Researchers say much of the increase can be attributed to the rise of dementia in developing countries. In those countries, the study concludes, there is an overall lack of awareness of Alzheimer's and other dementias. Many mistakenly perceive the medical conditions as a normal part of aging.
In 2010, the report estimates that 57.7 percent of all people with dementia are expected to live in low and middle income countries, rising to 63.4 percent in 2030 and then to 70.5 percent in 2050.
Latin America and Africa are expected to see a rapid increase in people affected.
Over the next 20 years, the numbers of people with dementia are anticipated to increase by 40 percent in Europe, 63 percent in North America and 125 percent in North Africa and the Middle East.
The Centers for Disease Control in Atlanta report that an estimated five million Americans have Alzheimer's disease. The disease usually begins after age 60.
Known risk factors, other than age, include family history, high cholesterol, high blood pressure and diabetes.
According to the CDC, there are several treatable diseases and conditions that can mimic symptoms of Alzheimer's disease. Those include depression, thyroid problems and dehydration.
There is no known cure for Alzheimer's.
AP contributed to this report.
- Link: 2009 World Alzheimer Report
- Link: CDC's guide to Alzheimer's Disease
- Link: Alzheimer's Disease Education & Referral Center