Neurodegenerative disease

Neurodegenerative disease
Classification and external resources
Para-sagittal MRI of the head in a patient with benign familial macrocephaly.
MeSH	D019636

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. The brain and spinal cord are composed of neurons that perform different functions such as controlling movements, processing sensory information, and making decisions. Cells of the brain and spinal cord do not readily regenerate en masse, so excessive damage can be devastating. Neurodegenerative diseases result from deterioration of neurons or their myelin sheaths, which may eventually lead to CNS-related dysfunction.^[1]

Some sources limit the term "degenerative" to conditions primarily affecting gray matter that are not associated with an obvious inciting event. ^[2]

Classification

Neurodegenerative diseases are crudely divided into two groups according to phenotypic effects, although these are not mutually exclusive:

• Conditions causing problems with movements, such as ataxia, and
• Conditions affecting memory and related to dementia

Pathophysiology

Neurodegeneration is often caused by misfolding of proteins (prions) in such way that they can no longer perform their cellular functions and instead trigger equivalent modifications in normal proteins, thus creating a cascade of damage that eventually results in significant neuronal death. In humans, this can cause Creutzfeldt-Jakob disease or variant CJD (Mad Cow Disease).

Normally, neurodegeneration begins long before the patient experiences any symptoms. It can be months or years before any effect is felt^{[citation needed]}. Symptoms are noticed when many cells die or cease to function.

Additionally, the role of microglia in modulating neuroinflammation in CNS-related degeneration is currently being studied.^[3][4][5][6]

Treatment

Initial treatment for neurodegenerative disorders is dependent on diagnosis of the underlying condition. Presently, few therapies are available for the treatment of most neurodegenerative diseases. Treatment with L-dopa can inhibit symptoms of Parkinson's Disease for a short time, but is thought to subsequently accelerate the progression of symptoms^{[citation needed]}. Efforts are being made to develop therapies for Alzheimer's Disease in order to stabilize cognitive function.

Epidemiology

Each specific kind of neurodegenerative disease has its own characteristics, but most affect middle-aged or older people. They usually worsen over time.

Research directions

Stem cell technology and stem cell treatments, as well as Gene therapy are gaining increasing attention for the treatment of neurodegenerative diseases.

Research is underway into biomarkers 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 patient has already suffered the majority of the neural damages.

List of neurodegenerative diseases and conditions

• Adrenoleukodystrophy (ALD)
• Alcoholism
• Alexander's disease
• Alper's disease
• Alzheimer's disease
• Amyotrophic lateral sclerosis (Lou Gehrig's Disease)
• Ataxia telangiectasia
• Batten disease (also known as Spielmeyer-Vogt-Sjögren-Batten disease)
• Bovine spongiform encephalopathy (BSE)
• Canavan disease

• Cockayne syndrome
• Corticobasal degeneration
• Creutzfeldt-Jakob disease
• Familial fatal insomnia
• 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
• Multiple sclerosis
• 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 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
• Toxic encephalopathy

See also

• Trinucleotide repeat disorders
• Proteopathy
• Central nervous system
• Central nervous system disease

References

External links

• Institute for Neurodegenerative Diseases
• National Center for Biotechnology Information
• Harvard NeuroDiscovery Center
• HOPES: Huntington's Disease Outreach Program for Education at Stanford]