Early Onset, Late Onset And Hereditary Alzheimer’s

caring for an altzheimers patient

This is a guest post by Janet McArthur.

Alzheimer’s dementia is a debilitating condition from which currently 5.2 million Americans suffer. It is a degenerative illness and once it develops its progress cannot be stopped. There has been much research carried out in the recent years, not only to find more effective treatments for Alzheimer’s, but also to understand the genetic links to the condition. Understanding the genetic dimension of the disease can in itself, help pharmaceutical companies develop more effective treatments than the ones which currently exist.

The three types of Alzheimer’s disease:

Early onset: When we talk about early onset of Alzheimer’s, we refer to the disease manifesting itself before age 65. This type of Alzheimer’s is very uncommon however and occurs in only around 10% of all cases.

The early onset of Alzheimer’s is linked to different genes. If a parent has suffered from the disease, their child has a 50% chance of developing it as well. Three genes have been identified in this case: Amyloid precursor protein (APP), Presenilin 1 (PSEN1) and Presenilin 2 (PSEN2). Any mutations of these genes results in the production of an amino acid combination known as amyloid-beta peptide. The peptides accumulate in the brain in much the same way as plaque on unwashed teeth. This cumulative effect of toxic peptides causes brain cells to die which results in Alzheimer’s.

Late onset: 90% of all cases of this disease are late onset Alzheimer’s. 50% of all people over the age of 85 are likely to suffer from the condition. Late onset Alzheimer’s may or may not be hereditary.

The late onset of Alzheimer’s has been linked to the APOE gene on chromosome 19. Inheriting one particular variant of this gene leads to an elevated risk of late onset Alzheimer’s. It should be noted that we all inherit one of the 3 known APOE genes from our parents. However, it is the APOE 4 variant that is linked to this type of dementia. Having the APOE2 gene seems to mitigate the risk whilst having the APOE1 gene does not seem to have any effect at all.

Familial Alzheimer’s: Scientific testing of certain genes and analysis of certain DNA sequences has shown that genetics and heredity play an important role in the development of Alzheimer’s. People who have had a relative suffer from the condition are in fact more likely to develop the condition themselves. If more than one blood relative has had the condition, the risk increases even further.

Inheriting one copy from just one parent or a copy from each parent of APOE4 (apolipoprotein E-e4) heavily determines whether or not you will develop this type of dementia. This said some individuals having this gene actually never develop the condition. This is an aspect of the gene that has baffled scientists and suggests, perhaps, that some environmental factor could be responsible for activating the gene. Further to this, there have been countless cases of people who do not inherit the APOE4 but still develop the illness.

Scientists have also found a number of other genes which seem to play a role in the development of Alzheimer’s. Studies are still ongoing.


Unfortunately, there is no true cure for the condition but there are many medications that are very effective in reducing the symptoms and managing the disease. The downside to these drugs is that they do not work for everyone. An Alzheimer’s sufferer may have to experiment with different drugs till he or she finds the one that is most effective in alleviating their symptoms. The type of drug prescribed depends on the stage of the disease and how much it has progressed. How advanced the disease is will be determined by assessing the sufferer’s cognitive abilities, problem solving skills and sense of time. When Alzheimer’s dementia reaches its advanced stages, medication may be stopped altogether. In some cases, no drug will work. However, there are other ways of managing the disease other than using medication.

A neurologist can suggest a number of strategic thinking problems and exercises that can help stimulate the mind of the Alzheimer’s sufferer.

Author Bio: Janet McArthur is a retired business woman who worked as a financial consultant for a leading pharmaceutical company.  Janet works as an author in her free time writing about age related conditions and medicines. A range of articles on a diversity of topics by the same author can be found by clicking here.

Photo credit: Caring for an Altzheimer’s patient image courtesy of Rosie O’Beirne via photopin cc

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