Despite thousands of studies, there remain many mysteries. Most studies involve extremely short experiments with few participants, and they often assess results after just a single session, using very specific tasks. That means results are not generally applicable to real-life situations or to all people. And nobody knows what the consequences might be of frequent use for long periods of time, which is how many people would like to use tDCS.
There is plenty of optimism that tDCS will eventually have real, even transformative applications. But that time does has not come. “At the moment, I don’t know about any protocol or device for which we could really say you could use for gaming or everyday tasks and it would improve performance and there would be no risks with it,” Nitsche says. “My advice would be to be cautious.”