Alzheimer’s disease is a type of dementia. Dementia, a group of brain disorders, causes memory loss and other problems with thinking. It usually occurs in older people.  

Important things to know: 

• Alzheimer’s disease does not have a cure, but treatment can slow symptoms and improve quality of life.
• Many people become forgetful with age. Forgetfulness does not necessarily mean you have Alzheimer’s.
• Research shows that healthy habits, such as exercising and spending time with loved ones, can lower your risk of Alzheimer’s.
• Scientists, including at the Layton Aging & Alzheimer's Disease Center, are striving to develop better treatments.

What is Alzheimer’s disease?

Alzheimer’s disease is the most common form of dementia. About 60-80% of people with dementia are diagnosed with Alzheimer's disease, according to the Alzheimer’s Association. 

With Alzheimer’s, brain cells gradually die. Their connections vanish, preventing sections of the brain from communicating. This causes: 

• Changes in emotion and behavior that can include depression, anger and restlessness
• Loss of memory, reasoning and thinking

Living with Alzheimer’s disease

Alzheimer’s gets worse over time. Treatment can't stop the disease, but it can slow symptoms.  

Early stages cause mild loss of memory and other functions. Gradually, people lose the ability to live on their own and need help with all activities. 

How quickly it gets worse varies by person and type of Alzheimer’s (early or late onset). Some people live with Alzheimer’s up to 20 years after diagnosis. Most live with it for four to eight years. 

Who gets Alzheimer’s disease?

About 6.9 million people in the U.S. are living with Alzheimer’s disease, according to the Alzheimer’s Association. About 1 in 9 people age 65 and older have it, as do 1 in 3 age 85 and older.

Alzheimer’s disease risk factors

Having a risk factor doesn’t mean you will get Alzheimer’s. Not having one doesn’t mean you won’t. 

• Age: Alzheimer’s isn't a normal part of aging, but it's most common among those 65 and older.
• Family history: People with a parent or sibling who has or had Alzheimer’s are at higher risk. Risk increases if you have more than one relative with Alzheimer’s.
• Gender: Women are at higher risk.
• Race and ethnicity: Black people have about twice the risk compared with white people. Latinos have about 1½ times the risk that white people do.  
• Genetics: Scientists have identified genetic changes that increase risk. They don't fully understand how the changes can lead to Alzheimer’s, though.
• Down syndrome: People with Down syndrome are more likely to develop Alzheimer’s. They also tend to develop it about 10 to 20 years earlier than others.
• Head trauma, or mild memory and thinking issues: People who have had a traumatic brain injury or who have memory or other thinking problems are at higher risk.

Lowering risk of Alzheimer’s disease

Lifestyle changes can lower risk. Alzheimer’s disease is linked to heart and blood vessel health, for example. 

To lower risk, you can: 

• Quit smoking.
• Get regular exercise.
• Get enough sleep.
• Eat a healthy diet with plenty of fruits and vegetables.
• Get treatment to manage health conditions. Be especially alert to depression, type 2 diabetes, high blood pressure and high cholesterol.
• Keep a healthy weight.
• Keep your mind active through lifelong learning.
• Spend time with family and friends.

Early-stage Alzheimer's disease

In early-stage Alzheimer’s disease, people begin to notice they are forgetful or confused. Symptoms may look like normal aging or those of other conditions. People can usually do most daily tasks.

Early-stage signs and symptoms: 

• Short-term memory loss, such as forgetting appointments or repeating questions
• Trouble with tasks that used to be easy
• Taking much longer with routines
• Putting things in unusual places and getting upset or suspicious when they aren't found
• Trouble with common words or with tracking conversations
• Confusion with times, dates or familiar places, such as getting lost on the way home
• Loss of interest in favorite activities or social events
• Less judgment with money, safety or health
• Mood or behavior changes, or being more impulsive 

Moderate-stage Alzheimer's disease

With moderate-stage Alzheimer's, signs and symptoms may interfere with self-care and other daily tasks. People may need more supervision. This stage can last many years.

Moderate-stage signs and symptoms:

Late-stage Alzheimer's disease

People with late-stage Alzheimer’s need constant help with daily tasks. They can't have a conversation or respond to what’s happening around them. 

They may have trouble swallowing. Food or drink can enter the lungs, causing aspiration pneumonia. For most people with Alzheimer's, this pneumonia is the direct cause of death.  

Late-stage signs and symptoms

When to get checked for Alzheimer’s disease

Everyone forgets things from time to time, especially as we age. But age-related memory problems are quite different from those that come with Alzheimer’s. 

People with Alzheimer’s disease may not realize they have a problem, even as family or friends notice changes. If you recognize signs in yourself or a loved one, see a doctor for a full exam.  

Your doctor can use tests to trace the cause of your symptoms and to rule out other possible causes. Learn about diagnosis and treatment at the Layton Aging & Alzheimer’s Disease Center.

What causes Alzheimer’s disease?

Doctors don’t understand the exact causes. Alzheimer’s may result from a combination of genetic, environmental and lifestyle factors. 

Alzheimer’s disease affects a type of brain cell called a neuron. Neurons send messages between parts of the brain, and between the brain and the rest of the body.

Changes to neurons and the brain from Alzheimer’s include: 

• Shrinkage: The brain shrinks as networks of neurons break down. This is also known as brain atrophy.
• Amyloid plaques: A naturally occurring protein called amyloid-beta can build up in the brain for reasons doctors don't fully understand. It can form clumps, known as plaques, between neurons that keep them from communicating.  
• Neurofibrillary tangles: Tau, another naturally occurring protein, builds up inside neurons. Tau forms threads known as tangles. The tangles keep neurons from communicating and transporting nutrients. Without nutrients, neurons die.

Types of Alzheimer’s disease

Early onset: Symptoms start in the person's 40s or 50s. The disease tends to worsen quickly. This type is much less common than late-onset Alzheimer’s, making up less than 5% of cases. 

Late onset: This is the most common type, typically affecting people age 65 and older. Symptoms usually worsen more slowly than in early-onset Alzheimer’s.

Familial Alzheimer’s disease: This rare type results from genetic changes passed down from parent to child. Familial Alzheimer’s makes up less than 1% of cases overall but about 60% of early-onset cases.

Genetic testing and Alzheimer’s disease

Testing can show whether you have a version (variant) of a gene that increases your risk of Alzheimer’s. Testing can also uncover the rare cases when an inherited genetic change, or mutation, causes Alzheimer’s. 

At OHSU, we generally do not recommend routine genetic testing for Alzheimer’s because: 

• Many factors can lead to the disease.
• Most people who develop Alzheimer’s do not have a related genetic variant.  
• Most people who have a variant do not develop the disease.  

Talk with your primary care doctor or to a medical geneticist to learn more or to better understand risk if you’ve taken a test on your own.

Learn more

• Alzheimer’s Disease, National Institute of Neurological Disorders and Stroke
• Alzheimer’s Disease, U.S. National Library of Medicine
• Alzheimer’s Association