Of course, there is research into using low dose electrical stimulation of the brain, a technique called transcranial direct current stimulation (tDCS). Dan Hurley published an article in the online magazine for The New York Times, Jumper Cables for the Mind, where he described the science and history of tDCS as well as his personal experience with it. It uses less than 1 percent of the electricity necessary for electroconvulsive therapy and can be powered by an ordinary nine-volt battery. Papers published in peer-reviewed scientific journals have claimed tDCS can improve:

Everything from working memory to long-term memory, math calculations, reading ability, solving difficult problems, piano playing, complex verbal thought, planning, visual memory, the ability to categorize, the capacity for insight, post-stroke paralysis and aphasia, chronic pain and even depression. Effects have been shown to last for weeks or months.

Felipe Fregni, the physician and neurophysiologist where Hurley received tDCS, said that it won’t make you superhuman, “but it may allow you to work at your maximum capacity.” He said the strongest evidence for its effectiveness was for depression. By itself, he said tDCS was as effective as Zoloft at relieving depression. “But when you combine the two, you have a synergistic effect, larger than either alone. That’s how I see the effects of tDCS, enhancing something else.” Looking at the JAMA Psychiatry abstract for Fregni’s published article, the researchers also found that out of 125 participants in the study, there were 7 cases of treatment-emergent mania or hypomania—5 of which were in the combined treatment group. So one the things enhanced by combining the use of Zoloft and tDCS was mania and hypomania.

Hypomania is a mood state that is less intense than mania. The individual is impulsive, shows a lack of restraint in social situations and is a poor judge of risky activities. Motor, emotional and cognitive abilities could be effected. The person may be euphoric or irritable, but typically to a lesser intensity than in mania. Their characteristic behaviors are being very energetic and talkative. They are quite confident while verbalizing a flight of creative ideas.

Because of the inexpensiveness and easy application of tDCS, people are treating themselves with kits and homemade devices. Hurley indicated that YouTube videos showing individuals experimenting on their own brains are available. They look more foolhardy than the cast of “Jackass,” he said.  “What they fail to realize is that applying too much current, for too long, or to the wrong spot on the skull, could be extremely dangerous.” Here seems to be one example of what he meant: “Still Zapping My Brain.” Yet there is a good bit of serious research a well: tDCS for Cogntive Enhancement or Centre for Brain Science: Transcranial Direct Current Stimulation (tDCS).

So-called DIY head zappers ignore the caution from scientists that tDCS is not ready for home use. The research is preliminary and stimulation could be dangerous. Home use is only as good as the person who built and operated the system. Some people have posted online images of scalp burns from improper current.  There have been some rare reports of manic episodes and even temporary paralysis.

“We are in such a fog of ignorance,” says neuroethicist Hank Greely of Stanford Law School, who studies how brain research intersects with society. “We really need to know more about how this works.”

Caroline Williams at NewScientist.com reported that Jared Horvath and others at the University of Melbourne reviewed more than 100 studies of tDCS and only found one that was convincing. He said there didn’t seem to be any significant or reliable effect of tDCS on blood flow, electrical, or evoked activity within the brain. tDCS supporters dispute the findings. Horvath and his research team are finalizing another analysis that looks at the evidence for cognitive and behavioral change after tDCS. Vincent Walsh, a cognitive neuroscientist at University College London is not convinced there will be any supportive results.

In terms of cognition, which is the other aspect that people make claims about, tDCS is massively hyped. The danger is that people have been promised better memories, better reading, better maths, increased intelligence… you name it. The effects are small, short lasting, and no substantial claims have been replicated across laboratories. This paper [Horvath’s] is hopefully the beginning of a counterweight to all the bullshit.

Horvath has recently published his further research into the efficacy of tDCS, claiming he found no evidence of cognitive effects from a single-session of tDCS. What was unique about this study is that Horvath and his colleagues only included independently replicated studies. This means an originally published study that another research group had repeated. “Our quantitative review does not support the idea that tDCS generates a reliable effect on cognition in healthy adults.” Of the 59 analyses conducted, no significant effect for tDCS was found—regardless of the inclusion laxity of the studies.

Neuroskeptic, a British neuroscientist, pointed out the exclusion of non-replicated studies was an unusual restriction. However, it seems to me that the intent was to correct for the research problems with publication bias (see “Open Access Could ‘KO’ Publication Bias”). He quoted Nick Davis, who has published several papers about tDCS, who said Horvath’s review was useful, helping researchers think about the way they talk about the effects of tDCS. Davis remains optimistic about the future of tDCS.

tDCS is still a developing technology. I think that with more principled methods of targeting the current flow to the desired brain area, we will see tDCS become one of the standard tools of cognitive neuroscience, just as EEG and fMRI have become.