Transcranial Brain Stimulation and Its Underlying Neural Mechanisms as a Novel Treatment for Auditory Hallucinations

The majority of patients with psychosis experience hallucinations, particularly auditory hallucinations are frequent. The hallucinations often leads to massive distress and impairments in social functioning and sometimes even order patients to commit acts of violence against themselves or others. The standard treatment for auditory hallucinations is antipsychotic medication. However, side-effects can be severe and about 25-30% of the patients do not respond to the medication. Transcranial direct current stimulation is a non-invasive brain stimulation technique, which modulates cortical excitability in a pain-free free with mild transient adverse effects, if any. Typically, cortical excitability underneath the anode is boosted while cathodal stimulation has inhibitory effects. Previous studies found that 2 daily sessions of 20 min tDCS for five subsequent days may reduce auditory hallucinations. Investigators want to further assess the efficacy of tDCS in sample that is large enough to detect medium to large effects. In addition, investigators want to investigate the neural mechanisms that underlie the tDCS treatment by examining various neuroimaging parameters before, immediately after treatment, and 3 months after treatment.

Inclusion criteria

• Diagnosed with schizophrenia spectrum disorder or other psychotic disorder
• Frequent auditory hallucinations (at least 5 times a week).
• Patients are on a stable dose of antipsychotic medication (which can also be zero) for at least 2 weeks.
• Mentally competent for informed consent.
• Provided informed consent.

Exclusion criteria

• Metal objects in or around the head that cannot be removed (i.e. cochlear implant, surgical clips, piercing)
• History of seizures, or a history of seizures in first-degree relatives.
• History of eye trauma with a metal object or professional metal workers
• History of brain surgery, brain infarction, head trauma, cerebrovascular accident, broken skull, brain tumour, heart disease, cardiac pacemaker.
• Skin disease on the scalp on the position of the tDCS electrodes
• Coercive treatment based on a judicial ruling
• Pregnancy in female patients