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What Is Alzheimer's Disease?

Alzheimer’s disease, the most common form of dementia, is a progressive, terminal brain disorder that has no known cause or cure. It affects people’s memories, but it involves far more than simple forgetfulness. It is still not known why Alzheimer’s disease affects some people and not others. Researchers worldwide are searching for its causes and ways to prevent, diagnose, treat, and cure it. Learn about the signs and symptoms of Alzheimer’s, treatments, prevention techniques, and ways to care for yourself or a loved one.

A series of brain scan images displayed in a grid, showing different cross-sectional views of the brain. The scans feature detailed visuals of various brain regions, highlighting structures in shades of orange and blue on a dark background.

Understanding Alzheimer’s Disease

Alzheimer’s steals the minds of its victims.

It takes a toll on families who provide the majority of caregiving. About 7 out of 10 people with Alzheimer’s or other dementias are cared for at home. Caregiving can be difficult—family and other unpaid caregivers may experience high levels of emotional stress and depression.

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Signs & Symptoms

Many people experience mild forgetfulness or memory delays, which are part of the normal aging process. We all have occasional difficulty remembering a word or someone’s name. Someone with Alzheimer’s or other types of dementia, however, will find such symptoms becoming more frequent and severe.

Memory loss

Any of us could forget where we placed our car keys. Someone with Alzheimer’s disease may place the keys in an unusual spot, like the refrigerator.

Confusion

Cognitive problems

Inability to care for oneself

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Neurodegeneration

How Alzheimer’s Affects The Brain

Alzheimer’s Disease Shrinks the Brain​

Alzheimer’s damages brain cells, ultimately resulting in their death. This causes the brain to progressively shrink, as seen above when comparing a normal brain (left) with an Alzheimer’s brain (right).

Reduced Blood Flow and Brain Activity​

PET scans showing metabolic activity of a normal (left) versus an Alzheimer’s (right) brain. The colors show an activity heatmap from low (blue/black) to high (red/yellow). The Alzheimer’s brain has reduced function and blood flow.

Alzheimer’s Brains Struggle to Remove Waste

Ventricles (red/yellow) are cavities filled with a fluid that flows throughout and around the brain to remove waste. Alzheimer’s impairs this process, allowing toxic proteins to build up.

Amyloid-Beta Plaques and Tau Tangles: Alzheimer’s Hallmarks​

In Alzheimer’s disease, tau tangles (orange) build up inside brain cells called neurons, while amyloid-beta plaques (blue) accumulate in the surrounding area.

Chronic Brain Inflammation in Alzheimer’s Disease

In a healthy brain, microglia (blue) protect neurons (green) and astrocytes (red) destroy waste. In Alzheimer’s, however, both perpetuate harmful inflammation.

A digital illustration comparing a normal brain to a brain with Alzheimer's disease.
A digital illustration of the ventricular system of the brain.
A digital illustration of a brain cell called a neuron with tau tangles inside the cell and amyloid-beta plaques outside the cell.
Brains cells in a dish

Risks & Prevention

Who is at Risk of Developing Alzheimer’s?

Portrait of a senior woman playing with crosswords at home

While there are many theories about what causes this disease, there is still no definitive answer.

However, there are some general risk factors to keep in mind, including:

  • Diminished blood flow
  • Excess accumulation of abnormal brain proteins
  • Toxins
  • Brain injury
  • Infection
  • Inflammation
  • Malnutrition

Browse other potential risk factors and how to lower your risk.

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By The Numbers

Facts & Figures

Nearly 7 Million

Americans age 65 and older are living with Alzheimer’s disease.

1 in 3

seniors die with Alzheimer’s or another dementia.

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13 Million

people aged 65 and older are projected to have Alzheimer’s and other dementias by 2050 unless scientists develop new approaches to prevent or cure it.

Program Impact

The need for a cure is more urgent than ever.

Unless scientists can unlock the secrets of this disease, the number of cases is expected to triple by the year 2050. This epidemic could overwhelm our healthcare system.

Researcher in the lab
Alzheimer’s Disease Research grant recipient Laia Montoliu-Gaya, PhD.

Alzheimer’s Disease Research has funded more than $180 million in research grants since inception.

By providing initial funding for highly innovative, experimental research and creative ideas, we spark revolutionary approaches and life-saving breakthroughs for this disease. We are currently supporting 112 active scientific projects worldwide.

Resources

Recent Resources & Information

Browse expert-vetted articles and resources to better understand and manage Alzheimer’s symptoms and treatment. And, read about the latest discoveries fueled by Alzheimer’s Disease Research-funded scientists.
Jeffrey L. Cummings, MD, ScD.
Zoom In on Dementia & Alzheimer's

Navigating Clinical Trials for Alzheimer’s Disease

Join our conversation with Dr. Jeffrey L. Cummings, renowned expert in dementia drug development and research studies, for insights into the different types, qualification processes, and phases of studies that may be right for you or your loved one.

Expert Information

Environmental Pollution Can Increase Your Alzheimer’s Risk, Say BrightFocus-Funded Scientists

Urban and rural communities alike face potential long-term health consequences from environmental toxins that could lead to Alzheimer’s disease.

Dr. Miia Kivipelto
Zoom In on Dementia & Alzheimer's

Can Lifestyle Changes Prevent Alzheimer’s? What the Research Reveals

Join us as lead scientist Dr. Miia Kivipelto discusses the science behind lifestyle interventions for reducing Alzheimer’s risk.

John Dwyer
Zoom In on Dementia & Alzheimer's

BIO-HERMES-002: Innovative Study to Advance Precise Alzheimer’s Diagnosis

Learn about the Bio-Hermes-002 study exploring blood and digital biomarkers for predicting Alzheimer’s pathology. Discover accessible detection methods and treatment eligibility.

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Downloadable Resource

Understanding Alzheimer’s Disease

Alzheimer’s disease affects people’s memories, but it involves far more than simple forgetfulness. Learn more about this devastating disease.

A mature African American businesswoman day dreams while looking out of her office window.
Downloadable Resource

Dementia and Alzheimer’s Disease: Understanding the Differences

Alzheimer’s disease and dementia are not one and the same. Learn about the differences between Alzheimer’s disease and dementia. 

Medlive Treating Early-stage Alzheimer's Disease video thumbnail.
Video

Treating Early-Stage Alzheimer’s Disease: Newly Available Treatments and What They Mean for Patients

This hour-long webinar helps caregivers and patients understand newly approved therapies that treat Alzheimer’s itself, not just the symptoms.

Suzanne E. Schindler, MD, PhD
Zoom In on Dementia & Alzheimer's

Blood Tests for Alzheimer’s Disease: An Overview

Join us to learn the basics of what blood biomarkers are, how they work, and why they’re considered a game-changer in Alzheimer’s research and clinical care.

David M. Holtzman, MD
Zoom In on Dementia & Alzheimer's

How Is Dementia Diagnosed?

Alzheimer’s expert Dr. David Holtzman shares insights on the latest diagnostic methods, when and how to seek a diagnosis, and how to navigate the process.

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Help Fund Groundbreaking Alzheimer’s Research

Alzheimer’s disease affects millions, and your donation can make a difference. By supporting research, you help bring us closer to a cure and provide essential information to those affected by this devastating disease.

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