Effects of modifying the electrode placement and pulse width on cognitive side effects with unilateral ECT: A pilot randomised controlled study with computational modelling.

BACKGROUND:The electrode placement and pulse width for electroconvulsive therapy (ECT) are important treatment parameters associated with ECT related retrograde memory side-effects. Modification of these parameters with right unilateral (RUL) ECT may have utility for further reducing these side-effects. OBJECTIVE:This study explored use of the frontoparietal (FP) placement for reducing retrograde memory side effects with ECT. We hypothesised that superior retrograde memory outcomes would occur with FP compared to temporoparietal (TP) placement and with ultrabrief (UB: 0.3 ms) compared to brief pulse (BP: 1.0 ms) width ECT. METHODS:In this randomised cross-over, double-blinded study, participants received a single treatment of BP TP, BP FP, UB TP and UB FP ECT. Neuropsychological testing was conducted prior to and immediately following each treatment. Computational modelling was conducted to explore associations between E-fields in regions-of-interest associated with memory. RESULTS:Nine participants completed the study. The FP placement was not superior to TP for retrograde memory outcomes. For both electrode placements UB pulse width was associated with significantly better visual retrograde memory compared to BP (p < .05). With TP ECT, higher E-fields in regions-of-interest were significantly associated with greater visual retrograde memory side-effects (hippocampi: r = -0.77, p = .04; inferior frontal gyri: r = -0.92, p < .01; middle frontal gyri: r = -0.84, p = .02). CONCLUSIONS:Modification of pulse-width had greater effects than electrode placement for reducing retrograde memory side-effects with RUL ECT. Preliminary findings suggested that higher E-fields may be associated with greater cognitive side-effects with ECT.