New way of defining Alzheimer's aims to find disease sooner

April 10, 2018 by Marilynn Marchione
New way of defining Alzheimer's aims to find disease sooner
In this May 19, 2015, file photo, R. Scott Turner, Professor of Neurology and Director of the Memory Disorder Center at Georgetown University Hospital, points to PET scan results that are part of a study on Alzheimer's disease at Georgetown University Hospital in Washington. Government and other scientists are proposing a new way to define Alzheimer's disease. basing it on biological signs, such as brain changes, rather than memory loss and other symptoms of dementia that are used now. (AP Photo/Evan Vucci, File)

Government and other scientists are proposing a new way to define Alzheimer's disease—basing it on biological signs, such as brain changes, rather than memory loss and other symptoms of dementia that are used today.

The move is aimed at improving research, by using more objective criteria like to pick patients for studies and enroll them sooner in the course of their illness, when treatments may have more chance to help.

But it's too soon to use these scans and other tests in routine care, because they haven't been validated for that yet, experts stress. For now, doctors will still rely on the tools they've long used to evaluate thinking skills to diagnose most cases.

Regardless of what tests are used to make the diagnosis, the new definition will have a startling effect: Many more people will be considered to have Alzheimer's, because the biological signs can show up 15 to 20 years before do.

"The numbers will increase dramatically," said Dr. Clifford R. Jack Jr., a Mayo Clinic brain imaging specialist. "There are a lot more cognitively normal people who have the pathology in the brain who will now be counted as having Alzheimer's disease."

He led a panel of experts, working with the Alzheimer's Association and the National Institute on Aging, that updated guidelines on the disease, published Tuesday in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.

ABOUT ALZHEIMER'S

About 50 million people worldwide have , and Alzheimer's is the most common form. In the U.S., about 5.7 million have Alzheimer's under its current definition, which is based on memory problems and other symptoms. About one-third of people over 70 who show no thinking problems actually have brain signs that suggest Alzheimer's, Jack said.

New way of defining Alzheimer's aims to find disease sooner
This Feb. 16, 2018, photo shows slices of human brains researchers at Northwestern University are using to study Alzheimer's disease in Chicago. Scientists are proposing a new way to define Alzheimer's disease, basing it on biological signs such as brain changes, rather than memory loss and other symptoms of dementia that are used now. (AP Photo/Teresa Crawford)

There is no cure—current medicines such as Aricept and Namenda just temporarily ease symptoms. Dozens of hoped-for treatments have failed, and doctors think one reason may be that the studies enrolled patients after too much brain damage had already occurred.

"By the time that you have the diagnosis of the disease, it's very late," said Dr. Eliezer Masliah, neuroscience chief at the Institute on Aging.

"What we've realized is that you have to go earlier and earlier and earlier," just as doctors found with treating cancer, he said.

Another problem: as many as 30 percent of people enrolled in Alzheimer's studies based on symptoms didn't actually have the disease—they had other forms of dementia or even other medical conditions. That doesn't give an accurate picture of whether a potential treatment might help, and the new definition aims to improve patient selection by using brain scans and other tests.

BETTER TESTS

Many other diseases, such as diabetes, already are defined by measuring a biomarker, an objective indicator such as blood sugar. That wasn't possible for Alzheimer's until a few years ago, when brain scans and spinal fluid tests were developed to do this.

They measure certain forms of two proteins—amyloid and tau—that form plaques and tangles in the brain—and signs of nerve injury, degeneration and brain shrinkage.

The guidelines spell out use of these biomarkers over a spectrum of mental decline, starting with early , through mild impairment and Alzheimer's dementia.

New way of defining Alzheimer's aims to find disease sooner
This Feb. 16, 2018, photo shows slices of human brains researchers at Northwestern University are using to study Alzheimer's disease in Chicago. Scientists are proposing a new way to define Alzheimer's disease, basing it on biological signs such as brain changes, rather than memory loss and other symptoms of dementia that are used now. (AP Photo/Teresa Crawford)

WHAT TO DO?

People may be worried and want these tests for themselves or a family member now, but Jack advises: "Don't bother. There's no proven treatment yet."

You might find a doctor willing to order them, but spinal fluid tests are somewhat invasive, and scans can cost up to $6,000. Insurance usually does not pay because they're considered experimental outside of research. A large study is underway now to see whether Medicare should cover them and when.

Anyone with symptoms or family history of dementia, or even healthy people concerned about the risk can consider enrolling in one of the many studies underway.

"We need more people in this pre-symptomatic stage" to see if treatments can help stave off decline, Masliah said.

Explore further: Brain amyloid PET scans enhance the diagnosis of Alzheimer's

Related Stories

Brain amyloid PET scans enhance the diagnosis of Alzheimer's

July 17, 2017
The build-up of amyloid protein in the brain is a hallmark feature of Alzheimer's disease, and its detection often relies on the testing of brain and spinal fluid samples. More recently, PET brain scans have been able to ...

Brain scans detect Alzheimer's before onset of symptoms

October 4, 2017
Researchers in New Mexico and Croatia have used a brain scanning technique known as magnetoencephalography, or MEG, to search for a new biological fingerprint of Alzheimer's disease. The results of the study are published ...

Blood-based marker for Alzheimer's disease shows diagnostic potential

February 2, 2018
Researchers in Japan and Australia have used the ratio of different forms of the hallmark Alzheimer's protein, amyloid, in blood to detect those who have high levels of the protein in their brain. Their findings are published ...

Is it Alzheimer's disease or another dementia?

July 26, 2017
A new method may help determine whether a person has Alzheimer's disease or frontotemporal dementia, two different types of dementia that often have similar symptoms, according to a preliminary study published in the July ...

Sleep problem linked to changes in hallmark Alzheimer's protein

November 10, 2017
Researchers in the US have found a link between the sleep disorder, obstructive sleep apnoea, and levels of a protein involved in Alzheimer's disease. Their findings are published today in the American Journal of Respiratory ...

New brain protein tied to Alzheimer's disease

July 16, 2014
Scientists have linked a new protein to Alzheimer's disease, different from the amyloid and tau that make up the sticky brain plaques and tangles long known to be its hallmarks.

Recommended for you

New discoveries predict ability to forecast dementia from single molecule

December 11, 2018
Scientists who recently identified the molecular start of Alzheimer's disease have used that finding to determine that it should be possible to forecast which type of dementia will develop over time—a form of personalized ...

Researchers classify Alzheimer's patients in six subgroups

December 5, 2018
Researchers studying Alzheimer's disease have created an approach to classify patients with Alzheimer's disease, a finding that may open the door for personalized treatments.

Neuroscientists pinpoint genes tied to dementia

December 3, 2018
A UCLA-led research team has identified genetic processes involved in the neurodegeneration that occurs in dementia—an important step on the path toward developing therapies that could slow or halt the course of the disease. ...

Detecting signs of neurodegeneration earlier and more accurately

November 30, 2018
Signs of neurodegenerative diseases, appearing years before the emergence of clinical manifestations, can be detected during the examination of medical samples by means of fluorescence microscopy by using new sensitive and ...

Never-before-seen DNA recombination in the brain linked to Alzheimer's disease

November 21, 2018
Scientists from Sanford Burnham Prebys Medical Discovery Institute (SBP) have identified gene recombination in neurons that produces thousands of new gene variants within Alzheimer's disease brains. The study, published today ...

New information on the pathological mechanisms of Alzheimer's disease

November 21, 2018
Researchers at the University of Helsinki have discovered a mechanism by which harmful tau protein aggregates are transmitted between neurons. Alongside amyloid plaques, tau aggregates in the brain are a significant factor ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.