Every morning, Li-Huei Tsai meditates in front of a flickering screen. Synchronized with the flashes of light are sharp sounds that resemble the clicks of a flamenco dancer’s castanets, only much louder. But the rhythm here is not for entertainment. The combination of flickering light and clicking sounds helps synchronize electrical processes in the brain known as gamma waves. To the uninitiated, such a light-sound procedure may seem like a new wellness fad. But Tsai, a neurophysiologist at the Massachusetts Institute of Technology (Cambridge, USA), has evidence that it can prevent the development of Alzheimer’s disease.
Li-Huei Tsai’s research represents a radically new approach to the prevention and treatment of the most common form of senile dementia. Today, approximately 50 million people worldwide suffer from dementia, and this number is expected to triple by 2050. From the neuroscientific point of view (according to the prevailing hypothesis), the main change associated with Alzheimer’s disease is the accumulation of toxic proteins (amyloid plaques) in the brain and the formation of tau protein aggregates inside neurons.
The loud clicking sound (such as the castanets used by flamenco dancers) can provide the brain with the necessary rhythm. As a result, both processes seem to sow chaos in our neurons and their synapses (the places where two neurons make contact and “communicate” with each other). Not surprisingly, most Alzheimer’s research over the past three decades has focused on finding drugs to remove these plaques – and yet we are still waiting for a breakthrough. And a number of new studies suggest that the answer may not be chemical, but electrical. And it all depends on the gamma rhythms, which seem to initiate a kind of cleaning process in the brain, removing toxins before they do any damage.
In everyday life, we often use the word “осенило” (which roughly translates to “it came to me”) when talking about a sudden burst of inspiration. In neurophysiology, “осенило” refers to a specific wave pattern in the brain, a rhythmic structure of electrical activity produced by groups of neurons throughout the brain at a specific frequency. Just as radio or television stations transmit their signal on a specific wavelength, different frequencies of brainwaves appear to be associated with specific neurological functions. We explain quickly, simply, and clearly what happened, why it matters, and what happens next. эпизоды – Episodes End of story. Podcast advertising. Gamma waves oscillate at a frequency of about 30 to 100 times per second. They are usually observed when we are concentrating or trying to remember something. Some very interesting studies in the early 2000s showed that patients with Alzheimer’s disease have particularly weak gamma waves, the fastest brain rhythms (compared to healthy people with no signs of mental decline), suggesting that the disruption of these rhythms may be involved in the disease. What was not clear was whether this was just another consequence of the general neurodegeneration that was already underway, or whether it might be its cause. Cai’s team of scientists decided to find out. To prove their hypothesis in principle, they first used a technique known as optogenetics, in which the neurons of a laboratory mouse are genetically modified to respond to light of a specific color. By placing a tiny light source in the skull of an animal, scientists can stimulate gamma waves with very high precision and observe the consequences. And what they saw was astonishing. Not only was there a significant reduction in amyloid plaques, but the researchers also discovered the mechanism of their formation.
Microglia cells resemble marine creatures with tentacles, but they are actually the guardians of our brains. Particularly interesting was the effect on brain microglia (macrophage cells, a kind of emergency rescue team, our brain’s bodyguards, taking care of its health). “They are like immune surveillance,” Tsai explains. “They monitor the situation and can eliminate pathogens, toxic waste and foreign substances.” Previous studies have shown that microglia often fail to do their job in Alzheimer’s patients. However, it appears that gamma waves are able to awaken macrophage cells, leading to a reduction in the number of amyloid plaques and tau protein accumulations. In addition, the effect of gamma-wave application is very rapid. Only one hour of stimulation was sufficient to activate microglia and achieve a significant reduction in the number of amyloid plaques. Such an effect of gamma waves on macrophage cells represents a tremendous leap forward in our understanding of Alzheimer’s disease (and the function of gamma waves), Tsai emphasizes. However, optogenetic stimulation is a procedure that is not easily applicable to humans. Tsai’s next step was to test whether less invasive forms of brainwave synchronization would work. In one of the experiments, scientists exposed mice to light flickering at a frequency of 40 Hz for one hour each day, while in other experiments the animals heard rapid clicking sounds at that frequency. And in each case it worked, synchronization occurred. Macrophage cells worked more actively, the level of toxic proteins decreased.
The flickering light and clicking sounds can tune the brain to begin generating waves of a certain frequency. Importantly, all of this affected the behavior of the mice. Those that received stimulation found a way out of the maze faster and remembered it better – unlike those that aged without stimulation. But will scientists be able to replicate these results in real Alzheimer’s patients? Цай сейчас приступает к клиническим испытаниям, чтобы исследовать долгосрочные преимущества стимуляции гамма-волн для людей.
Tsai is now embarking on clinical trials to explore the long-term benefits of gamma wave stimulation for humans. But another study has already produced some exciting data confirming that such stimulation does indeed lead to cognitive improvement. In a study led by Amy Clements-Cortes of the University of Toronto, Canada, tactile stimulation was used in addition to auditory stimulation. Participants diagnosed with various stages of Alzheimer’s disease sat in a chair with six speakers emitting low-frequency gamma-wave sounds. This was similar to the action of a subwoofer (a low-frequency acoustic system), Clements-Cortes describes, causing participants to feel slight vibrations throughout their bodies. After six 30-minute treatments, patients showed improvements on standard tests of several cognitive abilities, including mental arithmetic and short-term memory. “This looked especially amazing considering how short the stimulation period was,” notes Clements-Cortes. She also has testimony from another patient with mild signs of dementia who used a similar device at home for three years. “Three years later, we went to visit her,” says Clements-Cortes. “Her mental abilities had not deteriorated, they were about the same.”
Mice that received brain neuron stimulation found their way out of the maze faster and remembered it better than those that aged without stimulation. Clearly, much more data needs to be collected with larger samples, but the initial results are “incredibly inspiring,” according to Clements-Cortes. “It is possible that patients will be able to receive this type of therapy just by watching television or listening to the radio,” she says. Could it be that after so many years of fruitless attempts to find a cure for Alzheimer’s, there is finally a light at the end of the tunnel? It seems that the new method may be particularly valuable for early intervention in the disease. Martin O’Halloran of the National University of Ireland points out that although patients may experience cognitive difficulties, confirming the diagnosis of “Alzheimer’s” takes a long time, which delays the start of treatment because doctors do not want to risk side effects until they are sure of the diagnosis. “Any early intervention for these patients should be as non-invasive and safe as possible,” he says. “This includes the use of flickering lights or repetitive sounds.” (This is not appropriate for patients with epilepsy, because stimulation can provoke a seizure). Barry McDermott, a researcher at the National University of Ireland, is also optimistic about the results. “No doctor is going to prescribe Alzheimer’s drugs for prevention, but this method is something you can use in advance,” he notes. “It’s so simple and easy. Theoretically, you can even have an application like this on your smartphone.” Despite the rapid progress in research, both O’Halloran and McDermott, who recently wrote a review of the technology’s potential for the Journal of Alzheimer’s Disease Research, emphasize that there are still many questions to be answered. In addition to the need for further confirmation of the long-term usefulness of the method through clinical trials, it is also necessary to understand what frequency of gamma waves is ideal for use and what is the optimal duration of application. And although it seems unlikely that you will overdose on gamma waves, it will be useful to find out if excessive enthusiasm in using the method will cause side effects, the Irish scientists emphasize.
Gamma brain wave stimulation may be a new way to treat Alzheimer’s disease. In addition, it is necessary to understand whether stimulation of gamma waves improves the mental abilities of healthy people. Be careful here: she believes there is a limit to what gamma waves can do for a healthy brain. But she hopes the method can be useful as a preventive measure after middle age – to maintain normal brain function before the first signs of mental decline appear. “I think it is possible,” she says. Despite the many questions that still need to be answered, Tsai has already tested the device on herself. “And I feel great,” she says with a mischievous smile. Like any scientist, Li-Huei Tsai understands that her personal experience cannot be taken as convincing evidence. However, if the results of her research are confirmed, many of us may start our day with similar sound and light practices to keep our brains healthy. I’m sorry, but you have not provided any Russian text for me to translate into English. Could you please provide the Russian text you would like me to translate? David Robson lives in London and writes about popular science. His most recent book is The Intelligence Trap: Why Smart People Make Stupid Mistakes. I’m sorry, but since you haven’t provided any Russian text to translate, I can’t help you. Please provide the Russian text you’d like to have translated into English. You can read the original article on the BBC Future website.