MIT researchers have shown that it's possible to substantially cut back levels of beta amyloid plaque in the visual cortex characteristic to Alzheimer's disease in a mouse model.
Publishing their findings in the journal Nature, Li-Huei Tsai and colleagues said further research will have to be carried out to see if a similar approach could be used to treat Alzheimer's patients but the method they used holds a lot of potential as it is accessible and noninvasive.
Using LED lights set to flicker at a certain frequency, the treatment works by inducing brain waves called gamma oscillations, which not only suppress the production of beta amyloid in the brain but also energizes cells responsible for disposing of plaques.
Brain Wave Stimulation
Alzheimer's disease is characterized by the formation of beta amyloid plaque that interferes with normal brain processes and harms brain cells. Earlier studies have suggested that those with the disease suffer from impaired gamma oscillations. Ranging between 25 and 80 hertz, these brain waves are believed to affect normal brain functions like memory, perception, and attention.
For the study, Tsai and colleagues worked with mice that have been programmed genetically to develop Alzheimer's disease but have not exhibited behavioral symptoms or plaque accumulation yet, finding impairments in gamma oscillations in activity patterns crucial to memory and learning during a maze run.
Gamma oscillations were then stimulated at a 40-hertz frequency in a region of the brain known as the hippocampus, which is integral to forming and retrieving memories. These initial stages utilized a technique called optogenetics, which allows neurons that have been genetically modified to be controlled by shining light on them.
With optogeneticcs, the researchers were able to stimulate brain cells referred to as interneurons, which are tasked with synchronizing gamma activity in excitatory neurons.
Stimulation at 40 hertz for an hour resulted in a reduction of beta amyloid proteins within the hippocampus by 40 to 50 percent. When the researchers tried other frequencies, however, they were unable to replicate those results.
Gamma Oscillations And LED Lighting
The researchers built a device made up of a strip of LED lights set to flicker at varying frequencies. After an hour of exposure with the device at 40 hertz, they observed better gamma oscillations and a 50-percent reduction in beta amyloids in mice visual cortices. However, beta amyloid levels were back to their original levels in 24 hours.
The researchers experimented with using a longer course of treatment and discovered that free-floating amyloids and plaque were markedly reduced after a seven-day round of flashing light therapy set for an hour each day.
Additionally, they observed that better gamma oscillations translated to an improvement in the brain's ability to dispose of beta amyloids by boosting microglia function. Microglia are immune cells. In patients with Alzheimer's disease, they turn inflammatory and produce toxic chemicals that make brain cells sicker. With improved gamma oscillations though, they more actively clear out beta amyloid proteins.