Diagnosing Bipolar Disorder from a Blood Sample

Blood test that diagnoses bipolar disorder raises serious ethical concerns

by GrrlScientist for ScienceBlogs | @GrrlScientist

Vacutainer tubes used for collection of blood. During venipuncture, pressure differences between the vein and the vacuum in the Vacutainer pulls blood into the tube. (Credit: Tom Mallinson / CC BY 3.0)

According to the United States Department of Health and Human Services, serious mental illnesses affect approximately 44 million Americans. Serious mental illnesses include mood disorders; depression and bipolar disorder. Unfortunately, correctly diagnosing mental illnesses, such as bipolar disorder, appears to be a sort of voodoo science that depends upon the skill of the mental health professional making the diagnosis and the patient’s willingness to accurately describe their symptoms. But a research paper was just published that describes a blood test that was designed to identify bipolar disorder and thus, this test could provide an objective method for diagnosis.

Bipolar I disorder, formerly known as “manic depression”, is a mood disorder characterized by sudden shifts in one’s emotional state from acute depression to mania and back again. It may also include episodes of psychosis. These mood changes can occur over a period of time ranging from minutes to hours or days and may persist from days to months for each episode, often independent of external circumstances. Many people with bipolar disorder will experience a “remission” of symptoms where they are socially and professionally functional for various periods of time, but some people are always in either a manic or depressed mood state, with few times when they are “in between” these two extreme moods.

“Patients aren’t sure how ill they really are, and neither is the clinician — sometimes dismissing their symptoms, sometimes overestimating them,” reports Dr. Alexander Niculescu, a psychiatrist at Indiana University School of Medicine in Indianapolis, who led the research team. “Having an objective test for disease state, disease severity, and especially to measure response to treatment, would be a big step forward.”

To do this work, the researchers identified a group of 29 individuals suffering from bipolar disorder and collected a blood sample from each of them. The mRNA (messenger RNA) present in the sample was isolated, copied into a more stable form, amplified and then screened to identify those mRNAs that showed extremely variable expression patterns that correlated with changes in each person’s mood shifts for all members of the study group.

Out of more than 40,000 genes that have been identified by the human genome project, the research team identified 21 novel high-threshold biomarker candidate genes, eight of which had been previously reported as showing some involvement in mood disorders by other research groups using multiple independent lines of study. These high-threshold candidate biomarkers demonstrate high degree of reliability because they were present in at least 75 percent of all study subjects at the time that they reported either a high or low mood state.

The team selected the ten best biomarkers (five for high mood and five for low mood) and used them as the basis for a screening test, which they named the BioM-10 Mood panel. The predictive value of the BioM-10 Mood panel was tested on the initial group of study subjects and found to have an 85 percent accuracy in predicting high mood and 77 percent accurate in predicting low mood. Then the BioM-10 Mood panel’s accuracy was tested against two other independent groups of people, 19 suffering from bipolar disorder and 30 suffering from a variety of psychotic disorders, such as schizophrenia. In this situation, the BioM-10 Mood panel’s diagnostic value was 71 percent accurate in identifying high mood and 68 percent accurate in identifying low mood.

According to Dr. Niculescu, even though this isn’t perfect, the BioM-10 Mood panel’s accuracy rate is within range of other medical tests, such as some cancer screening methods. But even though more work needs to be done, this test could be available on the market in as little as five years from now.

This screening test opens up other avenues of diagnosis and research as well.

“Panels of such biomarkers may serve as a basis for objective clinical laboratory tests, a long-standing Holy Grail for psychiatry,” write the research team in their paper. “Biomarker-based tests may help with early intervention and prevention efforts, as well as monitoring response to various treatments” and will play an important role in personalized medicine in psychiatry as well as in the development of new psychiatric medications.

Unfortunately, this test also presents the possibility for extreme abuse; employers, law enforcement, universities, insurance companies and landlords could use this test to discriminate against people with bipolar disorder.

Source:

Le-Niculescu, H., Kurian, S.M., Yehyawi, N., Dike, C., Patel, S.D., Edenberg, H.J., Tsuang, M.T., Salomon, D.R., Nurnberger, J.I., Niculescu, A.B. (2008). Identifying blood biomarkers for mood disorders using convergent functional genomics, Molecular Psychiatry | doi:10.1038/mp.2008.11

Originally published at scienceblogs.com on 28 February 2008.