What is amyloid—and why does everyone keep talking about it?
Amyloid is one of the most talked-about words in Alzheimer's research. This short, interactive page explains what it actually is—without the jargon.
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In about 30 seconds
Amyloid-beta is a small protein fragment naturally produced in the brain. In some people, it stops clearing away properly and clumps together between brain cells into sticky deposits called amyloid plaques. This buildup is one of the hallmark biological changes seen in Alzheimer's disease.
Importantly, having amyloid in the brain does not mean a person has dementia. Many people carry amyloid for years without symptoms.
Amyloid is not the same thing as Alzheimer's disease
These three terms are often used interchangeably, but they describe very different things. Understanding the difference is one of the most useful takeaways on this page.
Amyloid-beta
A small protein fragment produced when a larger protein called amyloid precursor protein (APP) is broken down.
A normal biological molecule. Everyone produces it.
Amyloid plaque
An abnormal accumulation of amyloid-beta between brain cells.
A physical sign of pathology, not a diagnosis.
Alzheimer's disease
A biological disease involving amyloid pathology along with other changes in the brain, particularly abnormal tau and neurodegeneration.
A disease — more than just amyloid alone.
How do we know amyloid is there?
Clinicians and researchers can detect amyloid pathology in a few different ways. Each method tells us something—and each has limits. Select a card to learn more.
Quick knowledge check
If someone has amyloid in their brain, does that mean they have dementia?
Now that you understand amyloid…
These related explainers are coming soon. They'll build on what you've learned here.
What is tau?
Coming soon
What is p-tau217?
Coming soon
What does "Alzheimer's pathology" mean?
Coming soon
How is Alzheimer's disease diagnosed?
Coming soon
This explainer is provided for informational and educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for questions about diagnosis, treatment, or your personal health.