A team of researchers from the University of Arizona and University of Florida are investigating whether near-infrared light could help enhance cognition and reduce Alzheimer's disease risk in older adults.

With the support of a new $3.8 million grant from the National Institute on Aging – $1.8 million of which will go to the University of Arizona – researchers will expose study participants, who range in age from 65 to 89, to near-infrared light via caps placed on participants' heads and intranasal devices inserted in the nose.

"This is a novel intervention, and we're using something called near-infrared photo biomodulation, which is essentially near-infrared light that is presented with diodes that are placed on the surface of the head or in the nostril," said Gene Alexander, one of the project's principal investigators and a professor in the University of Arizona departments of psychology and psychiatry, the Evelyn F. McKnight Brain Institute and the BIO5 Institute.

"We think near-infrared light can help enhance energy metabolism and mitochondrial function; mitochondria are essentially the engines in the cell that produce energy," said Alexander, who is also director of the Brain Imaging and Fluid Biomarkers Core for the Arizona Alzheimer's Disease Center. "The idea is that we might be able to enhance cognitive and brain function by exposing people to this light for periods of time."

Near-infrared light has shown promise as a cognitive intervention in animal studies and in smaller human studies, which led Alexander and his collaborators at the University of Florida to further explore its potential.

"One the initiatives in the University of Arizona's strategic plan is to close the gap that exists between the cognitive health span and the human life span," said University of Arizona President Robert C. Robbins. "As people live longer, we want to make sure they also are living healthier and more meaningful lives. This research collaboration is an important piece of our ongoing work to better understand how to combat age-related cognitive decline and Alzheimer's disease, which affects millions of people all over the world."

The two universities will enroll 168 participants over the course of the five-year study. They will focus on older individuals who are cognitively healthy but have increased risk for Alzheimer's disease, due to family history and cognitive complaints.

"There's a lot of interest now in trying to identify people who are in the preclinical stages of Alzheimer's disease, because we think that's when we have the best chances of intervening and being able to prevent or delay its development," Alexander said.

Study participants will visit a lab three times a week for two weeks, then once a week for 10 weeks. At each visit, they will wear the near-infrared light caps and use the intranasal devices for 40 minutes. They'll also take home an intranasal device, which they will be instructed to use daily for about 25 minutes.

"We're trying to enhance function in some key areas of the brain that we think are important for aging and Alzheimer's risk – brain areas like the temporal and frontal lobes, which are important for aspects of memory and complex executive functions, like problem-solving skills," Alexander said.

While some participants will be randomly assigned to receive the light treatment, others will use the same equipment and procedures, but will not receive any near-infrared light exposure. Because near-infrared light can't be seen and doesn't emit heat, participants won't know whether they are getting the treatment or not.

Before and after the intervention, participants will complete a battery of neuropsychological tests and undergo MRI scans to measure resting state connectivity in the brain. Researchers also will use a special type of MRI scan known as magnetic resonance spectroscopy to measure aspects of mitochondrial function in the brain. Participants will be tested again three months after the intervention to determine whether there were any lasting effects or changes.

"As we age, we know that mitochondrial function seems to decrease, and there's a re-emerging interest in understanding whether mitochondrial dysfunction could be a part of the Alzheimer's disease story," Alexander said.

If proven successful, near-infrared light could be a safe, low-cost tool in the battle against cognitive decline and Alzheimer's disease.

"If it's something that turns out to be beneficial, it could help – possibly in combination with other treatments or on its own – to prevent cognitive aging and Alzheimer-related effects," Alexander said. "But a lot more work would need to be done."

Along with Alexander, the other principal investigators on the study are Dawn Bowers and Adam Woods at the University of Florida. Two other University of Arizona faculty members will serve as co-investigators: Alex Hishaw, associate professor of neurology and psychiatry, and Ted Trouard, professor of biomedical engineering and medical imaging and a member of the BIO5 Institute and Evelyn F. McKnight Brain Institute.