The effect of pulse width on subjective memory impairment and remission rate 6 months after electroconvulsive therapy

Objectives: The aim of this study was to compare the 0.5-millisecond pulse width with broader brief width stimulus and ultrabrief pulse width stimulus in respect to rates of subjective memory impairment and remission 6 months after completion of electroconvulsive therapy (ECT). Methods: This study used data from the Swedish National Quality Register for ECT. Inclusion criteria were bipolar or unipolar depression with or without psychosis, ECT with unilateral electrode placement, and data on the Montgomery-Åsberg Depression Rating Scale—Self-Assessment and the memory item of the Comprehensive Psychopathological Rating Scale (CPRS-M) before and 6 months after ECT. The primary outcomes were the distributions of patients with a maximum of 10 on the Montgomery-Åsberg Depression Rating Scale—Self-Assessment (remission) and a minimum of 2-step worsening in CPRS-M score according to the ECT pulse widths of 0.5 millisecond. Result: This study included 312 patients. The distributions of patients with remission or a minimum of 2-step worsening on the CPRS-M 6 months after completion of ECT showed no significant differences between the 3 pulse width groups. Older age was associated with a significantly higher rate of remission 6 months after ECT. Conclusions: In this cohort of patients, no support was found for the previous research finding of lower rates of subjective memory disturbances 6 months after ultrabrief pulse width ECT in comparison with brief pulse width ECT. Older age was associated with higher remission rate 6 months after ECT. Large randomized studies are required to exclude the possibility of long-term differential effects between pulse widths.