​London, April 24 (IANS) Far from making you smarter, electrical stimulation of the brain's cells while solving challenging tasks can lead to mental overload, warn researchers.

The researchers wanted to test whether a treatment that sends a very weak electrical current through the skull to the outer layers of the brain, so-called transcranial direct current stimulation (tDCS), can actually make us smarter.

The tasks for the participants were divided into three levels -- simple, medium and difficult.

The researchers found no effect of stimulation when participants performed the simple and medium tasks, yet they found a large negative effect on the most difficult tasks.

"tDCS had a disruptive effect only on the most difficult tasks that demanded a lot of concentration," said one of the lead researchers, James Roe from the University of Oslo in Norway.

"We saw that participants experienced severe problems concentrating when the task was most difficult and the brain was being stimulated," Roe noted.

"It was as though tDCS had completely overloaded a brain region crucial to performing the task, as though it crashed it," Roe explained in a paper published in the journal Neuropsychologia.

In recent times neuroscientists have been showing increased interest for tDCS. Many claim that the device can, among other things, help improve memory, increase self-control and make us more creative.

tDCS is already implemented in the rehabilitation of a range of psychiatric and neurological conditions, such as depression, stroke, Alzheimer's disease, fibromyalgia and tinnitus.

While the researchers acknowledged that tDCS can indeed have a positive impact, they said the study shed light on the effects of tDCS when we solve tasks of varying difficulty.​