Acute cognitive effects of subconvulsive electrical stimulation

Empirical titration procedures increasingly are being used to estimate initial seizure threshold. These procedures involve the administration of subconvulsive electrical stimulation. There has yet to be evaluation of the impact of such stimulation on the acute cognitive consequences of electroconvulsive therapy. In two studies we randomized depressed patients to right unilateral or bilateral ECT, with stimulus intensity maintained just above seizure threshold throughout the treatment course. These low dosage treatment groups received one or more subconvulsive stimuli in approximately 40% of treatment sessions, with a grand mal seizure also elicited at each session. Extensive neuropsychological evaluation was conducted at each session. We contrasted treatment sessions in which generalized seizures were preceded by subconvulsive stimulation with treatment sessions in which a single convulsive stimulation was applied. Across a variety of neuropsychological measures, there were no adverse cognitive consequences of subconvulsive stimulation.