This is a 4 week therapeutic pilot study with a 4 week follow-up period involving inpatients with treatment resistant DSM-IV schizophrenia or schizoaffective disorder diagnosis. Each eligible subject will receive either 20 minutes of active tDCS (transcranial direct-current stimulation) or sham stimulation twice a day on 5 consecutive weekdays for 4 weeks with a 4 week follow-up period.

The aim in this study is to conduct a pilot study on the efficacy of tDCS by assessing its efficacy in treatment refractory auditory verbal hallucinations in inpatients with chronic schizophrenia. Based on and expanding the findings by Brunelin et al. the hypothesis is that tDCS treatment with the cathode on the left temporal-parietal junction and the anode on the left dorsolateral prefrontal cortex can reduce the severity of auditory verbal hallucinations in patients with treatment refractory schizophrenia. The impact of tDCS on other schizophrenia symptoms in secondary exploratory outcome analyses together with the examination of the durability of an ameliorating effect will also be investigated.

Inclusion Criteria:

• Inpatient adults (age 18-65 years) who meet diagnostic criteria for schizophrenia or schizoaffective disorder (using the Structured Clinical Interview for DSM)
• Auditory hallucinations without remission over 5 years (remission is defined as a period of 4 weeks without hallucinations) as documented in the patients' medical record
• Failure to respond to two previous adequate antipsychotic trials with adequate duration and adequate dosage
• Screening PANSS total rating of > 70
• PANSS hallucinatory behavior item > 4
• Capacity and willingness to sign informed consent
• On a stable antipsychotic regimen 4 weeks prior to screening and for the duration of the trial
• Normal hearing
• If female and not infertile, must agree to use one of the following forms of contraception for the duration of study participation: systemic hormonal treatment, an interuterine device (IUD) which was implanted at least 2 months prior to screening, or "double-barrier" contraception
• Willing to wear the tDCS device.

Exclusion Criteria:

• Prior history of seizure, other than that induced by Electro Convulsive Therapy
• Family history of seizures
• Significant unstable medical condition
• Pregnancy or women of childbearing capacity not using a medically accepted form of contraception when engaged in sexual intercourse
• Inability to provide informed consent
• Actively suicidal and or showing violent behavior
• Significant organic brain pathology by history and neurological examination, inclusive of history of head trauma, loss of consciousness for more than 5 minutes; intracranial metal implants, known structural brain lesion, devices that may be affected by transcranial Direct Current Stimulation (tDCS) (pacemaker, medication pump, cochlear implant, implanted brain stimulator)
• Active substance abuse
• Increased intracranial pressure, unstable cardiovascular disease, sleep apnea
• Individuals with a clinically defined neurological disorder
• Frequent and persistent migraines
• History of adverse reaction to neurostimulation or open skin wounds that would preclude safe placement of tDCS electrodes
• Current use of medications known to lower seizure threshold (serotonergic or tricyclic antidepressants)
• If pregnant or breast feeding at the time of screening

Raters were blind as was PI.