What are Factors Causing the Late Onset Alzheimer's Diseases?- Alzheimer’s 07

The cartoon above is an illustration about a relationship of Brain and Heart that I pulled from the awkwardyetidotcom.

In previous posts, several signs of the early onset Alzheimer's dementia had been covered. Now, it is about the late onset, the symptoms appear when a person in the mid 60s and later of age.

The exactly causes of late onset are remaining unknown. The scientists believe the cause could be a combination of three factors:

- life style

- environment

- genetic.

Genetic markers related to the late onset form of Alzheimer's disease is associated with chromosome 19.

The mutation genes that cause increase Apoliprotein E (APOE). A person who inherit one copy of the APOE e4 has a big chance for developing this disease.

APOE primarily produced by liver and macrophages, and APOE4 is associated with hyperlipidaemia and hypercholesterolemia.

Generally, the APOE is associated with various conditions of disease progression, not only Alzheimer's Disease, but also:

- Multiple Sclerosis

- Parkinson's Disease

- Vascular Dementia

- Type 2 Diabetes Melitus

- Ischemia Stroke

- Type III Hyperlipoproteinemia. 

Astrocyte (Neuroscience, Purves et al).

In our brain, APOE is mainly produced by astrocyte

In the late onset Alzheimer's disease, there are three type APOEs:

- APOE2 is associated with reduced risk of Alzheimer's

- APOE3 the most common variant and is considered neutral

- APOE4 is associated with a greater risk.

The function of APOE is to regulate lipid transport from one cell type or tissue to another.

In our brain, APOE is mainly produced by astrocyte and its function is to transport cholesterol to our nerve cell (neuron) in the brain.

Whenever an imbalance between the production and clearance of beta-amyloid peptide in our brain, thus, the accumulation and aggregation of beta-amyloid will be occurred. This become a toxic in our brain.

This toxicity also depend on the paired helical filaments of the microtubuli-associated protein tau.

So, in the late onset Alzheimer's disease, the toxic in the brain destroy the nice balancing of healthy brain, prominently the two proteins which are called beta-amyloid and tau.