Two new risk factors for dementia have been identified: vision loss and high cholesterol. 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 preventive treatment, along with well-known health threats such as head injury, smoking, excessive alcohol consumption and air pollution.
As Canada’s senior population increases, so does the prevalence of dementia. Alzheimer’s Association of Canada estimates that one million Canadians will be living with dementia by 2030.
Dementia is a term used to describe symptoms of cognitive decline, including memory loss, loss of thinking, and loss of personality. Alzheimer’s disease is the most common cause of dementia.
Although aging is inevitable, cognitive decline in later life may not be. The Lancet Commission has reported that reductions in modifiable risk factors have the potential to prevent almost half of dementia cases.
Dr Gill Livingston, professor of geriatric psychiatry at University College London and lead author of the committee, said she hopes to shorten the period of decline at the end of life.
“If you ask people aged 50 and over what disease they are afraid of, the majority will say dementia,” she says.
Vision loss in old age affects more than just the ability to see
The committee looked at multiple studies and meta-analyses with data from a total of several million participants and found “considerable evidence” that vision loss is a risk factor for dementia.
Hearing loss was previously mentioned as a risk factor, because the loss of that sense reduces 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.
A meta-analysis A study by the Lancet team found that cataracts and retinal damage caused by diabetes had the strongest association with dementia.
Another study found that treating cataracts can reduce the risk of dementia. While people with cataracts had an increased risk of dementia, people with treated cataracts had no greater risk than people with healthy lenses.
While the idea of cataract surgery may be unsettling to some, Dr. Peter Kertes, chief ophthalmologist at the Kensington Eye Institute and professor and chair of the department of ophthalmology at the University of Toronto, said there are options to make the procedure accessible to people who currently have dementia.
“We see quite often that patients who are cognitively impaired and have significant cataracts,” he said. “After their cataract surgery, their cognitive impairment improves significantly and their lives improve significantly.”
Health habits in midlife influence risk of dementia later in life
Several of the risk factors identified in the report were age-specific. While treating vision loss in later life reduced the risk of dementia, midlife was identified as an important period for treating and moderating cholesterol levels.
Cholesterol is a waxy steroid found in the blood. It has many essential functions, including building other steroids and vitamin D.
Lipoproteins transport cholesterol through the body and one form, known as low-density lipoproteins (LDL), can stick to the walls of blood vessels, sometimes causing blockages.
High levels of LDL cholesterol, also known as the “bad” cholesterol, are mainly caused by the consumption of foods high in saturated fats.
Too much cholesterol in the brain is linked to an increased risk of stroke and to the build-up of harmful proteins linked to dementia.
Many risk factors for dementia, including cholesterol levels, interact with each other, Livingston said.
“People who are less physically active are more likely to have high blood pressure, be overweight and have diabetes, so they form a group,” she said.
‘Use it or lose it’
To stay mentally sharp, it’s important to keep your brain active by participating in activities that challenge your memory, attention, and decision-making.
According to Dr. Anthony Levinson, professor of health sciences education at McMaster University, people are generally aware of the importance of staying cognitively active.
“There are people who do try to stay involved, who do puzzles more often or who learn a new language,” he said.
Other activities that stimulate and maintain brain function include reading, writing, playing musical instruments, and participating in conversation.
The Lancet team noted that dementia prevention begins with childrearing.
However, new research shows that cognitive activity in middle age, even in people with little education, can also have a preventive effect.
While cognitively stimulating hobbies may help reduce dementia, the best thing you can do is have a job that is mentally challenging, as you will spend more time on your work than on hobbies, the Lancet report found.
The report found that high cognitive stimulation increases your “cognitive reserve” — the ability to function normally despite invisible changes in your brain.
Making the change
According to Levinson, reducing the risk of dementia starts with changing people’s perceptions of cognitive decline in later life.
“People have this misconception that if you live long enough, everyone will get dementia,” he said. “That’s not true.”
According to the Health Council, approximately one in four seniors aged 85 or older has been diagnosed with dementia. Canadian Institute for Health Information.
Not every dementia prevention technique requires a significant change in lifestyle. While some changes, such as diet and exercise, may be more difficult, simple actions like getting your hearing tested make a difference, Levinson says.
According to Dr. Samir Sinha, director of geriatrics at Mount Sinai and University Health Network Hospitals in Toronto, systemic changes in public health are also needed.
Primary care providers are key to managing a healthy lifestyle. one in five Canadians do not have access to regular primary care providers, such as a family doctor or nurse practitioner.
“We need to make sure that every Canadian has access to a primary care provider and that we have the right mix of specialists, including geriatricians, to really manage the care of older adults and prevent things like dementia,” Sinha said.