The Importance of Blood Tests for Alzheimer's Disease Patients: 2 Neuroscientists Explain the Recent Findings (2023)

(Photo : pxhere) Testing a suspected Alzheimer’s patient for biomarkers isn’t easy or cheap. Although the accuracy of an Alzheimer’s diagnosis has improved over the decades, it is still difficult.

A blood test to diagnose Alzheimer’s disease moved closer to reality this week after new findings were announcedat the Alzheimer’s Association International Conference on July 29, 2020. The test showed extremely high accuracy—around 90%—for detecting chemicals in the blood that are specific for Alzheimer’s.

Those who treat patients with Alzheimer’s say that the tests need only a bit higher level of accuracy before they can be used clinically, which could be in two to three years. This breakthrough could perhaps allow doctors to not only identify symptomatic patients with the disease, but also to identify people with no symptoms who are at risk of developing the disease, and thus begin interventions.

About 5.7 million people in the U.S.live with Alzheimer’s, but that number could triple by 2050, the Alzheimer’s Association estimates.

While blood tests have been slowly increasing their diagnostic accuracy, the new blood test—analyzing the amount of a brain protein, p-217, in the blood—appears to be accurate in over 90% of cases in a study looking at blood samples from people with definite Alzheimer’s disease. Accuracy rates of other tests will likely increase over time. But this result shows that a breakthrough test is indeed possible. Before the tests are available to the public through FDA approval, we’ll need another two to three years to complete the studies.

The Importance of Blood Tests for Alzheimer's Disease Patients: 2 Neuroscientists Explain the Recent Findings (1)

(Photo : pxhere)
Testing a suspected Alzheimer’s patient for biomarkers isn’t easy or cheap. Although the accuracy of an Alzheimer’s diagnosis has improved over the decades, it is still difficult.

(Video) Blood Tests for Brain Health in Alzheimer’s Disease and Related Dementias


As researcherswho have spent our professional livesstudying this disease and treating patients with it, we think this news is especially important. It represents a significant leap forward in our ability to use peripheral blood tests for detection of Alzheimer’s and possibly as a marker of effectiveness in developing medical treatments. Here is why.


Have we grabbed the ‘brass ring’ for diagnosis?

Just one year ago, we wrote a piece for The Conversation on blood tests for Alzheimer’s disease, ending it with the hope that several promising blood tests would soon emerge as accurate and specific. Now, it appears they have. The tests have been centered on the ability to test for either beta amyloid or tau, the characteristic proteins that are deposited in the brain in Alzheimer’s disease, and the tau tests lagged behind the beta amyloid tests. Now tau testing has jumped into the lead.

Until the early 1990s, with the routine use of brain MRI scans, it was difficult to be certain whether a person with cognitive loss had Alzheimer’s. Even the best neurologists would get the diagnosis wrong about one in four times. MRIs increased accuracy; it could show vascular disease and atrophy characteristic of Alzheimer’s or other dementias, but could not confirm the diagnosis with certainty. Diagnosis was even harder in people over 80, where the changes in thinking and memory with aging were not always easy to separate from early Alzheimer’s symptoms, and normal age-related atrophy made differentiation from disease-based brain shrinkage more difficult.

Until this century, the only definitive diagnosisof the disease occurred after death, at autopsy, by finding certain levels of two specific lesions, or areas of abnormal tissue. Those two lesions are beta-amyloid plaques and neurofibrillary tangles.

And it was not unusual to find, following autopsy, that someone diagnosed clinically with Alzheimer’s disease had another neurodegenerative disease, disease related to blood vessels in the brain, or some combination of these.

(Video) The role of biomarkers in Alzheimer's disease

RELATED: A Promising Blood Test May Diagnose Alzheimer's Disease


Marching toward answers

Over the last two decades, however, the medical field has made progress in detecting the disease by identifying specific diagnostic biomarkers, or biological signs of disease. MRI scans helped by showing shrinkage of the areas of the brain that underlie memory. But they are not specific for Alzheimer’s.

Two key biomarkers, amyloid protein, found in plaques, and tau protein, found in tangles, became the targets outside of the brain tissue itself, since their presence in the brain defines the disease.

With the identification of these biomarkers, doctors could test patients to see if either amyloid or tau, or both, were abnormal in patients in whom they suspected Alzheimer’s. But the testing has not been easy or cheap.

One way was a spinal tap, whereby doctors could obtain cerebro-spinal fluid, the fluid around your brain and spine, and measure levels of tau and amyloid, which change if the disease is present. While doctors consider this procedure safe and routine, it is not a favorite among patients.

Another method involves imaging the brain using a positron emission tomography (PET) scan following administration of compounds (amyloid or tau “tracers”)that bind one of the proteins that accumulates in the Alzheimer brain. The amyloid scans came first, about 15 years ago, and revolutionized research in Alzheimer’s; tau scans have been developed over the past several years, and reveal neurofibrillary tangles on the PET scans. Although extremely safe, individual PET scans are expensive—typically from US$3,000 up—and Medicare does not pay for them.

The impact of these advances is huge, especially in research and clinical trials, where maximum likelihood of the right diagnosis is required. But the medical community badly needs a more convenient, less expensive, less “invasive” way to diagnose Alzheimer’s. Enter … a blood test.

(Video) Brain Aging & Alzheimer's Disease: New Insights from New Technologies with Dr. William Jagust

READ MORE: Elderly Who Retain Sense of Smell Are at Lower Risk of Dementia


A new target, and an exciting test emerges

For years, efforts to find such an easily obtainable Alzheimer’s diagnostic biomarker in the blood came up empty—they were not accurate enough.

A major reason for inconsistency of the prior reports was the extremely small amounts of these protein fragments in the blood. The tests have to be sensitive enough to detect either amyloid or tau, and be accurate enough that the blood level changes occurring in people with Alzheimer’s can be clearly different from those of non-affected people.

Now, several publicationsand presentations at the recent Alzheimer’s Association International Conference have demonstrated that blood tests measuring amyloid and tau proteins have become much more sensitive and accurate enough to allow their possible future use as routine aids in Alzheimer’s disease diagnosis.

These various tests are at different stages of validation—assuring they’re accurate across many different patient populations. And, for each protein, there are several different methods for making the blood measurements. However, the research community is excited about the possibilities.

And one new tau blood test appears to meet a number of criteria necessary.

To be useful, the tests have to be nearly perfect predictors. Many aren’t there yet; so far, they seem to get it right up to over 85% of the time. And the accuracy will be very important if they’re to be used to screen people for positive tests and enter those people into clinical trials.

(Video) A Closer Look At...Alzheimer's Disease

The newest blood assay for the tau protein, developed to look for a different site on the tau molecule than other tau tests, has now emerged with the highest accuracy yet—with data from three different large populations of patients.

In these studies, the sensitivity—or the ability to detect the disease when it is really there—and the specificity—negative test in people who do not have Alzheimer’s—were above 90% to 95%. It even detected elevated tau in the blood of people who had the disease in their brains but had not yet had any symptoms, identifying people at risk for the disease to enroll in trials to prevent the disease. It is the result of advances in the technology of the assays, or analysis techniques, and the collaboration of researchers to provide blood samples from proven Alzheimer’s cases.

These tests mark real progress. Cost-effective screening and diagnostic tests will help us reach our goal of finding novel treatments that can better treat the clinical symptoms of Alzheimer’s or delay its development, or both.

READ NEXT: Educational Attainment Affects Risk of Dementia, Study Says


This article is updated from an original version, which was published Aug. 7, 2019.

This article is republished from The Conversationunder a Creative Commons license. Read the original article. | Authors:Steven DeKosky, Deputy Director, McKnight Brain Institute, Aerts-Cosper Professor of Alzheimer's Research, and Professor of Neurology and Neuroscience,University of FloridaandTodd Golde, Director, Evelyn F. and William L. McKnight Brain Institute Director, 1Florida Alzheimer's Disease Research Center, Professor, Department of Neuroscience, College of Medicine University of Florida,University of Florida

©2021 ScienceTimes.com All rights reserved. Do not reproduce without permission. The window to the world of science times.

(Video) Current Treatments and Research for Alzheimer's Disease

FAQs

Why are blood tests done for Alzheimer's? ›

“A blood test for Alzheimer's provides a huge boost for Alzheimer's research and diagnosis, drastically cutting the time and cost of identifying patients for clinical trials and spurring the development of new treatment options,” Bateman said.

Does Alzheimer's show up on a blood test? ›

Across all the blood samples, the scientists found that the blood test could effectively predict the presence of beta-amyloid in the brain. The test became even more accurate when the research team took into account the version of APOE (a gene linked to Alzheimer's disease risk) that each person had.

What do doctors look for in blood test for Alzheimer's? ›

For example, it is now possible for doctors to order a blood test to measure levels of beta-amyloid, a protein that accumulates abnormally in the brains of people with Alzheimer's.

What is the new Alzheimer's blood test? ›

The Lumipulse test is intended to measure the ratio of β-amyloid 1-42 and β-amyloid 1-40 (specific proteins that can accumulate and form plaques) concentrations found in human cerebral spinal fluid (CSF), which can help physicians determine whether a patient is likely to have amyloid plaques, a hallmark sign of ...

Can blood test detect neurological problems? ›

Chemical and metabolic testing of the blood can indicate some muscle disorders, protein or fat-related disorders that affect the brain and inborn errors of metabolism. Blood tests can monitor levels of therapeutic drugs used to treat epilepsy and other neurological disorders.

Why is it important to diagnose Alzheimer's early? ›

An early Alzheimer's diagnosis provides you with a better chance of benefiting from treatment. An opportunity to participate in clinical trials: An early diagnosis makes individuals eligible for a wider variety of clinical trials, which advance research and may provide medical benefits.

Can blood test detect memory loss? ›

Some of the most common blood tests ordered as part of a diagnostic evaluation for someone with changes in thinking or memory include: CBC (complete blood count), CMP (comprehensive metabolic panel), TSH (thyroid stimulating hormone), vitamin B12, RPR (rapid plasma reagin), HIV (human immunodeficiency virus).

How accurate is genetic testing for Alzheimer? ›

No reliable genetic test exists for the common sporadic form of Alzheimer's disease. Therefore, for most cases, genetic testing is not recommended because, at best, it can only point to susceptibility. The testing can never predict whether a person will or will not get Alzheimer's disease.

What lab tests are used to diagnose dementia? ›

How is dementia diagnosed?
  • Cognitive and neurological tests. These tests are used to assess thinking and physical functioning. ...
  • Brain scans. These tests can identify strokes, tumors, and other problems that can cause dementia. ...
  • Psychiatric evaluation. ...
  • Genetic tests. ...
  • Blood tests.
5 days ago

How do you get tested for Alzheimer's gene? ›

There are no approved predictive genetic tests for the most common form of Alzheimer's disease. However, regional genetics clinics offer testing for people whose family history of dementia suggests they might carry one of the causative mutations for inherited Alzheimer's or frontotemporal dementia.

How do you detect Alzheimer's disease? ›

Magnetic resonance imaging (MRI).

While they may show brain shrinkage of brain regions associated with Alzheimer's disease, MRI scans also rule out other conditions. An MRI is generally preferred to a CT scan for the evaluation of dementia.

What is the most useful screening test for dementia? ›

The Mini-Mental State Examination (MMSE)7 is the most widely applied test for dementia screening.

What blood tests check amyloid? ›

Bone marrow test and/or biopsy (tissue sample) to check for amyloid deposits.

Can high blood pressure cause Alzheimer's? ›

The association between high blood pressure and Alzheimer's disease is currently unclear. However, despite this apparent link between vascular dementia and high blood pressure, the results from randomised controlled trials into whether lowering blood pressure can prevent dementia have so far been inconclusive.

What tests are done for memory loss? ›

Diagnosing Memory Loss
  • Types of Memory Loss. Mild cognitive impairment is categorized by doctors as amnestic or nonamnestic. ...
  • Neurological Evaluation. ...
  • Cognitive Evaluation. ...
  • Neuropsychological Evaluation. ...
  • Psychometric Testing. ...
  • MRI Scan. ...
  • PET Scan.

What can be detected in a blood test? ›

It can be used to identify blood disorders (like anemia), diseases, clotting issues, inflammation, infection, and immune system problems.

What tests do neurologists perform? ›

These tests may include one or more of the following:
  • Blood and/or urine tests.
  • Imaging tests such as an x-ray or MRI.
  • A cerebrospinal fluid (CSF) test. ...
  • Biopsy. ...
  • Tests, such as electroencephalography (EEG) and electromyography (EMG), which use small electric sensors to measure brain activity and nerve function.
9 Sept 2021

Which neurological evaluation method is used to check for disability? ›

Manual Muscle Testing (MMT) or Myotomes can be used.

Should I be tested for Alzheimer's? ›

When testing is worthwhile. While screening for dementia when you don't have any symptoms doesn't make sense, Dr. Nelson states, "Any memory or cognitive changes that concern you—or the people close to you—warrant a visit to a geriatrician, neurologist, or neuropsychologist."

Why is it important to monitor signs and symptoms of dementia? ›

Getting a diagnosis of dementia can give you a better understanding of the condition and what to expect. Timely diagnosis can help you make important decisions about treatment, support and care. You may have been living with memory problems or other symptoms for some time.

How does Alzheimer's affect the brain? ›

In Alzheimer's disease, as neurons are injured and die throughout the brain, connections between networks of neurons may break down, and many brain regions begin to shrink. By the final stages of Alzheimer's, this process—called brain atrophy—is widespread, causing significant loss of brain volume.

What causes Alzheimer's disease? ›

Alzheimer's disease is thought to be caused by the abnormal build-up of proteins in and around brain cells. One of the proteins involved is called amyloid, deposits of which form plaques around brain cells. The other protein is called tau, deposits of which form tangles within brain cells.

What gene is responsible for Alzheimer's disease? ›

The three single-gene mutations associated with early-onset Alzheimer's disease are: Amyloid precursor protein (APP) on chromosome 21. Presenilin 1 (PSEN1) on chromosome 14. Presenilin 2 (PSEN2) on chromosome 1.

Is Alzheimer's hereditary or genetic? ›

Is Alzheimer's Genetic? Family history is not necessary for an individual to develop Alzheimer's. However, research shows that those who have a parent or sibling with Alzheimer's are more likely to develop the disease than those who do not have a first-degree relative with Alzheimer's.

What is used for genetic testing? ›

Genetic tests are done using a blood or spit sample and results are usually ready in a few weeks. Because we share DNA with our family members, if you are found to have a genetic change, your family members may have the same change.

Is there a blood test for early dementia? ›

But no blood tests can currently diagnose Alzheimer's before symptoms develop. This complicates studies of early treatments or preventive strategies. PET imaging and tests that use cerebrospinal fluid (CSF) can be used to identify Alzheimer's before dementia develops.

Can you test yourself for Alzheimer's? ›

The Self-Administered Gerocognitive Exam (SAGE) is a brief self-administered cognitive screening instrument used to identify mild cognitive impairment (MCI) from any cause and early dementia.

Is there a blood test for Alzheimer's in Canada? ›

The Alzheimer's disease biomarker test, which we have now made available to all Canadians, can help doctors accurately diagnose the disease even when only mild symptoms are present.

How is Alzheimer's disease prevented? ›

These include:
  1. stopping smoking.
  2. keeping alcohol to a minimum.
  3. eating a healthy, balanced diet, including at least 5 portions of fruit and vegetables every day.
  4. exercising for at least 150 minutes every week by doing moderate-intensity aerobic activity (such as cycling or fast walking), or as much as you're able to.

What is the most common clinical finding on the patient who is diagnosed with Alzheimer's disease? ›

The most essential and often earliest clinical manifestation of AD is selective memory impairment, although there are exceptions.

How does a neurologist help with Alzheimer's? ›

Neurologists are trained to detect subtleties of the brain that cause memory problems. Only they can conduct a thorough neurological exam and recommend subsequent treatment for brain disorders such as Alzheimer's.

What happens in Alzheimer's disease? ›

Alzheimer's disease is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that affects a person's ability to function independently.

What is the most significant risk factor for Alzheimer's disease? ›

Older age does not cause Alzheimer's, but it is the most important known risk factor for the disease. The number of people with Alzheimer's disease doubles about every 5 years beyond age 65. About one-third of all people age 85 and older may have Alzheimer's disease.

Is there a blood test for early dementia? ›

But no blood tests can currently diagnose Alzheimer's before symptoms develop. This complicates studies of early treatments or preventive strategies. PET imaging and tests that use cerebrospinal fluid (CSF) can be used to identify Alzheimer's before dementia develops.

How accurate is genetic testing for Alzheimer? ›

No reliable genetic test exists for the common sporadic form of Alzheimer's disease. Therefore, for most cases, genetic testing is not recommended because, at best, it can only point to susceptibility. The testing can never predict whether a person will or will not get Alzheimer's disease.

What tests are done for memory loss? ›

Diagnosing Memory Loss
  • Types of Memory Loss. Mild cognitive impairment is categorized by doctors as amnestic or nonamnestic. ...
  • Neurological Evaluation. ...
  • Cognitive Evaluation. ...
  • Neuropsychological Evaluation. ...
  • Psychometric Testing. ...
  • MRI Scan. ...
  • PET Scan.

Is Alzheimer's disease genetic or hereditary? ›

Family history is not necessary for an individual to develop Alzheimer's. However, research shows that those who have a parent or sibling with Alzheimer's are more likely to develop the disease than those who do not have a first-degree relative with Alzheimer's.

Can blood test detect memory loss? ›

Some of the most common blood tests ordered as part of a diagnostic evaluation for someone with changes in thinking or memory include: CBC (complete blood count), CMP (comprehensive metabolic panel), TSH (thyroid stimulating hormone), vitamin B12, RPR (rapid plasma reagin), HIV (human immunodeficiency virus).

What blood tests indicate dementia? ›

Lab tests: A new test called a Precivity AD test looks at the amounts of proteins such as beta amyloid and Apo E in blood. The presence or absence helps determine the probability of whether an imaging study (like a PET scan) can detect plaques in the brain, which indicate a possible Alzheimer's diagnosis.

How do you test for Alzheimer's memory and dementia? ›

Mini-Cog - The Mini-Cog is a 3-minute test consisting of a recall test for memory and a scored clock-drawing test. It can be used effectively after brief training and results are evaluated by a health provider to determine if a full-diagnostic assessment is needed.

Is there a reliable test for Alzheimer's disease? ›

There's no simple and reliable test for diagnosing Alzheimer's disease, but the staff at the memory clinic will listen to the concerns of both you and your family about your memory or thinking.

What gene is responsible for Alzheimer's disease? ›

The three single-gene mutations associated with early-onset Alzheimer's disease are: Amyloid precursor protein (APP) on chromosome 21. Presenilin 1 (PSEN1) on chromosome 14. Presenilin 2 (PSEN2) on chromosome 1.

What is the main cause of Alzheimer's? ›

Alzheimer's disease is thought to be caused by the abnormal build-up of proteins in and around brain cells. One of the proteins involved is called amyloid, deposits of which form plaques around brain cells. The other protein is called tau, deposits of which form tangles within brain cells.

What is the most useful screening test for dementia? ›

The Mini-Mental State Examination (MMSE)7 is the most widely applied test for dementia screening.

How do you test for memory? ›

The most common types of tests are:
  1. Montreal Cognitive Assessment (MoCA) test. A 10-15 minute test that includes memorizing a short list of words, identifying a picture of an animal, and copying a drawing of a shape or object.
  2. Mini-Mental State Exam (MMSE). ...
  3. Mini-Cog.
10 Dec 2020

How is Alzheimer's prevented? ›

These include:
  1. stopping smoking.
  2. keeping alcohol to a minimum.
  3. eating a healthy, balanced diet, including at least 5 portions of fruit and vegetables every day.
  4. exercising for at least 150 minutes every week by doing moderate-intensity aerobic activity (such as cycling or fast walking), or as much as you're able to.

What part of the brain is affected by Alzheimer's? ›

At first, Alzheimer's disease typically destroys neurons and their connections in parts of the brain involved in memory, including the entorhinal cortex and hippocampus. It later affects areas in the cerebral cortex responsible for language, reasoning, and social behavior.

Who is most likely to get Alzheimer's? ›

Who is affected? Alzheimer's disease is most common in people over the age of 65. The risk of Alzheimer's disease and other types of dementia increases with age, affecting an estimated 1 in 14 people over the age of 65 and 1 in every 6 people over the age of 80.

How does Alzheimer's affect the brain? ›

The effects of Alzheimer's disease

A person's ability to understand, think, remember and communicate will be affected. This could impact a person's ability to make decisions, perform simple tasks or follow a conversation. Sometimes people lose their way, or experience confusion and memory loss.

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