Degenerative diseases are characterized by a progressive degenerative change in tissue. The result of the degeneration is a reduction of structure or function of the associated tissue. These diseases usually follow a clinical course that includes an asymptomatic stage with a gradual progression in the manifestation of symptoms. Progression can continue from mild symptoms all the way to lethality. The incidence of degenerative diseases correlates well with aging and will more likely be symptomatic in the later years.

Degenerative diseases can strike any body organ or system. Most are not communicable and do not have an infectious etiology, although there are some exceptions to this. Acquired immune deficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV); stomach ulcers and cancer are associated with Helicobacter ...