Schizophrenia auditory hallucination trial#

To our knowledge, this is the first clinical trial of tACS for the treatment of symptoms of a psychiatric condition. Effect size analysis for the secondary outcomes revealed heterogeneous results across measures and stimulation conditions. However, effect size analyses show that tACS had the greatest effect based on the auditory hallucinations scale for the week of stimulation (1.31 for tACS 1.06 and 0.17, for sham and tDCS, respectively). Primary and secondary behavioral outcomes were not significantly different between the three arms. The Positive and Negative Syndrome Scale (PANSS) and the Brief Assessment of Cognition in Schizophrenia (BACS) were secondary outcomes. Symptom improvement was assessed using the Auditory Hallucination Rating Scale (AHRS) as the primary outcome measure. Here, we evaluated the feasibility and efficacy of transcranial alternating current stimulation (tACS) that we hypothesized would improve auditory hallucination symptoms by enhancing synchronization between the frontal and temporo-parietal areas of the left hemisphere.Ģ2 participants were randomized to one of three arms and received twice daily, 20 min sessions of sham, 10 Hz 2 mA peak-to-peak tACS, or 2 mA tDCS over the course of 5 consecutive days. These problems are common to studies of other psychiatric symptoms and should be considered when attempting to understand the basic neural mechanisms responsible for them.Īpproximately 30% of patients with schizophrenia experience auditory hallucinations that are refractory to antipsychotic medications.

We conclude that efforts to understand the pathophysiology of AVH using EEG and MEG have been hindered by poor anatomical resolution of the EEG and MEG measures, poor assessment of symptoms, poor understanding of the phenomenon, poor models of the phenomenon, decoupling of the symptoms from the neurophysiology due to medications and comorbidites, and the possibility that the schizophrenia diagnosis breeds truer than the symptoms it comprises. While most studies show differences in EEG and MEG responses between patients and controls, far fewer show symptom relationships. Third, we discuss studies addressing possible mechanisms of AVH, including spontaneous neural activity, abnormal self-monitoring, and dysfunctional interregional communication. They suggest a tendency to hallucinate is associated with competition for auditory processing resources. Second, we discuss 'trait' studies where EEG and MEG responses to sounds are recorded from patients who hallucinate and those who do not. EEG (electroencephalography) and MEG (magnetoencephalography) data point to frontal and temporal lobe activity, the latter resulting in competition with external sounds for auditory resources. These studies take 2 forms: passive studies, where brain activity during these states is compared, and probe studies, where brain responses to sounds during these states are compared. First, we describe 'state' (or symptom capture) studies where periods with and without hallucinations are compared 'within' a patient. We discuss 3 neurophysiological approaches to study auditory verbal hallucinations (AVH).

Thus our findings support the CAPD model and are consistent with that which postulate reduced prosodic processing during AHs. Further, a significant increase in relative power was observed in the left, but not in the right auditory cortex during AHs. Since coherence is a pairwise measure of functional correlation between regions, our findings suggest abnormally increased synchrony between the left and right auditory cortices during AHs in schizophrenia. There was no significant change observed in the coherence between Broca's and Wernicke's areas, but a significant increase was observed in coherence between the left and right superior temporal cortices during AHs compared with non-AHs, suggesting increased bilateral coherence between auditory cortical areas. Coherences between electrodes located over Broca's area (BA 44/45) and Wernicke's area (BA 22/42) and between electrodes located over left-right temporal cortices were examined. Four cortical regions were considered based on the existing dominant models for auditory hallucinations, the inner speech model and the central auditory processing deficit (CAPD) model. We studied the change in EEG alpha-band average coherence between auditory hallucination (AH) and non-auditory hallucination (non-AH) states in seven auditory hallucinating schizophrenia patients.

Schizophrenia auditory hallucination