Transcranial direct current stimulation for auditory hallucinations: Evidence from clinical and neurophysiological studies

Abstract

Some 25–30% of patients with schizophrenia report auditory hallucinations (AH) that fail to respond adequately to antipsychotic treatments. In such cases, transcranial direct current stimulation (tDCS) has been explored as a therapeutic option. Recently, clinical studies have showed promise of tDCS for reducing AH in patients with schizophrenia, in particular when tDCS was delivered using a fronto-temporal montage. Some studies have tried to explain the therapeutic effects of tDCS by investigating its cognitive and neurophysiological effects in patients with AH and in healthy subjects. Altogether, these studies may provide new evidence on the pathophysiology of AH. The purpose of the symposium is to present recent findings from investigators working at the cutting edge of the field and to discuss how tDCS studies help us understand the brain mechanisms underlying AH. Sanne Koops will present recent findings from an RCT investigating the effects of 2 mA tDCS on medication-resistant auditory hallucinations, general symptoms of psychosis and cognitive function. Ganesan Venkatasubramanian will present findings on the: – effects of tDCS on corollary discharge, mismatch negativity, resting state brain connectivity (fMRI); – neuroplasticity gene correlates of tDCS effects as well as; – clinical utility of MRI-guided High-Definition tDCS (HD-tDCS) in schizophrenia patients with persisting AH. Frederic Haesebaert will present recent findings from a study investigating the effects of tDCS on basic auditory processing, source-monitoring performances, and auditory hallucinations in patients with schizophrenia. Clara Fonteneau will present findings from a recent simultaneous PET-MRI study investigating the effects of fronto-temporal tDCS on subcortical dopamine release (using [11 C] Raclopride PET imaging), brain perfusion (using Arterial Spin Labelling) and resting state functional connectivity (using fMRI) in healthy volunteers.