The present study aims to investigate whether transcranial direct current stimulation (tDCS) reduces auditory hallucinations in patients with psychosis. In addition, the neuronal changes of tDCS will be examined.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
24
University of Bergen
Bergen, Hordaland, Norway
Auditory Hallucination Rating Scale (AHRS)
Self-report measure for severity of hallucinations; consists of seven items; Sum can range from 2 to 41; higher values indicate more severe hallucinations
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Hallucination Change Scale (HCS)
Measure for changes in severity of auditory hallucinations; participants rated in percent how much their symptoms had improved (or worsened). The range is thus -100 (symptoms reduced by 100%) to +100 (symptoms worsened by 100%)
Time frame: Change from Baseline to immediately after treatment
Positive and Negative Syndrome Scale (PANSS)
Positive Sum Score; conducted by clinical rater; consists of 10 items, range 7-49; higher scores indicate more severe symptoms
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Stroop Task
Measure of executive functioning, Stroop condition #3 in seconds; higher values indicate longer task duration and worse performance
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Trailmaking Test B
Measure of visuomotor speed
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Apathy Evaluation Scale
Total sum of AES score; consists of 18 items; range 18-72, higher values indicate higher degree of apathy
Time frame: Before, immediately after treatment, and at 3 month follow-up
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The Clinical Global Impressions Scale - Severity
Measure of global functioning; rated by clinician on a 7-point scale, with the severity of illness scale rated from 1 (normal) through to 7 (most severely ill)
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Global Assessment of Functioning - S
Measure of global functioning - Symptoms, rated by clinician; measures how much a person's symptoms affect their day-to-day life on a scale of 0 to 100, where 0 is severely impacted in daily life by symptoms and 100 is not affected at all
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Dichotic Listening Paradigm
Measure of executive functioning, forced left condition, percentage reported from left ear
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment
Dichotic Listening Laterality Index
Measure of language lateralization, laterality index in non-forced condition, laterality index is computed according to formula: LI=\[(R-L)/(R+L)\]\*100, where "L" and "R" are the number of correct left and right ear responses, respectively. values can range between -100 (only syllables from left ear correctly reported and +100 (only correct syllables from right ear reported)
Time frame: Change from Baseline to immediately after treatment and 3 months after treatment