Alzheimer's disease is the most common cause of dementia. Alzheimer's disease is the biological process that begins with the appearance of a buildup of proteins in the form of amyloid plaques and neurofibrillary tangles in the brain. This causes brain cells to die over time and the brain to shrink.
About 6.9 million people in the United States age 65 and older live with Alzheimer's disease. Among them, more than 70% are age 75 and older. Of the more than 55 million people in the world with dementia, 60% to 70% are estimated to have Alzheimer's disease.
Early symptoms of Alzheimer's disease include forgetting recent events or conversations. Over time, Alzheimer's disease leads to serious memory loss and affects a person's ability to do everyday tasks.
There is no cure for Alzheimer's disease. In advanced stages, loss of brain function can cause dehydration, poor nutrition or infection. These complications can result in death.
But medicines may improve symptoms or slow the decline in thinking. Programs and services can help support people with the disease and their caregivers.
Memory loss is the key symptom of Alzheimer's disease. Early in the disease, people may have trouble remembering recent events or conversations. Over time, memory gets worse and other symptoms occur.
At first, someone with the disease may be aware of having trouble remembering things and thinking clearly. As signs and symptoms get worse, a family member or friend may be more likely to notice the issues.
Brain changes from Alzheimer's disease lead to the following symptoms that get worse over time.
Everyone has trouble with memory at times, but the memory loss related to Alzheimer's disease is lasting. Over time, memory loss affects the ability to function at work and at home.
People with Alzheimer's disease may:
Alzheimer's disease causes trouble concentrating and thinking, especially about abstract concepts such as numbers. Doing more than one task at once is especially hard. It may be challenging to manage finances, balance checkbooks and pay bills on time. Eventually people with Alzheimer's disease may not recognize numbers.
Alzheimer's disease makes it hard to make sensible decisions and judgments. People with Alzheimer's disease may make poor choices in social settings or wear clothes for the wrong type of weather. Everyday problems may be hard to solve. Someone with Alzheimer's disease may not know how to handle food burning on the stove or how to make decisions when driving.
Routine activities that involve completing steps in a certain order also can be hard for people with Alzheimer's disease. They may have trouble planning and cooking a meal or playing a favorite game. As Alzheimer's disease becomes advanced, people forget how to do basic tasks such as dressing and bathing.
Brain changes that occur in Alzheimer's disease can affect moods and behaviors. Symptoms may include:
Despite major changes to memory and skills, people with Alzheimer's disease are able to keep some skills even as symptoms get worse. These are known as preserved skills. They may include reading or listening to books, telling stories, sharing memories, singing, listening to music, dancing, drawing, or doing crafts.
Preserved skills may last longer because they're managed by parts of the brain affected in later stages of the disease.
Several conditions can cause memory loss or other dementia symptoms. Some of those conditions can be treated. If you are concerned about your memory or other thinking skills, talk to your healthcare professional.
If you are concerned about the thinking skills you notice in a family member or friend, ask about going together to talk to a healthcare professional.
The exact causes of Alzheimer's disease aren't fully understood. But at a basic level, brain proteins don't function as usual. This disrupts the work of brain cells, also known as neurons, and triggers a series of events. The neurons become damaged and lose connections to each other. They eventually die.
Scientists believe that for most people, Alzheimer's disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time. In less than 1% of people, Alzheimer's is caused by specific genetic changes that almost guarantee a person will develop the disease. For people in this group, the disease usually begins in middle age.
The disease begins years before the first symptoms. The damage most often starts in the region of the brain that manages memory. The loss of neurons spreads in a somewhat predictable pattern to other regions of the brain. By the late stage of the disease, the brain has shrunk.
Researchers trying to understand the cause of Alzheimer's disease are focused on the role of two proteins:
Risk factors for Alzheimer's disease include age, family history, lifestyle and other factors.
Older age is the strongest known risk factor for Alzheimer's disease. Alzheimer's isn't a part of typical aging. But as you grow older, the chances of getting the disease goes up.
One study found that there were four new diagnoses per 1,000 people ages 65 to 74 every year. Among people ages 75 to 84, there were 32 new diagnoses per 1,000 people. For those 85 and older, there were 76 new diagnoses per 1,000 people.
The risk of getting Alzheimer's disease is higher if a first-degree relative such as a parent or sibling was diagnosed with the disease. How genes among families affect the risk is largely not understood. The genetic factors are likely complex.
A better understood genetic factor is a form of the apolipoprotein E (APOE) gene. Having the form of the gene known as APOE e4 increases the risk of Alzheimer's disease. About 25% to 30% of the population carries APOE e4. But not everyone with this form of the gene develops the disease. Having two copies of APOE e4 increases the risk of Alzheimer's disease more than having one copy.
Scientists have found rare changes in three genes that virtually guarantee a person who inherits one of them will develop Alzheimer's. But these changes account for less than 1% of people with Alzheimer's disease.
Many people with Down syndrome develop Alzheimer's disease. This is likely related to having three copies of chromosome 21. Chromosome 21 is the gene involved in the production of the protein that leads to the creation of beta-amyloid. Beta-amyloid fragments can become plaques in the brain. Symptoms tend to appear 10 to 20 years earlier in people with Down syndrome than they do for the general population.
Overall there are more women with the disease because they tend to live longer than men.
Someone with mild cognitive impairment, also called MCI, has a bigger decline in memory or other thinking skills than is usual for the person's age. But the decline doesn't prevent the person from functioning at work or socially.
However, people with MCI have a higher risk of getting dementia than are people who don't have mild cognitive impairment. When MCI affects mainly memory, the condition is more likely to progress to dementia due to Alzheimer's disease. A diagnosis of MCI offers people the chance to focus on healthy lifestyle changes and to come up with strategies to make up for memory loss. They also can schedule regular healthcare appointments to monitor symptoms.
Several large studies found that people age 50 or older who had a traumatic brain injury, also called TBI, had a higher risk of getting dementia and Alzheimer's disease. The risk is even higher in people with serious TBIs or multiple TBIs.
Studies in animals have found that air pollution particulates can speed the breakdown of the nervous system. Human studies have found that air pollution exposure — especially from traffic exhaust and burning wood — is linked to a higher risk of dementia.
Drinking large amounts of alcohol has long been known to cause brain changes. Several large studies and reviews found that alcohol misuse is linked to a higher risk of dementia, especially early-onset dementia.
Research has shown that poor sleep patterns, such as trouble falling asleep or staying asleep, are linked to a raised risk of Alzheimer's disease. Sleep apnea also may raise the risk of dementia.
Research has shown that the same risk factors for heart disease also may increase the risk of dementia. It's not clear if these factors raise risk by worsening Alzheimer's changes in the brain or by leading to blood vessel changes in the brain. The factors include:
High levels of low-density lipoprotein, known as LDL, cholesterol in middle age, in particular, raises the risk of dementia. Research has found that people younger than 65 with high LDL cholesterol levels have a higher risk of dementia. But taking medicines to lower LDL cholesterol didn't raise the risk.
These factors can all be modified, so changing lifestyle habits can to some degree alter your risk. For example, regular exercise and a healthy low-fat diet rich in fruits and vegetables are related to a lower risk of Alzheimer's disease.
Studies have found that people who have hearing loss are at risk of dementia. The worse the hearing loss, the higher the risk. However, wearing hearing aids protects against getting dementia.
Newer research suggests vision loss that isn't treated is a risk factor for cognitive impairment and dementia. The link may be due to a disease such as diabetes that can increase the risk of both vision loss and dementia. But some research suggests vision loss itself may increase the risk of dementia.
Studies have found that being social and doing activities that stimulate the mind throughout life can lower the risk of Alzheimer's disease. Low education levels — less than a high school education — appear to be a risk factor for Alzheimer's disease.
Alzheimer's disease can lead to a variety of complications. Symptoms such as memory loss, language loss, impaired judgment and other brain changes can make it harder to manage other health conditions. A person with Alzheimer's disease may not be able to:
As Alzheimer's disease moves into its last stages, brain changes begin to affect physical functions. The changes can affect the ability to swallow, balance, and manage stool and bladder movements. These effects can lead to other health issues such as:
Alzheimer's disease can't be prevented. But making lifestyle changes can lower your risk of getting the disease.
Research suggests that taking steps that lower your risk of cardiovascular disease may reduce the risk of dementia, as well. To follow heart-healthy lifestyle choices that may lower the risk of dementia:
One large, long-term study done in Finland found that making lifestyle changes helped reduce cognitive decline among people who were at risk of dementia. Those in the study were given individual and group sessions that focused on diet, exercise and social activities.
Several studies have found that following a Mediterranean diet leads to better cognitive function and a slower cognitive decline with age. A Mediterranean diet focuses on plant-based foods such as fruits, vegetables, grains, fish, poultry, nuts and olive oil. The diet includes less foods that are high in saturated fats and trans fats, such as butter, margarine, cheese, red meat, fried food and pastries.
It's also important to treat vision loss and hearing loss. Studies have found that vision loss that isn't treated is a risk factor for cognitive impairment and dementia. Studies also have found that people who have hearing loss are at higher risk of dementia. But wearing hearing aids made people less likely to get dementia.
Other studies have shown that staying engaged mentally and socially is linked to preserved thinking skills later in life and a lower risk of Alzheimer's disease. This includes going to social events, reading, dancing, playing board games, creating art, playing an instrument and other activities.
An important part of diagnosing Alzheimer's disease includes being able to explain your symptoms. It may help to get input from a close family member or friend about your symptoms and their impact on your daily life. Tests of memory and thinking skills also help diagnose Alzheimer's disease.
Blood and imaging tests can rule out other potential causes of your symptoms. They also can check for proteins in the brain that are linked to Alzheimer's disease. The tests may help your healthcare team better identify the disease causing dementia symptoms.
In the past, Alzheimer's disease was diagnosed for certain only after death when plaques and tangles were found while looking at the brain with a microscope. Today, healthcare professionals and researchers are able to diagnose Alzheimer's disease during life with more certainty.
They do this by using a combination of tests that may include tests for biomarkers. Biomarkers can detect if plaques and tangles are present in the brain. Biomarker tests include specific types of positron emission tomography, also known as PET, scans of the brain. Amyloid and tau proteins also can be measured in the fluid part of the blood or in the fluid that surrounds the brain and spinal cord, known as cerebrospinal fluid. Recently, blood biomarker tests have become accurate enough to tell if someone is likely to have amyloid in the brain.
Biomarker tests were mainly used in clinical trials until recently. But healthcare professionals have started using them along with other tests to help diagnose Alzheimer's disease. Biomarker tests also can let healthcare professionals know if the disease is in the early or later stages.
Diagnosing Alzheimer's disease would likely include the following tests:
A healthcare professional gives you a physical and neurological exam. This may include testing:
Blood tests may help rule out other potential causes of memory loss and confusion, such as a thyroid disorder or vitamin levels that are too low.
Newer blood tests can measure levels of beta-amyloid protein and tau protein. But these tests aren't available everywhere and may not be covered by insurance.
Your healthcare professional may give you a brief mental status test to check your memory and other thinking skills. Longer forms of this type of test may provide more details about mental function that can be compared with people of a similar age and education level. These tests can help establish a diagnosis and serve as a starting point to track symptoms in the future.
Images of the brain look for visible changes related to conditions other than Alzheimer's disease that may cause similar symptoms, such as strokes, injury or tumors. Newer imaging tests can help detect specific brain changes caused by Alzheimer's disease, such as amyloid plaques and neurofibrillary tangles. These newer tests are mainly used in major medical centers or in clinical trials.
Imaging of brain structures include:
A PET scan test can capture images of the disease process. During a PET scan, a low-level radioactive tracer is injected into the blood to reveal a particular feature in the brain. PET imaging may include:
Sometimes other tests may be used to measure amyloid and tau in the cerebrospinal fluid. This may be done if symptoms are quickly getting worse or if dementia is affecting someone at a younger age.
Research has established that biomarker tests can measure biological signs of disease in the brain. The tests can be used with other tools to help diagnose Alzheimer's disease after symptoms begin. Although these tests can look for signs of Alzheimer's before symptoms begin, the tests aren't being used in people without symptoms. The availability of biomarker tests may vary widely.
Genetic tests aren't recommended for most people who might have Alzheimer's disease. But people with a family history of early-onset Alzheimer's disease may consider being tested. Meet with a genetic counselor to talk about the risks and benefits before getting a genetic test.
Treatments for Alzheimer's disease include medicines that can help with symptoms and newer medicines that can help slow decline in thinking and functioning. These newer medicines are approved for people with early Alzheimer's disease.
An important part of any treatment plan is to adapt to the needs of a person with Alzheimer's disease. Create routine habits and cut down on tasks that require memory. These steps can make life much easier.
These are ways to support a person's sense of well-being and ability to function:
Herbal remedies, vitamins and other supplements are widely promoted for cognitive health or to prevent or delay Alzheimer's. But clinical trials have produced mixed results. There's little evidence to support them as effective treatments.
Some of the treatments that have been studied include:
Vitamin E. Although vitamin E doesn't prevent Alzheimer's, taking 2,000 international units daily may help delay symptoms from getting worse in people who already have mild to moderate disease. But study results have been mixed, with only some showing modest benefits. Further research into the safety of people with dementia taking 2,000 international units daily of vitamin E are needed before it can be routinely recommended.
Supplements promoted for cognitive health can interact with medicines you're taking for Alzheimer's disease or other health conditions. Work closely with your healthcare team to create a safe treatment plan. Tell your healthcare team about your prescriptions and any medicines or supplements taken without a prescription.
Healthy lifestyle choices promote good overall health. They also may play a role in maintaining brain health.
Regular exercise is an important part of a treatment plan. Activities such as a daily walk can help improve mood and maintain the health of joints, muscles and the heart. Exercise also promotes restful sleep and prevents constipation. It's beneficial for care partners, too.
People with Alzheimer's who have trouble walking may still be able to use a stationary bike, stretch with elastic bands or do chair exercises. You might find exercise programs for older adults at community centers or on TV, the internet or DVDs.
People with Alzheimer's may forget to eat, lose interest in meals or may not eat healthy foods. They may also forget to drink enough, leading to dehydration and constipation.
Offer the following:
Social activities can support preserved skills and abilities. They also help with overall well-being. Do things that are meaningful and enjoyable. Someone with dementia might:
People with Alzheimer's disease experience a mixture of emotions — confusion, frustration, anger, uncertainty, grief and depression.
If you're caring for someone with Alzheimer's, you can help them cope by being there to listen. Reassure the person that life can still be enjoyed, provide support, and do your best to help the person retain dignity and self-respect.
A calm and stable home environment can help reduce behavior problems. New situations, noise and large groups of people can cause anxiety. Being rushed or pressed to remember, or being asked to do complex tasks also may make someone with dementia anxious. When someone with Alzheimer's becomes upset, it's even harder to think clearly.
Caring for a person with Alzheimer's disease is physically and emotionally demanding. Feelings of anger, guilt, stress, worry, grief and social isolation are common.
Caregiving can even take a toll on the caregiver's physical health. Pay attention to your own needs and well-being. It's one of the most important things you can do for yourself and for the person with Alzheimer's.
If you're a caregiver for someone with Alzheimer's, you can:
Many people with Alzheimer's and their families benefit from counseling or local support services. Contact your local Alzheimer's Association affiliate to connect with support groups, healthcare professionals, occupational therapists, resources and referrals. You can find information about home care agencies, residential care facilities, a telephone help line and educational seminars.
Medical care for the loss of memory or other thinking skills usually requires a team or partner strategy. If you're worried about memory loss or related symptoms, ask a close relative or friend to go with you to an appointment with a healthcare professional. Having a partner can provide support and help you answer questions.
If you're going with someone who is having memory issues to a healthcare appointment, your role may be to provide some history or your thoughts on changes you have seen. This teamwork is an important part of medical care.
Your healthcare professional may refer you to a neurologist, psychiatrist, neuropsychologist or other specialist for further evaluation.
You can prepare for your appointment by writing down as much information as possible to share. Information may include:
Your healthcare professional asks questions to understand changes in memory or other thinking skills. Your healthcare professional may ask:
