June 29th, 2009

Reports the Pittsburgh Post-Gazette:

Mary Phillips peers into the brains of people with bipolar disorder, and what she has found there gives a whole new meaning to the term “bipolar.”

Dr. Phillips, a University of Pittsburgh psychiatrist, has discovered that each half of a bipolar patient’s brain may be responsible for a different extreme of the illness.

Bipolar patients often cycle between periods of paralyzing depression and hyperactive mania.

Using a brain imaging technique that shows the connections between different parts of the brain, Dr. Phillips’ group has shown that wiring problems in the left half of the brain may cause patients’ manic phases, while a different kind of wiring problem on the right half may create the episodes of depression.

Her study focused on a bundle of fibers known as the uncinate fasciculus, which connects an emotion-processing area known as the amygdala, at the bottom of the brain, with a regulatory area known as the orbital prefrontal cortex, at the front of the brain.

Simply put, she said, the amygdala “allows us to perceive the emotional salience” of things we experience, while the orbital prefrontal cortex areas on either side of the brain “act like brakes on the amygdala.”

Her study found that on the left side of the brain, which is associated with more positive feelings, the uncinate fasciculus was much thinner than normal, which could mean the front of the brain was less able to control those feelings in bipolar patients, sending them into hyperactive, sometimes grandiose episodes of mania.

On the right side, which is more linked to negative feelings, the wiring was thicker and had more cross-connections, which she said “can lead to sort of getting off the point and thinking too much, getting off into this reverberative, ruminative loop” of anxious, melancholy ideas.

Find out more at the Post-Gazette.