Using tDCS – mild electric jolts to stimulate your brain – actually hurts your IQ score.

Science Daily reports on University of North Carolina research that shows transcranial stimulation, the fascinating new tech that uses mild DC current to “switch on” parts of your brain, might really be lowering people’s intelligence:

Published in the journal Behavioural Brain Research, the study adds to the increasing amount of literature showing that transcranial direct current stimulation — tDCS — has mixed results when it comes to cognitive enhancement.

“It would be wonderful if we could use tDCS to enhance cognition because then we could potentially use it to treat cognitive impairment in psychiatric illnesses,” said Flavio Frohlich, PhD, study senior author and assistant professor of psychiatry, cell biology and physiology, biomedical engineering, and neurology. “So, this study is bad news. Yet, the finding makes sense. It means that some of the most sophisticated things the brain can do, in terms of cognition, can’t necessarily be altered with just a constant electric current.”

Frohlich, though, said that using less common alternating current stimulation — so-called tACS — could be a better approach, one that he has been investigating. Earlier this year, Frohlich’s lab found that tACS significantly boosted creativity, likely because he used it to target the brain’s natural electrical alpha oscillations, which have been implicated in creative thought.

With tDCS, scientists don’t target these brain waves, which represent neuronal patterns of communication throughout regions of the brain. Instead, they use tDCS to target brain structures, such particular regions of the cortex.

Personally, I’ve heard of creativity-boosting properties of transcranial stimulation for years. I wonder if this study is reflecting either a/ smug overconfidence in one’s boosted abilities (tortoise and the hare, only with electrodes taped to their scalps) or b/ the fact that getting into a creative groove is actually not a great way to do something as boring as take an IQ test.

On the other hand, the specific effects kind of lean away from that reading:

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.

When Frohlich and colleagues analyzed the test scores, they saw that the scores for three of the four main kinds of cognitive tests were very similar between the two groups of participants. But the scores for perceptual reasoning were much lower among people who underwent tDCS.

Perceptual reasoning tests fluid intelligence, which is defined as the ability to think logically and apply innovative problem solving to new problems.

Within the category of perceptual reasoning, the researchers saw the biggest differences in the subcategory of matrix reasoning — when participants viewed two groups of symbols and had to find the one symbol missing from the other group.