"The evidence of harm would be the evidence that you can hurt some cognitive functions with the same stimulation protocols that help another cognitive function. But they're completely correct that we don't have any evidence saying you're definitely hurting yourself. We do have evidence that you're definitely changing your brain."
interview:
http://www.wbur.org/commonhealth/2016/07/11/caution-brain-hacking
Paper:
http://onlinelibrary.wiley.com/doi/10.1002/ana.24689/references
I was aware of the variability of responses to stim, but not the paper that leveraging one brain function could impair another. This was also written to give the docs some info to help inform their patients.
edit
I'll also tuck this in here, as i posted it to open thread.
Texting changes brain waves to new, previously unknown, pattern.
http://sciencebulletin.org/archives/2623.html
Makes me wonder if they were using spell check, or the new, shortend speak. By using constructed kernels, or images of words and concepts, it looks like machine learning retrieval or construction is already being practiced here ?
A reply to the case that tDCS doesn't have enough current to actually be affective.
Response to the Response: Does tDCS Actually Deliver DC Stimulation?
paywalled http://www.brainstimjrnl.com/article/S1935-861X%2816%2930212-1/fulltext
there is a journal for brain stim now
http://www.brainstimjrnl.com/