The U.S. Food and Drug Administration recently approved the use of a compound called Amyvid to aid in the diagnosis of Alzheimer’s disease, which is often anything but straightforward. Amyvid contains a radioactive substance that seeks out and tags amyloid-beta, the plaques in the brain that are thought to be the cause of Alzheimer’s disease. Under a PET scan, the radioactive tags “light up,” highlighting any plaques that are present.
The symptoms of various brain diseases can overlap considerably. Currently, the only way to make a definitive Alzheimer’s diagnosis is from an autopsy. In general, doctors determine that patients likely have Alzheimer's based on an accumulation of symptoms, once they rule out other possibilities. The new technique (which is not covered by Medicare or most insurance plans) should provide a more reliable, yet still not foolproof instrument for correctly diagnosing Alzheimer's disease. But there are both medical and ethical concerns.
First, it can be difficult to interpret the results of the scans. A positive result doesn’t necessarily mean one has Alzheimer's; a negative result doesn’t necessarily mean one doesn’t. Eli Lilly, the company that makes Amyvid, points out that the new technique is meant to be used for people who already display symptoms of cognitive impairment. “It’s estimated that 1 in 5 patients clinically diagnosed with probable Alzheimer’s disease during their life do not end up having Alzheimer’s disease pathology upon autopsy,” says Dr. Daniel Skovronsky, global brand development leader for Amyvid. He says the new compound “offers physicians a tool that, in conjunction with other diagnostic evaluations, can provide information to help physicians evaluate their patients.”
Similarly, not everyone who has amyloid in their brain will eventually develop Alzheimer’s symptoms. “About 33 percent of people over 65 have amyloid in the brains and have no symptoms,” says Dr. Mary Sano, director of Alzheimer’s Disease Research at Mount Sinai Medical Center in New York City, and a member of the Alzheimer’s Association’s Medical and Scientific Advisory Council. “That's right: A third of normal elders have amyloid in their brain. We don’t yet know what this means. On the other hand, the absence of positive test results does not indicate that a person has no symptoms, or might not develop them very shortly.”
A Patient’s Perspective on Early Diagnosis of Alzheimer's
Given the long-term, irreversible effects of Alzheimer's, and the limits of current treatments, which can stave off some effects but not stop cognitive decline, would you want to know that a loved one had the disease, or that you had it yourself? If you have a family history of Alzheimer’s disease, would you want to be told there were plaques in your brain even if you didn’t have any symptoms? Early-onset Alzheimer's patients often remain highly functional for many years, at least in some cognitive areas. If you had the disease, without debilitating symptoms, would you rather remain unaware?
Some people with early symptoms of cognitive decline might prefer not knowing that they have the plaques in their brains. An early diagnosis can be demoralizing, and cast a pall over relationships with family, friends and co-workers. The stress of living with the diagnosis could be too much for some people to bear. But wider early diagnosis could also help researchers develop new and more effective treatments. And some patients embrace early diagnosis and the opportunities they feel it brings.
“It was beneficial to me to be diagnosed early, not just for me, but for my family,” says Alexander “Sandy” Halperin, a dentist in Tallahassee, Fla., whose father suffered from Alzheimer's and who received a diagnosis of early-onset Alzheimer’s a couple of years ago, at age 60. “It let me take a proactive role,” he says. Halperin believes that learning the probable cause of his symptoms gives him the best shot at slowing the disease's effects with medications, and gives him the most time to plan for the future. “I haven’t hidden my diagnosis; I’ve been verbal and open about it. I’ve been looking for Alzheimer’s studies I can participate in. And knowing early has allowed my wife and me to plan financially for the future.
“I don’t look at this as a death sentence,” Halperin says. “I look at it as a new stage of life. It’s challenging, but I’m facing it. This isn’t just about me. It’s about all patients and their families.” Halperin is one of 10 Alzheimer’s Association early-stage advisers across the country, patients who help the group advocate for financing for Alzheimer’s research, raise public awareness of dementia and advise the group about the best resources for people with early-stage Alzheimer’s.
How much one wants to know about the risk of developing any disease is a highly personal decision, one that more people will likely face in the years to come, as detection technology becomes more sophisticated. “After the diagnosis, my doctor told me to volunteer, not vegetate,” Halperin says, “and this is what I’d say to everyone else out there living with Alzheimer’s: Go get active.”
There are still questions to be answered about Alzheimer's detection, like why amyloid can be present in asymptomatic people, and why others may have very little amyloid but more extensive symptoms. But the coming years are likely to bring a greater understanding of the roots of this complex disease.
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