Efficacy and Mechanisms of Transcranial Direct Current Stimulation (tDCS) - Effects on Working Memory in Schizophrenia

Impairments of cognition are a core, severely disabling feature of schizophrenia leading to poor long-term outcome with no established treatment available. Particularly impaired executive functions (e.g working memory) are frequently observed and are consistently associated with reduced activation of the dorsolateral prefrontal cortex (dlPFC). Deficits in those functions have been shown to be closely related to negative symptoms, thought disorder, and functional outcome in schizophrenia leading to the notion that frontal lobe dysfunction is crucially important in schizophrenic psychopathology. Noninvasive brain stimulation like tDCS can enhance executive functions like working memory in healthy subjects as well as in patients. To identify the optimal parameters for this intervention in patients with schizophrenia, the investigators first test the effects of different polarities (anodal, cathodal), stimulation intensities (1mA, 2mA) and laterality (left, right) on working-memory performance (nback task) in a sham-controlled cross-over design (n=128). To elucidate mechanisms of action, oscillatory brain activity will be registered with electroencephalography (EEG). These experiments will provide reliable data for an evidence-based development of new clinical interventions to improve treatment of cognitive deficits in patients with schizophrenia and thus enhance schizophrenia prevention and recovery.