Bipolar disorder, a sometimes misdiagnosed mental illness characterized by wide emotional swings, may be identifiable by chemical abnormalities visible in victims’ brains, researchers said on Tuesday.

Detailed brain scans performed on 42 adults, half of whom had been previously diagnosed as bipolar, showed consistently different levels of five chemicals in areas of the brain that control behavior, movement, vision, reading and sensory information, they said.

The Mayo Clinic study used a high-power magnetic resonance imaging scanner that had twice the magnetic field strength of scanners previously used to examine the brains of bipolar patients.

“Bipolar disorder is challenging to diagnose because individuals can cover up the symptoms of the illness or may recognize only their depression, not the manic phase of the disorder,” Mayo Clinic radiologist John Port said in a report delivered to the annual meeting of the Radiological Society of North America.

“The psychiatric community clearly needs a tool to help diagnose bipolar disorder,” he said.

The types of therapy used with bipolar disorder differ from those employed to fight Depression, so a correct diagnosis is important, Port said. Most diagnoses are made based on conversations with the patient.

Roughly 2.3 million Americans suffer from bipolar disorder, according to the National Institute of Mental Health.