Magnetic resonance (MR) spectroscopy may prove to be the definitive diagnostic test for bipolar disorder based on identification of metabolic markers of the disease, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA).

In the current work, researchers at the Mayo Clinic used the technique to identify significant differences between the brain chemistries of people with and without bipolar disorder.

"The psychiatric community clearly needs a tool to help diagnose bipolar disorder," said John D. Port, MD, PhD, presenter of the study. "We are hopeful that very high-field MR spectroscopy will prove helpful by identifying metabolic markers of the disease."

"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," Port said. "It's also important to be able to distinguish bipolar disorder from major depression because a mistaken diagnosis can result in the wrong therapy and unstable moods for years."

According to the National Institute of Mental Health, approximately 2.3 million Americans have bipolar disorder. Left untreated, bipolar episodes typically become more frequent and more resistant to change through medication. Each year, approximately 30,000 depressed individuals commit suicide.

The researchers studied 21 patients with bipolar disorder who were not taking any medications and 21 individuals without the disorder who were matched by age, sex, and right- or left-handedness. Study participants ranged from age 18 to 54 years and included 26 women and 16 men.

Using MR spectroscopy, a special form of MR imaging that allows researchers to analyze the chemical properties of tissue, Port and colleagues studied 60 to 70 regions of the brain at a time, gathering thousands of data points. The spectroscopic scans enabled the research team to perform statistical analyses on 14 separate areas of the brain and 5 metabolites.

The preliminary findings indicated that certain metabolite levels differed significantly between the bipolar group and control group in 4 areas of the brain that control behavior, movement, vision and reading, and sensory information.

This is the first study to analyze drug-free bipolar patients using a 3T longbore magnetic resonance scanner, which has twice the magnetic-field strength of scanners used in recent bipolar disorder studies.