Can a Blood Test Diagnose Depression and Bipolar Disorder?

SYNLAB and ALCEDIAG recently launched the first blood test to assist in mental health diagnosis in France. The test is aimed at differentiating bipolar disorders from depression. The news may be surprising, given the challenges in diagnosing psychiatric conditions, especially when they share common symptoms such as recurrent depression and bipolar disorder.

Psychiatrists’ reactions to the new test are cautious. Many have echoed the sentiments of the French Association of Biological Psychiatry and Neuropsychopharmacology (AFPBN) and Stéphane Jamain, PhD, director of translational neuropsychiatry research (Inserm U955, Mondor Institute of Biomedical Research), who spoke with the Medscape French edition.

Early Diagnosis

Depression and bipolar disorders are two distinct psychiatric illnesses requiring different treatments. Early and accurate diagnosis and appropriate treatment are major challenges for clinicians, especially since untreated or inadequately treated bipolar disorder can lead to significant mental and physical health consequences for patients and their families.

Published studies indicate that it takes an average of 8-10 years, and sometimes even longer, to diagnose bipolar disorder. The diagnosis is based on a psychiatric clinical examination, which is conducted by a specialist using validated questionnaires and evaluation scales.

Early and accurate diagnosis of bipolar disorders that allows for appropriate treatment would be a significant advance for patients and their families. This is what the French laboratories SYNLAB, in partnership with ALCEDIAG, propose through myEDIT-B, a blood test described as “the first validated diagnostic aid test to differentiate depression and bipolar disorders.”

Whether this test, the availability of which has somewhat surprised the psychiatric medical and scientific community, will attract psychiatrists remains to be seen.

The French Association of Biological Psychiatry and Neuropharmacology stated in a press release that “to date, no test meets conditions for clinical use.” For a diagnostic test to be scientifically valid, ethical, and usable in clinical practice, its development must meet strict criteria, as highlighted by the AFPBN. The approximately 10 criteria include the validation of the scientific results in at least two independent clinical studies or cohorts, satisfactory sensitivity (detection of true positives) and specificity (detection of false negatives), and cost that is ethically responsible and allows patient access, independent of commercial interests.

ALCEDIAG has reported two clinical studies, but only one has been published so far (in Translational Psychiatry) involving 400 patients. In this case, “these patients already had a well-established psychiatric condition, did not quite present the same symptoms between patients with recurrent depression and those with bipolar disorder and were not taking the same treatments,” noted Jamain.

Differentiating between bipolar disorder and depression is crucial, especially regarding treatments, because antidepressants given to a patient with bipolar disorder can induce a manic shift if they are not accompanied by mood stabilizers, Jamain acknowledged. Nevertheless, he believes that based on what the laboratory has published, it is difficult to comment on the test at this time.

RNA Editing 

Moreover, myEDIT-B is based on a technique that measures RNA editing modifications of specific markers in patients’ blood, which could lead to differences in amino acids within proteins. The technique is unique to the ALCEDIAG laboratory, which coupled it with an artificial intelligence tool that specifically selected 8 RNA sequences for analysis from thousands of edited sequences to obtain a differential signature for unipolar and bipolar depressions. “This method is niche, the trademark of ALCEDIAG,” said Jamain, who questions the significance of this “editing” on the periphery of the CNS.

“This technique differs from that adopted by most international consortia, which are very active in this research field. The latter technique compares differences in genome [DNA] nucleotides between individuals in large cohorts involving tens of thousands of people and identifies the most frequently occurring patterns associated with a pathology to deduce a risk of developing a psychiatric illness,” said Jamain. “However, the information provided by these large-scale studies does not allow us to define who is at risk for developing the disease any more than the simple observation of the familial recurrence [heritability] of it does.” 

Scientific Validation 

While ALCEDIAG boasts a sensitivity and specificity of more than 80% for its test, the psychiatric world remains cautious. Interviewed by FranceInfoTV, Marion Leboyer, PhD, general director of the FondaMental Foundation, psychiatrist, and researcher (at AP-HP, Inserm in Créteil, France), highlighted the importance of encouraging research on psychiatric illnesses, especially that which will contribute to the understanding and treatment of patients with bipolar disorders. But she expressed caution regarding the test because of the absence of rigorous scientific validation through clinical trials.

Regarding “ALCEDIAG’s test and its commercial aspect, caution is warranted,” said Jamain. Only time will tell if psychiatrists will prescribe this €899 test, which currently is not reimbursed by social security (see box below). ALCEDIAG plans to submit a validation dossier to the US Food and Drug Administration.

Test Not Reimbursed by Social Security

The ALCEDIAG test will be available beginning in April 2024, by prescription, in SYNLAB France network laboratories. It is intended for patients aged 18 years and older who are being treated for a moderate or severe depressive episode. Test results are transmitted within 4 weeks to the prescribing psychiatrist, who will confirm the diagnosis to the patient during a consultation. Already available in Italy, this in vitro medical device has a CE-IVD marking. In France, however, it costs €899 and is not reimbursed by social security because of insufficient clinical evidence.

This story was translated from the Medscape French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. 

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