Alzheimer's disease
What is Alzheimer’s disease?
Alzheimer’s disease is a physical condition which attacks the brain resulting in impaired memory, thinking and behaviour.
It is named after Alois Alzheimer, the German physician who, in 1907, first described it.
As brain cells shrink or disappear abnormal material builds up as “tangles” in the centre of the brain cells, and “plaques” outside the brain cells. These disrupt messages within the brain, damaging connections between brain cells. The brain cells eventually die and this means that information cannot be recalled. As Alzheimer’s disease affects each area of the brain, certain functions or abilities are lost. Memory of recent events is the first to be affected, but as the disease progresses, long-term memory is also lost. The disease also affects many of the brain’s other functions and consequently many other aspects of behaviour are affected.
Once an ability is lost it can be rarely regained or relearned.
Forms of Alzheimer’s disease
There are two different types of Alzheimer’s disease:
- Sporadic Alzheimer’s disease can affect adults at any age, but usually occurs after age 65. This is by far the most common form of Alzheimer’s disease and affects people who may or may not have a family history of the disease. Direct inheritance of sporadic late onset Alzheimer’s disease does not seem to occur. However, it is possible that some people may inherit a greater or lesser likelihood than others to develop the disease later in life. Only one gene, ApoE14, carried by 25% of the Australian population, is known to be associated with a somewhat increased risk of late onset Alzheimer’s disease. Even so, half the people who carry that gene who live to be 85 do not have Alzheimer’s disease at that age. Researchers are trying to find other risk factor genes and environmental factors that might make Alzheimer’s disease more or less likely, but to date the only clear risk factor for developing the condition appears to be a history of a severe head injury in earlier life.
- Familial Alzheimer’s disease is a less common form in which the disease is passed directly from one generation to another. If a parent has a mutated gene, each child will have a 50% chance of inheriting it. The presence of the gene means that the person will eventually develop Alzheimer’s disease, usually in their 40s or 50s. This type of Alzheimer’s disease affects a very small number of people in Australia.
What are the symptoms?
In the early stages, the symptoms of Alzheimer’s disease can be very subtle. However, it often begins with lapses in memory and difficulty in finding the right words for everyday objects.
Other symptoms may include:
- Persistent and frequent memory difficulties, especially of recent events
- Vagueness in everyday conversation
- Apparent loss of enthusiasm for previously enjoyed activities
- Taking longer to do routine tasks
- Forgetting well-known people or places
- Inability to process questions and instructions
- Deterioration of social skills
- Emotional unpredictability
Symptoms vary and the disease progresses at a different pace according to the individual and the areas of the brain affected. A person’s abilities may fluctuate from day-to-day, or even within the one day, and can become worse in times of stress, fatigue or ill-health.
However, there is always deterioration over time. Alzheimer’s disease is progressive and degenerative, and is currently irreversible.
What causes Alzheimer’s disease?
Researchers are rapidly learning more about the chemical changes that damage brain cells in Alzheimer’s disease, but apart from the few individuals with Familial Alzheimer’s disease, it is not known why one individual gets Alzheimer’s disease and another does not.
A variety of suspected causes are being investigated, including factors in the environment, biochemical disturbances and immune processes. The cause may vary from person to person and may be due to one factor or a number of factors.
Who gets Alzheimer’s disease?
Any person can develop Alzheimer’s disease, but it is much more common after the age of 65 years. The prevalence rate for dementia rises with age. For females aged 65 to 69 years dementia affects 1 person in 80 compared to 1 person in 60 for males. For both males and females aged 85 and over the rate is approximately 1 person in 4.
How is Alzheimer’s disease diagnosed?
Currently there is no single test to identify Alzheimer’s disease. The diagnosis is made after careful clinical consultation. The clinical diagnosis might include a detailed medical history, a thorough physical and neurological examination, a test of intellectual function, a psychiatric assessment, a neuropsychological test and perhaps blood and urine tests.
These tests will help to eliminate other conditions with similar symptoms such as nutritional deficiencies or depression. After eliminating other causes, a clinical diagnosis of Alzheimer’s disease can be made with about 80% to 90% accuracy. The diagnosis can only be confirmed after death by examination of the brain tissue.
It is important to have an early and accurate diagnosis to determine whether the condition is caused by Alzheimer’s disease or whether a different, rarer condition requiring its own specific treatment is causing the symptoms.
How does Alzheimer’s disease progress?
The rate of progression varies from person to person. However the disease does lead eventually to complete dependence and finally death. A person may live from three to twenty years with Alzheimer’s disease, with the average being seven to ten years.
Is there treatment available?
At present there is no cure for Alzheimer’s disease. However some drugs appear to be providing some stabilisation in cognitive functioning for some people with mild to moderate Alzheimer’s disease.
Drugs may also be prescribed for secondary symptoms such as restlessness or depression, or to help a person with Alzheimer’s disease sleep better.
Support is available for the person with Alzheimer’s disease, their families and carers. This support can make a positive difference to managing the condition. Alzheimer’s Australia provides support, information, education and counselling for people affected by dementia. Up-to-date information about drug treatments is also available from Alzheimer’s Australia.
Last Reviewed: 01 July 2005
