Electroconvulsive Therapy Pulse Amplitude and Clinical Outcomes

Abstract

Introduction: Electroconvulsive therapy (ECT) pulse amplitude, which determines the induced electric field magnitude in the brain, is currently set at 800-900 milliamperes (mA) on modern ECT devices without any clinical or scientific rationale. The present study assessed differences in depression and cognitive outcomes for three different pulse amplitudes during an acute ECT series. We hypothesized that the lower amplitudes would maintain the antidepressant efficacy of the standard treatment and reduce the risk of neurocognitive impairment.

Methods: This double-blind investigation randomized subjects to three treatment arms: 600, 700, and 800 mA (active comparator). Clinical, cognitive, and imaging assessments were conducted pre-, mid- and post-ECT. Subjects had a diagnosis of major depressive disorder, age range between 50 and 80 years, and met clinical indication for ECT.

Results: The 700 and 800 mA arms had improvement in depression outcomes relative to the 600 mA arm. The amplitude groups showed no differences in the primary cognitive outcome variable, the Hopkins Verbal Learning Test-Revised (HVLT-R) retention raw score. However, secondary cognitive outcomes such as the Delis Kaplan Executive Function System Letter and Category Fluency measures demonstrated cognitive impairment in the 800 mA arm.

Discussion: The results demonstrated a dissociation of depression (higher amplitudes better) and cognitive (lower amplitudes better) related outcomes. Future work is warranted to elucidate the relationship between amplitude, electric field, neuroplasticity, and clinical outcomes.

Keywords: Electroconvulsive therapy; cognition; depression; pulse amplitude.

Conflict of interest statement

All authors report no disclosures to report.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.

Subject flow from recruitment and screening to the post-ECT assessment.

Figure 2:

Primary antidepressant outcome (Hamilton Depression Rating Scale 24-items, HDRS24) for right unilateral electrode placement. For the Figures A, B, C and D: The black dots are estimated marginal means, the blue bars are 95% confidence intervals, and the red arrows are for the comparisons between means; if the red “comparison arrow” from one mean does not overlap an arrow from another group, the difference is significant at a Tukey-HSD corrected significance level. Figure 2A: Longitudinal changes within each amplitude. The 600, 700 and 800 mA arms had early improvement, but the 600 mA arm had a response plateau after the mid-ECT assessment. Figure 2B: Amplitude contrasts at each assessment. Relative to the 600 mA arm, the 700 and 800 mA arms had lower (improved) post-ECT depression ratings. Figure 2C: Sex differences. Male and female subjects did not have differences in depression outcome. Figure 2D: Pulse width differences. Brief (1.0) and ultrabrief (0.3) pulse widths did not have differences in depression outcome.

Figure 3:

Primary cognitive outcomes (Hopkins Verbal Learning Test-Revised Retention Raw Scores, HVLT-R Retention Raw Score) for right unilateral electrode placement. For legend, see Figure 2. Figure 3A: Longitudinal changes within each amplitude. HVLT-R Retention Raw Score performance was similar throughout the ECT series for each amplitude arm (see Figure 2A for figure legend). Figure 3B: Amplitude contrasts at each assessment: Amplitude arms did not have HVLT-R Retention Raw Score differences at the mid- or post-ECT assessments. Figure 3C: Sex differences. Male and female subjects did not have HVLT-R Retention Raw Score performance differences. Figure 3D: Pulse width differences. Brief (1.0) and ultrabrief (0.3) pulse widths did not have HVLT-R Retention Raw Score differences.

Figure 4:

Secondary cognitive outcomes included the Delis Kaplan Executive Function System (DKEFS) Letter and Category Fluency. For legend, see Figure 2. Figure 4A: Longitudinal changes within each amplitude. For the Letter Fluency (A1), the 600 mA arm had no change in performance, but the 700 and 800 mA arms had impaired performance. For Category Fluency (A2), the 700 mA arm had no change in performance, but the 600 and 800 mA arms had impaired performance. Figure 4B: Amplitude contrasts at each assessment: Amplitude arms did not have Letter (B1) or Category (B2) Fluency differences at the mid- or post-ECT assessments. Figure 4C: Sex differences: Male and female subjects did not have Letter (C1) and Category (C2) Fluency performance differences. Figure 4D: Pulse width differences. Brief pulse width (1.0 ms) was associated with worse Letter Fluency (D1) at the mid-ECT assessment, but the post-ECT assessment did not demonstrate Letter Fluency differences. Brief (1.0) and ultrabrief (0.3) pulse widths did not have Category Fluency (D2) differences.