Efficacy of Transcranial Direct Current Stimulation in Treatment of Cognitive Deficits in Early Stages of Psychosis

Background: Cognitive deficits are a core symptom of schizophrenia even at the early stages of psychosis. To date, there has been reliable evidence that cognitive deficits are associated with outcomes in schizophrenia and early treatment could help to reduce the prominent disabling cognitive symptomatology which most schizophrenia patients still experience persistently. Outcomes in studies of repetitive transcranial magnetic stimulation in schizophrenia patients suggest the possibility that application of transcranial direct-current stimulation (tDCS) with inhibitory stimulation over the left temporo-parietal cortex and excitatory stimulation over the left dorsolateral prefrontal cortex could affect positive and negative symptoms, respectively. Positive effects of tDCS have also been reported on cognitive symptoms. The present study protocol hypothesis is that the development and utilization of potentially effective neuroenhancement tools such as a non-invasive brain stimulation technique like tDCS for the treatment and rehabilitation of cognitive impairment in early stages of Schizophrenia may contribute to the elucidation of the nature of the complex and dynamic processes in the brain during the early stages of the disease, and may lead to a better outcome. Objectives: The aim of the present study protocol is to evaluate the efficacy of tDCS in the treatment of cognitive symptomatology in the early stages of psychosis. Methods: Sixty patients in the early stages of psychosis will be randomly allocated to receive 20 minutes of active 2-mA tDCS or sham stimulation once a day on 10 consecutive weekdays. The anode will be placed over the left dorsolateral prefrontal cortex and the cathode over the left temporo-parietal cortex. Neuropsychological and psychiatric assessments will be performed at the time of consent (baseline), at 1 and 3 months following the end of the intervention (maintenance effect).