Electrical Brain Stimulation for Cognitive Impairment in Schizophrenia: a tDCS-fMRI Study

Investigating the Mechanism of Action of Electrical Brain Stimulation for Cognitive Impairment in Schizophrenia: a tDCS-fMRI Study

The purpose of this study is to investigate the mechanism of action of transcranial electrical brain stimulation over the dorsolateral prefrontal cortex for cognitive impairment in schizophrenia. To do so the effect of a 3-mA stimulation protocol on neurocognitive functions will be investigated using behavioral performance and fMRI.

Thirty schizophrenic patients will be recruited after meeting the inclusion criteria and will be randomly assigned to active and sham stimulation groups. A single session of concurrent prefrontal tDCS/fMRI will be conducted. Participants will undergo baseline task performance before the intervention. One week later, they will undergo the tDCS intervention (active or sham) next to the scanner during which they perform the working memory task varying in cognitive load. They will perform the task 24 h later again. They will be then transferred to MRI scanner right after stimulation

Inclusion Criteria:

• men or women (18-50 yrs old) with a DSM 5 SCZ diagnosis,
• If female, negative urine pregnancy test
• significant cognitive impairment (1 SD below the norm on the working memory/executive functioning task performance)
• feasibility for tDCS interventions according to safety guidelines
• stable medication regime especially the classical neuroleptics and all CNS-activating medications, if taken, 4-6 weeks before the experiment
• fluency in the native language
• right-handed
• ability to provide informed consent.

Exclusion Criteria:

• pregnancy
• alcohol or substance dependence
• history of seizure
• history of neurological disorder
• history of head injury
• Presence of ferromagnetic objects in the body that are contraindicated for MRI of the head (pacemakers or other implanted electrical devices, brain stimulators, some types of dental implants, aneurysm clips, metallic prostheses, permanent eyeliner, implanted delivery pump, or shrapnel fragments) or fear of enclosed spaces). Eligibility will be determined by the "MRI Safety Screening Questionnaire" and verified, if necessary, by a radiology consultant.