Researchers have developed a quick and simple blood test that combines with existing diagnostic tools to improve the diagnosis of bipolar disorder, which is often misdiagnosed as major depressive disorder. Such testing could ensure that people with bipolar disorder receive the right treatment and identify potential drug targets.
Bipolar disorder (BD) is often misdiagnosed as major depressive disorder because patients tend to seek medical help during depressive phases rather than manic episodes. Accurate diagnosis is important because each disease requires different medications.
In an effort to more accurately diagnose mania, researchers at the University of Cambridge have developed a finger-prick blood test to detect biomarkers of mania, to complement existing diagnostic tools.
"People with bipolar disorder experience periods of low mood and periods of high mood, or mania," said Jakub Tomasik, the study's lead author. "But patients often only see a doctor when they are feeling low, which is why bipolar disorder is often misdiagnosed as major depressive disorder."
The study participant sample and data were drawn from the UK Delta Study conducted between 2018 and 2020 to identify BD in patients who had received a major depressive disorder diagnosis within the past five years and had current depressive symptoms. The study recruited more than 3,000 participants, each of whom completed a comprehensive online mental health assessment containing more than 600 questions. Assessments include past or current depressive episodes, general anxiety, symptoms of mania, family medical history, and substance abuse.
Of those who completed the online assessment, about 1,000 were selected to send in a simple finger prick of dried blood, which the researchers analyzed for more than 600 metabolites. 241 participants were included in the study after completing the Comprehensive International Diagnostic Interview, a validated diagnostic tool used to confirm a diagnosis of mood disorders.
From more than 600 metabolites analyzed, the researchers identified 17 BD biomarkers, of which ceramide had the strongest effect. Previous research has linked ceramides to some psychiatric disorders, including BD. The identified biomarkers were primarily associated with lifetime manic symptoms and were validated in a separate group of patients with a new clinical diagnosis of major depressive disorder or BP during the study's one-year follow-up period.
The researchers found that the blood test by itself could diagnose up to 30 percent of patients with major depression, but combining it with an online psychiatric assessment significantly improved the diagnosis rate, especially for patients whose diagnosis was not obvious.
"Overall, online assessment was more efficient, but biomarker testing worked well and was faster," said co-author Sabine Bahn. "It would be ideal to combine the two methods because they are complementary."
The researchers say that although the blood test is just a proof of concept, it could help patients and medical professionals.
"Psychiatric assessments are very effective, but diagnosing bipolar disorder with a simple blood test can ensure patients get the right treatment the first time and take some of the pressure off medical professionals," Tomasik said. "We've found that some patients prefer biomarker testing because it's an objective result they can see. Mental illness has a biological basis, and it's important for patients to know it's not in their minds. It's a disease that affects the body, like any other."
Biomarker blood tests can have a range of applications. "In addition to the diagnostic capabilities of biomarkers, they can also be used to identify potential drug targets for mood disorders, leading to better treatments. It's an exciting time to be working in this area," Bahn said.
The study was published in JAMA Psychiatry.