The term neurodegeneration is a combination of two words – “neuro,” referring to nerve cells and “degeneration,” referring to progressive damage. The term “neurodegeneration” can be applied to several conditions that result in the loss of nerve structure and function.
This deterioration gradually causes a loss of cognitive abilities such as memory and decision making. Neurodegeneration is a key aspect of a large number of diseases that come under the umbrella of “neurodegenerative diseases.” Of these hundreds of different disorders, so far attention has been mainly focused on only a handful, with the most notable being Parkinson’s disease, Huntington’s disease and Alzheimer’s disease. A large proportion of the less publicized diseases have essentially been ignored.
All of these conditions lead to progressive brain damage and neurodegeneration. Although all three of the diseases manifest with different clinical features, the disease processes at the cellular level appear to be similar.
For example, Parkinson’s disease affects the basal ganglia of the brain, depleting it of dopamine. This leads to stiffness, rigidity and tremors in the major muscles of the body, typical features of the disease. In Alzheimer’s disease, there are deposits of tiny protein plaques that damage different parts of the brain and lead to progressive loss of memory. Huntington’s disease is a progressive genetic disorder that affects major muscles of the body leading to severe motor restriction and eventually death.
Causes of neurodegeneration
Only an extremely small proportion (less than 5%) of neurodegenerative diseases are caused by genetic mutations. The remainder are thought to be caused by the following:
A build-up of toxic proteins in the brain
A loss of mitochondrial function that leads to the creation of neurotoxic molecules
Although the cause may vary, experts generally agree that the result is the promotion of apoptosis or programmed cell death, which is deliberate suicide of the cell for the purpose of protecting other nearby neurons from toxic substances.