Using mice, scientists have gained a better understanding of the therapeutic benefits for Alzheimer’s disease from flickering light exposure.
A team of scientists from Atlanta’s Georgia Institute of Technology have discovered some reasons why lights flickering at 40 beats per second, or 40 hertz (Hz), have a beneficial effect on Alzheimer’s disease.
The findings, published in The Journal of Neuroscience, build on work conducted in 2016 by Dr. Annabelle Singer, a team member, with colleagues from the Massachusetts Institute of Technology in Cambridge.
Alzheimer’s
According to the Centers for Disease Control and Prevention (CDC), Alzheimer’s is the most common type of dementia, affecting up to 5 million people in the USA in 2014.
There is no known cure, but therapy typically focuses on improving the quality of life for people with Alzheimer’s, or trying to slow down the effects of Alzheimer’s.
Scientists really don’t know what causes Alzheimer’s. Scientists believe a variety of factors could contribute to a person developing Alzheimer’s, according to the CDC.
One positive trend lately, however, is research into flickering light.
Flickering light
Researchers found a connection between gamma and Alzheimer’s disease in 2016 research.
Gamma is a form of brainwave fluctuating between 20–50 Hz. Research 2016 has shown that gamma disturbances in mice have resulted in an increased accumulation of plaque protein between brain cells. Plaque protein is a significant hallmark of Alzheimer’s.
Alternatively, exposing the mice to 40 Hz flickering light helped improve gamma and decrease this plaque buildup by enhancing the development of microglia, the main immune cell of the brain.
However, it was not clear exactly how 40 Hz light increased microglia, and thus enhanced the immune response of the brain.
The scientists in the new study looked in detail at what immune processes occurred when they exposed the mice to 40 Hz light.
At the same time, the research was being used by a team of scientists from Emory University, Atlanta, GA to inform their work on 40 Hz light exposure with humans.
According to Kristie Garza, the study’s first author, “I’ll run samples from mice in the laboratory, and at about the same moment, a colleague will do a strikingly similar analysis on patient fluid samples.”
The scientists found that their brains released more cytokines— a type of protein that interacts with other cells— when they exposed the mice to 40 Hz light, and increased activation of phosphate proteins.
It immediately happened: “After an hour of stimulation we found a spike in cytokines,” says Kristie Garza. “After about 15 minutes of flickering we saw phosphoprotein signals.”
Dr. Singer says, “The phosphoproteins first showed up. It looked like they were leading and our theory is they caused cytokine release.”
In particular, it was the increased release of the cytokine Macrophage Colony-Stimulating Factor (M-CSF) which explained a connection to microglia promotion. “M-CSF was the thing that yelled,’ Microglia activation!’ as Dr Singer notes.’
Although the precise reason why microglial activity increased in the presence of 40 Hz light has not yet been determined, the team believes the results to be promising.
According to Dr. Levi Wood, co-leader of the study,” The vast majority of cytokines have gone up, some anti-inflammatory and some inflammatory, and it was a transient response. A transient inflammatory response can often promote pathogen clearance; it can help repair.
“Basically, you think an inflammatory response is bad if it’s chronic and it was fast and then dropped off so we think it’s probably helpful,” Dr. Singer says.
Other frequencies
As well as finding more details about the link between 40 Hz light and Alzheimer’s, the team also found that the brain was influenced by different light frequencies.
According to Dr. Singer, “Cytokine levels were way down at 20 Hz. That could also be helpful. Circumstances may exist in which you wish to suppress cytokines.
“We’re thinking different kinds of stimulation could potentially become a platform of tools in a variety of contexts like Parkinson’s or schizophrenia. Many neurological disorders are associated with immune response.”
– Dr. Annabelle Singer
The team makes it clear, though very positive, that this work is in the early stages and emphasizes that people should not experiment with light therapies.
The processes involved are not fully understood, and the use of wrong frequencies can cause harm to a person.
