TDCS For Cognitive Deficits In Patients With Schizophrenia:a Randomized Controlled Trial

Objective: Cognitive impairment is a core symptom of schizophrenia.However,currently no effective treatments for cognitive deficits are available.Transcranial direct current stimulation(tDCS)is considered as a safe non-invasive brain stimulation technique with a potential in improving cognitive function.At present,most studies were focused on whether an amelioration of clinical symptoms could be achieved after tDCS intervention,while only a few studies investigated the effects of tDCS on cognitive function with inconsistent results reported.Moreover,all of these tDCS-cognition studies only investigated the modulating effect either during treatment or right after the end of treatment without further follow-up to explore how long the tDCS benefit could last..The aim of the study was to further investigate the pro-cognition efficacy and safety of tDCS over a fourweek follow-up.Methods: A randomized,double-blinded,parallel-controlled trial was conducted.Inpatients with a DSM-5 diagnosis of schizophrenia were recruited.All patients were clinically stable and had cognitive deficits.Patients who met criteria were randomized into the active group or the sham group.Each patient received one session of tDCS per day on ten consecutive days(weekends and holidays excluded).The anode was placed over the left dorsal lateral prefrontal cortex and the cathode over the contralateral(right)supraorbital ridge.The active tDCS was given continuously for 20 min at 2mA.For the sham tDCS,electric current lasted only 40 seconds though the electrodes remained in place for 20 min.Adverse effects were assessed after each session.Both groups received treatment as usual in addition to tDCS intervention.The MATRICS Consensus Cognitive Battery(MCCB),the Paced Auditory Serial Addition Task(PASAT),CogState Battery,the Reading the Mind In the Eyes Test(RMET)and the Positive and Negative Syndrome Scale(PANSS)were administered at baseline,immediate after the last session,2-week follow-up,and 4-week follow-up to evaluate changes in cognitive functions and clinical symptoms.Results: 1.48 patients were randomized into two groups with 24 patients in each group.Two patients in the sham group were excluded from the full analysis set for the deterioration of symptoms.2.Significant time effect(F=0.000,p=0.000),group main effect(F=0.008,p=0.008),and group-bytime interaction(F=0.006,p=0.006)in processing speed in MCCB,as well as significant time effect(F=0.001,p=0.001)and group-by-time interaction effect(F=2.511,p=0.031)in 1-back task of CogState were found utilizing repeated measure ANOVA with baseline performance as the covariates.3.No effects were observed for PANSS total scores or PANSS subscale scores.4.Tingling,itching,and scalp pain were sensations patients the most commonly reported.One patient in sham group during the intervention experienced transient ischemia attack.Conclusion:Our findings suggested that tDCS might enhance the performance of processing speed and simple working memory in schizophrenia.Generally,tDCS was well tolerated.There remain a need for large-scale research to verify the results.