Studies done in the mid 1970s estimated that 2.5 million older Americans suffer from Alzheimer's disease. Now, a group of scientists supported by the National Institute on Aging (NIA) have conducted an in-depth study of Alzheimer's disease in one community, suggesting that these figures represent the tip of the iceberg.
Overall, the investigators found that 10.3% of the people over age 65 had what they called "probable" Alzheimer's disease. This figure is as high as previous estimates for Alzheimer's disease in addition to all other causes of dementia in older people.
In addition to the overall findings, the prevalence of Alzheimer's disease rose more rapidly with age than previously suspected. Of those people between the ages of 65 and 74 years, 3% had probable Alzheimer's disease, as compared with 18.7% in the age 75- to 84-year-old group, and a striking 47.2% over age 85. This figure for age 85 and older is nearly double previous estimates.
These data question the estimes for Alzheimer cases in the United States. Because the number of people over age 85 is rising faster than any other segment of the popu lation, there could be as many as 14 million Americans with Alzheimer's disease by the middle of the 21st century.
For more information, contact Marian Emr or Claire McCullough, 301496-1752.