Effects of transcranial direct current stimulation over frontal, parietal and cerebellar cortex for cognitive function during fasting in healthy adults

BACKGROUND: Transcranial direct current stimulation (tDCS) is a neuromodulation tool used to modify the cognitive function in subjects. There is a paucity of data on tDCS’ effect on cognitive function during Ramadan fasting. This paper aims to assess the effect of tDCS of three brain areas, including the right dorsolateral prefrontal cortex (DLPFC), posterior parietal cortex (PPC), and cerebellum on cognitive function, and obtain safety data in healthy adults during Ramadan fasting. METHODS AND MATERIAL: A total of 42 healthy, right-handed participants were randomly assigned to one of the 6 stimulation groups: active (anodal)-tDCS of right DLPFC, PPC, and cerebellum; or sham for DLPFC, PPC, and cerebellum after 8 h of fasting for Ramadan. Safety data and cognitive function, such as attention-switching tasks (AST), were obtained by employing the Cambridge Neuropsychological Test Automated Battery (CANTAB) before and after each tDCS session. The cognitive function outcome variables were the response time and the percentage of correct answers in AST. For sham stimulation, the placement of the electrodes was the same as for the active stimulation. RESULTS: An improvement in performance time in attention tasks was observed; however, it did not reach a significant level after anodal stimulation of the DLPFC, PPC, and cerebellum. Overall, there were no statistically significant differences between the active and sham tDCS groups in cognitive function. There were no significant side effects of tDCS during fasting for any group. CONCLUSIONS: Our data suggest that there are variable effects of tDCS on attention tasks during Ramadan fasting. TDCS appears to be safe, well-tolerated and adhered to the international standard of safety in the local population during Ramadan fasting. Further large sample size studies should be conducted to validate the current study findings and reach better conclusions.