to develop blood tests to diagnose different mental disorders. She added that there can be several neurochemicals involved in mental disorders, and it’s unclear still how chemical changes in the brain actually impact functioning.
Dr. Timothy Houchin, a forensic psychiatrist and the founder and president of 360 Mental Health Services, said in an email that serotonin is only one aspect of clinical depression or major depressive disorder.
A blood test can’t look into other factors causing depression, like stress caused by work. There can also be medical causes, such as vitamin D deficiency and thyroid disorders.
Houchin added that the term “depression” alone is more of a description, because there are different types of psychiatric diagnoses for depressive disorders that are very different from each other, including major depressive disorder and dysthymia.
There are also some people who report feeling depressed, but it is a normal, short-term reaction to some type of loss or bad news.
“Although this ‘depression’ blood test may one day prove to be a clinically useful tool, it should never be viewed as a substitute for a well-trained mental health professional,” Houchin said.
Dr. Mary Ann Block, author of “Just Because You’re Depressed, Doesn’t Mean You Have Depression,” said in an email that before a mental illness diagnosis is given, “all underlying medical causes should be ruled out,” but that is often not the case.
She said in many situations, the actual cause of depression happens to be hormonal imbalances, allergies, nutritional deficiencies or hypothyroidism.
“These medical problems can be determined with blood tests, so if using blood tests to determine the cause of someone's depression would give a more accurate diagnosis and treatment, it would be a real step forward,” Block said.
However, a neurotransmitter blood test would not necessarily be accurate, since she said the above conditions can also involve neurotransmitter changes but that does not mean the person being tested has a mental illness. They are depressed as a result of a medical problem.
Houchin, Timothy. Email interview. May 6, 2014.
Block, Mary Ann. Email interview. May 7, 2014.
Beurkens, Nicole. Email interview. May 7, 2014.
Medical University of Vienna. Depression is detectable in the blood. Web. May 7, 2014.
Scharinger, Christian and Rabl, Ulrich, et al. PLOS One. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity. Web. May 8, 2014.
Reviewed May 8, 2014
by Michele Blacksberg RN
Edited by Jody Smith