Dementia rates falling in the U.S.
Dementia is an umbrella term used to describe a variety of conditions and symptoms that occur when nerve cells die or no longer function properly. The malfunctioning of these neurons leads to memory loss, impaired reasoning and cognition, and sometimes personality changes.
Patients are diagnosed with the disorder when such impairment becomes severe and interferes with a person's ability to carry out daily tasks. Alzheimer's disease is the most common form of dementia, accounting for 60-80 percent of cases.
However, past research has suggested that some high-income countries may see a decline in dementia rates. In one study from Massachusetts, the annual number of new dementia cases fell by 20 percent over about three decades.
For the new study, Langa and colleagues analyzed data from a U.S. survey of people 65 years and older, including 10,546 people in 2000 and 10,511 in 2012.
The prevalence of dementia in 2000 was 11.6 percent, compared to 8.8 percent in 2012.
The decline occurred despite an increase in heart health risk factors like high blood pressure and obesity between 2000 and 2012, the researchers write.
The study offered some important clues about ways to prevent or delay dementia, she said. Education and heart health appear to have contributed to the decline in dementia cases, the study found.
Only people with at least a high school diploma experienced a significant decline in their risk for dementia, the study findings showed. Also, the researchers observed an improvement in overall heart health that paralleled the reduction in dementia risk.
"This does add evidence that controlling cardiovascular risk factors and increasing levels of education are good for your risk of developing dementia over time," said Keith Fargo, director of scientific programs and outreach for the Alzheimer's Association.
"It does not say that we don't have to worry about dementia anymore, or that we're not going to see an explosion of dementia cases as the baby boomers age," he added.
Seshadri and Fargo also cautioned that these findings may not apply to the United States as a whole, since the study participants were white and relatively well-off.
"The essential idea behind it is the more cognitively [mentally] healthy you are to begin with, the better able your brain is to withstand the slings and arrows of aging," he said. "This study tells us that formal education is extremely important to your brain health as you age."