Probable Cause of Alzheimer's Disease
The brains of people with Alzheimer's tend to show that nerve cells have become bunched together and knotted, a feature known simply as tangles. Around these cells tend to be clustered a kind of cellular debris known as plaques. Plaques are made up of dead cells and deposits of protein. In fact both tangles and plaques are protein-based.
The main protein component of tangles is called tau. In plaques, the main protein component is called beta-amyloid, which is produced from from a larger protein called beta-amyloid precursor protein. Ever since the discovery of these proteins researchers have been attempting to discover their role in the disease.
Various experiments involving the introduction of beta-amyloid precursor protein into the brains of mice have shown that both brain damage and memory impairment occurs. There is still a level of uncertainty about which of the various experimental approaches best mimics the effects of Alzheimer's in humans.
The importance of such research is vital if we are ever to discover the genetic mechanism that underpins Alzheimer's disease. Each experiment involves inserting new or modified genes into brain cells. It involves, for example, a painstaking process of knocking out specific genes and studying the effects, or varying the combinations of genes, or introducing various chemicals that might inhibit the development of certain proteins, and so on.
Great care has to be taken with any manipulation of genes. One research team found that knocking out a particular gene also had the effect of causing mice to overeat and become obese, even when given appetite-suppressant drugs. In another experiment mice became much more aggressive. Still, as animal models become more available they provide more and more knowledge. The next challenge will be to use these animal models to test and develop treatments for humans.
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