Revolutionizing Diagnosis: Blood Test Breakthrough for Alzheimer’s Disease

There is no single test that can determine if a person is living with Alzheimer’s or another dementia. Physicians use diagnostic tools combined with medical history and other information, including neurological exams, cognitive and functional assessments, brain imaging (MRI, CT, PET) and cerebrospinal fluid or blood tests to make an accurate diagnosis.

Revolutionizing Diagnosis Blood Test

In July, the first direct-to-consumer blood test designed to assess a user’s risk for developing Alzheimer’s disease hit the market. Test, which has not undergone Food and Drug Administration (FDA) review, measures the level of a protein called beta amyloid, a key component of plaques that form in the brains of Alzheimer’s disease patients, disrupting brain function

Zaldy Tan, MD, MPH, medical director of the Jona Goldrich Center for Alzheimer’s and Memory Disorders and the Carmen and Louis Wars chaw Endowed Chair in Neurology at Cedars-Sinai, sat down with the Cedars-Sinai Newsroom to answer questions about the test, as well as similar blood tests that are in development.

Medical history

During the medical workup, the health care provider will review the person’s medical history, including psychiatric history and history of cognitive and behavioral changes. He or she will want to know about any current and past medical problems and concerns, as well as any medications the person is taking. The doctor will also ask about key medical conditions affecting other family members, including whether they may have had Alzheimer’s disease or other dementias.

Physical exam and diagnostic tests

During a medical workup, the physician will likely:

Ask about diet, nutrition and use of alcohol.

Review all medications. (Bring a list or the containers of all medicines currently being taken, including over-the-counter drugs and supplements.)

Check blood pressure, temperature and pulse.

Listen to the heart and lungs.

Perform other procedures to assess overall health.

Collect blood or urine samples for laboratory testing.

Information from a physical exam and laboratory tests can help identify health issues that can cause symptoms of dementia. Common causes of dementia-like symptoms are depression, untreated sleep apnea, delirium, side effects of medications, thyroid problems, certain vitamin deficiencies and excessive alcohol consumption. Unlike Alzheimer’s and other dementias, these conditions often may be reversed with treatment.

If the diagnosis is Alzheimer’s or another dementia, you or your loved one are not alone. Join our free online community AL Connected to share questions, experiences and practical tips on message boards and in live chat rooms.

Neurological exam

During a neurological exam, the physician will closely evaluate the person for problems that may signal brain disorders other than Alzheimer’s. The doctor will look for signs of stroke, Parkinson’s disease, brain tumors, buildup of fluid in the brain, and other conditions that may impair memory or thinking.

The physician will test:

Reflexes.
Coordination, muscle tone and strength.
Eye movement.
Speech.
Sensation.
The neurological exam may also include a brain imaging study.

If the evaluation does not indicate Alzheimer’s disease or another dementia, but the symptoms continue to get worse over time, your doctor may need to order more tests, or you may wish to get a second opinion.

What do these new blood tests measure?

Blood tests for Alzheimer’s disease provide a convenient way for patients to see whether they might be developing Alzheimer’s-type changes or pathology in their brain years before memory issues even begin. The challenge here is that these brain changes do not necessarily mean that they have Alzheimer’s disease, which is a clinical diagnosis. What blood tests do is to look at traces of certain proteins that are known to develop in patients with Alzheimer’s disease.

Who should take this type of blood test?

First, it is important to remember that the test currently on the market has not been evaluated or approved by the FDA. Neither have any of the other, similar tests that are in development. And these blood tests should really be reserved for people who are at risk or are having early symptoms of memory issues. These types of blood tests do not have a place for people who do not have significant risk factors for developing memory problems, or are not having any functional or social issues related to cognitive change.

Does a blood test alone provide enough information to diagnose potential memory issues?

A blood test will not answer that question. Only a trained clinician can. So, for people who are interested in these kinds of blood tests, I would suggest that patients first speak with their healthcare professional to see if these tests are right for them.

Alternatives to these newer-on-the-market tests are things like cognitive testing, a neurologic examination, or consultation with memory specialists. These blood tests provide just one data point or piece of information among many that need to be collected to know if someone is having early signs of Alzheimer’s disease.

Do these blood tests help patients qualify for some of the new Alzheimer’s disease treatments such as lecanemab?

Currently, we confirm the presence of amyloid beta in the brain and qualify patients for these treatments through a PET scan of the brain or a lumbar puncture to test cerebrospinal fluid. These blood tests will need to be tested further and will need to be cleared by the FDA to make sure that they are reliable before they can be used to qualify patients for these new treatments.

What are the risk factors for Alzheimer’s disease?

Age is one of the main risk factors for developing dementia later in life. Others include family history, especially having dementia diagnosed in a first-degree relative. People who have had traumatic brain injury or have had a stroke or have Parkinson’s disease or other neurologic conditions may also be at increased risk of developing dementia.

What can people do to reduce their risk of Alzheimer’s disease?

So, what we need to do is to make sure that our brains get the blood supply that they need, and that is best assured by a healthy lifestyle: good diet, good sleep, exercise, increased socialization to make sure those connections between brain cells are nice and healthy. And of course, protecting your brain from trauma by wearing a helmet when you cycle or skate, wearing a seatbelt when you’re driving, is important. So, it’s really a combination of things in order to reduce the overall risk. Just like we do for our hearts and our bodies, we need to have a multimodal approach to risk reduction of brain disease, including Alzheimer’s disease.

Cognitive, functional and behavioral tests

Cognitive, functional and behavioral tests evaluate memory, thinking and simple problem-solving abilities, and may quickly assess changes in behaviors and symptoms. Some tests are brief, while others can be more time intensive and complex. More comprehensive cognitive, functional and behavioral tests are often given by a neuropsychologist to evaluate executive function, judgment, attention and language.

Examples of cognitive, functional and behavioral tests include:

Ascertain Dementia 8 (AD8)
Functional Activities Questionnaire (FAQ)
Mini-Cog
Mini-Mental State Exam (MMSE)
Montreal Cognitive Assessment (MoCA)
Neuropsychiatric Inventory Questionnaire (NPI-Q)

Computerized cognitive tests and devices

A growing area of research is the development of medical devices and technologies to help physicians evaluate cognition and function. Among these are medical devices or digital technologies including computerized testing software; these have several advantages, including giving tests exactly the same way each time.

Digital computerized assessments are designed to measure an individual’s performance on a variety of cognitive or functional tasks and may be appropriate for administration in randomized clinical trials or clinical settings, when lengthier standard assessments are not practical.

The U.S. Food and Drug Administration (FDA) has granted permission for several digital cognitive testing tools to be marketed:

Automated Neuropsychological Assessment Metrics (ANAM)
Cambridge Neuropsychological Test Automated Battery (CANTAB Mobile®)
CognICA
Cognigram
Cognivue
The FDA has also granted permission for a medical device called Cognision to be marketed. This device is a headset with electrodes that are affixed to the scalp to measure electrical activity in the brain responsible for cognitive function.

Brain imaging

A standard medical workup for Alzheimer’s disease often includes structural imaging with magnetic resonance imaging (MRI) or computed tomography (CT). These tests are primarily used to rule out other conditions that may cause symptoms similar to Alzheimer’s but require different treatment. Structural imaging can reveal tumors, evidence of small or large strokes, damage from severe head trauma, or a buildup of fluid in the brain

Blood tests

Researchers are investigating whether consistent and measurable changes in blood levels of specific markers may be reliably associated with Alzheimer’s related changes. These markers may include tau, beta-amyloid or other biomarkers the could be measured before and after symptoms appear.

An urgent need exists for simple, inexpensive, non-invasive and easily available diagnostic tools such as blood tests to diagnose the disease. These testing technologies would support drug development by helping to identify and follow treatment effectiveness in clinical trial participants and to increase the possibility of early detection, diagnosis and intervention. A blood test would also enable interpretation and understanding of the progression of Alzheimer’s in larger and more diverse populations.

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