What Is a Biological Mechanism for Dementia?

2 Comments

1. the crusader says:

   January 29, 2010 at 5:09 am

   When they ask for the biological mechanism for dementia, they are asking what is the biological cause of dementia.

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2. drakkina says:

   January 29, 2010 at 10:24 pm

   Honestly, that’s not an easy question to answer in a sentence or two.  Basically, a biological mechanism is a system by which a living organism modifies, changes, etc. itself and its environment.  I think it’s easier to grasp the concept by example.  There are “mechanisms” other than biological.  An abiotic system is free of biological organisms and abiotic transformations are accomplished, naturally, through non-biologic mechanisms.  For example, the modification of water from a liquid to a gasseous state by the application of heat is a result of an abiotic mechanism.  Another good example involves oil spill clean-ups.  There are a variety of methods used to clean oil from the water and shoreline.  One way is through the use of solvents and detergents. I’m familiar with one particular product that is a solution of diluted acids, water and sodium silicate that chemically reacts with hydrocarbon molecules and binds them into a solid silica matrix.  That would be an example of clean-up through the use of a chemical mechanism.  However, oil can also be removed by boremediation.  Boremediation is the use of certain bacteria (some laboratory-created) and fungi that sustain themselves on hydrocarbon.  When introduced, these living organisms “eat” the oil, producing modification/change of their environment.  That is an example of a biological mechanism.  So, essentially, you wil be focusing on the biological causes of dementia, whether the cause is viral, bacterial or prion-based.  I can think of a few…..symptoms of dementia can be seen in certain conditions caused by viruses.  Examples would be HIV-induced dementia, viral meningitis, viral encephalitis and PML, or progressive multi-focal leukoencephalopathy.  Both viral meningitis and encephaltitis can be caused by several types of viruses, while PML is caused by polyomavirus.  The HIV virus is able to pentrate the blood/brain barrier and infect the tissue directly.  Bacterial causes of dementia include Lyme disease (spriochete Borrelia burgdorferi), neurosyphilis (3rd stage of disease – caused by bacterium treponema pallidum).  Some persons would argue that dementia induced by prions should be classified as a biological mechanism.  Prions, or proteinaceous infectious particles are protein inside the body that becomes infectious.  The prion enters brain cell and converts the normal protein within that cell to a prion.  Prions are exactly the same as normal proteins, except that they do not fold normally – the helical structure of the amino acids, which is normally thighly wound, loosens up.  The priors completely clog the infected brain cell and it dies, releasing all the prions, which subsequently attack adjacent cells.    Eventually, the destruction of all of the brain cells creates holes in the brain tissue.  The problem with prions is that, like viruses, they are not similar to other living organisms and some believe that prions in fact, are not “alive” (many also argue that viruses are not “alive” by the usual definition of the word, as they have no basic metabolic activity and are incapable of procreation, eating and excreting).  However, I noticed that the EPA, after debate and scientific study, declared prions to be a “pest” under the current law, with “pest” defined as a form of animal life injurious to health.  So, it can be argued a biological mechanism for dementia are the actions of viruses and prions. 
   I hope that helped a little