Non Invasive Brain Stimulation to Improve Metaphoric Speech Processing in Schizophrenia: A Pilot Study

Background: An underestimated feature of schizophrenia is the impaired processing of the metaphoric speech, mainly due to a reduced activation of the right hemisphere. Objective/hypothesis: We investigated whether anodal tDCS over the right posterior superior temporal sulcus may improve the processing of metaphoric speech of schizophrenia patients (SCZ). Methods: Ten SCZ subjects were randomly allocated to receive a single session of active tDCS or sham stimulation. Metaphoric speech processing was investigated through a discrimination task between literal or metaphoric expressions. Results: tDCS improved significantly the reaction time but not the accuracy of the answers at the discrimination task compared to sham stimulation. Conclusion: These preliminary results should be verified in larger studies with more sessions of tDCS.