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Alzheimer's disease: Overview

Created: ; Last Update: June 29, 2017; Next update: 2020.


Alzheimer's disease is the most common cause of dementia. It takes its name from the psychiatrist Alois Alzheimer, who in the early twentieth century was the first person to describe the disease. Over time, people who have Alzheimer’s lose their memory and ability to concentrate. Orientation in space and time become increasingly difficult, and it is also harder for them to manage on their own in everyday life. Those affected need more support as the disease progresses.

The course of Alzheimer’s can be positively influenced by a number of different medications and non-drug treatments – but it is not possible to cure the disease or to keep it from progressing. This makes it even more critical for people with Alzheimer’s to receive good care and support: They need loving and stable relationships and a tolerant environment. Many family members need help and assistance too.

There are other possible causes of dementia besides Alzheimer’s disease. These include problems with the flow of blood in the brain (vascular dementia). Some people – particularly older people – have both Alzheimer’s and vascular dementia. Medical conditions such as Parkinson’s disease, brain injuries or tumors can also cause dementia. Long-term heavy alcohol consumption may lead to dementia too.

There are similarities, but also differences, between the different forms of dementia: The symptoms, the course the disease takes, and the treatment options can all vary. This overview is only about Alzheimer’s.


Most people mainly associate Alzheimer’s disease with forgetfulness. But it can cause many different symptoms and develop in very different ways. How someone reacts to having Alzheimer’s and copes with the disease not only depends on the changes in their brain, but also on that individual’s personality, life experiences, current circumstances and relationships with other people.

Memory and cognitive ability

Most people’s memory and other cognitive abilities gradually get worse as they get older. No longer being able to react as quickly and flexibly to new situations is a natural part of aging. It often becomes harder to recognize and solve problems in new areas. But it is still possible to access the knowledge that has been gained over the years, and stay oriented, independent, and able to make sound judgments.

This is different in people who have Alzheimer’s disease. Their memory gradually fades away. At first, short-term memory is affected more. This means that they forget about events that have just happened, but can still remember experiences from long ago. But long-term memory also fades with time. The ability to concentrate is affected too, making it more and more difficult to maintain orientation in time and space.

It becomes harder to link things that were learned in the past to new situations or impressions. There comes a point when it is no longer possible to understand contexts or assess information, formulate an opinion and then decide what to do. For example, a person who has late-stage Alzheimer’s can see that it's raining outside, and can express this fact in words. But they will not be able to draw conclusions for their own actions. They may then go out to do their shopping in an undershirt instead of putting on a raincoat or taking an umbrella.

Activities that are made up of several steps (like shopping or cooking) become more and more difficult as someone’s memory, comprehension and planning skills start to fade. In early-stage Alzheimer’s, completing more complex business matters can be a problem. For instance, doing taxes may become an insurmountable challenge. Forgetfulness might not only mean forgetting things like what you wanted to buy or why you left the house, but can also make you more likely to get lost and have problems finding your way home again.

Speech and language

We all have to search for the right word or feel tongue-tied now and then. But forgetting individual words more and more frequently is a different matter. As dementia progresses, it becomes more difficult to remember the right words, and people use words or phrases that do not match the context instead. This makes it difficult for others to understand them. And people with dementia also forget the meaning of words and are then often no longer able to follow conversations. This makes it increasingly harder to communicate verbally.

Mental health and changes in behavior

Many people with Alzheimer’s go through noticeable changes in their behavior. Later on their personality may also change considerably. They can become unusually fearful, distrustful or passive, or may become aggressive as well. These changes can happen suddenly, and might cause fits of rage – or they may develop gradually, as with listlessness. Abnormal behavior like this may be related to the disease. But fear, passivity or aggression can sometimes be perfectly normal reactions to the circumstances of living with the disease: After all, a person who has Alzheimer’s keeps finding themselves in situations that are confusing and in which they behave “wrongly.”

Plus there is the shame and frustration of forgetting more and more, being wrong a lot of the time, and gradually losing your independence. Many people who have Alzheimer’s feel that others are being patronizing, and are worried about being seen only as a sick and needy person. A considerable number of people with Alzheimer’s have depression and trouble sleeping, too. They might also experience unusually euphoric phases.


In Alzheimer’s disease, more and more brain cells are lost as time goes by. It isn't clear why this happens. One thing that is known is that people with Alzheimer’s don't have enough of an important chemical messenger called acetylcholine in their brain. And it has also been shown that small protein particles (for example plaques) build up in their brain. These might cause the nerve cells to die.

But it is still not known what actually causes Alzheimer’s disease. Several factors probably play a role.

Risk factors

The risk of developing Alzheimer’s increases with age, starting at about 65. Many studies have looked at whether particular life circumstances, diseases or behaviors can increase or lower the risk of Alzheimer’s. Although research hasn't yet produced any clear answers, it does suggest that the following factors may play a role:

  • Diabetes
  • Depression
  • High cholesterol
  • Smoking
  • Little social contact

Potentially preventive factors include:

  • Good education
  • High levels of mental and physical activity
  • Good social network
  • A balanced diet including a lot of fruit and vegetables, legumes and nuts, olive oil and whole grains, more fish than meat, and moderate alcohol consumption

Research has shown that some people are more likely to develop Alzheimer’s than others. But just because there's a relationship between two things, it doesn't necessarily mean that one of them is causing the other. For example, if dementia is known to be more common in people who have a lower level of education, their level of education isn't necessarily the cause of their dementia. People who have a lower level of education might also live in less healthy environments – and that might be what increases their risk of Alzheimer’s disease.

The actual role of different circumstances and behaviors in the development of Alzheimer’s – and whether there are particular measures that can help prevent it – needs to be studied more closely.

Genetic risk

Not many genes are known to influence whether someone gets Alzheimer’s. In some families, several members already develop the disease in middle age. Genetic tests can be used to find out whether they have what is called early-onset Alzheimer’s. If they do, it is very likely that their siblings and children will also develop it.

There are other genetic factors that are often identified as being linked to Alzheimer’s, but they do not make it possible to predict who will develop the disease and who will not. One example is specific types of a gene called the APOE gene, which plays a role in breaking down cholesterol. Testing for these particular genes wouldn't be much help because many of the people who have them don't end up developing Alzheimer’s. So getting tested might give someone a scare for no good reason.

Genetic tests can often be misleading and have serious consequences for those involved. For this reason they should only be done at human genetics institutes where they are given carefully prepared information and consultation.


In Germany there are about 1.4 million people who have dementia. Most of them are women, mainly due to the fact that women tend to live longer than men. Dementia is mostly diagnosed in older people: About 2% of all 65 to 69-year-olds will develop it, compared to about 10% of all 80 to 84-year-olds. It is estimated that around 70% of people who have dementia have Alzheimer’s.


Alzheimer’s is a chronic disease that progresses over the course of many years. It typically begins after the age of 65. Alzheimer’s that starts at a younger age will usually progress faster than if it had developed later on.

Alzheimer’s disease has three stages, each of which has its own characteristic symptoms. But the changes that happen, and how fast they happen, can vary from person to person. Some symptoms may appear earlier, and others may not occur at all.

Early-stage Alzheimer's

In early-stage (mild) Alzheimer’s, people have a bit more trouble managing their lives on their own, but they can usually still lead independent lives. It's often difficult to tell the difference between early-stage symptoms and normal forgetfulness due to aging. There is no clear cut-off point between the normal problems associated with aging and mild Alzheimer's. But forgetfulness, absentmindedness and trouble concentrating mean that more complex everyday tasks are difficult to perform.

People who have early-stage Alzheimer’s will almost always need help with business and financial matters or official appointments. Driving and taking medication regularly are two other critical areas.

Behavior and mood can already change in early-stage Alzheimer’s. The limitations resulting from the disease can cause fear, stress, anger, or even feelings of shame: It can be embarrassing to forget things and lose your orientation. And it takes a lot of strength to find strategies to deal with these problems.

A person’s inner drive and interest in hobbies or other activities may fade. Some people feel down or irritable, or they may have intense mood swings. These mood swings – making people suddenly burst into tears for no apparent reason, for example – are often puzzling as well as draining for other family members.

Middle-stage Alzheimer's

People with middle-stage (moderate) Alzheimer’s usually have to give up living independently. They can still eat, drink and wash themselves, and perhaps do simple tasks around the home or garden, but may have to be reminded and asked to do so. Cooking, shopping, keeping their home clean, and going out on a walk are only possible with the help of others.

They are more likely to get lost, not find their way back home, leave the stove on and endanger themselves or others. Patterns of behavior such as frantic pacing, seemingly meaningless rummaging through drawers and fiddling with clothing become more frequent. Fits of rage, distrust and aggressive behavior are also consequences of problems associated with Alzheimer’s that affect the person’s perception and limit their abilities.

People’s daily sleep-wake cycle is often affected. It becomes more difficult for them to express things in words and understand what other people say. They also confuse the past with the present. For instance, they may falsely believe that their parents are still alive and are expecting them to come back home.

Late-stage Alzheimer's

In late-stage (severe) Alzheimer’s, people need constant help from others. Speech and language problems may start making conversation barely possible. They now even need help to accomplish simple everyday activities, and to eat and drink.

People who have late-stage Alzheimer’s are often restless, hallucinate or confuse the past with the present. They no longer recognize people who they used to know very well. The control of bodily functions and the ability to coordinate movement may also be lost.

On average, people with Alzheimer’s die about six years after being diagnosed. But many people also live with the disease a good deal longer.


It isn’t yet possible to diagnose Alzheimer’s with complete certainty using the currently available tests while the person is still alive. The disease is diagnosed if someone has the typical symptoms and no other cause can be found. Looking at the brain using imaging techniques like computed tomography (CT) or magnetic resonance imaging (MRI) is not enough to tell whether or not someone has Alzheimer’s disease.

Because symptoms like forgetfulness, changes in behavior and problems with orientation can have many different causes, it is important not to rush to a diagnosis of Alzheimer’s.

The symptoms might also be caused by depression or other physical conditions like meningitis, a stroke or bleeding in the brain. A fluid or vitamin deficiency, or side effects of medication, can sometimes also cause symptoms like these.

There are often good treatments for these things and the symptoms will then improve or disappear completely. Alzheimer’s is diagnosed only if symptoms have lasted for more than six months and any other causes are considered to be unlikely.

This means that comprehensive diagnostic tests are necessary. People generally go to their family doctor first. If it is thought that someone might have Alzheimer’s, specialists (neurologists, psychiatrists, radiologists) often work together. It can be helpful to have an appointment at hospital that specializes in memory problems, particularly when the disease is still in the early stages.

Talk with the doctor

The doctor will first ask about the person’s symptoms, problems in everyday life, and general life situation. They will also ask them about their mental state, for example about whether they experience mood swings or whether their emotional state has changed. Medication use, lifestyle, and physical and mental illnesses will also be discussed. It can be helpful for the person being diagnosed to bring someone along to the appointment for support. Relatives or friends often notice changes in behavior that the person affected by the disease doesn’t notice. Or the person may be too ashamed or embarrassed to talk about it.

Psychometric tests

Certain tests are done to get an idea of how far the disease has advanced and how it might progress. There are short tests where a trained specialist asks questions and gives the person short tasks testing their memory, judgment, speech and concentration. These tests usually last about 15 minutes.

Some of the commonly used tests include the mini-mental state examination (MMSE), the clock-drawing test and the dementia detection test (DemTecT). These tests can give an indication of how limiting the disease has become. To get a more exact diagnosis, though, neuropsychological testing is often needed. This is more extensive.

Medical tests

There are a number of tests that can help show whether other diseases or conditions are possibly causing or influencing the symptoms. These include a physical examination, blood tests or imaging techniques like computed tomography or magnetic resonance imaging (MRI). A lumbar puncture may also be done to take a sample of cerebrospinal fluid.


People who have Alzheimer’s need long-term help and treatment. Depending on their needs, their life situation and the stage of disease, a whole team of people may be involved in providing care. These could include trained doctors, psychologists, nurses and social workers, as well as volunteers. Both treatment with medications and non-drug interventions aim to

  • increase quality of life,
  • keep the ability to do everyday tasks and stay independent for as long as possible,
  • reduce mental health problems, and
  • help family members to cope better.

The most common medications used to treat Alzheimer’s disease include cholinesterase inhibitors, memantine and extracts from the leaves of the Ginkgo biloba tree.

Examples of non-drug treatments include memory and orientation training, doing everyday activities as a group, or art therapy, aromatherapy, and animal-assisted or music therapy. Physical activities and massages can help too. Caregiver training for family members is important too.

Everyday life

The diagnosis “Alzheimer's” usually comes as a shock, and has a life-altering effect. Sometimes the diagnosis makes it easier to understand previously inexplicable changes in behavior or personality.

Every person who develops Alzheimer’s experiences their situation differently, and copes with it differently. Some people are able to accept the disease and to go on living an active and satisfying life for as long as possible despite having Alzheimer’s. Others have a harder time. They may become withdrawn, and are often sad or depressed. Still others will try to ignore the disease and its symptoms.

Especially right after they hear the diagnosis, many people feel torn between the desire for independence and the need for security and support. Most people who have Alzheimer’s disease do realize that they will need help at some point. But only very few will find it easy to come to terms with the gradual loss of their abilities and accept the support they need.

On the one hand, most people who have been diagnosed with Alzheimer’s think it is important to live in the present and to enjoy doing what they can still do. On the other hand, many people are worried about the future and may wonder how to go about planning the rest of their life. There are suddenly new concerns to confront: Can I carry on working, and if so, for how much longer? Who should make my decisions for me when I no longer can? How long will I still be able to drive a car or live on my own? What will I do when I need to be cared for?

Over time, many people manage to deal with these kinds of questions and conflicts, and come to accept life with Alzheimer’s. An important part of that is the support they receive from others, and especially from their family. But the disease will also affect relationships with family members and friends.

It becomes more difficult to pursue common interests. Many of the roles and responsibilities shared by family members or couples will need to be reorganized. For example, if a woman who has always kept track of the couple’s finances is no longer able to do so, her husband would have to take on this responsibility instead.

Some people say that the emotional warmth and closeness within the family increased after they were diagnosed with Alzheimer’s. Some couples feel like a team that has to stick together, now more than ever. But there may still be tension and conflicts over the course of the disease. Many family members who care for someone with Alzheimer’s find it hard to cope with, and may need support themselves after a while.

A lot of people with Alzheimer’s disease benefit from dealing openly with their condition and are met with understanding and support. Humor may also be a good way to deal with the disease in certain situations. But unpleasant experiences, such as failing at something or getting negative reactions from other people, can’t be avoided.

Sharing experiences with others affected by the disease, for example in a self-help group, is often considered to be helpful. It’s important to stay active and keep up hobbies such as singing, hiking, cooking and painting. It is still possible to do many of these activities for a long time despite Alzheimer’s. Activities also help to keep someone’s mind off their disease.

There will be many decisions to be made eventually: about everyday practicalities, but also about treatments, planning ahead, care at later stages of the disease, and the most suitable place to live (at home, in a nursing home or in group living). People who have Alzheimer's are now making it increasingly clear that they would like to be involved in these decisions. They would like to play an active role in the decisions that affect them and their concerns for as long as possible. They want people to talk with them, not just about them.

Further information

As Alzheimer’s progresses, people with this disease gradually lose their independence. They not only become dependent on others for care, but also when it comes to making decisions that will affect their life.

This can make it even more important to make arrangements for the time when it‘s no longer possible to make independent decisions. Appointing a health care power of attorney (POA) will make it clear who will be responsible for doing that later on, and the conditions under which it will take effect can also be stipulated. An advance health care directive can also be used to determine whether and which life-sustaining measures should be taken if the person becomes severely ill.

Psychological care, nursing care and support for family members who provide care become more and more important as Alzheimer’s progresses.

Many cities in Germany offer assistance for people with Alzheimer’s in everyday life or help for caregiving family members. This includes services providing daytime care, training courses on how to care for people with Alzheimer’s, as well as self-help groups for family members. The main caregiver also has a legal right to request additional care if they get ill themselves or need some time off.

Many cities across Germany have care support centers [in German: Pflegestützpunkte] which can be contacted for information on nursing care insurance, outpatient care and other support services available in the local area.

The German Federal Ministry of Health also offers information on nursing care.


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Bookshelf ID: NBK279360


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