Brain polarization: behavioral and therapeutic effects

Polarization is the passage of small constant direct currents through the brain. During the last 12 years some authors have investigated its therapeutic effectiveness in psychiatric patients with different and sometimes contradictory results. Although there seems to be a "fairly consistent body of evidence concerned with the effects of direct currents applied to the head in psychiatric patients" (Nias, 1976), only the procedure involving pulsating low-level currents (electrosleep) has received increasingly more attention in recent years, while polarization (constant d-c currents) is not even mentioned in most standard textbooks. This review concentrates on work dealing with behavioral and therapeutic effects of polarization. The procedure involves the continuous flow of low-level current (up to 1 ma) between cephalic and noncephalic electrodes during prolonged periods of time (usually hours), without inducing convulsions (as in electroconvulsive therapy) or sleep, the subject being almost unaware of the treatment. Because of its implications for research, attention is also devoted to some representative work on physiological effects of polarizing currents.