Alzheimer’s Disease is a chronic, degenerative disease which means that it progresses slowly and gets worse as it progresses. Around six million Americans have Alzheimer’s Disease—a number that is expected to reach 14 million by the year 2050. It seems that the incidence of Alzheimer’s Disease has increased in recent years to near epidemic proportions. While improvement in diagnosis has contributed to the rise, the real answer lies in the average length of life for human beings. Alzheimer’s is more prevalent now because more and more people are living long enough to develop the disease.

The following lesson from NIH Senior Health, National Institutes of Health, may help you better understand Alzheimer's Disease: nihseniorhealth.gov/alzheimersdisease/toc.html.