Breakthrough in the treatment of Alzheimer's?
Can regular treatment of sounds and light signals help alleviate the symptoms of Alzheimer's? A US research team has now found in a study that the daily stimulation of the senses by light pulses and sounds improves memory and contributes to a significant reduction of so-called amyloid plaques.
The scientists at the Massachusetts Institute of Technology (MIT) found in their current research that daily stimulation of the senses by light and sound can alleviate the symptoms of Alzheimer's and thus reduce memory degradation. The physicians published the results of their study in the English language journal "Cell".
What is Alzheimer's?
Alzheimer's is one of the most common neurodegenerative diseases in the world. In Germany, about 1.3 million people suffer from the disease. Alzheimer's destroys our brain cells, which is associated with an ever-increasing loss of memory. Unfortunately, there is currently no cure for the disease and physicians can only slow down the course. At the moment, several studies and clinical trials are underway investigating about three dozen new drugs against Alzheimer's disease.
Studies found positive effects of 40-hertz flashes of light
Several years ago, experts at the Massachusetts Institute of Technology (MIT) noted that stimulating the senses with special light stimuli in Alzheimer's mice reduces some symptoms of the disease. Exposing the mice to 40-Hertz flashes was associated with a reduction in existing amyloid plaques in the visual center. Not only can Alzheimer's affect the visual center, but also other regions of the brain are affected, such as brain centers, which are very important for learning, memory, and other higher thinking functions (e.g., the hippocampus and the medial prefrontal cortex, mPFC). Therefore, it is important that stimulation also affects these parts of the brain, the experts say.
Effects of acoustic stimulation
The scientists first tested the effects of acoustic stimulation on the mice. Animals suffering from Alzheimer's disease in the early stages were exposed to 40-hertz per-hour short tones per day for one hour. This led to noticeable changes after just one week: there was a clear improvement in memory function, in addition, the stimulation also seemed to have a positive effect on the brain. This was demonstrated, for example, by the fact that mice treated with sensory stimulation could better remember the position of a submerged platform in a pool compared to untreated mice. In addition, the treated mice better recognized previously seen objects.
A very clear change was also apparent in the brain of the mice. With a one-week tone stimulation, the amount of plaques and beta-amyloid in the hearing center and hippocampus decreased by 40 to 50 percent. This suggests that acoustic stimulation can reduce amyloid load even outside the primary sensory cortex. Other positive effects were that certain immune cells (microglia) increased by 60 percent through the sound stimulation. Microglia are able to break down amyloid plaques. An extension of the veins by 50 to 100 percent also enabled the study to improve circulation in the hippocampus and auditory center of the experimental animals.
Combined treatment led to impressive success
The results were even more impressive when the tone stimulation was combined with the already studied light flashes. "If we combine visual and auditory stimulation for a week, we see an extension of the positive effects on the prefrontal cortex and a very dramatic reduction in amyloid," study author Li-Huei Tsai of the Massachusetts Institute of Technology said in a press release. Such combined stimulation of the senses could be a promising approach for the prevention and treatment of Alzheimer's disease in the future. This form of sensory stimulation has an effect on different cell types of the brain and different brain regions. "We have shown here that we can use a completely different sensory modality to induce gamma oscillations in the brain. This auditory gamma-induced gamma can reduce amyloid and tau pathology not only in the sensory cortex but also in the hippocampus, "study author Tsai continues.
What causes stimulation in the brain?
The stimulation probably promotes the production of certain brainwaves, which are referred to as gamma oscillations. These waves seem to cause the positive effects. Unfortunately, the effect of stimulation does not last very long. When the daily treatment is stopped, the amount of plaques also begins to increase again. Therefore, it is important that a regular and permanent pacing therapy is performed.
Further investigations are necessary
Further research now has to find out if combined light and sound stimulation is also effective in humans. Attempts have already been made with stimulation therapy on human healthy volunteers in order to verify a general tolerability of the treatment. The next step would now be tests on volunteers with Alzheimer's. Volunteers are already being sought to participate. (As)