Sound and light stimulation helps with Alzheimer's, while in mice, but the results are encouraging

    The first methods that use sensory stimulation to improve Alzheimer's disease were developed about two years ago, then it was about light stimulation. Now scientists have applied sound and are developing a combined light-sound technique. A week ago an article appeared on the website of the Massachusetts Institute of Technology (hereinafter referred to as MIT) that groups led by Anthony Martorell and Li-Huei Tsai achieved sound stimulation.

    According to neuroscientists, they managed to find a unique combination of sound and light stimuli, which in experiments on laboratory mice was able to reduce amyloid plaques, and as a result, improve memory and partially eliminate cognitive impairment associated with Alzheimer's disease. Scientists are preparing to conduct a study in humans. The experiment is likely to bring stimulation therapy for Alzheimer's disease to a new level. Under the cut, more about the new method and the results of the study, as well as a couple of words about the disease itself.

    A bit about Alzheimer's

    Alzheimer's disease is the most common neurodegenerative disease on the planet in which amyloid plaques and neurofibrillary tangles (intracellular beta-amyloid plaques) accumulate. It affects both the cortex and some subcortical structures of the brain. Today, Alzheimer's is one of the most common forms of dementia.

    To the end, the pathophysiological mechanisms of the disease have not been studied, but it is known that the accumulation of deposits of beta-amyloid and cellular material around and inside cells (plaques and tangles) and their uncontrolled growth cause massive death of neurons. This in turn leads to a rapid loss of memory and a deterioration in cognitive processes.

    One of the most significant problems in the treatment of Alzheimer's disease is the high density and insolubility of amyloid deposits. Plaques appear due to impaired protein synthesis in the neuron, or more precisely, due to excessive phosphorylation of the Tau protein. As a result of this process, protein strands begin to stick together and form amyloid plaques and tangles. Dense deposits lead to the disintegration of microtubules in the cells, which ultimately leads to the death of neurons.

    At the moment, there are no methods of radical treatment of Alzheimer's disease, however, palliative methods are widely used, among which stimulation therapy is not the least.

    The essence of the MIT experiments

    An experiment with light
    Two years ago, Nature magazine reported that researchers at the Institute exposed Alzheimer's mice with high beta-amyloid content in the cerebral cortex to flickering light. The mice were left in the room with a light flickering at a frequency of 40 Hz. The exposure lasted one hour per day, and was applied for one week. Researchers have suggested a relationship between gamma and amyloid beta.

    Light shimmering “baths” were enough to significantly reduce the synthesis of beta-amyloid by 40-50% in young mice with its high content, and in old (with a pronounced Alzheimer's form) - led to the resorption of already formed plaques. Exposure to a light stimulus flickering at a different frequency in the control group did not cause such an effect.

    Analysis of gene expression under the influence of a light stimulus demonstrated the induction of genes responsible for the activation of macrophages in microglia, which in turn carry out the capture of amyloid beta.

    All phenomena were observed mainly in the cells of the visual cortex and did not affect other areas of the brain. Meanwhile, plaques in Alzheimer's disease affected not only the visual part of the cortex, so the researchers decided to improve the method.

    Experiment with light and sound
    In the process of developing a previous experiment, scientists exposed mice with Alzheimer to a combination of visual and auditory stimuli of the desired frequency. As in the previous experiment, the researchers sought to induce gamma activity of neurons and thus reduce the number of amyloid plaques simultaneously in both the visual and auditory cortex.

    Initially, experiments were conducted on auditory stimulation. The assumption by the head of the Institute, Li-Hui Tsai, that gamma-induction caused by sound stimulation can reduce the conversion of Tau proteins to amyloid plaques not only in the sensory cortex, but also in the hippocampus. After that, scientists switched to a complex effect.

    The result exceeded expectations. A week-long experiment showed improved memory function and cognitive abilities. Plaques dissolve in large areas of the brain. Deposits disappeared in areas of the brain critical for functions such as thinking, learning, and memory.

    Li-Huei Tsai, head of the MIT Institute for Memory Studies, said: "When we combine visual and auditory stimulation for a week, the effects on the prefrontal cortex and a very sharp decrease in amyloid levels are obvious." This means that the combined effect has affected not only the sensory cortex, but also the areas of the brain responsible for thinking.

    Scientists are optimistic about human tests. At the moment, preliminary studies have been conducted on the safety of the method for healthy people.

    A bit about how it works

    Brain neurons are able to generate electrical signals, signals are able to synchronize and form the so-called brain waves in several frequency ranges. It was noted that patients with Alzheimer's disease have violations of the gamma activity of neurons, ranging from 30 to 60 Hz. It is assumed that this wave activity is important for such brain functions as attention, perception and memory.

    The researchers reasonably suggested that sound and light stimulation would cause gamma induction in brain cells, which in turn would trigger immune responses (macrophage activation) and amyloid beta resorption processes.


    It is too early to talk about victory over Alzheimer's disease, but the results voiced by the authors of the study cannot but impress. Scientists do not hide optimism, and studies on people can give results this year. Traditionally, I hope for your opinions on the methodology and its prospects in the comments. Photo

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