Early Onset Alzheimers: Who Gets It?

Tragically, in 2006, Alzheimer's disease was the sixth leading cause of death. Every 70 seconds someone gets Alzheimers. It's estimated 5.3 million people have Alzheimer's disease. Approximately, one in eight people 65 and over have late onset Alzheimers while 5% to 10% or approximately 200,000 are diagnosed with early onset Alzheimer's disease. The most common cause of dementia, Alzheimers is a progressive disease beginning with forgetfulness and misplaced items and ending with death.

Early Alzheimers has the same symptoms and stages as the late onset form of the disease. The only difference is the age it strikes. While late onset Alzheimer's disease usually strikes at 65 years of age or beyond, the early onset form of the disease most commonly strikes people in their fifties. However, it can occur in the thirties and forties too.

Approximately, 25% of all Alzheimer's cases is familial or genetic. To be considered familial in nature, two or more persons in a family has Alzheimers. Of this 25%, 15% to 25% is the last onset familial type of the disease while less than 2% is the early onset familial type. In approximately, 75% of the cases the causes of Alzheimer's disease are unknown. These unknown cases could be genetic, environmental, or a combination of the two.

Although both types of Alzheimers can be genetic in nature, they are caused by different genes. Late onset Alzheimers can be caused by four different types of APOE genes. However, not all people with Alzheimers have one of these genes, and not all people who have one of these genes gets Alzheimers. Approximately, 42% of those with Alzheimers, do not have the APOE gene.

One of the gene mutations, APOE-e-4 causes a protien to be made that carries cholesterol in the blood. The APOE-e-4 is present in 15% of the Caucasion race and occurs even more frequently in those with African descent. If you inherit one of these genes, there is a three-fold risk of inheriting Alzheimers,5 and if you inherit two of these genes, there is a 12 to 15 fold risk of inheriting Alzheimers. Accordingly, everyone inherits one type of APOE gene from each of their parents. However, those who inherit one APOE-e-4 gene from their parents have a higher risk for Alzheimers, and those who inherit two APOE-e-4 genes have even a greater risk. In addition to the APOE genes, there are other genes which may be responsible for the development of Alzheimers. These genes are: SORL1, A2M, GST01, GAB2, and CALHM1.

Unlike late onset Alzheimer's disease, the genes that cause early onset Alzheimers are different. These genes are presenilin 1 (PS1), presenilin 2 (PS2), and an amyloid precursor protien (APP). A mutation in one these genes passed on by a parent can cause early Alzheimers. There is a strong, genetic tendency for early Alzheimer's disease to run in families.

The PS1 gene has over 40 mutations. A mutation in the PS1 gene is the most common cause of early Alzheimers. This gene mutation accounts for almost half of early onset Alzheimer's cases. People with this gene mutation tend to get Alzheimer's disease at the earliest age. In addition to developing Alzheimers at an earlier age, they also tend to develop weakness in their legs and more pronounced changes in the brain.

An inherited APP gene mutation is the second most common cause of early Alzheimers. It accounts for 5% to 20% of early Alzheimer's cases. These people tend to develop Alzheimers around 50 years of age. There are at least six mutations in this gene. Beta amyloid protiens are partially responsible for the plaques in Alzheimers. This protien is a fragment of the amyloid precursor protien or APP.

The chances of getting Alzheimers from a mutation in the PS2 gene is very rare.Mutations of the PS2 gene have only been found in six families, five German families and one Italian family. Researchers have even found people with a mutated PS2 gene that did not get Alzheimer's disease. In those people who did get Alzheimer's from this gene, the length of the Alzheimer's disease tends to be longer, and the age of onset varies more within families.

Genetic testing is available to test for the presence of these genes.

The main cause of Alzheimers is plaques and tangles in the brain. Whereas plaques are deposits of beta amyloid protien in between nerve cells, tangles are deposits of tau protien within the nerve cells. Although most people have some plaques and tangles as they age, people with Alzheimers have a far greater number. Scientists do not fully understand what causes these deposits or how they destroy the brain cells. The cause of the abnormal accumulation of protien deposits could be due to a variety of factors. These factors could include genetic, environmental, and lifestyle choices. One theory about why the nerve cells die is the plaques and tangle disrupt the nerve's abilities to communicate and make it difficult for them to survive.

Early-onset and late-onset Alzheimer's disease follow the same progression and have the same symptoms. According to the Alzheimer's Association, there are ten warning signs to be aware of. These symptoms are:

• Memory loss that affects daily life
• Inability to plan or solve problems they were once able to do
• Completing tasks they once were able to do
• Disorientation about dates, times, or places
• Vision problems judging distance or determing color or contrast
• Misplacing things and being unable to retrace steps or misplacing things in unusual places
• Poor judgement in respect to financial matters, hygiene, etc.
• Withdrawal from hobbies, social activities, or work
• Changes in personality and mood

Although many people may experience these symptoms once in awhile, someone with Alzheimers experiences them with more frequency and intensity.

There are two different types of Alzheimers: early onset and late onset .Whether you have early onset or late onset is dependent on what kind of mutated gene a person inherits and other factors.  However, whereas early Alzheimers is usually genetic and runs in families, this is not necessarily so in late-onset Alzheimers. Regardless of what type of Alzheimers you get, they both have the same symptoms and stages. If you think you or a loved one has any of the symptoms Alzheimer's disease, ytou should set up an appointment with your medical provider.