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What is Alzheimer's disease

Alzheimer's disease is a fatal, progressive and degenerative disease that destroys brain cells. It is the most common form of dementia, accounting for 64 per cent of all dementias in Canada.

Alzheimer's disease is not a normal part of aging. Symptoms include having difficulty remembering things, making decisions and performing everyday activities. These changes can affect the way a person feels and acts. There is currently no way to stop the disease, but research is improving the way we provide care and will continue to search for a  cure.

What’s the difference between Alzheimer’s Disease and dementia? If you have been confused by these terms in the past, or mistakenly thought that they were the same thing, watch the video:

The material was created by TCD, through the NEIL Programme at the Institute of Neuroscience with support from GENIO.

© 2014 The Provost, Fellows, Foundations Scholars, and the Other Members of Board, of the College of the Holy and Undivided Trinity Of Queen Elizabeth, near Dublin. Permission to use this material was granted by TCD which reserves all rights in the material.

What causes Alzheimer's disease?

We do not yet know what causes Alzheimer's disease but researchers have identified risk factors associated with it.

Aging

  • The most important risk factor is aging. A minimum age needs to be reached for Alzheimer's disease to develop.  People do not get the disease in their teenage years or even in their 20s. It is well-established that aging can impair the body's self-repair mechanisms. And of course, many of the risk factors increase with age, such as blood pressure, stress, and obesity.

Genetics

  • There is no doubt that genetics play a role in the disease. Yet only a small percentage of cases is associated with the specific genes that cause the inherited form of the disease. Risk genes increase the likelihood of developing a disease, but do not guarantee it will happen.

Other factors

  • Research is being done on other factors such as existing diseases or conditions that the person may have, infections, toxins in the environment, education level, alcohol and tobacco use, diet and exercise.

Are there treatments for symptoms of Alzheimer’s disease?

Several medications are now available to treat some symptoms of Alzheimer’s disease. These drugs are not a cure for the disease. They do not stop its progression. Ask your doctor if there is a treatment suitable for you.

Will my children get Alzheimer's disease?

The sporadic form of Alzheimer's disease (which used to be called "late onset Alzheimer's disease"), was formerly assumed to have no family linkages. We now know, however, that a person with a direct relative (parent or sibling) with Alzheimer's disease has a three times greater chance of developing the disease than someone who does not . The risk increases further if both parents have the disease. So aside from the FAD-related genes there are Alzheimer's disease-related genetic factors shared by family members.

A very small percentage of people have an inherited form of the disease. This rare form is called familial autosomal dominant (FAD) Alzheimer's disease. In certain families, it passes directly from one generation to another. Having more than one family member with Alzheimer's disease does not necessarily mean that your family has the inherited form.

Is there genetic testing for Alzheimer's disease?

Genetic testing for the disease is not widely available in Canada. It is usually limited to people with a strong family history of the disease who are enrolled in specific research studies. Some testing is also done on referral from a family physician. You cannot request genetic testing on behalf of another family member.

How does Alzheimer's disease progress?

Alzheimer's disease typically follows certain stages that cause changes in the person's and family's lives. Because the disease affects each individual differently, the symptoms, the order in which they appear and the duration of each stage vary from person to person. In most cases, the disease progresses slowly, and the symptoms of each stage may overlap, often making the move from one stage to another quite subtle. The duration of the disease is usually seven to ten years but may be much longer in some people.

What are related dementias?

  • Related dementias include vascular dementia, frontotemporal dementia (including Pick's disease), Creutzfeldt-Jakob disease and Lewy body dementia.
  • Each of the related dementias has unique aspects but all share common symptoms: gradual and ongoing decline of short- and long-term memory, changes in language abilities, mood and behaviour, judgment and reasoning, making it impossible over time to perform simple tasks.
  • Dementia eventually affects all aspects of a person's life, including how the person thinks, feels, acts and reacts to his environment.
  • Currently, there is no known cure for these diseases but studies show that lifestyle changes can help slow the progression of the disease.
  • Researchers are confident that within seven to ten years there will be treatments that target the disease process itself, not just the symptoms.
  • Dementia is commonly diagnosed in people 65 and older, but mounting evidence suggests it can begin to develop well before signs appear, as early as age 40.

As Alzheimer’s disease progresses and affects different areas of the brain, symptoms become more severe. The result is changes in abilities and/or behaviour. Once an ability is lost, it is not known to return, but research now suggests that some relearning may be possible.

Dr. Alois Alzheimer first identified the disease in 1906. He described the two hallmarks of the disease: "plaques," which are numerous tiny, dense deposits scattered throughout the brain that become toxic to brain cells at excessive levels, and "tangles," which interfere with vital processes, eventually choking off the living cells. When brain cells degenerate and die, the brain markedly shrinks in some regions.

The image below shows that a person with Alzheimer's disease has less brain tissue (right) than a person who does not have the disease (left). This shrinkage will continue over time, affecting how the brain functions.

MRI brain scan of Alzheimer's disease

MRI images courtesy of Sunnybrook and

Women's College Health Sciences Centre

Learning about the disease

[From the Shared Experiences: Suggestions for those with Alzheimer's disease booklet and audio files by the Alzheimer Society of Canada. To get a copy, contact your local Alzheimer Society.]

Learning what you can about Alzheimer's disease and how it progresses may help you adjust to the changes that you are experiencing. The changes are due to the disease; they are not your fault. Encourage your family members and friends to also learn about Alzheimer's disease. Your family doctor and the local Alzheimer Society are good sources of information.


Last Updated: 03/26/15
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