I had to get into the medical publications on this subject because a friend approached me one year ago with the idea of commercializing tDCS devices. I warned him that it looked like a fraud.

The thing is, scientists are using transcranial MAGNETIC stimulation (TMS) more and more these days as interesting results are appearing. However, TMS is hard to do correctly. In the meantime, tDCS got branded as "almost the same thing" (I suspect that "tDCS" is a new term purposefuly chosen to sound similar to TMS) and quoted publications about TMS to claim a proven effect.

tDCS is pretty easy: put two electrodes on the cranium and impose a small current between them. Mass-manufacturing them is easy and cheap. The only problem is that they have nothing to do with the tech proven to work.

An important caveat from the inclusion criteria (touched on in the body of the IEEE piece, to their credit):

> We chose to exclude measures that have only been replicated by a single research group to ensure all data included in and conclusions generated by this review accurately reflect the effects of tDCS itself, rather than any unique device, protocol, or condition utilized in a single lab.

If you looked at the (paywalled) appendix Table S3, you will see that (by eye) 100-something measures have been excluded.

The researchers had justifiable reasons for doing so and it is a decision I (as a non-expert, granted) agree with, but it means the headline is incorrect; the analysis found no effect for a certain set of measures (albeit quite a few -- more than I want to type or count) in four domains.

Also, like all good articles it includes a few paragraphs on limitations; I found the following one particularly interesting (and probably relevant to "brain hackers", of which I am not one):

> This paper only explores cognitive measures undertaken during or following one session of tDCS. As noted in the results section, there are many studies which have utilized a multiple-day stimulation paradigm. It is wholly possible that several sessions of tDCS are required in order for a reliable effect to be seen. In this instance, it has been argued tDCS impacts cognition via repeated exposure and, possibly, overnight consolidation.

And the rest of the measures are unproven because they haven't been replicated (by different teams, presumably).

Therefore, on the balance, no measures have been shown to be effective (either because they're not effective, or because they haven't been replicated).

Something really fascinates me about medicine... it's so incredibly difficult to actually tell if anything works!

I mean look at the debates over antidepressant drugs. There are some large studies that claim most are no better than placebo, and others that claim otherwise.

I feel like there has to be room for improvement here. Maybe we need to start learning to go beyond large studies at a distance and start really measuring things in real time, e.g. with something like an evolved connected descendant of the FitBit.

It's because most scientists and the organizations funding them are not interested in advancing our knowledge of nature so much as looking like they're advancing our knowledge of nature. If we want to be less wrong, we need more replication. Scientists don't want to do replication because it advances our knowledge of nature without looking like it is. So instead they keep trying to find fainter and more obscure effects, so faint that they exceed their own abilities to recognize statistical significance. It fools reviewers, journal editors and employers though, so they keep it up.

To argue, scientists/corporations are interested in the illusion of advancement is a fair point, albeit a pessimistic one.

"Scientists don't want to do replication because it advances our knowledge of nature without looking like it is"

To argue they therefore purposely want to prevent actual progress (on a whole) seems disingenuous.

As one who lives amongst Australians let me assure you that nothing, not even vigorous beatings on the cranium with a heavy stick, will have any measurable effect on the brain activity of the average Australian.

The problem with this meta study is the tDCS methods are not controlled. It's possibly true, but this seems to be pretty much up in the air!

Agreed. There are too many various electrodes, machines and protocols for the same applications. It would be interesting to see a study that incorporates readings of neurotransmitters, MRI & EEG prior to and post tDCS application over a longer period.

I also think the chief science officer of Thync was avoiding making any medical claims as tDCS is yet to be FDA approved.

It will be particularly interesting to see if Thync tries to get studies from third parties. It looks like tDCS hasn't been solidly proven or disproven, so it will be exciting if this gets more researchers to look into the effectiveness of tDCS.