Risk of dementia is falling, researchers not sure why

Three decades worth of data from the Framingham Heart Study could challenge conventional assumptions about dementia rates. While the incidence of the disease is predicted to climb as people live longer, numbers from the Framingham investigation suggest the rate is actually falling in high-income nations. An analysis of the data reveals that, of 5,206 persons tracked since 1975—all aged 60 years or older—the risk of dementia has gradually slipped over the years to achieve a 44% decline by the late 2000s and early 2010s.