Alzheimer's disease is a progressive, degenerative disease. Several changes occur in the brains of people with Alzheimer's disease. The brain cells shrink or disappear, and are replaced by dense, irregularly-shaped spots, or plaques. Another indicator of the disease is thread-like tangles within existing brain cells. These tangles eventually choke healthy brain cells.

As the image below shows, 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.

As Alzheimer's disease affects each area of the brain, certain functions or abilities are lost. This results in specific symptoms or changes in behaviour. It is important to remember that once an ability is lost it can rarely be relearned.

Although the disease results in changes, it does not affect the person's ability to appreciate, respond to and experience feelings such as joy, anger, fear, love or sadness.

While it is not possible to restore function to brain cells damaged by Alzheimer's disease, there are treatments and strategies that can help both the person with the disease and the caregiver.

Forms of Alzheimer's Disease

Sporadic Alzheimer's disease is the more common form of the disease and accounts for 90 to95 per cent of all cases. The role of heredity in this form is unclear and is the subject of much research.

Familial Autosomal Dominant Alzheimer's disease is a less common form of the disease and accounts for 5 to 10 per cent of known cases. In certain families, this form is passed directly from one generation to another.

Further Information

• National website 
• 2009 statistics about Alzheimer's disease and other dementias
• Diagnosis
• 10 Warning Signs
• Causes of Alzheimer's Disease
• Getting the Most From a Visit to Your Doctor (pdf)
• Just 4 Kids: Alzheimer Society of Saskatchewan