Alzheimer's disease is a progressive brain disease that takes a toll on memory and thinking skills, as well as the capacity to carry out even the most basic tasks. Symptoms of Alzheimer's disease usually show later in life in most persons. Experts estimate that more than 6 million Americans, the majority of whom are 65 or older, may have dementia caused by Alzheimer's disease. Alzheimer's disease is now the sixth biggest cause of mortality in the United States, but new estimates suggest it may be in third place, just after heart disease and cancer, as a cause of death among the elderly.
Parkinson's disease (PD) is a neurodegenerative condition that primarily affects dopamine-producing ("dopaminergic") neurons in the substantia nigra region of the brain. Symptoms usually appear gradually over time. Because of the variability of the condition, the course of symptoms varies from one person to the next. The cause is still a mystery. Although there is no cure, there are a variety of treatment options available, including drugs and surgery. While Parkinson's disease is not lethal in and of itself, it can cause catastrophic complications. Complications from Parkinson's disease are the 14th leading cause of mortality in the United States, according to the Centers for Disease Control and Prevention (CDC).