Time to get your eyes checked: Vision loss among growing list of risk factors for dementia, study says
CBC
Two new risk factors for dementia — vision loss and high cholesterol — have been identified in a sweeping new report in a leading medical journal.
The 2024 Lancet Commission on dementia lists 14 risk factors for dementia, many of which can be influenced by lifestyle changes. Among them, untreated vision loss and high cholesterol stand out as new targets for preventative treatment alongside well-known health threats such as head injuries, smoking, excessive alcohol consumption and air pollution.
As Canada's senior population rises, so too does the prevalence of dementia. The Alzheimer Society of Canada estimates one million Canadians will be living with dementia by 2030.
Dementia is a term used to describe symptoms of cognitive decline including loss of memory, thinking and personality. Alzheimer's disease is the most common cause of dementia.
While aging is inevitable, late-life cognitive decline may not be. The Lancet Commission has reported that reductions in modifiable risk factors have the potential to prevent nearly half of dementia cases.
Dr. Gill Livingston, a professor of psychiatry of older people at University College London who is the commission's lead author, said she hopes to decrease the period of deterioration at the end of life.
"If you ask people who are age 50 and over what illness they fear, and most, a majority of them will say dementia," she said.
The commission looked at multiple studies and meta-analyses with data from a combined total of several million participants and found "considerable evidence" supporting vision loss as a risk factor for dementia.
Hearing loss had previously been listed as a risk factor, as losing that sense decreases brain stimulation. The same thing happens when you lose your sight — when you can't see, it's hard for you to interpret and interact with the world.
One meta-analysis cited by the Lancet team found cataracts and retina damage caused by diabetes had the strongest associations with dementia.
Another study found that treating cataracts may decrease the risk of dementia. While people with cataracts had an increased risk of dementia, those with treated cataracts had no greater risk than people with healthy lenses.
Though the idea of cataract surgery can be unnerving to some, Dr. Peter Kertes, ophthalmologist-in-chief at the Kensington Eye Institute and professor and chair of the University of Toronto's ophthalmology department, said that there are options available to make the process accessible even to those currently experiencing dementia.
"We find not infrequently that patients who are cognitively impaired who have significant cataracts," he said. "After their cataract surgery, their cognitive impairment improves considerably and their life improves considerably."
Several of the risk factors identified in the report were age-specific. While treating vision loss in late life decreased risk of dementia, mid-life was identified as a key time for treating and moderating cholesterol levels.
