No one has really figured out the exact cause of Alzheimer’s disease. It is speculated after studies on the subject that it exists because of genetic factors among others. Genetic research of Alzheimer’s disease right now is focused on heredity factor in the process – how qualities and illnesses transfer from the parent to the children – and the role it plays in determining the risk of Alzheimer’s disease and it’s development.

The huge number of cases that may be considered for study are quite spread out in the sense that all of them are not known to genetically inherited. A mere 0.1 per cent of these cases are there because of familial forms of autosomal-dominant inheritance – something that sets in before 65 years of age.

Cases of Alzheimer’s disease caused by autosomal-dominant inheritance can be traced to three root causes – amyloid precursor protein (APP), presenilins 1 or presenilins 2. All these three contribute to an increase in the manufacture of Aβ42 which is the main constituent of senile plates. Some mutations only change the Aβ40 levels thus increasing the difference between its levels and the Aβ42 levels. This will lead to the disease caused even if the amount of Aβ produced is lessened. This also shows that presenilin has a further role to play in the occurrence of Alzheimer’s disease apart from just contributing to the production of Aβ – this in cases like changes in the role of APP and its other fragments.

A large number of cases though of Alzheimer’s disease do not have autosomal-dominant inheritance causes. They are called sporadic Alzheimer’s disease. Despite this, genetic factors do have a strong influence on them as risk factors. One of the best examples is ε4 allele of the apolipoprotein E (APOE). The number of patients with APOE allele is anywhere between 40 and 80 percent. This makes the chances of disease attacking heterozygotes thrice more and five times that much in homozygotes.

It is also in unanimous agreement that researchers say that there are other genes that actually protect the body from Alzheimer’s disease. There are genes – 400 in number – that have proved to have no effect at all when associated with late-onset sporadic Alzheimer’s disease.

So finally in conclusion we can say that if Alzheimer’s disease is seen early and is seen frequently enough in a family that it can be easily given the tag: Early-onset familial Alzheimer’s disease. Some researchers are of the opinion that the gene solution to Alzheimer’s disease is over while some still think that there are a lot more to be found. But one of the problems that a solution has to be found for is the manner by which nerves convert sugar (glucose) and make it energy. The whole process is called glucose metabolism.This among other conditions that ought to exist alongside Alzheimer’s disease