Alzheimer's disease is characterized by a gradual loss of memory, increasing difficulty in performing routine tasks and feelings of disorientation. Alzheimer's disease may also cause loss of language skills, personality changes, impairment of judgment and inability to plan.
Parkinson's disease is identified as a motor system disorder which is chronic (meaning it occurs over a long time) and progressive (gradually getting worse). It is not contagious, nor is it usually inherited.
In 1817, James Parkinson, a British physician first called the disease "the shaking palsy." In the early 1960s, researchers identified a primary brain defect: the loss of brain cells that produce a chemical (dopamine) that helps direct muscle activity. This discovery has led to many new treatments and therapies.