The Effect of Transcranial Direct Current Stimulation on Cognitive Side Effects of Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is an effective treatment for a variety of psychiatric disorders. However, despite continued advances in ECT technique, neurocognitive dysfunction continues to be a frequent adverse effect. Declarative memory and less so selective memory are often impaired after an ECT course. Immediate memory, however, is broadly preserved. It is hypothesized that memory impairments are due to ECT induced disruptions on long term potentiation as well as in cerebral flux and glutamatergic and cholinergic systems. Different pharmacological agents for the treatment of ECT induced cognitive dysfunction have been tried. Agents such as opioids, vasopressin, neuropeptides, cholinergic agents, thyroid hormone, and stimulants have been used with equivocal results, and no controlled studies showed clear efficacy. Transcranial direct current stimulation (tDCS) is a non-invasive, painless brain stimulation treatment that uses direct electrical currents to stimulate specific parts of the brain. Electrical currents are applied constantly at low intensities (1-2 mA) over a long period, usually in minutes (5-30 minutes), to achieve changes in cortical excitability by influencing spontaneous neural activity. There are two types of stimulation with tDCS: anodal and cathodal stimulation. Anodal stimulation acts to excite neuronal activity while cathodal stimulation inhibits or reduces neuronal activity. Several studies demonstrated moderate to strong effect sizes of tDCS in various neurocognitive and neuropsychiatric settings. Majority of studies show positive effects of tDCS on cognitive functioning among healthy volunteers and subjects with neurological or psychiatric conditions. Beneficial effects of online stimulation applied over the left dorsolateral prefrontal cortex have been reported for working memory, attention and information processing in depressed patients. To the investigators' knowledge no studies have evaluated the potential efficacy of tDCS for the p