[Reading Science] Depression and Dementia 'Miraculous Treatments'?..."Long Way to Go"

Boston University in the US Publishes Paper Analyzing 'Brainwave Electrical Stimulation Method'
"Many Short-Term Effect Studies, Questions on Reliability and Accuracy"

Methods of stimulating the human brain with electric currents to treat insomnia, improve memory and concentration, as well as alleviate depression and Alzheimer's dementia are being researched. But do they really work? Many papers report short-term functional improvement effects, and some countries have officially approved these methods. However, doubts about reliability remain, and there are calls for more precise and extensive research.

The international academic journal Nature reported that a research team from Boston University in the United States published a paper on the 24th (local time) in Science Translational Medicine analyzing over 100 studies worldwide related to this technology.

This technology, known as transcranial alternating current stimulation (tACS), is increasingly studied as a potential treatment for brain-related diseases such as depression, Parkinson's disease, Alzheimer's dementia relief, and drug addiction. There is also transcranial direct current stimulation (tDCS), which uses direct current instead of alternating current. It is a non-invasive method that attaches electrodes to the scalp and sends a weak, painless current to the brain. The goal is to stimulate, disrupt, or synchronize brain waves to enhance brain function. Although the U.S. Food and Drug Administration (FDA) has not yet approved it, Europe, Brazil, China, Australia, and Mexico have authorized the use of tDCS for treating depression and pain.

The research team investigated and analyzed over 100 papers to determine whether these current-based brain stimulation techniques are effective. The results showed that these methods produce modest improvements in attention, long-term memory, working memory, and the ability to process new information and solve problems. Cognitive function improvements were better after treatment ended than during treatment. However, higher intensity stimulation was not necessarily more beneficial. Computer simulations predicting how currents pass through the brain and their effects helped develop more efficient treatment methods. Shree Grover, a professor of cognitive neuroscience at Boston University and co-author of the paper, explained, "The results confirm the need to continue researching tACS techniques," adding, "At least in the short term, it appears capable of producing significant changes in human mental functions."

However, the research team also identified a major weakness that must be addressed in this treatment method: doubts about the reliability of the results. For example, among the 102 related papers analyzed, 98 were found not to have been preregistered. This means researchers did not disclose their hypotheses or methodologies to academic journals before starting experiments. In such cases, researchers are more likely to fall into 'publication bias,' emphasizing only positive results when writing papers. Studies conducted without preregistration are unlikely to be published if they fail.

Criticism has also been raised against the research team's conclusion that "there were some effects." The studies analyzed were so varied that their reliability is questioned. Existing research on brain stimulation techniques targeted very diverse brain regions, and electrode arrangements on the scalp, as well as current frequency and intensity, varied widely. Experimental subjects also differed greatly in cognitive functions performed, age groups, health status, and existing diseases, failing to ensure consistency for reliability. ?lvaro Pascual-Leone, a professor at Harvard Medical School, said, "It is risky to draw overall conclusions based on similar studies that do not yield the same results under identical conditions," adding, "Differences in brain stimulation methods are very important, and this study is meaningful in that it provides an overview of the entire research field."