High blood pressure, smoking, hearing loss and diabetes are some of the factors that raise the risk of cognitive decline. But does failing eyesight signal dementia? A recent study suggests that vision loss has a significant link with dementia in the elderly, adding one more to the list of already established 12 risk factors.

Researchers from the University of Michigan evaluated 3,000 participants over 71, who were part of a larger study, titled the National Health and Aging Trends study (NHATS). They assessed the participants' eyesight – their short-distance vision, long-distance vision and ability to distinguish objects against different backgrounds. The research team also identified the participants who had dementia through a screening interview.

The study's findings, published in JAMA Ophthalmology, suggest a significant association between cognitive and visual health.

Out of the total participants, around 12.3% displayed dementia-related symptoms. In participants with distance visual impartment, the rate increased to 19.5%. The rate of dementia-related symptoms was 21.5% in people with near visual impairment and 32.9% in those with moderate to severe visual impairment.

"This is a crucial time for dementia research, as evidence builds about how factors such as sight loss are linked to dementia. Studies like this are crucial for identifying possible new dementia risk factors and ultimately working out how to potentially prevent some cases of dementia from happening in the first place," said Susan Mitchell, head of policy at Alzheimer's Research UK.

"This new study provides important new evidence linking sight loss to dementia and ties in with previous studies. But this isn't definitive, and it will be important for future studies to find out precisely what is causing this apparent link, as this will determine what if any, potential there is for prevention," Mitchell, who was not involved in the study, added.

Several possibilities explain the association between vision loss and cognitive health. The shared brain pathways for vision and memory could be one reason. It could also be due to conditions such as diabetes that can cause both vision loss and dementia.

Although the exact mechanism is not known, the study suggests the need for minimizing sight problems to reduce the risk of dementia in the elderly.

Modifiable risk factors of dementia account for up to 40% of cases. Here are the 12 factors that affect cognitive health:

1. High blood pressure
2. Smoking
3. Diabetes
4. Obesity
5. Lack of exercise
6. Poor diet
7. Alcohol consumption
8. Lack of cognitive engagement
9. Brain injury
10. Depression
11. Hearing Loss
12. Social isolation