Disorders of the nervous system
Most neurones in the central nervous system cannot repair or renew themselves, unlike other cells in the body. So, if some die through illness or damage, the nervous system can permanently lose some of its abilities. The symptoms of disorders of the nervous system depend on which part is attacked - Alzheimer disease destroys cells in the memory area of the brain, for example. There are currently no cures for these disorders, but promising research includes new drug treatments, vaccines and nerve cell transplants.