Developing new tests that predict Alzheimer's disease years before people ever get symptoms helps them plan and hope that treatments begun at an early stage might work better.
Alzheimer's Association says that many patients are never given a specific diagnosis. It's not easy to diagnose Alzheimer's disease even after it develops. Usually, doctors base a diagnosis on symptoms, but it's not an exact science and other brain injuries, including stroke, can cause similar symptoms such as memory loss.
"The disease doesn't start when the memory problems become apparent," said Dr. William Klunk, a neurology professor at the University of Pittsburgh and an adviser to the Alzheimer's Association.
Marilyn Albert, who directs the Alzheimer's Research Center at Johns Hopkins University, tracked 189 middle-aged people who were normal to start with.
A combination of six tests including assessment of two proteins associated with Alzheimer's: amyloid and tau, MRI scans to watch for brain shrinkage, standard tests of memory, blood tests were done to predict mild cognitive impairment within five years.
The combination of tests could be useful for drug companies trying to find people who are likely to develop Alzheimer's but who don't have symptoms yet, to see if medications might prevent them.
"Earlier diagnosis or, better still, the ability to predict the onset of Alzheimer's, would significantly increase the window of opportunity a person with Alzheimer's has to formulate an informed response to the news and empower them to be an active participant in decision-making while they still have the ability," Carrillo added.
Maartje Kester and colleagues at VU University Medical Center in Amsterdam found levels of another protein, called neurogranin were higher in spinal fluid from people who developed Alzheimer's. It may signal damage to nerve connections called synapses are dying.
Shraddha Sapkota and colleagues at the University of Alberta in Canada used a technique called liquid chromatography mass spectrometry to find compounds that might be more common in the saliva of people who later develop Alzheimer's.
The saliva test showed higher levels of six compounds, which were higher in people who later developed Alzheimer's disease. "That could be a test in the mall someday, if it was developed enough," said Klunk.
The Alzheimer's Association says 5.3 million Americans have the disease, including 200,000 people under the age of 65.
"Barring the development of medical breakthroughs, the number will rise to 13.8 million by 2050," the association says in its annual report — with two-thirds being women