There are different kinds of medical pseudoscience that we tackle here at SBM. Some therapies and claims are pseudoscience because they are not conceptually valid – they break the laws of physics, or rely on outdated, superstitious, or just wrong concepts of biology and health. Often they rely on phenomena such as “life force” which don’t seem to exist. Others are based on real scientific phenomena but grossly misapply them. Detox fits into this category. Toxins exist and can cause harm and so removing them can be beneficial, but popular detox treatments are not targeted against actual toxins, there is no evidence the treatments remove any toxins, and there is no evidence of any health benefits.
A third category of medical pseudoscience is perhaps the most pernicious, legitimate cutting-edge medical science that is currently being researched and developed, but unscrupulous gurus make claims for specific treatments that are years or perhaps decades ahead of the science, trying to capitalize on the hype. Stem cell therapy is the poster child for this category – using stem cells to treat serious disease is an active area of research, but we are probably decades away from the sort of applications that people think of, and yet fraudulent stem cell clinics began popping up almost 20 years ago.
Brain stimulation also fits into this third category, using specific frequencies, intensities, and locations of electrical (either direct current or alternating current) or magnetic stimulation to alter brain function. Conceptually I have not problem with this approach and it should be considered perfectly legitimate. The brain is an electrical organ and its function depends on the electrical activity of specific circuits in the brain. Either increasing or decreasing the functional activity of specific brain regions or circuits should therefore be a possible mechanism of intervention.
The hype
As with stem cells, however, it is still early days for this kind of approach. My sense is that it is a bit further along, with some actual approved (if basic) interventions, such as treating seizures, movement disorders, or aborting migraine headaches. But brain stimulation is not a panacea. There is no evidence and no reason to think that it alters the biology of the brain (the health of brain cells), but it can immediately alter the electrical activity of the brain. The challenge is that there are many variables to consider, and so it will take a long time to do the research to dial in which specific interventions will have which specific effects in which populations of people. These variables include the type of stimulation (AC, DC, magnetic), the intensity and duration of stimulation treatments, the targeted part of the brain, and the frequency of the stimulation.
And yet, there are already a number of home brain stimulation devices on the market. What claims are made for these devices? A familiar list of vague and allowable claims, such as improved mood, focus, stress reduction, and improved sleep. Some include the “quack Miranda warning” that they are not intended to treat a disease. Because these are devices, and not drugs, they can easily obtain FDA “clearance” without having to prove efficacy.
Unfortunately, the background of legitimate research into brain stimulation inadvertently feeds this unscrupulous industry, through less-than-skeptical reporting. A recent study shows where the state-of-the-art is for brain stimulation for memory function, and also how lazy reporting can be a problem. The BBC headline reporting on this study is “Brain stimulation boosts memory for a month“. This makes it seem like memory function is improved for a month after treatment, but that is misleading. The study itself is actually quite good, let’s review what it actually shows.
The science
The researchers are extending existing research into brain stimulation to improve working memory (WM) and long term memory (LTM). Previous research has been inconclusive, as the authors of the current study summarize:
Rhythmic activity in the theta and gamma frequency ranges are thought to contribute to both WM and LTM function, particularly during free recall. However, previous attempts at modulating these rhythms to improve memory have yielded inconsistent findings. Although there are some suggestions of improvements in WM with modulation of parietal theta rhythms, changing theta rhythms in the frontal regions and gamma rhythms in the parietal and frontal regions have yielded contradictory results.
Their study design is very thorough. They first look at their hypothesis based on prior research, the use of low frequency stimulation in the parietal cortex and the use of high frequency stimulation in the pre-frontal cortex. They gave the subjects 10 minutes of stimulation per day for four days, and encoded verbal memory for words during stimulation. They studied healthy older adults from 65-88 and tested their immediate recall on the days of stimulation and then recall for the words one month later. They found a statistically significant improved in short term and long term recall for these types of stimulation, and further there seemed to be a dose-response with more successive days of stimulation having a greater effect, and improving in memory on day 4 predicting improving at one month. They used a double-blind sham-controlled protocol.
I like the fact that they then performed two internal controls. They did a second study where they reversed the high and low frequency stimulations, and showed no benefit. This is important to rule out nonspecific effects – for example, perhaps the stimulation (which they could feel) just made subjects overall more alert. This second experiment showed the results are frequency dependent. They then did a third experiment replicating the results of the first study in a fresh sample, again showing significant results. I have mentioned previously that internal replications should become standard, to minimize the publication of false positives.
The limitations
So – this was a nice series of studies suggesting that stimulation using transcranial alternating current stimulation at specific locations and frequencies may improve short and long term recall of words. But any reporting of this, especially in the context of an existing dubious industry of at-home brain stimulation, should carefully point out what this study does not show. First, the effect was only seen for memory during stimulation. The headline suggests a persistent effect over a month, as if brain function improved for a month, rather than just an immediate effect of improved memory for words during stimulation.
This, of course, significantly limits applications of this approach. You would need to be using the device while studying, and your memory outside the window of stimulation would not be affected. We don’t know how long this effect lasts for, and previous research does suggest a declining effect from continued stimulation. We also need to study what the long-term effects are (both longer duration stimulation and greater number of sessions). It’s plausible there could be a negative long-term effect. Might memory function decline between sessions? Does this effect extend beyond memory for words?
Also, it needs to be pointed out that this is not a disease treatment. While Alzheimer’s is mentioned both in the study and the reporting, Alzheimer’s is a biological disease of the brain. At best this would be a symptomatic treatment and would not slow or reverse progression.
We are still early in this kind of research. While I am hopefully for the potential of electrical interventions for brain function, the authors acknowledge that specific applications are likely far in the future. It is certainly too early for home brain hacking through portable devices.