Retrograde Amnesia and Bilateral Electroconvulsive Therapy

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Retrograde Amnesia and Bilateral
Electroconvulsive Therapy

• Long Term and Follow-up

Squire, Slater, Miller (1981)
Summarized by Bobbie Perkins
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Introduction

• Electroconvulsive therapy (ECT)
• small, carefully controlled amount of electricity
  is introduced into the brain.
• used in conjunction with anesthesia and muscle
  relaxant medications
• produces a mild generalized seizure or convulsion
• most effective in the treatment of severe
  depression
• Bilateral ECT is when electrodes are placed on
  both sides of the head.

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Introduction

• ECT is sometimes used as a treatment for severe
  depression.
• Memory loss is one prominent side effect of
  electroconvulsive therapy.
• Most patients will report some retrograde amnesia
  for events that preceded ECT.
• Memory functions generally improve after
  treatment is completed.
• Forgetting may be due to pretreatment depression,
  antidepressant drugs, or the unreliability of
  informal reports.

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Methods

• 4 groups (43 psychiatric inpatients)
• ETC patients
• Control group (7 inpatients)
• None of the patients in the control group was
  receiving ECT and none had received it in the
  past.
• In the experimental group 12 of the 43 patients
  had received ECT before but not within the
  previous 12 months.
• The patients psychiatrists determined the number
  of treatments and prescriptions of psychotropic
  drugs during and after ECT.

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Methods

• ECT was administered 3 times a week on alternate
  days after medication with atropine sulfate,
  methohexital sodium and succinylcholine chloride.
• Treatments were given with 140 to 170 V for 0.5
  to 1.0 s.
• Electrode placement was bitemporal
• In all cases the attending physician reported
  that the current produced a grand mal seizure.

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Methods

• 4 different tests
• Public events recognition
• Public events recall
• Recall of television programs
• Recall of personal events

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Methods

• Previous studies have indicated that memories
  acquired a few years prior to ECT can be lost
  without the disturbance of older memories.
• On test 4
• 1st six questions dealt with remote past
• Last 3 dealt with recent past
• 8th question events that were 6 to 37 months old
• 9th question events 14 to 19 months old
• 10th question events 2 to 36 days old
• The results for the 7th question were excluded

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Methods

• Repeated testing
• Some subjects took tests 1-4 on two or more
  occasions
• Considered that performance may noticeably
  improve
• Gave tests 1 and 2 to control subjects and scores
  were slightly improved but it doesnt seem like
  the ECT patients could have benefited from
  repeated testing.

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Results
10
Results
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Results
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Results

• For test 4 they also used a reminding procedure.
• When previously recalled information was omitted
  it was presented to the patients and asked if it
  was familiar.
• 2nd interview ECT patients needed more reminders
  then control patients.
• 3rd interview ECT patients needed reminders as
  often as control patients.
• Control patients the reminding procedure was
  effective 100 of the time.
• ECT patients the reminding procedure was
  effective only 71 of the time.
• Failure to recognize material when reminders were
  provided was considerably more frequent for
  recent events than for more remote events.

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Discussion

• It was found that long lasting subtle amnesias
  can occur after a course of 8-9 ECT treatments,
  and the amnesias are most prominent for the
  period just prior to treatment.
• This supported what Janis found in her study.
• Janis hypothesized that ECT affected the
  retrieval process reducing access to certain
  memories.
• Squire suggested that ECS may affect both
  retrieval of already stored memories and their
  continued consolidation.
• The return of supposedly forgotten memories
  supports the retrieval-failure hypothesis.
• The persistent loss for other memories suggests
  that some material in long-term store is still
  susceptible to disruption.

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References

• Squire, Slater, Miller. (1981). Retrograde
  Amnesia and Bilateral Electroconvulsive Therapy.
  Archives of General Psychiatry, 89-95.
• Terry, W. S. (2003). Human Memory Conceptual
  Approaches. Learning and Memory Basic
  Principles, Processes, and Procedures, 193-229.
• Barstow, Donald. Electroconvulsive Therapy.
• http//www.ehendrick.org/healthy/000468.htm