Monday, August 22, 2016

Neuroscience researchers caution public about hidden risks of self-administered brain stimulation

Public Release: 7-Jul-2016
Neuroscience researchers caution public about hidden risks of self-administered brain stimulation
Penn and Harvard researchers lead charge in warning 'Do-it-yourself' users of transcranial direct current stimulation seeking enhanced brain function of potential unintended results
University of Pennsylvania School of Medicine

The growing trend of "do-it-yourself" transcranial direct current stimulation (tDCS) poses hidden risks to healthy members of the public who seek to use the technique for cognitive enhancement. Researchers from the Perelman School of Medicine at the University of Pennsylvania and Beth Israel Deaconess Medical Center, a Harvard Medical School teaching hospital, along with several members of the (cognitive) neuroscience research community warn about such risks involved in home use of tDCS, the application of electrical current to the brain. Their Open Letter will appear in the July 7th issue of Annals of Neurology.


"Published results of these studies might lead DIY tDCS users to believe that they can achieve the same results if they mimic the way stimulation is delivered in research studies. However, there are many reasons why this simply isn't true," said first author, Rachel Wurzman, PhD, a postdoctoral research fellow in the Laboratory for Cognition and Neural Stimulation at Penn. "It is important for people to understand why outcomes of tDCS can be unpredictable, because we know that in some cases, the benefits that are seen after tDCS in certain mental abilities may come at the expense of others."


First, it is not yet known whether stimulation extends beyond the specific brain regions targeted. These indirect effects may alter unintended brain functions. "We don't know how the stimulation of one brain region affects the surrounding, unstimulated regions," said co-author Roy Hamilton, MD, MS, an assistant professor of Neurology and director of the Laboratory for Cognition and Neural Stimulation at Penn. "Stimulating one region could improve one's ability to perform one task but hurt the ability to perform another."

In addition, what a person is doing during tDCS - reading a book, watching TV, sleeping - can change its effects. Which activity is best to achieve a certain change in brain function is not yet known.

Wurzman, Hamilton and colleagues go on to say that they have never performed tDCS at the frequency levels some home users experiment with, such as stimulating daily for months or longer. "We know that stimulation from a few sessions can be quite lasting, but we do not yet know the possible risks of a larger cumulative dose over several years or a lifetime," they wrote.

The authors also suggest that small changes in tDCS settings, including the current's amplitude, stimulation duration and electrode placement, can have large and unexpected effects; more stimulation is not necessarily better.

Finally, the group warns that the effects of tDCS vary across different people. Up to 30 percent of experimental subjects respond with changes in brain excitability in the opposite direction from other subjects using identical tDCS settings. Factors such as gender, handedness, hormones, medication, etc. could impact and potentially reverse a given tDCS effect.


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