'A current of two thousandths of an ampere (a fraction of that needed to power a digital watch) applied for 20 minutes is enough to produce a significant improvement, according to data presented this week at the annual meeting of the Society for Neuroscience, held in San Diego,' said Nature magazine. 'And apart from an itchy sensation around the scalp electrode, subjects in the trials reported no side-effects.'
According to Nature, Meenakshi Iyer of the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland, ran the current through 103 initially nervous volunteers. But recruitment was easy once she convinced them that the current was harmless. "I had to explain it in detail to the first one or two subjects," she said.
After being wired, the volunteers were asked to name as many words as possible beginning with a particular letter.
Given around 90 seconds, most people get around 20 words. But when Iyer administered the current, her volunteers were able to name around 20% more words than those who had the electrodes attached but no current delivered, said the Nature
A smaller current of one thousandth of an amp had no effect.
While conceding that more work needs to be done, Iyer suspects the current changes the electrical properties of brain cells in the prefrontal cortex, the brain region through which it passes, said Nature.
These cells fire off signals more easily after the current has passed through, and this would make the area in the brain region involved in word generation more active, she believes.
Nature said Iyer's group, led by Eric Wassermann, ran the tests after considering problems facing researchers studying the effect of magnetic fields on the brain. While magnetic fields can cause seizures and require bulky equipment, some researchers believe they could boost activity in areas of the brain which have suffered cell loss owing to dementia.
Low electric currents will offer a safer, easier alternative, hopes Iyer, who plans to test patients with frontal temporal dementia, a brain disease that causes speech problems, after completing more safety tests, Nature said.
"This won't be a cure," she warned. "But it could be used in addition to drugs."
