Many people with bipolar disorder (BD), a mental illness that causes extreme shifts in mood, energy and the ability to think clearly, are often misdiagnosed with major depressive disorder. But a particular area of the brain may help doctors correctly distinguish between these two mental illnesses, which have similar symptoms, suggests new research published in Biological Psychiatry: Cognitive Neuroscience and NeuroImaging, reports the Westmead Institute.

For the study, a research team from the Westmead Institute for Medical Research and the University of Sydney used sophisticated MRI scanning to see how the amygdala—a set of neurons that play a key role in processing emotions—responds as a patient processes facial emotions (anger, sadness, fear, disgust and happiness).

Scientists found that in people with BD the left side of the amygdala is less active and connected with other parts of the brain than those with depression. (When researchers used the amygdala to differentiate between those with bipolar disorder and those with depression, they were accurate 80 percent of the time.)

“Such a marker could help us better understand both these disorders, identify risk factors for developing these disorders and potentially enable clear diagnosis from early onset,” said Mayuresh Korgaonkar, PhD, the lead researcher of the study.

It may take up to 10 years for those living with bipolar disorder to receive an accurate diagnosis, which can, in turn, lead to improper treatment and poor social and economic outcomes.

Phase II of the study is currently under way. Researchers hope to further characterize the identified markers among a larger group of participants.

Click here to learn how among people with BD being female is linked with antidepressant usage as well as manic episodes triggered by these medications.