• Posted October 25, 2023

Blood Test Could Speed Diagnosis of Bipolar Disorder

Researchers say they have developed a simple blood test that can spot biomarkers associated with bipolar disorder, potentially easing diagnosis.

For the study, British researchers used both an online psychiatric assessment and a blood test to diagnose the condition. Many patients had previously been misdiagnosed with major depressive disorder.

“People with bipolar disorder will experience periods of low mood and periods of very high mood or mania,” said first author Jakub Tomasik, a senior research associate at the University of Cambridge.

“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," he said in a university news release.

On its own, the blood test could diagnose up to 30% of patients, researchers said. It was even more effective when combined with a digital mental health assessment.

While still a “proof of concept” study, the blood test could eventually complement existing diagnostic tools, the authors said. It could also help researchers understand the biological origins of mental health conditions.

“When someone with bipolar disorder is experiencing a period of low mood, to a physician, it can look very similar to someone with major depressive disorder,” said study leader Dr. Sabine Bahn, a professor of neurotechnology at the University of Cambridge.

“However, the two conditions need to be treated differently: if someone with bipolar disorder is prescribed antidepressants without the addition of a mood stabilizer, it can trigger a manic episode," Bahn said in the release.

Bipolar disorder affects an estimated 1% of the population. About 40% are misdiagnosed with major depressive disorder.

A full psychiatric assessment can accurately diagnose bipolar disorder, but there may be a long wait to get one.

“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 pressures on medical professionals,” Tomasik said.

Researchers recruited more than 3,000 people who were part of a U.K. health study between 2018 and 2020 to identify bipolar disorder in patients who were diagnosed with major depressive disorder within the previous five years. Each had current symptoms.

Each completed an online mental health assessment of more than 600 questions. It asked about past or current depressive episodes, generalized anxiety, symptoms of mania, family history and substance abuse.

About 1,000 of those who completed the online assessment were asked to provide a dried blood sample from a simple finger prick. Researchers used mass spectrometry to analyze these for more than 600 byproducts of metabolism called metabolites.

After completing the Composite International Diagnostic Interview, a diagnostic tool to establish mood disorder diagnoses, the study had 241 participants.

Even after accounting for factors such as medication, researchers saw a significant biomarker signal for bipolar disorder.

The identified biomarkers were correlated mainly with mania. They were validated in a separate group of patients who received a diagnosis of major depressive disorder or bipolar disorder during a one-year follow-up.

The combination of patient-reported information and the biomarker test significantly improved diagnostic outcomes for people with bipolar disorder.

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

Tomasik noted that some patients preferred the blood test, because it provided 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,” he said.

Bahn said blood tests could also be used to identify potential drug targets for mood disorders, which could lead to better treatments.

Cambridge Enterprise, a commercial arm of the university, has filed a patent on the research.

Study findings were published Oct. 25 in JAMA Psychiatry.

More information

The U.S. National Institute of Mental Health has more on bipolar disorder.

SOURCE: University of Cambridge, news release, Oct. 25, 2023