improving cognition in schizophrenia using tdcs

Conditions: Schizophrenia

Summary: this study will examine the benefits of transcranial direct current stimulation (tdcs), a new tool that is being developed as a safe and non-invasive neurostimulation method, for improving neurocognitive and social cognitive functions in schizophrenia. this procedure is non-invasive and painless and it results in increase or decrease of spontaneous neuronal firing in the brain. its safety and beneficial effect on cognition has been demonstrated in healthy individuals and several clinical populations. in this pilot study, the investigators will examine the effect of tdcs on cognitive functions in 40 individuals with schizophrenia. each participant will arrive for three visits, with approximately one week between each visit. during the first visit, participants will be interviewed about their psychiatric symptoms, personal life experiences, and emotional well being by a specially-trained interviewer. on each of the three visits, participants will receive one of three stimulations: a type of tdcs designed to increase neuronal firing, an alternative form of tdcs designed to decrease neuronal firing, and a sham tdcs (stimulation with no current). immediately following the stimulation, participants will be asked to complete measures of mental abilities, including tests presented on a computer screen and paper-and-pencil tests. during each visit, participants will also undergo a standard measure of brain activity (eeg) while listening to tones. the first visit will last approximately five hours, and the other two visits will last approximately four hours each. the project will take approximately two years to complete.

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.

Eligibility criteria:
inclusion criteria: * diagnostic and statistical manual of mental disorders (dsm)-v diagnosis of schizophrenia * must understand spoken english sufficiently to comprehend testing procedures * estimated premorbid intelligence quotient (iq) \> 70 (based on reading ability) * ongoing care of a psychiatrist, psychologist, or other qualified mental health professional exclusion criteria: * metal in cranium * cardiac lines/pacemaker * medication pump * increased intracranial pressure * lifetime history of serious head injury (loc \> 1 hr.) * sedatives or benzodiazepines within 12 hours of testing * clinically significant neurological disease (e.g., seizures) * history of mental retardation or developmental disability * alcohol or substance dependence in the last 6 months * alcohol or substance abuse in the last 1 month * change in medication in past 6 weeks * change in in living situation in the last 2 months * inpatient hospitalization in past 3 months * participation in prior studies involving tdcs