Although other studies have measured increases in the overall volume of the brain, Bearden said, this imaging method allowed the researchers to see exactly which brain regions were affected by lithium.
"Bipolar patients who were taking lithium had a striking increase in gray matter in the cingulate and paralimbic regions of the brain," she said. "These regions regulate attention, motivation and emotion, which are profoundly affected in bipolar illness."
While conventional MRI studies have measured brain volume in total, this new image analysis allows researchers to examine differences in cortical anatomy at a much greater spatial resolution.
In this study, Bearden and colleagues at UCLA used computer analysis to analyze brain scans collected by collaborators at the University of Pittsburgh in order to determine whether bipolar patients showed changes in brain tissue and, if so, whether those changes were influenced by lithium treatment. Specifically, they employed high-resolution MRI and cortical pattern-matching methods to map gray matter differences in 28 adults with bipolar disorder ?70 percent of whom were lithium-treated ?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.
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."
Source:University of California - Los Angeles