6 minute read

Alzheimer’s Disease: What We Know So Far

Published July 26, 2023

Alzheimer's disease is a devastating brain disorder that slowly destroys a person’s memory and thinking skills. It’s the 6th leading cause of death in the United States¹ and affects over 6 million Americans.² One in three older adults dies with Alzheimer's or another form of dementia—killing more people than breast cancer and prostate cancer combined.²

The impact of Alzheimer's is felt by everyone who is touched by the disease, including the person with the diagnosis, their family, friends, and caregivers. Many loved ones will bear the weight of this disease, facing significant challenges along the way. Witnessing someone you love gradually lose their memory and abilities takes an undeniable emotional and physical toll. The ripple effect of Alzheimer's disease is a reminder that its reach goes far beyond those living with the disease.

What is Alzheimer’s disease?

Alzheimer's is a brain disorder that can severely disrupt a person's life. While losing things from time to time can be a natural part of getting older—it's important to know that Alzheimer's isn’t a normal part of aging. Alzheimer’s is more than just memory loss. This form of dementia can worsen over time and slowly steal a person’s memories, abilities, and ultimately, their life.² ᵃⁿᵈ ³

What causes Alzheimer’s?

Scientists are still learning about what causes Alzheimer's disease. Experts think it’s caused by a combination of things, like your age, genetics, and lifestyle.¹ But what we do know is that one of the signs of Alzheimer's disease is the buildup of certain proteins in the brain.

Your brain is the control center of your body. It’s made up of billions of nerve cells, called neurons. Neurons are like tiny wires that send messages to each other. These messages allow us to think, remember, and do just about everything else we do. In Alzheimer’s disease, clumps of protein start to build up in or around the neurons in the brain. These clumps can block the messages that neurons send to each other. When neurons can't work together, it can cause problems in one area of the brain, which can then lead to problems in other areas. As this damage spreads, neurons can’t do their jobs and die, which causes irreversible changes in the brain. 

What proteins are key to understanding Alzheimer's?

The 2 main proteins behind Alzheimer’s disease are beta-amyloid plaques and tau tangles.³

  1. Beta-amyloid (BAY-tuh AM-uh-loyd) plaques are clumps of protein that build up in the spaces between neurons. ³
  2. Tau (rhymes with “cow”) tangles are twisted fibers of protein that build up inside cells.³

Protein build-up in the brain can damage the areas that help us remember, learn, and talk. These changes often start silently and may not be noticeable for years. As Alzheimer's disease progresses, people living with the disease will start to forget things, become more confused, and find everyday tasks difficult.

How is Alzheimer’s different from natural aging?

It's happened to all of us at some point. We're on autopilot, going about our daily routine, and we've forgotten why we went into a certain room or where we put our phone. It can be frustrating, but usually, we can quickly jog our memory and solve the mystery within a few minutes. But Alzheimer's is different. The severity of the disease causes people to forget not only small details but also loved ones and cherished memories. It’s a heartbreaking reality that affects over 6 million Americans today. And by 2050, that number is projected to double to nearly 13 million.²

The Alzheimer’s Association created a list of warning signs that can help you tell the difference between age-related changes and Alzheimer’s disease or other dementias.⁴ If you or someone you love is experiencing any of the warning signs, please talk with a doctor right away. Early diagnosis and treatment are important for slowing the disease and improving quality of life.

So, what’s the difference between Alzheimer's disease vs normal aging?

Natural aging⁴

  • Making a bad decision once in a while
  • Missing a monthly payment
  • Forgetting the date and remembering later
  • Sometimes forgetting which word to use
  • Losing things from time to time

Alzheimer’s disease⁴

  • Poor decision making and judgement
  • Losing the ability to manage a budget
  • Losing track of the date or season
  • Difficulty having a conversation
  • Misplacing things and unable to retrace steps to find them

Source: Alzheimer’s Association

These lists are not for a diagnosis of Alzheimer's disease. If you’re concerned you or someone you care about may have Alzheimer's disease, it's important to see a doctor for a professional evaluation.

Is there a cure for Alzheimer’s disease? 

Currently, there’s no cure for Alzheimer's. But there are treatments that can help slow the progression of the disease and improve quality of life. That's why it's so important to detect Alzheimer’s disease early on. Early detection can help people plan for their future and slow down the progression of the disease so they can continue living the life they want to—for longer.

How is Alzheimer’s diagnosed?

In the past, doctors relied on cognitive tests and brain scans to diagnose Alzheimer's, but this was often difficult because it was hard to distinguish Alzheimer's from other forms of dementia.

Today, doctors review a person’s medical and family health history and use a variety of tests to help diagnose Alzheimer's disease, including:

  • Cognitive and functional assessments check how well a person remembers things, thinks, and does everyday tasks.
  • Physical and neurological exams check how well a person can walk and move.
  • Brain scans like computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) can help support or rule out an Alzheimer’s diagnosis.
  • Genetic tests look for certain genes in the blood like the apolipoprotein E (ApoE) gene that’s associated with an increased risk of Alzheimer's disease. 
  • Cerebrospinal fluid analysis involves a spinal tap to collect cerebrospinal fluid (CSF). The fluid is then measured for the levels of proteins that are linked to Alzheimer's disease.

Is there a screening test for Alzheimer’s?

Before the tests that are available today, amyloid buildup could only be seen after death, through an autopsy. But advances in brain imaging and blood biomarker tests have now made it possible. Brain imaging can measure beta-amyloid plaque buildup over time and identify which parts of the brain are most affected. Blood biomarker tests can measure certain proteins in the blood to help identify a person’s risk for developing Alzheimer’s disease.

Quest offers a new screening test called AD-Detect Test for Alzheimer's Disease Risk that can help assess your Alzheimer’s risk with a single blood test. AD-Detect Test for Alzheimer's Disease Risk measures 2 biomarkers and 1 calculated ratio that can help detect early signs of Alzheimer’s disease. Finding these signs early can help with treating and managing the disease better.

What is a blood biomarker—and what blood biomarkers does AD-Detect Test for Alzheimer's Disease Risk measure?

A blood biomarker is a substance that can be found and measured in the blood. It helps doctors know if someone has a disease or health condition. It can also help doctors see how the disease changes over time and help them decide which treatments to use.

AD-Detect Test for Alzheimer's Disease Risk measures 2 blood biomarkers and 1 calculated ratio:

  1. Beta-amyloid 40
  2. Beta-amyloid 42
  3. The calculated ratio of Beta-amyloid 40 and Beta-amyloid 42

Here’s a table that shows the differences between the biomarkers measured in the test:

  Beta-amyloid 40 Beta-amyloid 42
Length 40 amino acides 42 amino acids
Potential to form into an amyloid plaque Lower Higher
Occurence in the brain More common Less common
Relative amount in people living with Alzheimer's disease Lower Higher

But what does all of this mean?

Beta-amyloid 40 and beta-amyloid 42 are two proteins that can be found in the brain. They’re made up of strings of amino acids, which are the building blocks of proteins. They are both made from amyloid precursor protein (APP), but they differ in length. Beta-amyloid 40 is 40 amino acids long, while beta-amyloid 42 is 42 amino acids long.

The length of the protein matters because it affects how likely it is to form amyloid plaques. Amyloid plaques are sticky clumps that are linked to Alzheimer's disease. People living with Alzheimer's disease tend to have higher levels of beta-amyloid 42 in their brains than people who don’t have the disease. AD-Detect Test for Alzheimer's Disease Risk helps determine if a person's mild cognitive impairment is likely due to Alzheimer's disease or another form of dementia.

No doctor visit is required to buy your own lab test at questhealth.com. PWNHealth and its affiliates review your purchase to ensure it is medically appropriate before submitting the test order for processing. PWNHealth also reviews your test results and will contact you directly if they require prompt attention. Included in each purchase is the option to discuss your test results with an independent physician; however, you are also encouraged to speak with your primary health care provider. 


  1. Centers for Disease Control and Prevention (CDC). Alzheimer’s Disease and Related Dementias. Accessed July 14, 2023. https://www.cdc.gov/aging/aginginfo/alzheimers.htm. 
  2. Alzheimer’s Association. Alzheimer’s Disease Facts and Figures. Accessed July 14, 2023. https://www.alz.org/alzheimers-dementia/facts-figures.
  3. Alzheimer’s Association. What is Alzheimer’s Disease. Accessed July 14, 2023. https://www.alz.org/alzheimers-dementia/what-is-alzheimers. 
  4. Alzheimer’s Association. Is It Alzheimer’s or Just Signs of Aging? Accessed July 14, 2023. https://www.alz.org/national/documents/aa_brochure_10warnsigns.pdf. 


  1. Quest Diagnostics. Alzheimer’s and Dementia Testing. Accessed July 14, 2023. https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/neurological-disorders/alzheimers.
  2. Gu L, Guo Z. Alzheimer's Aβ42 and Aβ40 peptides form interlaced amyloid fibrils. J Neurochem. 2013;126(3):305-311. doi:10.1111/jnc.12202
  3. Bright Focus Foundation. Amyloid Beta. Accessed July 14, 2023. https://www.brightfocus.org/alzheimers/amyloid-beta.
  4. Alzheimer’s Association. Is Alzheimer’s Genetic? Accessed July 21, 2023. https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors/genetics.