Neurodegenerative disease

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Neurodegenerative disease (Greek νέυρο-, néuro-, "nerval" and Latin dēgenerāre, "to decline" or "to worsen") is a condition in which cells of the brain and spinal cord are lost. Aside from a small number of neural stem cells that are created daily, cells of the brain and spinal cord are not readily regenerated en mass, so excessive damage can be devastating. Neurodegenerative diseases result from deterioration of neurons which over time will lead to neurodegeneration and disabilities resulting from this. They are crudely divided into two groups according to phenotypic effects, although these are not mutually exclusive:

conditions causing problems with movements
conditions affecting memory and conditions related to dementia

Following Pruisner, some hypothesise that infectious proteins called prions are pathogens that result in the degeneration of the central nervous system. Prions are proteins that suffer post-translational modification(s) that change their shape so that they can no longer perform their cellular functions. Worse, they are hypothesized to trigger equivalent modifications in normal proteins, thus creating a cascade of damage that eventually results in significant neurodegeneration. In humans, the result is Creutzfeldt-JaKob Disease.

Neurodegenerative diseases can result from stroke, heat stress, head and spinal cord trauma, and bleeding that occurs in the brain, the pressure from which eventually causes the death of one or more neurons.

In recent studies it has been suggested that Monosodium Glutamate (MSG), a food additive, can result in neurodegenerative diseases. MSG appears to cause lesions at specific locations in the brain of laboratory animals as well as concomitant proliferations of neuroendocrine dysfunction. Glutamic acid, where MSG is a source of, has no been identified as a neurotransmitter which transmits impulses. These neurotransmitters develop specific types of neurodegenerative diseases.

[edit] List of neurodegenerative diseases

Ataxia telangiectasia
Batten disease (also known as Spielmeyer-Vogt-Sjogren-Batten disease)
Bovine spongiform encephalopathy (BSE)
Canavan disease
Cockayne syndrome
Corticobasal degeneration
Creutzfeldt-Jakob disease
Huntington disease
HIV-associated dementia
Kennedy's disease
Krabbe disease
Lewy body dementia
Machado-Joseph disease (Spinocerebellar ataxia type 3)
Multiple sclerosis
Multiple System Atrophy
Parkinson disease
Pelizaeus-Merzbacher Disease
Pick's disease
Primary lateral sclerosis
Prion diseases
Refsum's disease
Sandhoff disease
Schilder's disease
Schizophrenia
Spielmeyer-Vogt-Sjogren-Batten disease (also known as Batten disease)
Spinocerebellar ataxia (multiple types with varying characteristics)
Spinal muscular atrophy
Steele-Richardson-Olszewski disease
Tabes dorsalis

At present there are few therapies for the wide range of neurodegenerative diseases. Treatment with L-dopa can inhibit symptoms of Parkinson's Disease for a short time, but then causes acceleration of the symptoms. Efforts are being made to develop therapies for Alzheimer's Disease that will stabilize cognitive function at the level existing at time of diagnosis and treatment. It is unclear whether therapies to reverse the effects of neurodegenerative disease will be within reach in the 21st century.

Research is underway into so-called Bio-Markers as part of an attempt to understand the progression of certain types of neurodegenerative disease. In theory, if relevant bio-markers were identified, people could be treated for such diseases prior to onset of symptoms, thus resulting in a significant extension of their normal functional lifespan. As yet, however, the science of bio-markers is in its infancy and consequently diagnosis of neurodegenerative disease tends to occur after the majority of neural damage has already been suffered by the patient.