Alzheimer's Disease

  • Medical Author: Rodrigo O Kuljis, MD
  • Medical Editor: Nestor Galvez-Jimenez, MD
  • Medical Editor: Francisco Talavera, PharmD, PhD
  • Medical Editor: Helmi L Lutsep, MD
Reviewed on 11/23/2021

Alzheimers Disease Facts

A brain in Alzheimer's disease.
A brain in Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia in industrialized nations. Dementia is a brain disorder that interferes with a person's ability to carry out everyday activities.

  • The brain of a person with Alzheimer's disease (see Multimedia file 1) has abnormal areas containing clumps (senile plaques) and bundles (neurofibrillary tangles) of abnormal proteins. These clumps and tangles destroy connections between brain cells.
  • This usually affects the parts of the brain that control cognitive (intellectual) functions such as thought, memory, and language.
  • Levels of certain chemicals that carry messages around the brain (neurotransmitters) are low.
  • The resulting losses in intellectual ability are called dementia when they are severe enough to interfere with everyday functioning.

Alzheimer's disease affects mainly people aged 60 years or older.

  • The risk of developing Alzheimer's disease continues to increase with age. People aged 80 years, for example, have a significantly greater risk than people aged 65 years.
  • Millions of people worldwide have Alzheimer's disease. Many others have mild, or minimal, cognitive impairment, which frequently precedes dementia.
  • The number of people with Alzheimer's disease is expected to rise substantially in the next few decades because of the aging of the population.
  • The disease affects all races and ethnic groups.
  • It seems to affect more women than men.

Alzheimer's disease is a progressive disease, which means that it gets worse over time. It cannot be cured or reversed by any known treatment.

  • The symptoms often are subtle at first.
  • Over time, people with the disease lose their ability to think and reason clearly, judge situations, solve problems, concentrate, remember useful information, take care of themselves, and even speak.
  • Changes in behavior and personality are common.
  • People with mild Alzheimer's disease usually require close supervision and help with everyday tasks such as cooking, shopping, and paying bills.
  • People with severe Alzheimer's disease can do little on their own and require complete full-time care.

Because of this, Alzheimer's disease is considered a major public health problem.

  • The cost of caring for people with the disease is estimated at over $100 billion per year in the United States. The average yearly cost per affected person is $20,000 to $40,000, depending on the severity of the disease.
  • That cost doesn't take into account the loss of quality of life for the affected person, nor the physical and emotional toll on family caregivers.

What causes Alzheimers disease?

We do not know exactly what causes Alzheimer's disease. There is probably not one single cause, but a number of factors that come together in certain people to cause the disease.

  • Most experts believe that Alzheimer's disease is not a normal part of aging.
  • While age is a risk factor for the disease, age alone does not seem to cause it.
  • Family history is another risk factor. The disease does seem to run in some families. However, few cases of Alzheimer's disease are familial. Familial Alzheimer's disease often occurs at a younger age, between ages 30 and 60 years. This is called early-onset familial Alzheimer's disease.

At least three different genes have been linked to Alzheimer's disease.

  • The one we know the most about controls production of a protein called apolipoprotein E (apoE), which helps in distribution of cholesterol through the body.
  • Everyone has one of the 3 forms of the apoE gene. While one form seems to protect from AD, another form seems to increase the risk of developing the disease.
  • The other genes-apart from ApoE-are known to be mutated in some people with the disease. These actually cause the disease in a few rare cases.
  • Probably there are other genes that contribute to Alzheimer's disease, but we haven't found them yet.

Much of the research in Alzheimer's disease has focused on why and how some people develop deposits of the abnormal protein in their brains. Once the process is understood, it may be possible to develop treatments that stop or prevent it.

What are the symptoms of Alzheimer's disease?

Early warning signs of Alzheimer's disease include memory problems such as difficulty recognizing familiar people or things, trouble remembering recent events, inability to solve simple arithmetic problems, and more

Alzheimer's disease begins with a mild, slowly worsening memory loss. Many older people fear that they have Alzheimer's disease because they can't find their eyeglasses or remember someone's name.

  • These very common problems are most often due to a much less serious condition involving slowing of mental processes with age.
  • Medical professionals call some of these cases benign senescent forgetfulness, age-related memory loss, or minimal cognitive impairment.
  • While these conditions are a nuisance, they do not significantly impair a person's ability to learn new information, solve problems, or carry out everyday activities, as Alzheimer's disease does.

Early warning signs of Alzheimer's disease include memory problems such as the following:

  • Difficulty recognizing familiar people or things (not just forgetting a name)
  • Trouble remembering recent events or activities
  • Inability to solve simple arithmetic problems
  • Problems finding the right word for a familiar thing
  • Difficulty performing familiar tasks

As the disease progresses, however, the symptoms become more serious. They may include the following:

  • Inability to carry out everyday activities, often called activities of daily living, without help - Bathing, dressing, grooming, feeding, using the toilet
  • Inability to think clearly or solve problems
  • Difficulties understanding or learning new information
  • Problems with communication - Speaking, reading, writing
  • Increasing disorientation and confusion even in familiar surroundings
  • Greater risk of falls and accidents due to poor judgment and confusion

In the later stages of the disease, the symptoms are severe and devastating:

  • Complete loss of short- and long-term memory - May be unable to recognize even close relatives and friends
  • Complete dependence on others for activities of daily living
  • Severe disorientation - May walk away from home and get lost
  • Behavior or personality changes - May become anxious, hostile, or aggressive
  • Loss of mobility - May be unable to walk or move from place to place without help
  • Impairment of other movements such as swallowing - Increases risk of malnutrition, choking, and aspiration (inhaling foods and beverages, saliva, or mucus into lungs)

These symptoms typically develop over a period of years. The disease progresses at different rates in different people.

Emotional problems such as depression and anxiety are common in older people. These problems can leave elderly people feeling confused or forgetful. Because these emotional problems are reversible in many people, it is important that they be distinguished from Alzheimer's disease and other brain disorders.

When should I seek medical care for Alzheimers?

Some slowing of thinking processes is normal in aging. However, any change in thinking, memory, reasoning, attention, grooming, behavior, or personality that interferes with the person's ability to take care of himself or herself, maintain health and safety, or participate in activities that he or she enjoys warrants a visit to the person's health care provider.

An early diagnosis allows treatment to begin earlier in the disease, when it has the best chance of offering significant symptom relief. Early diagnosis also allows the affected person to plan activities and make arrangements for care while he or she can still take part in making the decisions.

How is Alzheimers disease diagnosed?

Primary healthcare professionals are able to diagnose and treat Alzheimer's disease. Some healthcare professionals specialize in the problems of older people (gerontologists) or of the brain (neurologists and psychiatrists). If you or a relative have symptoms that suggest Alzheimer's disease, you may want to consult a specialist.

When the health care provider hears that an elderly person is having one or more cognitive problems, he or she will probably suspect Alzheimer's disease. However, many other conditions can cause dementia or dementia-like symptoms in an elderly person, including both medical and psychological problems. Many of these conditions can be reversed, or at least stopped or slowed. Therefore, it is extremely important that the person with symptoms be checked thoroughly to rule out treatable conditions.

The only way to confirm the diagnosis of Alzheimer's disease is to look at the brain directly and to identify senile plaques and neurofibrillary tangles. This is possible only at autopsy, after a person's death. The diagnosis in a living person is usually made on the basis of symptoms and ruling out other conditions. This is done by a combination of medical interviews, physical and mental examinations, lab tests, imaging studies, and other tests.

The medical interview involves detailed questions about the symptoms and how they have changed over time. Your health care provider will also ask about medical problems now and in the past, family medical problems, medications, work and travel history, habits, and lifestyle.

A detailed physical examination is done to rule out medical problems that might cause dementia. The examination should include a mental status evaluation. This involves answering the examiner's questions and following simple directions. In some cases, the health care provider will refer the person for neuropsychological testing.

Neuropsychological testing

Neuropsychological testing is the most accurate method of pinpointing and documenting a person's cognitive problems and strengths.

  • This can help give a more accurate diagnosis of the problems and thus can help in treatment planning.
  • The testing involves answering questions and performing tasks that have been carefully prepared for this purpose. It is carried out by a specialist called a neuropsychologist.
  • It addresses the individual's appearance, mood, anxiety level, and experience of delusions or hallucinations.
  • It assesses cognitive abilities such as memory, attention, orientation to time and place, use of language, and abilities to carry out various tasks and follow instructions.
  • Reasoning, abstract thinking, and problem-solving are tested.

Lab tests

These include blood tests to rule out infections, blood disorders, chemical abnormalities, hormonal disorders, and liver or kidney problems that could cause dementia symptoms.

Imaging studies

Brain scans cannot detect Alzheimer's disease. A scan usually is necessary to rule out other conditions such as brain tumors and stroke that can also cause dementia.

  • MRI or CT scan of the brain may be done to rule out other brain conditions.
  • Single-photon emission computed tomography (SPECT) scan is used in certain cases when the diagnosis of Alzheimer's disease is especially doubtful. It is especially good at detecting certain less common causes of dementia.

Other tests:

Any of these tests may be ordered as part of the workup of dementia.

  • Electroencephalography (EEG) is a measurement of the electrical activity of the brain. It can be useful in some cases to rule out other conditions.
  • Genetic testing for apolipoproteins is sometimes used in research studies of Alzheimer's disease risk, but it is of little if any value in confirming the diagnosis in individual patients. Other genetic tests are also not routinely done.
  • Spinal tap (lumbar puncture) is a method of obtaining a sample of cerebrospinal fluid. This may be done to rule out certain other brain conditions that can cause dementia.

What is the treatment for Alzheimers disease?

There is no cure for Alzheimer's disease. Treatment focuses on relieving and slowing down the progress of the symptoms, behavior changes, and complications.

An individual with AD should always be under medical care. Much of the day-to-day care, however, is handled by family caregivers. Medical care should focus on optimizing the individual's health, safety, and quality of life while helping family members cope with the many challenges of caring for a loved one with AD. Treatment most often consists of medications and nondrug treatments such as behavior therapy.

Living at Home with Alzheimer's Disease

Many individuals with Alzheimer's disease in the early and intermediate stages can live independently.

  • With regular checks by a local relative or friend, they can live for some time without constant supervision.
  • Those who have difficulty with activities of daily living require at least part-time help from a family caregiver or home health aide.
  • Visiting nurses can make sure that these individuals take their medications as directed.
  • Housekeeping help is available for those who cannot keep up with household chores.

Other affected individuals require closer supervision or more constant care.

  • Round-the-clock help in the home is available, but it is expensive and out of reach for many.
  • Individuals who require this level of care may need to move from their home to the home of a family caregiver or an assisted living facility.
  • These options give the individual the greatest possible independence and quality of life for as long as possible.

For those people who can remain at home or retain some degree of independent living, the surroundings must be familiar and safe.

  • The individual must be comfortable and safe if he or she is to continue to function independently.
  • Changes may be needed in the home to make it safer.
  • The balance between safety and independence must be assessed often. If the person's situation changes, changes in the living situations may be needed.

Individuals with Alzheimer's disease should remain physically, mentally, and socially active as long as they are able.

  • Daily physical exercise helps maximize body and mind functions and maintains a healthy weight. This can be as simple as a daily walk.
  • The individual should engage in as much mental activity as he or she can handle. It is believed that mental activity can slow the progression of the disease. Puzzles, games, reading, and safe hobbies and crafts are good choices. These activities should ideally be interactive. They should be of an appropriate level of difficulty that the person does not become overly frustrated.
  • Social interaction is stimulating and enjoyable for most people with early or intermediate stages of Alzheimer's disease. Most senior centers or community centers have scheduled activities that are suitable for those with dementia.

A balanced diet that includes low-fat protein foods and plenty of fruits and vegetables will help maintain a healthy weight and prevent malnutrition and constipation. An individual with ADD should not smoke, both for health and safety reasons.

What is the medical treatment for Alzheimers disease?

Even though Alzheimer's disease is not reversible, treatment can slow the progression of symptoms in some people. Relieving symptoms can improve function significantly. Some of the important treatment strategies in dementia are described here.

Nondrug Alzheimer's Disease Treatments

Behavior disorders such as agitation and aggression may improve with various interventions. Some interventions focus on helping the individual adjust or control his or her behavior. Others focus on helping caregivers and other family members change the person's behavior. These approaches sometimes work better when combined with drug treatment.

Alzheimer's Disease Drug Treatment

The symptoms of Alzheimer's disease can sometimes be relieved, at least temporarily, by medication. Many different types of medications have been or are being tried in dementia. The medications that have worked the best so far are the cholinesterase inhibitors.

  • Cholinesterase is an enzyme that breaks down a chemical in the brain called acetylcholine. Acetylcholine acts as an important messaging system in the brain. Brain acetylcholine level is low in most people with Alzheimer's disease.
  • Cholinesterase inhibitors, by stopping the breakdown of this neurotransmitter, increase the amount of acetylcholine in the brain and improve brain function.
  • These drugs not only improve or stabilize cognitive functions; they may also have positive effects on behavior and activities of daily living.
  • They are not a cure, but they do slow down the rate of decline in some people. In many people the effect is modest, and in others, the effect is not noticeable.
  • The effects are temporary since these drugs do not change the underlying cause of dementia.
Another drug, memantine (Namenda), is showing promise in Alzheimer's disease. This new drug works by blocking brain damage caused by another brain chemical called glutamate.

Certain drugs are being used on a trial basis in people with Alzheimer's disease. Experts think these drugs might help based on what we know from research about Alzheimer's disease. None of these drugs have yet achieved widespread acceptance as a treatment for the disease.
  • Anti-inflammatory drugs are being tried on the premise that inflammation is one cause of senile plaques and neurofibrillary tangles.
  • The antioxidant tocopherol (vitamin E) is believed by some to counteract damage in brain cells, which may have a role in causing Alzheimer's disease or its progression.
  • Hormone replacement therapy has been given to some women who have been through menopause and have Alzheimer's disease, but this approach has been questioned by many experts. The rationale is that the loss of estrogen at menopause takes away one line of protection from the disease.

Other drugs are used to treat specific symptoms or behavior changes.

  • Mood swings and emotional outbursts may improve with antidepressant or mood-stabilizing drugs.
  • Agitation, anger, and disruptive or psychotic behavior are often relieved by antipsychotic medication or mood stabilizers.

What are the medications for Alzheimers disease?

The cholinesterase inhibitors and memantine have been approved by the US Food and Drug Administration (FDA) specifically for Alzheimer's disease. The drugs listed here are some of the most frequently prescribed from each class.

All drugs cause side effects. The aim in prescribing a drug is that the benefits of the drug outweigh the side effects. Seniors are especially likely to experience drug side effects. People with dementia who are taking any of these drugs must be checked often to make sure that if side effects occur, they are tolerated and do not cause serious problems. These drugs may interact with each other or with other drugs. This is important in seniors, who often take several different drugs for various medical disorders. Side effects may be due not to one specific drug, but to combinations of drugs.

What is the follow-up for Alzheimers disease?

After a person has been diagnosed with Alzheimer's disease and treatment has begun, the individual will require regular checkups with his or her healthcare professional.

  • These checkups allow the healthcare professional to see how well treatment is working and make adjustments as necessary.
  • They allow the detection of new medical and behavior problems that could benefit from treatment.
  • These visits also give the family caregiver(s) an opportunity to discuss problems in the individual's care.

Eventually, the person with Alzheimer's disease will become unable to care for himself or herself, or even to make decisions about his or her care.

  • It is best for the person to discuss future care arrangements with family members as early as possible so that his or her wishes can be clarified and documented for the future.
  • Your health care provider can advise you about legal arrangements that should be made to ensure that these wishes are observed.

How do prevent Alzheimers disease?

There is no known way to prevent Alzheimer's disease. Being alert for symptoms and signs may allow earlier diagnosis and treatment. Appropriate treatment can slow or relieve symptoms and behavior problems in some people.

Some experts think that education and other forms of intellectual challenge may have a protective effect against the disease. Individuals with low levels of education and mental/intellectual activity are said to be at a higher risk for the disease and to be more likely to have more severe disease, but this has not been proven conclusively.

What is the prognosis for Alzheimers disease?

Alzheimer's disease starts slowly but finally results in severe brain damage. People with the disease gradually lose cognitive functions, the ability to carry out activities of daily living, and the ability to respond appropriately to their surroundings. They eventually become completely dependent on others for care. These losses are inevitable, but the speed with which they occur varies from person to person and maybe slowed down by treatment.

Alzheimer's disease is considered to be a terminal disease. The actual cause of death usually is a physical illness such as pneumonia. Such illnesses can be debilitating in a person who is already weakened by the effects of aging and the disease. On average, a person with Alzheimer's disease will live 8-10 years after the disease is diagnosed. Some people live for as long as 20 years with good nursing care.

Alzheimers Disease Support Groups and Counseling

If you are a caregiver for a person with Alzheimer's disease, you know that the disease tends to be more stressful for the family members than for the affected person. Caring for a person with Alzheimer's disease can be very difficult. It affects every aspect of your life, including family relationships, work, financial status, social life, and physical and mental health. You may feel unable to cope with the demands of caring for a dependent, difficult relative. Besides the sadness of seeing the effects of your loved one's disease, you may feel frustrated, overwhelmed, resentful, and angry. These feelings may in turn leave you feeling guilty, ashamed, and anxious. Depression is not uncommon but usually gets better with treatment.

Caregivers have different thresholds for tolerating these challenges. For many caregivers, just "venting" or talking about the frustrations of caregiving can be enormously helpful. Others need more but may feel uneasy about asking for the help they need. One thing is certain, though: if the caregiver is given no relief, he or she can burn out, develop his or her own mental and physical problems, and become unable to care for the person with Alzheimer's disease.

This is why support groups were invented. Support groups are groups of people who have lived through the same difficult experiences and want to help themselves and others by sharing coping strategies. Mental health professionals strongly recommend that family caregivers take part in support groups. Support groups serve a number of different purposes for a person living with the extreme stress of being a caregiver for a person with Alzheimer's disease:

  • The group allows the person to express his or her true feelings in an accepting, nonjudgmental atmosphere.
  • The group's shared experiences allow the caregiver to feel less alone and isolated.
  • The group can offer fresh ideas for coping with specific problems.
  • The group can introduce the caregiver to resources that may be able to provide some relief.
  • The group can give the caregiver the strength he or she needs to ask for help.

Support groups meet in person, on the telephone, or on the Internet. To find a support group that works for you, contact the following organizations. You can also ask your health care provider or behavior therapist, or go on the Internet. If you do not have access to the Internet, go to the public library.

For more information about support groups, contact these agencies:

  • Family Caregiver Alliance, National Center on Caregiving - (800) 445-8106
  • Alzheimer's Association - (800) 272-3900
  • National Alliance for Caregiving
  • Eldercare Locator Service - (800) 677-1116

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  • In the early stage (pre-clinical), symptoms of Alzheimer's disease are subtle. The main symptom is memory loss.
  • In the middle, or intermediate, stage (mild cognitive impairment), individuals begin to lose their ability to think and reason clearly, judge situations, communicate, understand new information, and take care of themselves.
  • As the disease progresses to the late stage (Alzheimer's' disease), individuals may experience changes in personality and behavior, anxiety, agitation, disorientation, paranoia, severe memory loss, loss of mobility, delusions, and hallucinations.
Reviewed on 11/23/2021
Medically reviewed by Joseph Carcione, DO; American board of Psychiatry and Neurology


"Epidemiology, pathology, and pathogenesis of Alzheimer disease"