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Blood Tests for Schizophrenia and Depression: Not Ready for Prime Time

Blood Tests for Schizophrenia and Depression: Not Ready for Prime Time

Some psychiatric researchers and clinicians warned recently that blood-based biomarker tests to aid in the diagnosis of schizophrenia and depression are “not ready for prime time” and their early commercialization could “exploit the suffering of patients.”

When asked to comment on the article on biomarker tests for schizophrenia in the August issue of Psychiatric Times,1 Gregory Light, PhD, Associate Professor of Psychiatry at UCSD, and Associate Director of the UCSD Schizophrenia Research Program, noted that “laboratory tests for psychiatric illnesses have come and gone over the decades. Researchers have tried lots of different kinds of tests from EEGs to blood-based biomarkers. Now genetic tests are a very popular means of trying to understand different psychiatric disorders.”

Potential biological markers for mental illness have been of considerable interest through the history of psychiatry—monoamine metabolites in cerebrospinal fluid, the dexamethasone suppression test, and genotyping of receptors—according to Steven Balt, MD, a clinical psychiatrist working with the UCLA/Kern Medical Center. “While enticing, this interest has not translated into significant clinical utility.” Balt describes biomarkers as “a way to make psychiatry more like other branches of medicine.”

“If we are using biomarkers to di-agnose a disease or to predict disease risk, what we are really doing is substituting a biochemical test for what should be a thorough clinical examination,” he said. “At present, there is nothing a biomarker will tell us that a seasoned, experienced clinician wouldn’t be able to determine in a full psychiatric evaluation.”

According to Emily Deans, MD, Clinical Instructor in Psychiatry at Brigham and Women’s Hospital in Boston, biologic markers have always been the holy grail of psychiatry, but there is a basic nosology issue.

“Since the diagnoses are based on a recipe list of symptoms from DSM-IV and not known brain pathology, new biologic markers and tests are re-searched and validated against the formal diagnostic criteria. These criteria are designed to be assessed by mere observation and questioning of the patient. Thus, biomarkers only end up as valid as the original criteria, or less so, depending on the validation of the scale used in research,” she said.

When used to discover pathology and to improve understanding of the biologic process of mental illness, “biomarkers are fascinating,” Deans acknowledged. “But for an experienced clinician, except for cases of feigned disease for secondary gain, or perhaps for a patient who needs to be convinced he or she needs treatment, biomarkers based on DSM-IV will never be as useful as ground up research to link known brain, gene, and MRI findings to the patient’s symptoms.”

Light, who is involved in bio-marker research, said he strongly favors prioritizing the development of biomarkers for understanding and treating our sickest patients. But he believes that this work is far from ready for mass commercial appeal. “Currently, these kinds of tests can’t help us differentiate between the causes and the effects of mental disorders,” he said.

Of particular concern to Light is what he describes as the “commercialization of science.” Patients and their loved ones are suffering after initially receiving the diagnosis, he said, and they are desperate for additional information. “To sell a blood test that has not been validated for use in a clinic and that does not guide treatment decisions may be just exploiting the suffering of these patients for profit,” he added.

He is also troubled by the commercialization of tests before studies have been published and before training in their interpretation and proper use is given to care providers.

“What are you supposed to tell patients and their families? What do you tell someone who has a basic unawareness of their illness about the results of their blood test?” He added that clinicians need to know when to use the tests and what kinds of treatments to provide based on the test results.

“At this point, patients and their physicians are already squeezed for time,” he said. “Who has the time to engage in a speculative discussion about unvalidated blood test results with their schizophrenia patients? Would these tests result in even less available time to discuss and clarify symptoms?”

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