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LONDON — Millions of people who suffer from common age-related eye diseases could be in danger of developing dementia, warns a new study. The risk of dementia, one of the leading causes of death, is up to 60 percent higher among people with eye diseases, according to scientists. About 80 million Americans have potentially blinding eye diseases and more than six million have Alzheimer’s disease — the most common form of dementia.

A number of health conditions like diabetes, high blood pressure, heart disease, depression, and strokes can increase a person’s chances of developing dementia. The odds of having these increase with age, but the same is true for eye conditions like cataracts, age-related macular degeneration (AMD), glaucoma, and conditions related to diabetes. Yet whether eye diseases themselves have a link to conditions such as Alzheimer’s has remained a mystery — until now.

“Age-related macular degeneration, cataract and diabetes-related eye disease but not glaucoma are associated with an increased risk of dementia. Individuals with both ophthalmic and systemic conditions are at higher risk of dementia compared with those with an ophthalmic or systemic condition only,” says Dr. Xianwen Shang at the Guangdong Academy of Medical Sciences in China, in a media release.

Diabetes can be devastating for the eyes and the brain

The team analyzed data on 12,364 adults between 55 and 73 years-old who participated in the UK BioBank study. Study authors assessed the participants between 2006 and 2010 and then again in early 2021, with doctors diagnosing 2,304 cases of dementia in total.

Eye diseases, including AMD, cataracts, and those related to diabetes all appear to have a connection to a higher risk of dementia. Compared to those with healthy vision, the risk of dementia was 26 percent higher for people with AMD, 11 percent higher for those with cataracts, and 61 percent higher for diabetes-related eye diseases. Glaucoma, a condition where the optic nerve becomes damaged, did not, however, increase the risk of dementia, the study finds.

At the start of the study, researchers also examined each participant for depression and asked whether they had experienced a heart attack, angina, stroke, high blood pressure, or diabetes. Dr. Shang adds that having one of these conditions as well as an ophthalmic condition increases the risk of dementia further. Researchers discovered that the risk is greatest when diabetes-related eye diseases occur along with a systemic condition.

The team notes that the number of eye diseases documented during the study is likely less than the actual number which impacts dementia risk as participants self-reported their eye conditions. Also, medical and death records may not have captured all cases of dementia during the study.

“Newly developed hypertension, diabetes, stroke, heart disease and depression mediated the association between cataract/diabetes-related eye disease and dementia,” the researchers conclude.

The study appears in the The British Journal of Ophthalmology.

South West News Service writer Tom Campbell contributed to this report.

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