RESEARCH WEEKLY: Biomarkers for SMI Require Caution By Elizabeth Sinclair Hancq (August 24, 2022) Earlier this summer, there was fanfare in scientific media outlets regarding newly published research about the potential for biomarkers to help diagnose bipolar disorder. This was in part due to the title of the research article that was published in Translational Psychiatry, “A game changer for bipolar disorder diagnosis using RNA editing-based biomarkers.” However, caution is needed when evaluating results of studies like these on biomarkers for psychiatric conditions, as they are still years away from being a part of routine clinical practice. First, this blog will explain why having a biomarker for bipolar disorder diagnosis could be so impactful. Second, it will summarize the new research article on the topic and lastly will discuss why the title and resulting fanfare may be misleading. Bipolar disorder diagnosis Bipolar disorder is characterized by both depressive and manic episodes, can be very disabling for individuals who experience it and often requires medications to address symptoms. However, especially when the onset episode of the illness presents as depression, individuals can often be misdiagnosed as having unipolar depression. In fact, the average time from illness onset to diagnosis for individuals with bipolar disorder is seven years. Therefore, biomarkers to distinguish bipolar disorder from unipolar depression would be very useful clinical tools and could tremendously improve outcomes by diagnosing and treating individuals earlier. We wrote in a January 2021 Research Weekly blog: “Biomarkers are powerful clinical and public health tools. They can be diagnostic, inform treatment decisions, or help determine disease risks if prevention measures are needed.” Examples of biomarkers include blood pressure as a measure of cardiovascular health and levels of Cancer Antigen 125 in blood to understand risk and treatment monitoring for ovarian cancer. Biomarkers in clinical practice would be a game changer for the diagnosis of bipolar disorder. However, we are still years away from that occurring. New research on biomarkers for bipolar disorder diagnosis The research study on the development of biomarkers for bipolar disorder was published this past May in Translational Psychiatry from a group of international researchers from France, Switzerland and the United States. The researchers recruited patients with depression to participate, who were given a variety of different symptom scales to assess their condition. Clinicians then assessed whether patients had bipolar disorder and collected blood samples for the biomarker analysis. The researchers analyzed the RNA, or unique genetic material, of participants’ blood samples through bioinformatics, which is the process of determining the genetic sequences of the individual blood samples and putting the information into a computer to examine similarities and trends. Based on previous research, they had narrowed down the search to examine sites where the RNA had a specific type of edit that impacted the gene it was coding for. The researchers examined how these editing sites differed between individuals with depression, bipolar disorder or healthy controls. Researchers originally identified 646 sites where there were significant differences between individuals with bipolar disorder and unipolar depression, but later narrowed these down to just seven based on stricter criteria, such as those that were present in at least 25% of individuals. Ultimately, after using a machine learning approach, the researchers were able to establish eight sites that could distinguish depression from controls and six that distinguished unipolar from bipolar disorder. Why caution is needed in the interpretation of these results On its surface, this study allows for cautious optimism. Researchers have developed possible biomarkers for determining a differential diagnosis between unipolar depression and bipolar disorder. However, there are many limitations of these results. First, the study needs to be replicated by a separate research group. Second, the biomarkers need to be tested on a mixed population of people with and without psychiatric conditions to see if they are still able to distinguish different diagnoses. The biomarkers found were included if they were present in at least 25% of individuals. Therefore, many individuals with depression or bipolar disorder did not have the presence of any of these biomarkers. Last, it is unclear how feasible it is for this type of bioinformatics and machine learning testing to be implemented in clinical settings among real patients. So, while biomarkers for bipolar disorder would be a game changer in psychiatric clinical practice, caution is needed in the interpretation of research results until they are proven to be true and clinically useful. References Salvetat, N., et al. (2022). A game changer for bipolar disorder diagnosis using RNA editing-based biomarkers. Translational Psychiatry. Elizabeth Sinclair Hancq is the director of research for the Treatment Advocacy Center. View as Webpage To receive Research Weekly directly in your email inbox on a weekly basis, click here. Questions? Contact us at [email protected] Research Weekly is a summary published as a public service of the Treatment Advocacy Center and does not necessarily reflect the findings or positions of the organization or its staff. 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