Neurodegenerative disease

# Overview
Neurodegenerative disease (Greek -, neuro-, "nerval" and Latin degenerare, "to decline" or "to worsen") is a condition in which cells of the brain and spinal cord are lost. The brain and spinal cord are composed of neurons that do different functions such as controlling movements, processing sensory information, and making decisions. 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, such as ataxia
- conditions affecting memory and conditions related to dementia
Following Stanley Prusiner, some hypothesize 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 (Mad Cow Disease).
Neurodegenerative diseases can result from stroke, heat stress, head and spinal cord trauma (blunt or infectious pathology), and bleeding that occurs in the brain, the pressure from which eventually causes the death of one or more neurons.
Many times neuronal death begins long before the patient will ever experience any symptoms. It can be months or years before any effect is felt. Symptoms are noticed when lots of cells have died and certain parts of the brain have been weakened to the point that they can no longer function properly.
Regulation, or production of microglia by the immune system, in a process of neuroinflammation, is currently being rigorously studied for its role in neurodegenerative diseases.
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 not been identified as a neurotransmitter which transmits impulses. These neurotransmitters develop specific types of neurodegenerative diseases.

# List of neurodegenerative diseases
- Alcoholism
- Alexander's disease
- Alper's disease
- Alzheimer's disease
- Amyotrophic lateral sclerosis
- 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
- Frontotemporal lobar degeneration
- Huntington's disease
- HIV-associated dementia
- Kennedy's disease
- Krabbe's disease
- Lewy body dementia
- Neuroborreliosis
- Machado-Joseph disease (Spinocerebellar ataxia type 3)
- Multiple System Atrophy
- Narcolepsy
- Niemann Pick disease
- Parkinson's disease
- Pelizaeus-Merzbacher Disease
- Pick's disease
- Primary lateral sclerosis
- Prion diseases
- Progressive Supranuclear Palsy
- Refsum's disease
- Sandhoff's disease
- Schilder's disease
- Subacute combined degeneration of spinal cord secondary to Pernicious Anaemia
- 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
These diseases have their own characteristics which usually affect middle aged or older people. They usually worsen over time.

# Treatment
Initial treatment is dependent on diagnosis of underlying disorder.  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.
Research is highly invested in stem cell technology and stem cell treatments, as well as Gene therapy.
Research is underway into 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.