Alzheimer’s Disease and Flashing Lights

In recent years, neuroscientists have found a new way to combat Alzheimer’s through the use of stimulus-based methods.

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One unsuspecting morning, Andrea Gillies wakes up and looks in the mirror. However, she cannot recognize the person she is looking at. Met with strangers who attempt to convince her that they’re her family, she feels like she is going crazy.

This is starting to become a reality for many people. Alzheimer’s is a brain disorder that plagues an estimated 6.5 million people, causing numerous deaths annually. It has already cost the United States $321 billion along with billions of hours of care for patients. Plaque, the buildup of protein, in different areas of the brain affects the neurotransmitters involved with sending messages around the body. One such transmitter is acetylcholine, which is involved with short-term memory. The buildup of plaque increases the activity of acetylcholinesterase, an enzyme that decomposes the transmitter. Eventually, the plaque leads to the shrinkage of different parts of the brain. There are a variety of symptoms ranging from “simple” memory loss to losing the ability to communicate. Despite this, many people have a very superficial understanding of such symptoms as they lack relevance in most Americans’ lives.

Equally terrifying is the fact that this disease lacks a cure of any kind. Most treatments temporarily alleviate mild symptoms. The only promising treatment, Aducanumab, which is able to decrease the amount of beta-amyloid plaque, is surrounded by controversies regarding its effectiveness and astronomical cost. However, recent studies have pointed toward an unorthodox treatment: flashing lights.

In 2015, an experiment was conducted at the Massachusetts Institute of Technology (MIT) by neuroscientist Dr. Li-Huei Tsai and her colleagues. The researchers presented flashing lights at 40Hz every day for an hour to mice that were genetically modified to produce the proteins underlying the buildup of plaque in Alzheimer’s disease. With this method, they were able to find reduced amounts of plaque in the visual cortex where visual information is processed. They also experimented with sound-based stimuli that produced comparable results in the auditory cortex—involved with processing sound—as well as the hippocampus. This is groundbreaking as the hippocampus is responsible for memory consolidation and learning. The mice had much higher cognitive performances and significantly improved memory. The neurologists combined the two methods and discovered an exponential effect across the brain including the prefrontal cortex, which controls executive function. The breakthrough provides new hope for many Alzheimer’s patients. However, while this research has only recently been explored, the foundation for this discovery has been around for centuries.

In the late 1800s, a German psychiatrist named Hans Berger pioneered electroencephalography (EEG), a method of measuring electric activity in the brain by attaching an electrode, or a series of small metal discs connected by wires, to the scalp. EEG is now an instrumental part of many contemporary neurological practices and diagnoses. More importantly, however, Berger was the first to make crucial observations among brain waves such as the alpha (which was subsequently named the Berger wave) and beta waves with the EEG. These waves occur at different frequencies and correspond to different states of the brain. This opened up the path for discovering three other brain waves, namely the gamma, theta, and delta waves. They correspond to states of concentration, deep relaxation, and sleep, respectively.

Brain waves are, in a sense, a rippling effect. Neurons in the brain transfer messages by having electrical currents sent through them. However, the average neuron is connected to thousands of other neurons, meaning each is affected simultaneously and creates a synchronization between all of them as the currents pass through. The frequencies being able to match up is absolutely crucial in the organization of the data that is being communicated, becoming the “key to perception” in the human body. The EEG measures the frequency, or how fast these currents are occurring, and the various types of waves depict the varying speeds at which these currents are sent. However, these waves can become interrupted or amplified in disorders such as Parkinson’s, depression, and, unsurprisingly, Alzheimer’s disease.

In the case of Alzheimer’s, gamma waves have been observed to decrease. As mentioned before, gamma waves correspond to the state of the brain related to concentration and occur at frequencies upwards of 25Hz. Neuroscientists have discovered that between this range at 40Hz, brain functions like “conscious awareness, perception, and memory” occur. As a result, this decrease in gamma waves is detrimental to one’s cognitive abilities. Dr. Tsai and many other researchers are trying to undo this reduction in gamma waves. Through flashing lights and sounds at 40Hz, the scientists hope to match the speed of neurons in the brain with these stimuli and restore the connections. Think of this treatment almost as a metronome for neurons to match up with. This type of entrainment also promotes the engagement of microglia, cells that swallow up proteins involved with Alzheimer’s such as amyloid beta. Studies with these methods have produced increased memory and concentration from volunteers that were subjected to the flashing lights and sounds.

Despite many positive and promising results from experiments done on rats and humans alike, there are still limitations to such studies. The method of flashing lights at 40Hz has many complications regarding its safety. These experiments are also still relatively new without many extensive studies with mass trials. In addition, there has been a lack of a placebo—something for the treatment to be tested against—which prompts reluctance to accept the results of these studies yet. However, this does not take away from the innovation of this new effective treatment; the experiment provides hope for people suffering from cognitive dysfunctions such as Alzheimer’s for generations to come.