Scientists at The Jackson Laboratory in the U.S. have made a discovery that could change how doctors detect Alzheimer’s disease and other dementias in the future.
Their research, recently published in the journal Alzheimer’s & Dementia, found that changes in the tiny blood vessels of the eye might give early warning signs of brain disease—years before symptoms appear.
The team studied mice with a common genetic mutation called MTHFR677C>T, which is found in up to 40% of people. This gene is linked to a higher risk of Alzheimer’s.
The researchers noticed unusual changes in the mice’s retinas, such as twisted and swollen blood vessels and fewer branches, starting as early as six months old. These same types of changes are often found in the brains of people with dementia and are linked to poor blood flow and higher chances of cognitive decline.
What’s exciting is that the retina is part of the central nervous system—just like the brain. This means that the retina can give us clues about what might be happening in the brain. Dr. Alaina Reagan, who led the study, explained that the retina is like an extension of the brain that doctors can see easily during a routine eye exam.
“Your retina is essentially your brain, but it’s much easier to access,” Reagan said. “The neurons and immune cells are very similar, and they respond in the same way if there’s a disease.”
The researchers also found changes in the proteins of the brain and retina, showing that the MTHFR mutation might disrupt how cells make energy, clean up damage, and support healthy blood vessels. This supports the idea that poor blood vessel health might be one of the early warning signs of diseases like Alzheimer’s.
They also observed differences based on age and sex. Female mice with the mutation showed more severe changes by 12 months, including fewer blood vessels and less branching. This matches findings in humans, where women are more likely than men to develop dementia.
In earlier work from 2022, the same team found similar blood vessel damage in the brains of mice with the same mutation. Together, these studies strengthen the idea that the eye could be used as a window into brain health.
The team now plans to work with doctors and dementia specialists at Northern Light Acadia Hospital in Maine to see if these eye changes happen in people too. The hope is that by recognizing the signs in the eye, doctors can identify people at risk long before any memory problems appear.
Dr. Reagan said that most people over age 50 already visit the eye doctor regularly. If optometrists or ophthalmologists knew what to look for, they might be able to help spot dementia early and recommend further testing. This could happen 10 or even 20 years before a person or their family notices any signs of memory loss.
If these findings are confirmed in people, it could change the way we diagnose and treat Alzheimer’s—catching the disease early and giving people a better chance of protecting their brain health.
The study is published in Alzheimer’s & Dementia.
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