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Ask the Mental Health Expert Archives 2001-2004

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Temporary Memory Loss

Q. I have recently undergone a series of 7 ECT sessions. I am rather distressed about the memory loss suffered since. I know that a certain amount is to be expected and that for most patients this is temporary. What constitutes temporary? In particular, I am most distressed by my inability to retain new information. Has there been anything written on this that you could possibly refer me to?

A. I can understand why you are distressed, but, depending on what you mean by "recently", your experience may be both normal after ECT, and transient. Here's the background. ECT is the most effective treatment known for severe depression. Efficacy rates are in the range of 70-90%. It is also a very safe procedure, with about the same medical risk as having your tonsils out--that is, the risk is largely that of general anesthesia. The general public has many unwarranted fears about memory loss stemming from ECT--probably a result of sensationalized portrayals of ECT in movies like "One Flew Over the Cuckoo's Nest". But the truth is, there's a great deal of variability in the memory loss associated with ECT, as one expert, Dr. Charles Kellner, has noted.

For many people, the memory problems are, indeed, relatively minor and temporary. And yet, some people report more serious and persistent problems. Much depends on the type of ECT administered--that is, which side of the brain the electrical stimulus is applied to, and how strong the dose of electricity is. Memory problems are much less common when ECT is applied unilaterally (on the non-dominant side of the brain), and when the dose of electricity is not too far above the amount needed to produce a seizure in the brain.

It is also hard to know whether a patient's subjective report of memory problems represents a true side effect of ECT; whether the patient is still slightly depressed and thus subject to depression-related memory problems; whether memory problems may be due to medications prescribed after ECT; or whether the person is simply hyper-focused on memory problems. Thus, it isn't always clear that ECT is the cause of the memory complaint.

We do know this: patients often report patchy memory gaps for events that occurred during and immediately surrounding the course of ECT. For example, the patient may not remember who visited him during the course of treatment in a hospital setting. Two to three months after the ECT course has ended, these gaps are often less prominent and may even disappear--though not always. Memories recorded closest in time to the start of ECT are the most vulnerable to being lost, and memories recorded in the more remote past are least likely to be affected--so, the patient is very unlikely to forget important memories from years preceding the ECT. Patients are very unlikely to forget important personal information, as opposed to, say, current events information.

In addition to this retrograde memory problem--that is, affecting pre-ECT memories--patients undergoing ECT may have difficulty recording new memories after receiving ECT, as you describe. This is termed anterograde memory dysfunction (AMD). AMD is usually worst immediately after ECT and usually subsides within days or a few (4-5) weeks. You may take some solace in the fact that neuropsychological testing done 6 months after ECT has failed to document objective problems with memory, even though some patients may complain of this. Many patients actually report improved memory shortly following ECT, probably because their depression has been treated.

Finally, as Dr. Kellner's group puts it, "Most patients report that the amount of memory loss is acceptable, given the benefit of recovery from severe depression; and that as more time elapses, they are less bothered by any residual memory gaps." [Kellner et al, Handbook of ECT, American Psychiatric Press, 1997]. If you have further questions about your memory, I strongly suggest you discuss this with your psychiatrist and/or the doctor who administered the ECT.

June 2001

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