Alzheimer's disease - It is a progressive, neurodegenerative disease that occurs in the brain and often results in the following: impaired memory, thinking, and behavior, confusion, restlessness, personality and behavior changes, impaired judgment, impaired communication, inability to follow directions, language deterioration, and emotional apathy.
When Alzheimer's was first identified by German physician, Alois Alzheimer, in 1906, it was considered a rare disorder. Today, with one in 10 people over age 65, and nearly half of people over age 85, affected, Alzheimer's disease is recognized as the most common cause of dementia.
Alzheimer's disease is distinguished from other forms of dementia by characteristic changes in the brain that are visible only upon microscopic examination during autopsy. Brains affected by Alzheimer's disease often show presence of fiber tangles within nerve cells and clusters of degenerating nerve endings.
Coma - is a deep state of unconsciousness, during which an individual is not able to react to their environment. Someone in a coma cannot respond to any form of stimulation whatsoever. Coma can be caused by an underlying illness, or it can result from head trauma. A comatose person is still very much alive, but he or she is not simply asleep. The brain wave activity in a comatose person is very different from that of a sleeping person; you can wake up a sleeping person, you can't wake a person in a coma. A coma usually does not last for more than a few weeks. Many people recover their full physical and mental functioning when they emerge from a coma. Others require various forms of therapy to recover as much functioning as possible. Some patients never recover anything but very basic body functions.