Alzheimer’s Disease (AD) is a chronic degenerative disease of the brain which leads to progressive dementia, which is the loss of the mental faculties of a person. Memory, personality, judgement and reasoning can get severely impaired. The development of AD has a strong genetic component, which may be complicated to understand, but I will try to simplify it here.
There is a gene called APOE. This gene encodes a protein called apolipoprotein E. There are 3 variants of the APOE gene (ε2, ε3, ε4). Each of us inherits 2 variants of the gene, so we all are either ε2/ε2, or ε2/ε3, or ε3/ε3, or ε3/ε4 or ε4/ε4 or ε2/ε4.
The combination ε4/ε4 has the highest possibility of AD. According to one study, at 85 years of age, people with this combination would have a possibility of 51-52% of developing the disease if male, and 60-68% if female. The combination with the lowest possibility is ε2/ε2, it has a 4-5% possibility of AD if male and 6-8% if female. All the other combinations are in between.
It is important to note that this gene is not the only one associated with AD. If you know your particular combination, it is best to consult a healthcare provider for proper advice.
Marco A. Ramos MD
Further reading here:: http://www.ncbi.nlm.nih.gov/pubmed?cmd=Search&term=9343467