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.

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Understanding Alzheimer’s Disease

A pair of hands bearing indicators of old age hold a small, black and white photo of a younger man.

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.

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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.

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Confusion

Alzheimer’s can cause confusion, such as not even remembering the purpose of car keys in the first place.

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Cognitive problems

This can include mood conditions such as depression, anxiety, irritability, apathy, and poor performance on cognitive tests.

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Inability to care for oneself

The inability to communicate or care for oneself usually occurs at a later stage, and those affected generally become more unresponsive.

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Neurodegeneration

How Alzheimer’s Affects The Brain

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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.
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.
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
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Risks & Prevention

Who is at Risk of Developing Alzheimer’s?

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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

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More than 7 million

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

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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.

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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.
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Zoom In on Dementia & Alzheimer's

The Next Generation of Alzheimer’s Treatments

Join behavioral neurologist Dr. Marwan Sabbagh for an in-depth discussion about emerging Alzheimer’s therapeutics now in late-stage clinical development.

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Expert Information

Why Some Brains Stay Sharp With Age

Learn how cognitive reserve can make some people more resistant to memory decline.

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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.

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Downloadable Resource

FDA-Approved Alzheimer’s Therapies Infographic

Although there is no cure for Alzheimer’s disease, certain treatments can help control or delay its symptoms, particularly in the early stages of the disease. Talk to your physician to see if these medications are right for you.

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Zoom In on Dementia & Alzheimer's

The Gut Microbiome and Alzheimer’s Disease: Understanding the Connection

Join Dr. Beau Ances of Washington University in St. Louis to learn about the emerging science linking gut health and brain health.

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Story

“Help the One You Can”

Meet Mel and Irene Sahyun, donors to BrightFocus’ Alzheimer’s Disease Research program.

Laura Baker, PhD.
Zoom In on Dementia & Alzheimer's

U.S. POINTER Study Update: Lifestyle Program Significantly Improves Cognition in Older Adults

Can everyday lifestyle choices really protect your memory? Dr. Laura Baker, professor at Wake Forest University School of Medicine, will share results from the groundbreaking U.S. POINTER trial—the largest study of its kind to test how lifestyle changes impact brain health.

Zoom In on Dementia & Alzheimer's

Non-Invasive Light and Sound Stimulation Therapy in Alzheimer’s: Update on HOPE Study

Can light and sound help slow Alzheimer’s? Join Christian Howell, CEO of Cognito Therapeutics, as he shares the latest on the HOPE Study. Discover how non-invasive 40 Hz light and sound stimulation may protect memory, thinking, and daily function—and what’s next for this promising technology.

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Zoom In on Dementia & Alzheimer's

Can GLP-1 Weight Loss Drugs Treat Alzheimer’s?

Recent research suggests that GLP 1 analogs—a class of drugs used to control blood sugar—may also protect brain health, improve memory, and slow neurodegeneration.

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