NurseWeek

Bipolar disorder may lie in brain chemistry

By Tim Bergling
Health24News
October 3, 2000


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Washington (H24N). New research is pointing to genetic and biological roots for human bipolar disorder. A study from the University of Michigan shows that people with the disorder-once called "manic depression" – have an average of 30 percent more of an important class of signal-sending brain cells.

Bipolar disorder is marked by cyclical mood swings, which typically begin in a person’s late teens or twenties and strike men and women with equal frequency. Its milder, type II form causes depression alternating with hyperactivity, while the more severe type I disorder produces frenzied, even psychotic episodes that may send the patient to the hospital, followed by deep, crippling depressions. Current treatment uses a mix of mood-stabilizing, anti-psychotic and antidepressant drugs, but patients and physicians often struggle to strike the right combination.

The study, which looked at 16 patients suffering from the disorder, used brain scans to examine the density of cells that release key brain chemicals like dopamine, serotonin, and nor epinephrine. These chemicals send signals between brain cells, or neurons; they’re involved in mood regulation, stress responses, pleasure, reward, and cognitive functions like concentration, attention, and executive functions. Scientists have hypothesized their role in bipolar disorder for decades, but have never proven it.

"To put it simply, these patients’ brains are wired differently, in a way that we might expect to predispose them to bouts of mania and depression," says Jon-Kar Zubieta, MD, Ph.D., assistant professor of psychiatry and radiology at Michigan. "Now, we must expand and apply this knowledge to give them a treatment strategy based on solid science, not on the current method of trial and error. We should also work to find an exact genetic origin, and to relate those genetic origins to what is happening in the brain."

The study, which is published in the American Journal of Psychiatry, solidifies the idea that the disorder has unavoidable biological and genetic roots, and may explain why it runs in families.According to the National Depressive and Manic Depressive Association, more than 17 million adults in the U.S. suffer from an affective disorder each year, or one out of every seven people. Although these illnesses can occur at any age, many have their onset within the 25-44 age range.