After years of debate about whether non-invasive brain zapping of electrical currents can improve a person’s mental function, a vast analysis of past research has likely provided an answer. However, some have questioned this conclusion, arguing that the analysis spanned different experiments and could not provide a firm answer.
Over the past six years, there has been a surge in the number of studies testing the therapeutic effects of a type of technique called transcranial electrical stimulation. These treatments send a weak, painless electrical current to the brain through electrodes placed on the outside of the scalp. The goal is to excite, disrupt, or synchronize signals in the brain to improve function.
The researchers used transcranial alternating current stimulation (tACS) and its sister technique tDCS (transcranial direct current stimulation) in both healthy volunteers and those with neuropsychiatric disorders such as depression, Parkinson’s disease and addiction. tested to But researchers have questioned the tool’s effectiveness, as results have been inconsistent or irreproducible.
The authors of this new analysis, led by Robert Reinhart, director of the Cognitive and Clinical Neuroscience Laboratory at Boston University in Massachusetts, compared more than 100 studies of the technology to quantify whether tACS holds promise. It states that the report was compiled by Oscillating current to the brain. “There are so many contradictory findings in the literature that we need to examine whether this technique actually works,” said Shuree Glover, a cognitive neuroscientist at Boston University and author of the paper. .
Their meta-analysis was published on 24 May. chemistry translational medicineThey concluded that tACS treatment resulted in modest improvements in attention, long-term memory, working memory, the ability to process new information and solve problems, and other high-level cognitive processes. The discovery gave the researchers reason to continue studying tACS in humans, Glover said. The technology “seems to have profound changes in mental function, at least in the short term,” he says.
“Certainly, further research could be fruitful,” says Sarah Lithumby, a psychiatrist specializing in neuromodulation at the National Institute of Mental Health in Bethesda, Maryland. “I don’t think it’s conclusive yet whether this will lead to the development of future therapeutic interventions.”
Importantly, the meta-analysis could help inform future research plans, says Lishamby. For example, the report found that cognitive improvements were generally better after completion of treatment than during treatment, and that high-intensity stimulation was not always beneficial. The report also notes that research using computational simulations to predict how electrical currents flow in the brain has helped researchers place electrodes on people’s heads in more effective patterns. clarified.
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The biggest impact of the meta-analysis may be highlighting serious weaknesses in tACS research that need to be improved, Lishamby said. For example, the research team found that 98 of the 102 studies were not pre-enrolled. This means that the researchers did not document their hypotheses and methods in journals or on sites such as clinicaltrials.gov before starting the experiment. This leads to publication bias (positive results are more likely to be published than negative results) because if a study is not pre-registered and fails, its results are less likely to be shared. high risk).
However, not everyone finds meta-analyses all that useful. “The problem I have with this paper is that it lumps together studies that are effectively different interventions,” says Alvaro Pascual-Leone, a neurologist at Harvard Medical School in Boston.
Pascual-Leone notes that the studies included in the meta-analysis differed greatly in terms of which parts of the brain were targeted, the placement of electrodes on the scalp, and the frequency and intensity of the current. The cognitive tasks performed by the participants differed in each study, and the participants themselves were equally diverse, young and old, healthy and diseased.
Drawing overall conclusions based on such disparate studies, many of which have not been replicated, risks misleading conclusions, says Pascual-Leone. “The difference in stimulation is actually very important,” he says. “this [report] “It’s a comprehensive effort that provides a great overview of the whole field, and it’s all admirable, but I’m not sure we’ll be able to learn it all because it’s a mix and match process. yeah.”
Glover replied that tACS is an emerging technology and the team intended to do an “expansive analysis” of its general effectiveness. However, he acknowledges that future analyzes should focus on more specific experimental designs.
So, it looks like the debate is inconclusive.
Although the U.S. Food and Drug Administration has not approved tACS or tDCS therapy for any disease, other regulatory agencies in Europe, Brazil, China, Australia, and Mexico have approved it for some conditions such as depression and pain. has approved tDCS for the treatment of .
This article is reprinted with permission and was first published on May 26, 2023.
