Vision loss, high cholesterol among growing list of risk factors for dementia, review says

Vision loss and high cholesterol have been identified as two new risk factors for developing dementia, a leading medical journal has found. 

In a major review involving meta-analyses from several million participants, the 2024 Lancet Commission on dementia lists 14 modifiable risk factors for dementia. The majority of them are already well-known, such as smoking, diabetes, excessive alcohol consumption and social isolation, but untreated vision loss and high cholesterol were previously unknown risk factors. 

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With a rising senior population, the Alzheimer Society of Canada predicts nearly one million Canadians will be living with dementia by 2030. Worldwide, 153 million people are expected to be living with dementia by 2050 — more than double what it was in 2019 — the commission reports. 

An aging population is inevitable but dementia isn’t: nearly half of the dementia cases worldwide could potentially be prevented by eliminating those 14 risk factors, the commission writes.  

This is a message stressed by Dr. Samir Sinha, director of geriatrics at Mount Sinai, who tells CTV Your Morning there are lifestyle changes people can make to prevent and delay dementia. It’s not surprising that vision loss has been added as a risk factor, he says, as hearing loss — another sensory impairment — has also been linked to dementia. 

“When you’re not actually maintaining your senses well and you're not actually correcting challenges with those, then that actually decreases the sensory input to our brains [and] we're not getting our brain the information it needs,” he explains. 

When it comes to prevention and treatment, treating cataracts may help decrease the risk of dementia, the Lancet review notes. People 65 and older who had cataract surgery had about a 30 per cent lower risk of developing dementia compared with older adults with cataracts who did not receive the surgery to correct their vision, according to one of the studies referenced in the report.

Meanwhile, treating high cholesterol — such as through regular exercise — can also help prevent blockages of arteries in the brain that can lead to dementia, Sinha adds. 

“Keeping a healthy heart keeps a healthy brain,” he says, adding that it doesn’t mean you need to start running marathons or pumping iron. “That could be just going for a walk every day for about 30 minutes.”

However, many risk factors outlined in the review, such as air pollution and lack of education, will also require public health interventions rather than individual modifications. Some factors are also harder to eliminate: genetics and old age remain the biggest risk factors for developing dementia.

While primary care plays a vital role in diagnosing and treating dementia, more than six million Canadians are without a family doctor. Systemic changes in Canada’s public health are therefore also needed in order to leverage the findings of this review, Sinha says. 

“This is the challenge. We not only have a shortage of primary care providers but we also have a shortage of specialists, like geriatricians or neurologists,” he says. “We need to make sure that more people have access to this care so that things like managing cholesterol can be done with a professional. It's hard to do that on your own.”