Is it hereditary?
Alzheimer's disease is not usually hereditary. It is therefore not caused by the genes received from a person's parents. Even if several members of a family have in the past been diagnosed as having Alzheimer's disease, this does not mean that another member of the family will necessarily develop it, as the majority of cases of Alzheimer's disease are not genetic. However, as the disease is so common in the elderly, it is not unusual for two or more family members over the age of 65 to have it.
Whether or not there are other members of a family with Alzheimer's disease, everyone risks developing the disease at some time. However, it is now known that there is a gene, which can affect this risk. This gene is found on chromosome 19 and it is responsible for the production of a protein called apolipoprotein E (ApoE). There are three main types of this protein, one of which (ApoE4), although uncommon, makes it more likely that Alzheimer's disease will occur. However, it does not cause the disease, but merely increases the likelihood. For example, a person of 50, would have a 2 in 1,000 chance of developing Alzheimer's disease instead of the usual 1 in 1,000, but might never actually develop it. Only half of people with Alzheimer's disease have ApoE4 and not everyone with ApoE4 suffers from it.
Last Updated: Thursday 22 October 2009