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Could Light Therapy Help People with Alzheimer’s Disease?

October 19, 2021

A newly proposed study seeks to explore whether delivering light to people with Alzheimer’s disease may help them to sleep better and to ease depression and insomnia, as well as improve thinking and memory skills. The study, recently funded by the National Institutes of Health, will look at two forms of light therapy. One delivers pulses of light to the brain to stimulate electrical brain waves involved in cognition. The other exposes patients to simulated daytime light, which has been shown to foster sound sleep. 

“Light can be powerful but often overlooked health factor,” said Mariana Figueiro, the leader of the new study and director of the Light Health Research Center at the Icahn School of Medicine at Mount Sinai in New York. “We hope to harness the power of light to relieve the suffering that millions of Alzheimer’s disease patients and their loved ones experience every day.” 

The study will enroll patients with early-stage Alzheimer’s disease or mild cognitive impairment, a condition that progresses to full-blown Alzheimer’s in 10 to 20 percent of cases. The researchers will compare the effect of light therapy in people with Alzheimer’s or mild cognitive impairment with their peers who do not have dementia or other serious memory problems. 

In one part of the study, researchers will use specially designed goggles to deliver flashing pulses of light at a frequency of 40 times a second to stimulate electrical activity in the brain. The light targets “gamma” brain waves, which help connect and process information throughout the brain. Gamma waves play an important role in learning and memory, and are diminished in people with Alzheimer’s disease. Earlier studies in mice that were genetically engineered to develop specific traits of Alzheimer’s found that the light flickers helped reduce levels of beta-amyloid, the toxic protein that builds up in the brain of Alzheimer’s disease. 

In another part of the study, participants will be exposed daily to light boxes that simulate natural daylight. Exposure to natural sunlight helps to reset the sleep-wake cycle and prime the brain for better sleep. Light boxes designed for lux therapy or light therapy have been shown to be beneficial for people with seasonal affective disorder or other forms of depression. Exposure to bright light every morning, particularly during the winter months, can provide a boost in mood and provide sounder sleep at night. 

Many people with Alzheimer’s disease suffer from sleep-related problems, including agitation and daytime sleepiness. Sleep is thought to provide a cleansing function, helping to rid the brain of toxic proteins that can damage brain cells. In a previous study, the toxic Abeta component at the origin of amyloid-plaques has been shown to decrease at night. Depression is also common in people with Alzheimer’s.   

“Our sleep-wake cycles play a critical role in brain health,” Dr. Figueiro said. “By using a rigorous, two-pronged approach to light therapy, it is possible that we could push the brains of Alzheimer’s patients into a healthier state.” 

Earlier research has found that light therapy, in various forms, can provide benefits for people with Alzheimer’s, and various studies of light therapy for Alzheimer’s are ongoing. Light therapy has been shown to ease agitation and depression. Light therapy is also far safer than antipsychotic drugs, which are often prescribed to people with Alzheimer’s to ease agitation and aggression but which can have serious side effects. 

According to this hypothesis, spending more time outdoors getting natural sunlight may also have benefits for people with Alzheimer’s disease. Two important aspects of this body of work are the amount of light received daily and the time of day the person is exposed to light. Exposure early in the morning might be particularly beneficial to signal to the brain that the night is over. Dr. Figueiro recommends that those with Alzheimer’s have regular exposure to natural light in their homes during the day and go outside whenever possible. If you’re caring for someone with Alzheimer’s, take them out during the day for a walk, she said.  

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University. 

Source: National Institutes of Health, Icahn School of Medicine at Mount Sinai.  

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