June 17, 2005
Bipolar Disorder Linked to Specific Brain Regions; Certain Drugs Alter Brain Metabolism
PITTSBURGH, June 17 "“ Late-breaking research, including a study that identifies the specific regions of the brain that may be responsible for manic behaviors, will be presented in a special session at the Sixth International Conference on Bipolar Disorder, held June 16 to 18 at the David L. Lawrence Convention Center in Pittsburgh.
The special session includes 12 presentations that specifically focus on the most recent and promising research developments that are of interest to the more than 1,000 participants attending the only scientific meeting devoted exclusively to bipolar disorder research.
Highlights of the these "rapid communications" presentations include the following:
CHILDHOOD GAME OF "RED LIGHT, GREEN LIGHT" ADAPTED TO STUDY BRAIN NETWORK IN BIPOLAR PATIENTS
Bipolar disorder is widely associated with behaviors including elation, hyperactivity and impulsive, often reckless behaviors during patients' manic phases. But the specifics about what in the brain actually causes these behaviors are still unclear. Researcher Stephen Strakowski, M.D., of the University of Cincinnati College of Medicine examined brain activity in response to an impulse control task that showed manic bipolar patients may have difficulties modulating the brain regions that monitor task performance, namely, those regions that detect error and promote accurate responses.
Dr. Strakowski noticed such difficulties in studies that used functional magnetic resonance imaging (fMRI), which is useful in mapping changes in the brain that correspond to mental operations. Both manic bipolar patients and healthy subjects were fitted with special goggles through which they viewed random blue letters and occasional targets, indicated by a blue letter X. Subjects were instructed to respond to the blue letter X targets by pressing a button. However, when the letter X turned from blue to red, they were asked to refrain from pressing the button.
STUDY FINDS TWO DRUGS NECESSARY TO TREAT BIPOLAR'S PHASES
While mood stabilizers and antipsychotics are essential for the treatment of bipolar disorder, both the complex nature of this illness and medication side effects pose problems for achieving an effective long-term maintenance therapy.
Researcher Allan Young, Ph.D., and colleagues from the University of Newcastle in Newcastle-upon-Tyne in the United Kingdom, finds that no single medication licensed in either the United States or the U.K. for the treatment of bipolar disorder is effective for treating both the depressive phase and the manic phase of this illness.
Dr. Young's analysis is the first to include all commonly used bipolar medications, with results suggesting the need for a two-pronged pharmacologic approach of both a mood stabilizer and an antipsychotic in order to prevent both depressive and manic recurrences.
ALTERATION IN BRAIN CHEMICAL MAY PROVIDE CLUES INTO CAUSES OF BIPOLAR DISORDER AND LEAD TO NOVEL TREATMENTS
Preliminary research has suggested that during the depressive phase, bipolar II patients have abnormally elevated metabolism, or activity, in specific regions of the brain, providing clues into the causes of the disease and suggesting novel treatment approaches. Bipolar disorder II is characterized by episodes of less severe mania, called hypomania, and major depression.
Using PET imaging, researcher Carlos Zarate, M.D., of the National Institute of Mental Health, studied the brains of patients with bipolar II depression before their symptoms emerged, and repeated the studies after the patients had received a six-week course of the antidepressant pramipexole, a drug that increases neurotransmitter activity by stimulating dopamine receptors.
Compared to patients who received placebo, pramipexole resulted in decreased brain activity in certain regions that in earlier scans had shown high activity, as well as decreased depression and anxiety symptoms. In contrast, pramipexole treatment did not alter metabolism in other brain regions, such as the amygdala, that have been implicated with conventional antidepressants but instead, pramipexole was found to increase activity in the premotor cortex, hippocampus, posterior cingulate cortex, and superior temporal gyrus.
The Sixth International Conference on Bipolar Disorder is being presented by the University of Pittsburgh School of Medicine and Western Psychiatric Institute and Clinic of the University of Pittsburgh Medical Center.
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