New studies show that the rate of Alzheimer's disease and other dementias is falling in the United States and some other rich countries even though the total number of cases continues to rise because more people are living to an old age.
One study finds that an American over age 60 today has a 44 lower chance of developing dementia than a similar-aged person did roughly 30 years ago.
Dementia rates also are down in Germany.
Scientists think the trend is due to better education and control health factors such as lowering blood pressure and cholesterol.
Some poor countries are seeing the opposite trend, a rise in dementia.
The studies were discussed Tuesday at an Alzheimer's conference in Copenhagen.