Published on: March 1, 2013
by Jaimie Dalessio for Everyday Health:
Scientists have learned that Alzheimer’s may take as long as 15 years to develop in the brain, suggesting a wider window for possibly halting or reversing the disease than previously thought.
Researchers at the Mayo Clinic in Rochester, Minn., found that beta amyloids, plaques in the brain linked to declines in memory and thinking, build up over 15 years before reaching a plateau. They used PET imaging, a type of scan that produces 3-D images, on 260 participants in Mayo Clinic studies on aging and Alzheimer’s and a mathematical model to estimate annual accumulation. The results of their research, reported in the March 5 issue of the journal Neurology, suggest plenty of room for prevention of full-blown Alzheimer’s.
Information like this is essential to validating the idea that, as with cardiovascular disease, Alzheimer’s disease moves along a continuum, says Heather M. Snyder, PhD, the director of Medical & Scientific Operations at the Alzheimer’s Association.
In 2011 the Alzheimer’s Association, in conjunction with the National Institute on Aging, published revised guidelines on how Alzheimer’s is diagnosed, putting focus on a progression that’s 10, 15, and possibly 20, 25, or 30 years in the making.
“With cardiovascular disease, if you go to a physician and have high cholesterol in your twenties or thirties, there are things you can do to intervene at that point to reduce risk of later in life having a heart attack or stroke,” says Dr. Snyder, who was not involved in this latest research. “This is potentially looking at what are those earliest changes [in Alzheimer’s], so when there is that therapy — whether it’s a drug or lifestyle changes — when we understand more about what those are, we can identify those people that will benefit.”
Hope for Future Alzheimer’s Prevention Therapies
There is no cure for Alzheimer’s, so the very few treatments that exist work to slow its progression. So far the FDA has approved five drugs that can temporarily slow worsening of Alzheimer’s symptoms, according to the Alzheimer’s Association, but they work for only about half the people who take them.
At the moment, screening and intervening early are not necessarily going to change the average person’s life or experience as it relates to Alzheimer’s, says Snyder. Alzheimer’s expert P. Murali Doraiswamy, MD, agrees. Dr. Doraiswamy is a psychiatry professor in the School of Medicine at Duke University who did not work on the study but has led previous research on amyloid plaques.
“It’s a bit of a Pandora’s box,” says Doraiswamy. “There are some 150 million elderly people worldwide who probably have silent brain amyloid plaque buildup but don’t know that they have it. We don’t have a magic bullet to prevent Alzheimer’s. That’s why at this point I don’t recommend these technologies be used as a screening tool.”
“A negative scan has a strong negative predictive value,” he adds, “but we still don’t fully understand what a positive scan means in asymptomatic people.”
At this point, Snyder says, it’s too early for this to be a viable screening method. But the study is a good sign that the field as a whole is moving in the right direction.
Doraiswamy expresses a similar sentiment. “The main reason the existence of a possible window is important is that it allows us to test experimental strategies such as anti-amyloid therapies or lifestyle modification, for example, exercise and brain training,” he says, and several studies on these strategies are ongoing or planned. “These studies will also tell us whether amyloid plaques are the cause of Alzheimer’s or not, which is something we still don’t know for sure.”
The Mayo study also suggests that treatment after amyloid plaques reach a plateau might be less effective, which supports the current belief among researchers that treatment earlier in the course of Alzheimer’s progression will work better than later.
For that reason, much of current Alzheimer’s research is focused on looking for biological changes in the brains of people who are not experiencing the cognitive changes or thinking and memory problems we associate we Alzheimer’s.
Catching Alzheimer’s Early
If you’re concerned about your risk for Alzheimer’s disease, Doraiswamy recommends staying mentally and physically active, watching your numbers — weight, blood pressure, and blood sugar — and avoiding risky activities that might lead to a head injury. Snyder recommends watching for the 10 earliest signs of Alzheimer’s, which include:
–Memory loss that disrupts daily life
–Challenges in planning or solving problems
–Difficulty completing familiar tasks at home or at work
–Confusion with time or place
–Trouble understanding visual images and spatial relationships
–New problems with words in speaking or writing
–Misplacing things and losing the ability to retrace steps
–Decreased or poor judgment
–Withdrawal from work or social activities
–Changes in mood and personality
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