Scientists in Maine are researching whether a simple eye exam could help detect Alzheimer’s disease, other types of dementia or similar diseases in patients before symptoms begin to appear.

Gareth Howell, a professor at The Jackson Laboratory in Bar Harbor, said if the research is proven in humans, he believes it’s realistic the test could be given at optometrists’ offices across the country within the next few years.

“This could be huge,” Howell said. “You would be able to treat people prior to their cognitive decline. This is like changing the plug in a lamp before the lamp is actually broken.”

Jackson Lab, Northern Light Health and the University of Maine are collaborating on the research, which has gone beyond testing in laboratory mice and will be tested on people as part of a $300,000 pilot program.

Jackson Lab’s research on mice was published in February in the scholarly journal Molecular Neurodegeneration. The research showed that changes in blood vessels in eyes could predict cognitive declines in the mice.

Alzheimer’s is a deadly and devastating disease that robs patients of cognitive abilities like memory and eventually leaves them unable to complete basic tasks. About seven million people in the United States have Alzheimer’s disease, including 29,000 in Maine, according to the Alzheimer’s Association.

Howell said his research into eye diseases like glaucoma and macular degeneration led him to theorize that the eye could help reveal whether changes that occur when people have Alzheimer’s and similar diseases were happening in the brain.

“The eye is a window to the brain. The retina is like the brain sticking out of the skull,” Howell said. “The research holds a lot of promise in using the eye for early detection.”

The scientists are researching whether changes in retinal blood vessels correspond to similar damage occurring in blood vessels in the brain, Howell said.

The eye test would be another tool for early diagnosis of degenerative brain diseases. A blood test that assists with early diagnosis was approved by the Food and Drug Administration this spring and is a major advancement in early detection. Scientists all over the world are examining various ways that these diseases could be diagnosed earlier.

Dr. Cliff Singer, a psychiatrist and geriatrician with Northern Light Health who is part of the research team, said “early identification and screening is where this whole field is headed.”

Recently approved medications, such as Leqembi, that help slow the progression of Alzheimer’s are more effective the earlier the patient is diagnosed. Singer said the eye test results could also be a wake-up call for patients to take better care of their overall health, similar to when a patient receives a bad cholesterol result from their annual physical.

“This could motivate people to really focus on a healthy diet, healthy sleep, physical activity and maintaining social connectedness, all of which are healthy brain behaviors and prolong brain health,” Singer said.

Alaina Reagan, associate research scientist at Jackson Lab who is working with Howell on the study, said patients “having that information early is critical.”