alzheimer's screening could be part of your next eye exam
detection of brain diseases, like alzheimer's, before symptoms appear has researchers excited about the potential to slow, or even stop, progression.
6 minute read
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joshua armstrong, a research scientist for the alzheimer society of canada, says he’ll never forget walking up to his grandmother’s house and seeing her look at him like he was a stranger. she had late onset alzheimer’s disease in her late 70s. as his mom ages, she’s very worried about developing alzheimer’s herself, with genetics playing a role in heightened risk of the disease.
and at age 44, armstrong is following lifestyle habits that are proven for the prevention of dementia, like healthy eating, socializing, working his brain by tackling new challenges, good sleep and regular activity — walking, running and biking in the warmer weather near his home in thunder bay, ont.
the common perception is that this is something to think about later in life, but that’s just not true.
brain changes happen long before symptoms
“what we understand about alzheimer’s disease is that many changes going on in the brain are happening years if not decades before you see any symptoms,” says armstrong, who leads the alzheimer society’s landmark study which released its first report last september that looks at rising incidence and the power of risk reduction.
alzheimer’s is the most common form of dementia, and it becomes more severe over time, impacting things like memory, mood, language and judgment, and physical abilities including coordination, bladder control and walking. estimates suggest there are almost 600,000 canadians living with alzheimer’s today.
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“even by the time you hit 25, you should be thinking about your brain health and making sure that you’re optimizing it, so then you’re not getting some of these challenges later in life,” says armstrong. “by the time you’re 40, you’re definitely having some changes related to aging going on in your brain,”
prevention, clearly, is something he’s keen to talk about, especially because the prevalence of alzheimer’s in canada is going to balloon as the large demographic of baby boomers heads into their 80s over the next 30 years. most dementia happens in people over 65, but there is younger onset dementia that can happen in middle age or younger.
“age is the highest risk factor for dementia, so it’s this large group of people. so even by the end of 2030, we’re projecting over a million canadians living with dementia,” he says. by 2050, more than 1.7 million are expected to have dementia with an average of 685 individuals being diagnosed each day.
that puts a lot of strain on health-care systems and families. we see not only the individuals affected, but also their families who are deeply affected because they have to provide ongoing care, for not just a short time. people can live with dementia for three to 20 years.”
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the good news is that the pace of change in terms of treatment and early detection is inspiring — along with our fundamental understanding of the brain, armstrong says. consensus used to be you were born with your neurons and that’s it, and any damage that occurred was irreparable. now we know there’s a lot of plasticity involved where a healthy brain can be rewired and healed.
clues to alzheimer’s disease in the eye
another hopeful advancement is emerging knowledge about the brain-eye connection, where the eye can be a window to what’s actually going on in the brain and reflect a person’s cognitive health.
cnn recently reported on a new study in the journal acta neuropathologica where researchers at cedars-sinai medical center in los angeles looked at human donor tissue from the eye and the brain. certain changes in the retina, the layer at the back of the eye, corresponded with changes in the brain and cognitive function. they compared tissues samples of those with normal cognitive function to those with mild cognitive impairment and those with later-stage alzheimer’s disease.
“what’s interesting is that they can see this relationship between proteins in the eye and the proteins in the brain and the expression of those proteins,” armstrong says. while people may have abnormal deposits in their brain of the different plaques or tangles — that build up between nerve cells and can impair proper function — they might not have dementia.
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identifying characteristics in the eye can be a tool for early screening for alzheimer’s.
“we’re all building up damage over time, but if we can we can identify those people that are starting to have a buildup of damage early on, we can focus attention on their lifestyle or whatever other forms of prevention work we can do,” he says. “if we can treat people’s heart disease, their blood pressure, their diabetes, that’s going to also impact the brain positively, which can reduce risk of developing dementia or slow the aging process down a bit.”
alzheimer’s research in canada
researchers in canada are also shedding light on the brain-eye connection and alzheimer’s early detection. dr. sandra black, a cognitive neurologist and senior scientist at sunnybrook research institute in toronto, is a pioneer in the field. her lab has focused on eyes and how they reflect brain health.
“the eye is a window into the brain because, first of all, it is part of the brain. it’s an extension of the brain,” she says. “so it would not be surprising that it might show similarities to what happens to the small vessels in the brain, but also to the various pathologies that can affect the brain, in particular alzheimer’s disease.”
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her team has studied blood vessels in the eye to determine early signs of cognitive decline, and a current project with the ontario neurodegeneration research initiative involves measuring the thickness of different layers in the eye in relation to what’s going on in the brain.
the eye structure is part of the cholinergic system of the brain that regulates your attention and higher cognitive processing. when it gets attacked by alzheimer’s or parkinson’s disease, people often have trouble focusing and retrieving information.
“another interesting thing, it looks like glaucoma and macular degeneration may be associated with alzheimer’s disease more than just by chance,” says black. “it might actually be that we’re seeing something going on in the eye that’s reflecting something that’s going on in the brain in a way that we never really understood until people start to sort of show associations.”
she also says there’s been a lot of interest to measure amyloids in the eye, which are markers of inflammation for possible disease — like the research to identify inflammation by the team at cedars-sinai.
she’s collaborating with montreal-based optina diagnostics, inc. which uses amyloid positron emission tomography (pet) scans to visualize plaques in the brain in patients. the plaques light up on the scan of the brain. the company also used special imaging to look for amyloids in the eyes and found a significant correlation. next up is the development of a camera for detection of amyloids in the eyes that could be on the market in the next year or two for eye specialists to use in routine eye exams.
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early testing for alzheimer’s
“we’re already looking at some studies where we’re bringing people in while they’re cognitively normal, but they may have a family history,” says black. “we do blood tests that can tell you that you have amyloids in the brain, then we do the pet scans and the mri scans. we’re trying to prevent the development of symptoms, so this has a lot of implications for screening. but the eye gives you an extra sense of it happening in the brain.”
black says the dream is that you might go for your eye checkup when you’re 55-years-old and be offered a screening test to give you an early signal that you’re at risk for alzheimer’s. she compares it to early identification of heart attack risk where a test shows cholesterol is causing plaque buildup in your arteries. then people can make lifestyle changes and get the right medications to help slow the process.
her best advice, like armstrong, comes down to lifestyle habits that can protect your brain from dementia: healthy eating, social connections, good sleep and regular exercise.
“the eye and the brain are connected. there’s also the heart-brain connection. we’re all like one big organism,” she says. “one of the things that’s interesting about aerobic exercise, for those who can do it, is that the muscles create a molecule that goes to the brain and stimulates the hippocampus to make new memories. so the memory part of the brain is stimulated by aerobic exercise. that brain-muscle connection is fascinating.”
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karen hawthorne is a toronto-based writer.
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