From scientists conducting experiments in the laboratory to the infamous ECT scene in One Flew Over the Cuckoo’s Nest, the images that are conjured up by a mention of electrical brain stimulation vary.
What you are unlikely to picture is an individual sitting in their bedroom, applying electricity to their own brains recreationally. However, there are hundreds – and potentially thousands – of people across the world doing just this. There is an increasing number of people practicing brain stimulation with electricity on themselves, often using kits bought via the internet or made at home. But what are the causes of this growing trend? And most importantly, is it safe?
tDCS: An Introduction
The method of electrical stimulation that these people are taking part in is transcranial direct current stimulation (tDCS). This is a type of neurostimulation that has traditionally been used to help patients who have suffered from a brain injury, such as a stroke.
It is much less intense than its notorious relative, electroconvulsive therapy (ECT), which uses a relatively strong current to shock the brain in an attempt to essentially ‘re-set’ it. tDCS, on the other hand, sends small amounts of electricity into the brain to alter the activity of neurons. It therefore doesn’t ‘shock’ the brain as such, but influences the threshold at which it becomes active.
Brain activity can be increased or decreased depending on the placement of the anodal or cathodal electrode. Activity is increased when the anodal electrode is placed on the area that is to be stimulated, and decreased when the cathodal electrode is placed on the area. For example, if someone wanted to increase mathematical ability, then the anodal electrode would be placed over the dorsolateral prefrontal cortex, which is located on the forehead. The idea is that the anodal stimulation will increase the threshold – meaning the likelihood of the brain being active in that area – and this in turn will help improve mathematical ability.
Researchers at Coventry University have recently been using tDCS to investigate a brain area involved in supernatural beliefs. This study is just coming to an end and results should be published soon – you can keep up to date with the project via the Neurostimulation of Belief project page.
Out of the Laboratory
It certainly sounds like the sort of practice that should be reserved for the laboratory, but there is a growing trend for people buying tDCS kits for use at home. There are online communities for those who practice tDCS on themselves, where discussions range from the types of kits used and the various positioning of the sponges (known as montages), to the results that people have gotten from them. There are also more kits appearing on the market – even travel-sized versions for people to take and use on the go.
So why are these people taking what seems to be such a high risk by applying electricity to their own brains? There are several reasons why individuals may be interested in brain stimulation. Firstly, there are people who do the treatment to improve their memories, sharpen their focus or to improve in a particular skill, such as mathematics. Others use the method to target specific mental health problems that they believe have been unresponsive to drugs, such as depression or anxiety.
Treating conditions of this type with electricity is certainly nothing new; electricity has been used over the centuries in an attempt to cure people with ailments including epilepsy, headaches and melancholy (a condition we would now identify as akin to depression). Feedback from the online community seems to thus far be positive, with many anecdotal accounts of people performing better in academic exams or seeing their mood alter considerably following sessions of tDCS. But is it safe to do at home?
The Risks of At-Home tDCS
Dr Ute Kreplin, from the Coventry University Brain, Belief and Behaviour research theme group, says:
“In regards to people making their own kits at home, this is certainly not advisable. Devices that are sold are usually fitted with safety features, such as limits on the duration/intensity, and emergency switches. Homemade kits probably don’t have these, and people are also without the advice and help that is usually available from a reputable seller.
“Also, devices used in research are never connected to the mains, but I don’t know what the story would be with homemade kits. If they were powered this way, then they would also leave individuals more open to harm via burns or even electrocution.
“I think what’s more important here, though, is that the evidence on whether tDCS works is a little mixed. Wiethoff et al (2014) looked into this with a motor task, and they found that only 38% of their sample reacted to anodal and cathodal stimulation in the expected direction. That’s quite a small number for the big claims of what tDCS is supposedly capable of.”
Dr Kreplin also expresses concerns over the “positive publication bias” that surrounds tDCS, meaning that often only results that are positive and in favour of the practice tend to get published. “This isn’t a reason to completely give up on tDCS, but more research into its reliability is needed.”
There are also further complications of tDCS relating to the effect that stimulating one part of the brain can have on another part. For example, stimulating the part of the brain that increases the amount of attention you pay to a task, may come at the cost of task-switching.
Similarly, there is the issue of the ‘reference’ or ‘inactive’ electrode. This is the electrode that is placed over a (supposedly) unrelated area to the one that is being stimulated. Dr Kreplin explains: “For example, I might be interested in cognitive inhibition and my ‘active’ area is the right inferior frontal gyrus (rIFG). Technically, it would be safe to place my reference electrode just above the eyebrow, as this is an area that is not related to cognitive inhibition. Yet my reference electrode is not inactive, but has the opposite polarity to my ‘active’ electrode. That means that when I use an anodal electrode to increase activation over the rIFG, I also decrease activation in the area just above the eyebrow where I placed my ‘reference’ electrode.
“This means that every time I activate an area, there is also an area that I deactivate. This shouldn’t matter to my cognitive inhibition task, but I might deactivate areas of the brain that are important to other aspects of my life. The reference electrode in our example lies over an area that is relevant to emotion regulation or my sense of self, so decreasing activity in these areas may have longer term negative effects on my emotional wellbeing.”
There are clearly many potential problems surrounding the unsupervised at-home use of tDCS, yet interest in the practice is likely to keep rising. In order for people to stay as safe as possible, Dr Kreplin suggests that 3 key things should happen:
- tDCS devices should all be properly regulated to include all of the safety features necessary;
- Individuals should be informed of the possible side effects of tDCS, and of that fact that there may be some that researchers do not yet know of;
- More research should be done into tDCs, and the findings – both positive and negative – should be made available to all, enabling people to make informed decisions on whether they wish to take part in brain stimulation.
For more information on the research that Dr Kreplin and her colleagues carry out, visit the Brain, Belief and Behaviour theme page.