Non-Invasive Direct Current Stimulation for Cognition in Schizophrenia

Non-Invasive Direct Current Stimulation for Cognition in Schizophrenia

This study proposes to assess the effect of trans-cranial direct current stimulation (tDCS) on cognitive control, working memory, functional, clinical, and cognitive outcomes in schizophrenia patients.

Cognitive functions and EEG correlates will be thoroughly assessed in schizophrenia patients undergoing a tDCS treatment and compared with patients receiving a placebo stimulation. The treatment will involve 20 minutes of tDCS application to the left prefrontal and temporo-parietal cortex, twice a day for five days, a procedure shown to be effective in improving other symptoms of psychosis such as negative symptoms and hallucinations. Critically, in addition to standard neuropsychological testing, cognitive assessments will involve tasks that tap cognitive control and working memory, impairments in which comprise two of the core cognitive disturbances in schizophrenia and which have been linked to brain rhythm disturbances measurable by EEG recordings. Investigators will also assess changes in functional outcome by tDCS and investigate relationships between improvements in cognition, brain rhythms and functional outcome. All these assessments will occur just prior to tDCS application, just after completion of the tDCS series, and then again at 2 months follow-up. There will be two separate independent groups of patients who will be randomized to active versus sham treatments. The first group will have early course schizophrenia (less than 5 years of antipsychotic treatment; n=40). The second group will be chronic schizophrenia (greater than 5 years of antipsychotic treatment; n=40).

Relevance

This proposal would be the first integrated study of the effects of tDCS on cognitive symptoms, brain function and functional outcome in schizophrenia. A positive outcome would represent a marked improvement in clinical therapeutics for cognition in psychosis and provide a powerful tool for improving functional outcome in this debilitating disorder. Understanding the impact on brain rhythm disturbances could support the study of similar stimulation-based therapeutic approaches to other neuropsychiatric disorders that shows similar disturbances in cognition and brain rhythms activity, such as bipolar disorder and autism.

Inclusion Criteria:

Early course psychosis:

• DSM-V diagnosis of Schizophrenia, Schizoaffective disorder, or schizophreniform disorder.
• ages 18-50 years
• on stable doses of medication for at least one month
• not taking benzodiazepines or mood stabilizers.
• Mild to severe cognitive impairment in MATRICS Consensus Cognitive Battery (composite scores < 40)

Chronic psychosis:

Same as early course psychosis but >5 years of antipsychotic treatment

Exclusion Criteria:

• Diagnostic and Statistical Manual-Version V (DSM-V) diagnosis of mental retardation
• significant head injury
• medical illness affecting brain function or structure
• pregnancy or postpartum (<6 weeks after delivery or miscarriage)
• significant neurologic disorder (e.g seizure disorder)
• inability to provide informed consent
• significant color blindness that affects task performance
• Comorbidity for DSM-V substance abuse disorder within the past one month
• Temporal relation between illness onset and head injury
• Taking benzodiazepines or mood stabilizers (lithium allowed)
• Positive drug screen (excluding THC at baseline)