Three-D MR imaging has led to new insights concerning the relationship between dysfunctional gray matter and the physiological effects of lithium(Drug information on lithium) therapy for bipolar disorders. The findings were reported in April in an online version of the journal Biological Psychiatry.
Three-D MR maps of brain structure confirmed earlier findings suggesting that lithium helps rebuild underused gray matter or repairs dysfunctional gray matter in specific regions of a bipolar patient's brain, according to principal investigator Carrie Bearden, Ph.D., an assistant professor of psychiatry at the University of California, Los Angeles. The maps also provide clues into the way lithium may exert its therapeutic effects.
"Given that most effective medications we have now for psychiatric disorders have been discovered serendipitously, it is important for us to try and understand the mechanisms by which these medications work in patients with the disorder," Bearden said.
Three-D MRI is helping Bearden's group develop new treatments that match the effectiveness of lithium for biopolar disorders but avoid its toxic effects, she said.
Bearden and colleagues enrolled 28 adult patients with bipolar disorder, 70% of whom were being treated with lithium, and 28 healthy control subjects. The investigators used the 3D MR technique to obtain spatial analyses of gray matter density by measuring gray matter spots at multiple cortical locations.
They found that gray matter density was significantly greater in bipolar patients relative to control subjects in the brain regions that control attention, motivation, and emotion (left hemisphere p = 0.0082; right hemisphere p = 0.0015). The greatest differences occurred in the bilateral cingulate and paralimbic cortices and, to a minor degree, in the right anterior cingulate.
Documentation of physiological symptoms and their response to treatment helps to establish bipolar syndromes more firmly as physical disease, rather than a behavioral disorder, according to Dr. John Port, an assistant professor of radiology at the Mayo Clinic in Rochester, MN. The distinction is of great importance to patients and their families.
"The stigma of psychiatric illness is a terrible one," Port said.
But the results can be interpreted in several ways, said Dr. Michael W. Weiner, director of the center for imaging of neurodegenerative disease at the VA Medical Center in San Francisco. Lithium treatment may be helping to increase gray matter in affected areas, or patients with more brain matter may be reacting to treatment in a different way from patients with less gray matter.
That question can be answered with a prospective longitudinal treatment study, he said.
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