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Shock Therapy Has Similar Effect to Antidepressant Drugs on 5-HT2 Receptors among Depressed Patients: Presented at CPA
By Bonnie Darves
Special to DG News
BANFF, ALBERTA -- November 5, 2002 -- New research using positron emission tomography (PET) shows that electroconvulsive therapy (ECT) and antidepressant therapy have similar effects on the brain's 5-HT2 receptors.
The new findings run contrary to this belief, according to Lakshmi N. Yatham, MD, of the Mood Disorders Clinical Research Unit, University of British Columbia, in Vancouver, British Columbia, Canada.
He presented the results of this study here November 3 at the annual meeting of the Canadian Psychiatric Association (CPA).
His team's aim was to determine the role 5-HT2 receptors play in relieving the symptoms of depression and the mechanisms of action in ECT in regulating those receptors. The study's finding is important, Dr. Yatham said, because animal studies previously showed antidepressants and ECT to influence 5-HT2 receptors in opposite directions -- with ECT up-regulating the receptors and antidepressants down-regulating them.
Dr. Yatham said that little research has been done to determine whether the same effects occur in humans. As such, the researchers studied the effects of ECT, using PET scans to assess effects on 5-HT2 receptors. Dr. Yatham and colleagues had conducted a similar study of the effects of desipramine (Norpramine, Pertofrane) on 5-HT2 receptors over a four- to six-week period.
In the new study, 16 patients who had been diagnosed with major depression (according to Diagnostic and Statistical Manual - Revision IV criteria) and had been referred for ECT underwent two PET scans -- one before and another after treatment. Patients had to be 10 days drug free before the start of the study.
Researchers used [18F] setoperone as a ligand to measure receptor activity. After treatment, the patients showed significant decreases in 5-HT2-receptor binding in several cortical areas -- the left occiptal gyrus, the right curneus and the left insula.
"The important thing is that this shows that ECT down regulates 5-HT2 receptors in depressed patients in the same way that antidepressants do, which may explain why [those] treatments produce symptom relief," Dr. Yathsam said, adding that his earlier study found the same results following treatment with either desipramine or paroxetine.
Further studies are needed, he said, to look at longer-term effects of either ECT or antidepressants on 5-HT2 receptor changes and to better understand why those changes occur.
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