When you think of dementia, most people automatically think of Alzheimer's disease, too. But, under a new definition of Alzheimer's, the two terms no longer will be considered interchangeable.
The new definition is part of a new framework for researching Alzheimer's disease that the Alzheimer's Association and the National Institute on Aging developed and released.
"Alzheimer's disease is one cause of dementia," Dr. Clifford Jack Jr., a Mayo Clinic radiologist and Alzheimer's researcher, says. "It's the most common cause, but it's certainly not the only cause. And that has been a source of major confusion."
Jack helped lead a team of scientists with the Alzheimer's Association and the National Institute on Aging releasing the new Alzheimer's research framework.
Currently, Alzheimer's is diagnosed by evaluating symptoms and cognitive behavior associated with the disease. But, Jack says, that can be misleading for research.
So, in the new research framework, Alzheimer's disease is not diagnosed based on symptoms. Instead, it is diagnosed by its neuropathology, referred to as plaques and tangles. This can be done at autopsy or using biomarkers when a person is still living. That means through cerebral spinal fluid or through brain imaging.
Jack says the change is significant.
"What we're saying is that symptoms are a consequence of the disease," he says. "They're not the definition of the disease. People can have the pathology in the brain and be symptom-free. They still have the disease even though they have no symptoms. If they have the pathology, they have the diseases. It's controversial in some circles because, historically, the presence of symptoms was the definition. Now we're saying [that's] no longer so."
