Research Findings on Memory and Cognitive Impairment in ECT
There was a significant amount of information in the literature regarding the effects of ECT on autobiographical or retrograde personal memory. The majority of the studies in the literature tend to focus on the subacute affects, which is the 24-hour to 2-week time period after ECT. Immediately after ECT, there’s limited evidence to suggest that bilateral electrode placement is associated with greater impairment. In the subacute time period, 24 hours to 2 weeks, there is conclusive evidence to suggest that bilateral ECT is associated with greater impairment of autobiographical memory compared to unilateral, right unilateral or unilateral nondominant ECT. However, there’s limited evidence with respect to the effects of sine wave or high energy dose. There’s also evidence to suggest a decline from baseline test performance during this time period.
For the medium term, which is the two week to less than three month time period, there are limited data regarding the effects of electrode placement, pulse, or energy dose. The data are also limited with respect to change from baseline, although there are some studies that suggest no change or improvement with the use of ultrabrief pulse.
There was a single study comparing maintenance ECT with drug therapy. The results suggested that pharmacologic treatment demonstrated improvement relative to post-ECT performance whereas maintenance ECT demonstrated no change from the post-ECT baseline. At six months, there was only one study which suggested a return to baseline test performance with unilateral ECT. However, there was continued decline with bilateral placement in sine wave pulse.
The meta-analysis of the most commonly used instrument, the Autobiographical Memory Interview Scale, conducted by FDA, will be discussed following my presentation.
Assessment of subjective memory is problematic according to the literature due to the use of self-report scales, are dependent upon the timeframe which these scales are completed by patients, and may be related to the degree of improvement in depressive symptoms. In general, patients are more likely to report memory impairment immediately following ECT treatment. Bilateral was associated with greater impairment than unilateral ECT in the subacute time period, but by six months, there was no difference with respect to electrode placement, waveform, or sham versus ECT.
Improvement or no change from baseline appears evident at six months post-ECT.
To summarize, the systematic review of the cognitive adverse events literature indicates that ECT is associated with cognitive and memory impairment. The degree and duration of the impairment appears to be domain-specific and related to certain ECT treatment parameters. Specifically, there appears to be a greater risk of cognitive and memory impairment associated with bilateral and dominant hemisphere electrode placement and high energy dose ECT.
The key impaired cognitive domains from the review of the literature include disorientation, which is common but typically transient and resolves within seconds to minutes after seizure termination. Of the major cognitive domains, memory dysfunction is apparent for both anterograde and retrograde memory over the short term but may return to either baseline level or possibly improve. Specifically, the literature suggests that bilateral ECT is associated with greater autobiographical memory impairment compared to unilateral ECT, and there’s limited evidence to suggest these deficits may return to pre-ECT baseline test performance at six months.
The next slide, this next table, is a little busy but attempts to summarize the evidence in the literature regarding the pre- to post-ECT changes from baseline cognitive test performance. To try and orient you to the slide, the upward arrows indicate consensus in the literature of improvement relative to baseline test score. The downward arrows indicate consensus in the literature suggesting a decline from baseline test performance. The dashes indicate that the consensus in the literature suggest no change from baseline, and the one +/- sign that you see at six month under retrograde memory indicates that the results are different depending upon the ECT treatment parameter. Finally, the color coding is an attempt to indicate that the red arrow indicates that there is relatively conclusive evidence in the literature to support the finding. The blue arrow indicates that there is limited or equivocal evidence in the literature to support the finding.
Summary of ECT’s Effects on Brain and Memory Functioning
So to try and summarize this table for you, immediately post- ECT, there are deficits across nearly all cognitive domains. The cognitive deficits tend to persist up to two weeks with perhaps the exception of non- verbal memory function. From about two weeks to less than six months, cognitive test performance appears to either return to baseline or possibly improve. The data are limited at six months or greater. However, the available studies reviewed suggest there’s no evidence for persistent cognitive deficits except for perhaps autobiographical memory in which bilateral electrode placement in sine wave ECT appear to be associated with decline from baseline while unilateral brief pulse ECT appears to approach or return to baseline.
U.S. Food and Drug Administration. (2013). Research Findings on Memory and Cognitive Impairment in ECT. Psych Central. Retrieved on August 3, 2015, from http://psychcentral.com/lib/research-findings-on-memory-and-cognitive-impairment-in-ect/