We have previously shown the efficacy of bi-anodal transcranial direct current stimulation (tDCS) over the prefrontal cortex (PFC) regions with extracephalic references placement in improving negative symptoms in schizophrenia. In this ancillary investigation, the effects of this intervention on insight levels, other clinical outcomes, cardio-respiratory and autonomic functions were examined and the potential of biomarkers for treatment response was explored.
Schizophrenia patients were randomly allocated to receive 10 sessions of bi-anodal tDCS over the PFC regions with extracephalic references placement (2 mA, 20 min, twice daily for five weekdays) or sham stimulation. We examined, in 60 patients at baseline, immediately after stimulation and at follow-up visits, the insight levels, other clinical outcomes, blood pressure, respiratory rate, heart rate, and heart rate variability (HRV).
Insight levels as assessed by the abbreviated version of the Scale to Assess Unawareness in Mental Disorder in schizophrenia (SUMD) awareness of the disease, positive and negative symptoms dimensions and beliefs about medication compliance as assessed by Medication Adherence Rating Scale (MARS) were significantly enhanced by active stimulation relative to sham. No effects were observed on cognitive insight, other clinical outcomes, cardio-respiratory and autonomic functions. HRV indices as biomarkers were not associated with the clinical response to the intervention.
Our results provide evidence for bi-anodal tDCS over the PFC regions with extracephalic references placement in heightening the levels of insight into the disease and symptoms as well as and beliefs about medication compliance in schizophrenia, without impacting other clinical outcomes and cardio-respiratory/autonomic functions.
© The Author(s) 2020. Published by Oxford University Press on behalf of CINP.