• Log in with Facebook Log in with Twitter Log In with Google      Sign In    
  • Create Account
              Advocacy & Research for Unlimited Lifespans

Adverts help to support the work of this non-profit organisation. To go ad-free join as a Member.

- - - - -

tDCS found to decrease IQ


  • Please log in to reply
8 replies to this topic

#1 Invariant

  • Guest
  • 176 posts
  • 60
  • Location:-

Posted 11 May 2015 - 05:54 PM

Big news for self-experimenters:


Popular electric brain stimulation method used to boost brainpower is detrimental to IQ scores



Using a weak electric current in an attempt to boost brainpower or treat conditions has become popular among scientists and do-it-yourselfers, but a new study shows that using the most common form of electric brain stimulation had a statistically significant detrimental effect on IQ scores.

In the Behavioural Brain Research study, Frohlich's team -- including graduate student Kristin Sellers, the paper's first author -- recruited 40 healthy adults, each of whom took the standard WAIS-IV intelligence test, which is the most common and well-validated test of IQ. It includes tests for verbal comprehension, perceptional reasoning, working memory, and processing speed.

A week later, Frohlich's team divided the participants into two groups. Electrodes were placed on each side of each participant's scalp, under which sat the frontal cortex. Duke University collaborator and co-author Angel Peterchev, PhD, created imaging simulations to ensure Frohlich's team targeted the same parts of the cortex that previous tDCS studies had targeted.

Then the placebo group received sham stimulation -- a brief electrical current, which led participants to think they had been receiving the full tDCS. The other participants received the standard tDCS for twenty minutes -- a weak electrical current of 2 millioamperes.

All participants then retook the IQ tests. Frohlich expected that most, if not all, IQ scores would improve because of the practice effect, but that tDCS would not markedly improve scores.

Frohlich's team did find that all scores improved. Surprisingly, though, the participants who did not receive tDCS saw their IQ scores increase by ten points, whereas participants who received tDCS saw their IQ scores increase by just shy of six points, on average.


Here is the original study:

Transcranial direct current stimulation of frontal cortex decreases performance on the WAIS-IV intelligence test
  • Kristin K. Sellers
  • Juliann M. Mellin
  • Caroline M. Lustenberger
  • Michael R. Boyle
  • Won Hee Lee
  • Angel V. Peterchev
  • Flavio Frohlich 


Attached Files

  • Informative x 1
  • like x 1
  • Agree x 1

#2 mcleodx

  • Guest
  • 16 posts
  • 5
  • Location:Canberra, Australia

Posted 23 March 2016 - 12:43 PM

My personal experiences with tDCS would be in-line with this.  I actually performed worse on online brain-training testing during tDCS as well as afterwards.  I know that brain-training scoring isn't exactly a strict representation of IQ, however a more accurate way I'd say it is that it generally had a negative effect on cognition.

Edited by mcleodx, 23 March 2016 - 12:44 PM.

sponsored ad

  • Advert

#3 Omega 3 Snake Oil

  • Guest
  • 257 posts
  • 3
  • Location:USA
  • NO

Posted 25 March 2016 - 05:01 PM

damn. I wonder where the popularity is coming from...

#4 mcleodx

  • Guest
  • 16 posts
  • 5
  • Location:Canberra, Australia

Posted 26 March 2016 - 07:34 AM

It's subjective.  Nootropics are another really good example of a huge variation between what some people think to other people, even when talking about the same compound and the same amounts.  tDCS is no different.  

#5 Omega 3 Snake Oil

  • Guest
  • 257 posts
  • 3
  • Location:USA
  • NO

Posted 26 March 2016 - 04:13 PM

what is the best test to determine if tcds is effective? eg a certain type of IQ test, and when to take, etc?

#6 mcleodx

  • Guest
  • 16 posts
  • 5
  • Location:Canberra, Australia

Posted 27 March 2016 - 11:06 AM

I use online brain training to measure.  I won't post the name of the website, but if you type in "brain training online" it'll be the top result.  Spend two weeks + doing their training at least once a day, then use that as a control and start using tDCS before, during and after completing training.

#7 treonsverdery

  • Guest
  • 1,298 posts
  • 160
  • Location:where I am at

Posted 19 December 2016 - 10:02 PM

This study https://www.ncbi.nlm...pubmed/25346688 says it raises "performance" IQ in people with alzheimers.  lots more studies and metanalysis would be beneficial

Edited by treonsverdery, 19 December 2016 - 10:03 PM.

#8 Ben

  • Guest
  • 2,006 posts
  • -3
  • Location:South East

Posted 09 June 2017 - 02:17 AM

This study is queer. It really measures the magnitude of the effect of having already done the test. tDCS people were 6 points better for having the practice and the non-tDCS were 10 points better.


Can the statement "tDCS found to decrease IQ" be made from such a study (even if it a perfect study)? No.


Of interest is whether tDCS can improve general intelligence or reaction speed. Also, can it improve video game or military performance? How long does this effect last for?  This study answers none of those interesting questions.

Edited by Ben, 09 June 2017 - 02:17 AM.

sponsored ad

  • Advert

#9 AlwaysLearning

  • Guest
  • 43 posts
  • 10
  • Location:Seattle, WA
  • NO

Posted 11 September 2019 - 09:06 PM

I realize this is an old thread, but it's worth mentioning that the study used bizarre montages with cathodes over Cz, which I've never seen mentioned in the literature before.

Also tagged with one or more of these keywords: tdcs

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users