More powerful shocks of electroconvulsive therapy (ECT) speed relief of depression, researchers at Wake Forest University Baptist Medical Center and two other centers report in the May 15 issue of Archives of General Psychiatry, an American Medical Association publication.
At the same time, the larger shocks increase temporary loss of memory - even for autobiographical facts, said W. Vaughn McCall, M.D., M.S., associate professor of psychiatry and behavioral medicine and lead investigator.
ECT, also known as shock treatment, has been used for years for patients who have what psychiatrists refer to as "major depressive episode." In more recent years, doctors have been testing whether applying a shock to just one side of the brain would relieve depression as well as applying ECT to both sides of the brain, while decreasing side effects.
At lower doses, "the antidepressant efficacy [of treating one side of the brain] has been low compared with bilateral ECT," McCall reported.
The new study compared patients given a moderate ECT dose with those given high-dose treatments, both only on the right side. The moderate dose was a variable amount, linked to 2.25 times the patient''s "initial seizure threshold," the point at which shock induces a convulsion. The high dose was the same fixed amount for all patients.
The team reported that 66.7 percent of patients on the high dose treatment experienced relief of depression, compared to 38.9 percent of those on the moderate, variable dose.
Nonetheless, nine of the 72 patients studied were removed from the protocol "because of insufficient clinical response" and switched to the more traditional bilateral ECT.
The investigators determined that the higher the ECT dose, the greater the efficacy.
"The difference in antidepressant efficacy for the two groups has practical implications," McCall said. A typical course of therapy is six to eight treatments at the rate of three per week. The patients on the moderate dose ended up with an average of 1½ additional ECT treatments, which means their complete course of ECT lasted an additional 3½ days.
The team found temporary memory disturbances, using a test called the Mini Mental State Exam, among both groups. The rate of cognitive disturbance among the high dose group was 30.3 percent, compared to just 6.7 percent among the moderate group. It also took the high dose group longer to get reoriented.
And the high dose group had more trouble with autobiographical items. "Typical examples of autobiographic memory loss include inability to remember events in the last few weeks," said McCall. "For example, if a person had ECT during May, then their memory of what had happened in the months of April and May would be at risk of being forgotten, perhaps forever. In contrast, more distant memories, such as Thanksgiving or Christmas, are likely to be preserved."
McCall reported that increasing the ECT dose had an bigger effect on memory than on depression. "We routinely discuss these memory effects with patients prior to ECT, and most patients find this an acceptable trade for a chance at having their depression relieved."
Modern ECT is vastly different from ECT of the 50s and 60s as portrayed in the movies. It is administered under anesthesia and the convulsion is extremely limited, causing only a slight tremor in the patient that can barely be seen.
The researchers also included David M. Reboussin, Ph.D., of the Department of Public Health Sciences, Richard D. Weiner, M.D., Ph.D., of the Department of Psychiatry at Duke University School of Medicine, and Harold A. Sackeim, Ph.D., of the Departments of Psychiatry and Radiology at the College of Physicians and Surgeons, Columbia University.
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