Electroconvulsive therapy (ECT) plays an important role in the treatment of severely depressed patients, especially those who do not respond to antidepressant medications. However, its cognitive adverse effects restrict its use. The dosage of the electrical stimulus and the anatomic placement of stimulating electrodes are critical in determining the efficacy and cognitive adverse effects of ECT.1- 4 Nonetheless, with ECT, control over the spatial distribution and magnitude of intracerebral current density is limited by high skull impedance, which shunts most of the electrical stimulus through the scalp and cerebrospinal fluid. There are also individual differences in skull anatomy that result in uncontrolled variation in intracerebral current density.
Lisanby SH, Schlaepfer TE, Fisch H, Sackeim HA. Magnetic Seizure Therapy of Major Depression. Arch Gen Psychiatry. 2001;58(3):303-305. doi:10.1001/archpsyc.58.3.303