Forms Of

Researchers have identified two forms of Alzheimer's disease: Sporadic Alzheimer's Disease and Familial Autosomal Dominant Alzheimer's Disease (FAD).

Sporadic Alzheimer's Disease may or may not be inherited, but FAD is clearly passed on from generation to generation.

In addition, research shows that people with a family history of Alzheimer's disease (for example, an affected parent or sibling) have a greater chance of developing the disease when compared to people with no affected relatives.

However, it can be very difficult to determine the exact chance or risk of a person developing Alzheimer's disease.

Separating the role of genes from other factors, such as toxic agents, viruses and head injuries, is difficult. It may well be that in most families an inherited susceptibility and a particular "trigger" are both required before an individual develops the disease.

• People with this form may or may not have a family history of the disease.
• Children of someone with Sporadic Alzheimer’s Disease have a higher risk of developing the disease, when compared to people with no family history of the disease.
• Advancing age and a family history of the disease are two known risk factors that may increase a person’s chance of developing Alzheimer’s disease.
• Scientists are studying other risk factors such as education levels, head injury, Down syndrome and environmental factors.
• At present, there is no reliable test to determine if a person will develop Sporadic Alzheimer’s Disease.
• The role of heredity in this form of Alzheimer’s disease is not clearly understood and continues to be the subject of much research.

Familial Autosomal Dominant Alzheimer’s Disease (FAD)

FAD is a rare form of the disease and makes up five to ten percent of all cases of Alzheimer’s disease

• In certain families it is passed from generation due to a dominant inheritance pattern. If a parent has the mutated gene, each child has a 50 percent chance of inheriting it. The presence of the gene means the individual will eventually develop Alzheimer’s disease.
• A genetic risk assessment can identify genetic risk factors that may increase an unaffected person’s chance of developing Alzheimer’s disease.
• The presence of more than one family member with Alzheimer’s disease does not necessarily indicate one of the strongly-inherited forms of the disease.
• Researchers are exploring the ethical implications of genetic testing. If genetic assessment or testing is done, the person should give informed consent, receive conselling and be guaranteed confidentiality.