The causes of alzheimer's disease
The causes of
Alzheimer’s disease are not fully known and scientists continue to investigate this area. So far, research into the causes of this
brain disease has found two main forms of neural damage or abnormalities that can be linked to the disease and its progression.
Genetic studies have shed new light on possible causes of Alzheimer's disease, but these must be researched further.
Aluminium and
zinc as causes were the topics of controversial studies and are discussed in less detail.
Tangled nerve cell fibres (neurofibrillary tangles)
Microscopic study of the brain of a person who has died from
Alzheimer’s disease reveals tangled nerve cell fibres in certain areas of the brain. (Nerve cell fibres are typically found inside nerve cells.) As the nerve fibres become tangled, protein deposits called plaques build up in the affected tissue. A
protein called tau is found in the tangles. Scientists are not sure how these neurofibrillary tangles are formed, but they are characteristic of the condition.
Senile or neuritic plaques
These patches are situated outside the nerve cells and are surrounded by dying
neurons (nerve cells). The plaques contain a sticky protein,
beta amyloid, which cause malfunctioning of
nerve cells that eventually results in death of these cells. The plaques are made of
amyloid precursor protein (APP) molecules, which are usually essential components of the brain. Plaques are formed when an enzyme takes APP apart at a specific location and leaves the fragments (beta amyloid) in brain tissue, where they deposit abnormally. The presence of neuritic plaques may be linked to a reduction in
acetylcholine, an important chemical that is instrumental in relaying messages in the
brain.
Genetics
The association between
Down syndrome and
Alzheimer's disease has led scientists to look for genetic factors on chromosome 21, the chromosome involved in Down syndrome.
Chromosomes are found in each cell
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