Improving Cognition in Schizophrenia Using tDCS

The investigators plan to recruit 40 individuals diagnosed with Schizophrenia. Participants will range from 18-55 years old. We will select stable, medicated patients who have not been hospitalized nor had any changes in their antipsychotic medications during the previous two months. Participants will not be tested within 12 hours of taking medications that may affect cognition (such as benzodiazepines and anticholinergics). All medications will be recorded. The investigators expect most of the patients to be relatively chronic (mean illness chronicity approximately 15 years, based on previous studies), although we will not select for chronicity. All participants will provide written informed consent after receiving a full explanation of the procedures according to approvals by the Institutional Review Boards. They will arrive for three visits. In the first visit, they will be consented, complete the diagnostic interview, the rating scales, and will undergo one of three randomly assigned stimulation conditions: 1) anodal tDCS, 2) cathodaltDCS, and 3) sham stimulation. They will also undergo an electroencephalography (EEG) procedure, in order to more directly assess the effect of tDCS on brain function. This visit will take approximately five hours to complete, and breaks will be given as needed. Immediately following stimulation, participants will complete neurocognitive, social cognitive, and EEG measures. There will be two 20-minute stimulation sessions, with a break of one hour between the sessions. After each session, participants will be asked to complete a portion of the basic cognitive, social cognitive, and EEG measures, so that half of the measures will be completed after the first 20 minute stimulation session and the other half will be completed after the second 20 minute stimulation session. The order of administration of the neurocognitive, social cognitive, and EEG measures will be randomized across participants within each group. During the second and third visits, participants will undergo the remaining two stimulation conditions, one randomly assigned condition each visit. These visits will take approximately four hours to complete, and each visit will be separated by at least one week from the previous visit.