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