When visiting the doctor for an annual physical, it is routine procedure for a patient to have blood work done to check for many common illnesses, such as diabetes and heart disease. Sometimes additional blood tests will be ordered to facilitate an accurate diagnosis. Although helpful for many physical ailments, blood tests are not yet available for mental illnesses, and for a long time were thought impossible. Typically, diagnoses for mental health disorders are based upon patients’ discussion of certain subjective symptoms, such as mood and feelings, rather than biomarkers, which provide a more objective way to diagnose a condition. Research is underway searching for biomarkers of mental health conditions to make them easier to diagnose, or to screen for prevention. One recent study has found that it may be possible to create a blood test to diagnose depression.
What is Depression?
An estimated 14.8 million adult Americans (6.7 percent) meet the diagnostic criteria for major depressive disorder each year. Depression can occur in anyone of any age, background, gender, socioeconomic class, or race, although it is most common in women and the median age of onset is 32.5. Depression is a complex medical condition that can disrupt a person’s relationships, professional life, and daily life. In fact, it is the leading cause of disability among Americans aged 15 to 44.
The main symptom of depression is persistent feelings of sadness and hopelessness that last for at least two weeks, although people might also feel fatigued, have a lack of energy, experience changes in weight or appetite, or no longer enjoy favorite activities. People suffering from depression often have feelings of worthlessness, ennui, and lack motivation. It is common for someone with depression to isolate him or herself and be absent from school or work. Although potentially debilitating, depression is treatable, typically by a combination of psychotherapy and antidepressant medication.
The Role of Serotonin in Depression
Researchers from MediUni Vienna recently published a study that provides the foundation for creating a blood test for mental illness. Although further research is needed to get approval to market the test, the research provides a promising first step on the road to such a diagnostic tool by demonstrating the possibility of testing serotonin levels in the blood to screen for depression.
Serotonin is a neurotransmitter that plays an important role in both the cause of and treatment for depression. Scientists are still unclear about the exact mechanisms behind depression, including serotonin’s role. They do know that serotonin is a neurotransmitter involved in most neurological processes, including mood. Most antidepressants, such as SSRIs (selective serotonin reuptake inhibitors), work by increasing the levels of serotonin in the brain, reducing or eliminating symptoms of depression. The serotonin transporter (SERT), a protein in the cell membrane, facilitates the transportation of serotonin into a cell.
Serotonin in the Body
Brain cells are not the only cells with a serotonin transporter. Other body systems, including the blood, also rely on serotonin for functioning. In fact, about 90 percent of the body’s serotonin is in the GI tract and the blood. Recent studies have shown a correlation between the function of the serotonin transporter in the blood and that in the brain. The SERT in the blood makes sure that the blood platelets maintain an appropriate concentration of serotonin in blood plasma, similar to what they do for brain cells.
Researching the Connection of Serotonin in the Blood and the Brain
In this recent study, the researchers used functional magnetic resonance imaging (fMRI) of the brain, along with pharmacological investigations, to demonstrate the correlation between the speed of serotonin uptake in the blood platelets and the function of a particular depression network in the brain. This network has been termed the “default mode network” because it is primarily active during rest and processes feelings of contentment with strong self-reference. Previous studies have found that it is actively suppressed during complex thought processes, which allows for greater concentration. Studies have also found a correlation between depressed patients and difficulty suppressing the network during thought processes, which can lead to negative thoughts and difficulty concentrating.
Participants in the study were right-handed, healthy individuals of European ancestry between the ages of 18 and 45, in order to limit some variables in the testing. They also underwent thorough assessments to ensure they were healthy individuals. Participants took the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I) to ensure the absence of any past or present psychiatric diagnosis. Additionally, they had to score below eight on the 21-item version of the Hamilton Depression Scale (HAM-D). They also underwent a routine physical exam including blood tests, urine drug screening, a physical and neurological exam, and an electrocardiogram to ascertain their medical status.
Creating a Blood Test for Depression
This study provides the first demonstration of the ability to predict activity of a major depression network in the brain by looking at a blood test. The findings of the study show that in healthy individuals, there is a correlation between the SERT levels in the blood to those in the brain. This shows that it is possible to use a blood test to diagnose depression, and possibly other mental health disorders, by looking at the levels of serotonin in the blood. The findings of this study could lead to the development of a simple blood test to diagnose depression, which will help millions of people by streamlining the process and facilitating an accurate diagnosis, so that they can start the necessary treatment.
Depression Treatment at Sovereign Health Group
Sovereign Health Group provides comprehensive, evidence-based residential treatment for depression, as well as other mental health disorders and substance abuse. Each patient undergoes a comprehensive assessment to recognize all underlying and co-occurring conditions, which informs his or her customized, holistic treatment plan. You can call our admissions team at 866-264-9778 to learn more about our treatment programs for mental health, addiction, and dual diagnosis.