Three-dimensional magnetic resonance imaging shows that lithium increases the volume of gray matter in key areas of the brain in patients with bipolar disorder compared with patients who do not use lithium and people without the disorder, according to an article available online and to be published in the July issue of Biological Psychiatry.

Carrie Bearden, PhD, a clinical neuropsychologist and assistant professor of psychiatry at UCLA, and Paul Thompson, MD, associate professor of neurology at the UCLA Laboratory of Neuro Imaging, led researchers in using a novel method of three-dimensional magnetic resonance imaging to map the entire surface of the brain in people diagnosed with bipolar disorder.

Researchers employed high-resolution scanning and cortical pattern-matching methods to map gray matter differences in 28 adults with bipolar disorder - 70 percent of whom were treated with lithium - and 28 healthy control subjects. Detailed spatial analyses of gray matter distribution were conducted by measuring local volumes of gray matter at thousands of locations in the brain.

While the brains of lithium-treated bipolar patients did not differ from those of the control subjects in total white-matter volume, their overall gray-matter volume was significantly higher, sometimes by as much as 15 percent. The increases were seen in the cingulate and paralimbic regions, areas that are critical for attention and controlling emotions.

These new findings suggest that lithium may work by increasing the amount of gray matter in particular brain areas, which in turn suggests that existing gray matter in these regions of bipolar brains may be underused or dysfunctional.

This is the first time researchers were able to look at specific regions of the brain that may be affected by lithium treatment in living human subjects, said Bearden.

Unfortunately, said Bearden, there is no evidence that the increase in gray matter persists if lithium treatment is discontinued. “But it does suggest that lithium can have dramatic effects on gray matter in the brain,” she said. “This may be an important clue as to how and why it works.”