Abstract :
Convulsive therapies have been in continuous use for more than 60 years. For most of that time, the fundamental view was the production of a generalized seizure provides the necessary and sufficient conditions for therapeutic effects in mood disorders. Recently, this perspective was shown to be erroneous. The efficacy of ECT is largely determined by the anatomic positioning of electrodes and electrical stimulus dosage, and generalized seizures of adequate duration can be reliably elicited that lack efficacy. These findings indicate that the magnitude and spatial distribution of current paths are critical to antidepressant effects. Isolating the critical anatomic distribution offers a new method to explore the neuroanatomy of mood disorders and the mechanisms of action of effective treatment. Three theories offer alternative explanations for this specificity. These theories link the efficacy of ECT to effects on (1) bilateral cortical systems, (2) diencephalic systems, or (3) anterior frontal systems. Evidence from the effects of ECT on neuropsychological, biochemical (prolactin), and brain imaging (rCBF, quantitative EEG) parameters will be presented that test these alternative theories.
