New evidence linking sight loss to dementia

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By Arjun Sanganee | Thursday 13 July 2023

JAMA Ophthalmology: Objectively Measured Visual Impairment and Dementia Prevalence in Older Adults in the US

A new study suggests that sight loss in people over 71 years old may be linked to dementia. The study was published today (Thursday 13th July 2023) in the Journal of the American Medical Association (JAMA) Ophthalmology.

The researchers at the University of Michigan in the US analysed data from nearly 3,000 US citizens over 71 years old, who were part of a larger study, the National Health and Aging Trends Study (NHATS). This larger study tested the participants’ eyesight and recorded their scores for short-distance vision, long-distance vision and how well they were able to distinguish objects against different backgrounds. They also found out whether the participants had dementia from the NHATS study data.

What they found was that participants with sight loss were more likely to have dementia compared to people with no problems with their vision.

Up to 40% of dementia cases could be influenced by 12 risk factors which we may be able to prevent or influence, such as smoking, high blood pressure and hearing loss. Sight loss is not currently one of these 12 important risk factors, but the new evidence published today suggests that there is a link between sight loss and dementia.

 

Dr Susan Mitchell, Head of Policy at Alzheimer’s Research UK, said:

“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.

“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. There are several possibilities – for example, diabetes is a key risk factor for dementia, and this condition can also cause vision problems. Or it might be that there are shared pathways in the brain that cause both vision loss and a decline in memory and thinking abilities.

“Some cases of sight loss are preventable, and others can be treated successfully – if this link is confirmed, this could mean people who take steps to minimise sight problems as they get older could also help reduce their risk of conditions like dementia.

“In the meantime, we can all take action to protect our brain health, from keeping our hearts healthy to enjoying new activities and social interactions.  If you want to know more about how your own lifestyle checks out in terms of keeping your brain healthy, you can take Alzheimer’s Research UK’s ‘Think Brain Health check-in’ by visiting https://www.alzheimersresearchuk.org/brain-health/check-in/

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Arjun Sanganee