For the first time in 27 years, the definition of Alzheimer's disease is being recast in new medical guidelines that reflect fast-mounting evidence that it begins ravaging the brain years before the symptoms of dementia.
The guidelines, to be issued Tuesday by the National Institute on Aging and the Alzheimer's Association, divide the disease into three stages: a phase when dementia has developed, a middle phase in which mild problems emerge but daily functions can still be performed, and the most recently discovered phase, in which no symptoms are evident but changes are brewing in the brain.
“We’re redefining Alzheimer’s disease and looking at this in a different way than had ever been done,” said Creighton Phelps, director of the National Institute on Aging’s Alzheimer’s Disease Centers Program. “I think we’re going to start to identify it earlier and earlier.”
The drive to diagnose Alzheimer’s before it has progressed into profound dementia is also reflected in a bill introduced in Congress this month, which would create specific Medicare cost codes for Alzheimer’s diagnosis, including steps involving discussions between the patient’s doctor and caregivers, a recognition that keeping family members well-informed can result in better planning and care.
“Early diagnosis is really the key to this,” said Representative Edward J. Markey, Democrat of Massachusetts and a sponsor of the bill. “Oftentimes family members notice the symptoms in their loved ones, but it’s only years later that they get diagnosed or understand what resources are available.”
The most striking addition to the guidelines concerns methods that assess brain changes involved in Alzheimer’s, including brain scans and tests of cerebral spinal fluid. Such methods measure what are called biomarkers, physiological indicators that someone is likely to develop dementia eventually, just as cholesterol and blood pressure are biomarkers of impending heart disease.