VOA常速英语:New Tests Provide Hope for Alzheimer's Early Detection

For the past 10 years, researchers have been looking for ways to slow down the progression of Alzheimer's disease, a degenerative neurological illness that ultimately wipes away a person's ability to recognize family members and perform simple functions such as getting dressed or even swallowing. But now, there's hope that doctors will be able to catch the disease earlier and even stop its progression. 

Doctors know that people's brains start changing 10 to 15 years before they show symptoms of Alzheimer's disease. Since there is no cure, at least not yet, researchers have been looking for inexpensive ways to test people early on so they can eventually delay - or even someday stop -  the progression of the disease.

Dr. Madhav Thambisetty is with the National Institute of Aging which is part of the National Institutes of Health.

"We're looking for blood proteins that might be indicative of the extent of brain damage that we know occurs very early on in patients with Alzheimer's disease," said Thambisetty.

Dr. Thambisetty spearheaded a study that uses a blood test to detect the levels of a particular protein in the brain, beta-amyloid, that is thought to be a hallmark of the disease.  Beta-amyloid is also present in spinal fluid of people with Alzheimer's.

The common ways to detect Alzheimer's disease are through brain scans using MRI (magnetic resonance imaging) or PET (positron emission tomography) scanning devices.  These tests are expensive.  Another method, taking a sample of a patient's spinal fluid, is invasive. A blood test would be cheap and could be given widely to seemingly healthy people before the symptoms of Alzheimer's set in.

In this particular study, researchers analyzed blood samples from 57 older volunteers who were symptom-free. They also measured the amyloid protein using PET scans.  They found that those with high blood levels of the protein had significantly greater amounts of it in the part of the brain that controls memory.

"Recent studies suggest that the deposition of amyloid might happen several years before symptoms of memory impairment begin in somebody with Alzheimer's disease," added Thambisetty.

Another test involves a new type of brain scan that could detect protein in the brain. The FDA recently held hearings on a dye that attaches to the protein and can be seen on PET scans. While PET scans are nothing new, the special radioactive dye is.

People who were near the end of their lives agreed to have both the brain scan, and after they died, an autopsy. The researchers reported that in almost all of the people who died during the study, the scan results matched those of the autopsies.

Dr. Thambisetty was part of an independent advisory panel to the Food and Drug Administration. The panel recommended that the FDA give conditional approval for the drug.

Dr. Neil Buckholtz is chief of the dementias of aging branch of the National Institute on Aging. He says early intervention is key, as is learning how the brain changes before dementia sets in.

"Our hope is we will be able to identify the earliest changes that occur in the brain, how these changes progress over time, so that we'll be able to target those for drug intervention, and again, eventually we'll be able to slow the progression and, hopefully, stop the disease in its tracks," said Buckholtz.

There's a sense of urgency in the research to control the progression of Alzheimer's disease because people the world over are living longer. That means more people, more caregivers, more families and more health care money will be impacted by this disease which already affects 20 million people worldwide.