New Alzheimer's Test Could Detect Signs of Disease Decades Before Symptoms Show

A blood test which can diagnose the brain changes linked to Alzheimer's disease with 94 percent accuracy could be available in the doctor's office in a matter of years and could help speed up the creation of new treatments, according to researchers.

The tests detect levels of beta-amyloid, a protein linked to the neurodegenerative condition. A build-up of beta-amyloid can become a sticky plaque which is thought to block signalling between cells at synapses and cause Alzheimer's disease.

A total of 158 adults aged over 50 took part in the study. The participants gave a blood sample, cerebrospinal fluid, and had a PET brain scan. This involves injecting a radioactive substance into the body and seeing where it collects, to provide a clue as to how the brain is working and whether there is an abnormal build-up of beta-amyloid protein. The team also looked at whether the participants had the APOE gene linked to Alzheimer's.

One hundred of the participants came back for a second PET scan. Those who tested negative for beta-amyloid during the first PET scan had a 15-fold risk of later testing positive if they had Aβ42/Aβ40 (beta-amyloid 42/beta-amyloid 40) in their blood, the authors found.

PET scans are used to detect beta-amyloid, but are far from perfect as they use radiation, are expensive and aren't readily available in the same way as a blood test.

Study co-author Dr. Suzanne Schindler, assistant professor of neurology at the Knight Alzheimer's Disease Research Center, Washington University School of Medicine, told Newsweek: "The blood test appears to be very sensitive to the early changes of Alzheimer disease."

"[The] blood test, especially in combination with age and APOE e4 status, is very accurate in diagnosing the brain changes of Alzheimer's disease," explained Schindler. "It also suggests that some results thought to be false positive (positive blood test, negative amyloid PET scan), are actually indicating very early disease."

Experts worked for years to find a way to measure levels of beta-amyloid 42 and beta-amyloid 40 in plasma, and published their findings in the journal Neurology.

There is currently no cure for Alzheimer's disease, and scientists do not know its cause. Identifying the condition in an individual as soon as possible can help doctors to reverse and treat some symptoms.

Study co-author Dr. Randall J. Bateman, professor of neurology and director of the Dominantly Inherited Alzheimer's Network (DIAN) at Washington University in St. Louis, told Newsweek he believes the blood test will likely be used for screening in trials within a year and potentially available in the clinic in one to two years.

Schindler gave a more conservative estimate, predicting it could arrive in clinics within three to five years. The test will help to recruit participants for Alzheimer's disease drug trials, said Schindler.

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Stock image of a doctor speaking to an elderly patient. Scientists believe they are a step closer to creating a new test for Alzheimer's disease. Getty

"We have learned through the failure of multiple drugs for Alzheimer disease that effective treatment needs to begin very early in the disease process, likely before symptoms are even present," she explained. "Therefore, we need a test that can detect Alzheimer's disease brain changes in people who are still cognitively normal. If individuals test positive, they could be enrolled in drug trials for Alzheimer's disease. Drugs may be more successful in preventing dementia than reversing dementia."

Bateman explained in a statement: "Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years. But with a blood test, we could potentially screen thousands of people a month. That means we can more efficiently enroll participants in clinical trials, which will help us find treatments faster, and could have an enormous impact on the cost of the disease as well as the human suffering that goes with it."

Experts not involved in the study told Newsweek they welcome the findings.

Dr. James Pickett, head of research at Alzheimer's Society, said: "A simple blood test that can detect the early brain changes leading to dementia would really revolutionize the search for new treatments, and our funded research has identified changes in the blood of those in the earliest stages of Alzheimer's.

"While the idea of an Alzheimer's blood test feels like it has been around for decades, advances in technology over the last couple of years mean that it is now a becoming a reality, and fast. This is an incredibly exciting area of progress in dementia research."

However, Pickett stressed the test isn't for dementia, but rather amyloid deposits, which are found in those with Alzheimer's but also healthy older people.

"This test will speed up dementia research by identifying those at risk of Alzheimer's who might be suitable for clinical trials aimed at preventing or delaying the development of dementia. In the meantime, we're eagerly awaiting the results of larger studies to validate this blood test."

Dr. Sara Imarisio, head of research at Alzheimer's Research UK, commented: "The results of the study using this blood test are promising but at the moment they cannot tell us if the people with high levels of blood-based amyloid will go on to develop dementia. Improving the accuracy of blood tests has long been a goal for researchers and using additional information about genetic risk to bolster a test like this is an encouraging step forward."

New Alzheimer's Test Could Detect Signs of Disease Decades Before Symptoms Show | Health