Quick, simple blood test takes the guesswork out of bipolar diagnosis

Researchers have developed a quick and simple blood test that, combined with existing diagnostic tools, improved the diagnosis of bipolar disorder, a condition commonly misdiagnosed as major depressive disorder. The test could ensure that people with bipolar disorder receive the correct treatment and identify potential drug targets.

Bipolar disorder (BD) is often misdiagnosed as major depressive disorder, as patients tend to seek medical help during depressive periods rather than manic episodes. It’s important that an accurate diagnosis is made, as each condition requires different pharmacological treatments.

To diagnose BD more accurately, researchers from the University of Cambridge developed a finger-prick blood test for biomarkers of the condition that could be used to complement existing diagnostic tools.

“People with bipolar disorder will experience periods of low mood and periods of very high mood or mania,” said Jakub Tomasik, lead author of the study. “But patients will often only see a doctor when they’re experiencing low mood, which is why bipolar disorder frequently gets misdiagnosed as major depressive disorder.”

Study participants’ samples and data were taken from the UK Delta study conducted between 2018 and 2020 to identify BD in patients who’d received a diagnosis of major depressive disorder within the previous five years and had current depressive symptoms. More than 3,000 participants were recruited, and each completed a comprehensive online mental health assessment of over 600 questions. The assessment included topics such as past or current depressive episodes, generalized anxiety, symptoms of mania, family history and substance abuse.

Of those who completed the online assessment, around 1,000 were selected to send in a dried blood sample from a simple finger prick, which the researchers analyzed for more than 600 metabolites. After completing the Composite International Diagnostic Interview, a validated diagnostic tool to establish a mood disorder diagnosis, 241 participants were included in the study.

From the more than 600 metabolites analyzed, the researchers identified 17 biomarkers for BD, with ceramide emerging as the strongest. Previous studies have linked ceramide to some psychiatric disorders, including BD. The identified biomarkers correlated primarily with lifetime manic symptoms and were validated in a separate group of patients who received a new clinical diagnosis of major depressive disorder or BP during the study’s one-year follow-up period.

The researchers found that, on its own, the blood test could diagnose up to 30% of patients with BD, but combining it with the online psychiatric assessment significantly improved the diagnosis rate, especially in people whose diagnosis was not obvious.

“The online assessment was more effective overall, but the biomarker test performs well and is much faster,” said Sabine Bahn, a co-author. “A combination of both approaches would be ideal, as they’re complementary.”

Although the blood test is still a proof of concept, the researchers say it could assist both patients and medical professionals.

“Psychiatric assessments are highly effective, but the ability to diagnose bipolar disorder with a simple blood test could ensure that patients get the right treatment the first time and alleviate some of the pressure on medical professionals,” Tomasik said. “We found that some patients preferred the biomarker test because it was an objective result that they could see. Mental illness has a biological basis, and it’s important for patients to know it’s not in their mind. It’s an illness that affects the body like any other.”

They say the biomarker blood test could have a range of applications.

“In addition to the diagnostic capabilities of biomarkers, they could also be used to identify potential drug targets for mood disorders, which could lead to better treatments,” Bahn said. “It’s an exciting time to be in this area of research.”

The study was published in the journal JAMA Psychiatry.

Source: University of Cambridge