https://www.ncbi.nlm.nih.gov/m/pubmed/29954701/
“Irrespective of the stimulation intensity, data analysis showed a significant higher WM accuracy during active tDCS than during sham tDCS (p = 0.019), but no main effect of stimulation intensity (p = 0.392). Subsequent separate analyses revealed a significantly improved WM performance only during 1 mA (p = 0.048). TDCS facilitated WM functioning in schizophrenia, with an advantage of 1 mA over 2 mA. Our results support the notion that tDCS may be a potential treatment for cognitive deficits in schizophrenia and emphasize the need for future research on the specific stimulation parameters.”