RUL ECT vs Low Amplitude Seizure Therapy (LAP-ST)

Out on PubMed, from the team in Augusta, Georgia, is this study:

Double-Blinded Randomized Pilot Clinical Trial Comparing Cognitive Side Effects of Standard Ultra-Brief Right Unilateral ECT to 0.5 A Low Amplitude Seizure Therapy (LAP-ST).

Youssef NA, McCall WV, Ravilla D, McCloud L, Rosenquist PB.Brain Sci. 2020 Dec 13;10(12):E979. doi: 10.3390/brainsci10120979.PMID: 33322138

The pdf is here.

And from the Introduction:

In theory, LAP-ST can be helpful because of the direct effect of lower electric current, but the principal reason is that LAP-ST has a more focal electric field (EF) [34,35]. The current amplitude is the primary factor that drives the EF into brain regions located deeper in the brain and is responsible for cognition and memory such as the hippocampus and temporal lobe [33,35]. This extra focality of the EF can minimize or avoid high EF stimulation to the deeper hippocampal and temporal lobe regions [33,35]. Minimization of deeper stimulation by using LAP-ST is hypothesized to minimize CSE of ECT. In theory, this should not affect the more superficial cortical regions implicated in the antidepressant efficacy including the Dorsolateral Prefrontal Cortex (DLPFC) [36]

And from the Discussion:

The present report is consistent with the initial proof of concept LAP-ST study (n = 22), providing further support for the premise that LAP-ST at 0.5 A has less CSEs (as measured by TRO) and preserved efficacy compared to standard UB-RUL ECT [32].
Longer TRO after ECT has been shown to prospectively predict long-term memory side effects [24,40,41]. Moreover, in prior studies TRO reported by using both standard RUL or bilateral ECT were much longer [9,24,25,42,43] than LAP-ST shown in this study.
This pilot study represents the first randomized and blinded clinical trial examining LAP-ST at 0.5 A compared to standard UB-RUL ECT. LAP-ST had numerically faster time to reorientation (Figure 2). The antidepressant efficacy was not different from the standard UB-RUL ECT group (Figure 3).

And a figure:

This is an interesting pilot study (see also blog post of December 3, 2020) about the manipulation of one of the parameters of the ECT stimulus (current amplitude).  It falls into the category of research into refining ECT technique, with the goals of improving cognitive tolerability while preserving antidepressant efficacy. With an "n" of only 7, the authors are appropriately cautious about the highly preliminary nature of the results. Time to reorientation (TRO) is used as a proxy for overall cognitive effects; while TRO may be correlated with deficits in other cognitive domains, the authors correctly state it does not replace a more comprehensive neurocognitive battery for definitive results.

From a review of the references in this paper, it appears that Peterchev et al. (2015) coined the name Low-Amplitude Seizure Therapy, in a paper reporting on both MST and ECT in primates. As I mentioned in the post of December 3, I am not sure that such nomenclature is necessary or helpful; this is really ECT with a slightly different stimulus parameter set. 

It is crucially important not to sacrifice the antidepressant efficacy of ECT on the altar of transient cognitive effects; these authors are fully aware of this, but I think it bears repeating here.

Dr. Youssef and colleagues are to be commended for their ongoing innovative research efforts.