New York: Contrary to popular belief, electric brain stimulation method used to boost brainpower is actually detrimental to IQ scores, a new research has found.

Using a weak electric current in an attempt to boost brainpower or treat conditions has become popular among scientists and do-it-yourselfers, but the new 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 study senior author Flavio Frohlich, assistant professor in University of North Carolina School of Medicine.

‘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, cannot necessarily be altered with just a constant electric current,’ Frohlich cautioned.

The tDCS boom started in 2000, when German scientists published a paper showing that tDCS could change the excitability of neurons in the motor cortex - the brain region that controls voluntary body movement.

In the new study, the 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.

The researcher found that 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.

The study appeared in the journal Behavioural Brain Research.