The thought of developing dementia in old age is terrifying for many, especially if they’ve watched a loved one suffer under its grip. A bit of good news, though; a study in JAMA Internal Medicine showed that overall dementia rates in the United States fell 24% from 2000 to 2012. That means about one million fewer Americans had the condition. 
Dr. Kenneth Langa, a professor of internal medicine at the University of Michigan and a coauthor of the new study, said:
“It’s definitely good news. Even without a cure for Alzheimer’s disease or a new medication, there are things that we can do socially and medically and behaviorally that can significantly reduce the risk.”
The term “dementia” refers to a loss of memory or other mental abilities severe enough to interfere with daily life. Alzheimer’s disease, caused by a buildup of plaques and neurofibrillary tangles in the brain, is the most common form of dementia. Vascular dementia, which can occur after a person has suffered a stroke, is the 2nd most common form of dementia.
Determining the Numbers
The study, which began in 1992, looked at over 21,000 adults over age 50. Data were collected on the individuals every two years. Researchers conducted detailed interviews with the participants about their health, income, cognitive ability, and life circumstances. The investigators also conducted physical tests and body measurements, and took blood and saliva samples. They discovered the following:
- Dementia prevalence among adults 65 and older decreased from 11.6% in 2000 to 8.8% in 2012
- Participants who had more education had the lowest rates of dementia
- The average years of education increased significantly from 11.8 years in 2000 to 12.7 years in 2012.
- The drop in dementia prevalence occurred despite a significant age- and sex-adjusted increase in between the data-collection years in the cardiovascular risk profile (e.g., prevalence of hypertension, diabetes, and obesity) among older U.S. adults.
Contributing Factors to the Decline
The reasons behind the drop in dementia rates aren’t clear, but there are some findings that stand out.
The JAMA study shows – as do past studies – that both early education and lifelong education appear to help keep the mind healthy and sharp. The authors suggest that perhaps education ought to be viewed as “a potent strategy for the primary prevention of dementia in both high- and low-income countries around the world.”
In fact, according to the authors, past studies have shown that:
“…the relationships among education, brain biology, and cognitive function are complex and likely multidirectional; for instance, a number of recent population-based studies have shown genetic links with level of educational attainment and with the risk of cognitive decline in later life.”
Additionally, highly educated individuals are more likely to not smoke, to get more exercise, and to eat a healthier diet. This is also true of people who have more cognitively complex occupations.
Better access to healthcare also played a role in the decline, the researchers wrote.
Dementia is Still a Serious Problem
The advice embedded in the results is clear: stay active, both physically and mentally. Never stop learning. Eat right. Don’t smoke. More people are getting the message that staying propped up in front of the TV is hazardous to health, and are heeding the warning.
Overall, the drop in dementia rates could be largely due to the better control of cardiovascular risk factors, like high blood pressure and diabetes.
Keith Fargo is the director of scientific programs and outreach, medical and scientific relations, at the Alzheimer’s Association. He said:
“If you control those risk factors, it’s natural to expect that rates of vascular dementia will go down. It’s also reasonable to expect that Alzheimer’s-related dementia may go down as well because now, instead of having both, you have Alzheimer’s in an overall healthier brain.” 
However, Alzheimer’s disease and other forms of memory loss remain a huge public health challenge and a significant financial burden. There are currently about five million Americans suffering with dementia. As people continue to live longer, that number is expected to triple by 2050. 
The number of Americans over age 65 is expected to double by 2050, to 84 million. That means that even if the percentage of elderly people who develop dementia is smaller than previously estimated, the total number of Americans with dementia will continue to increase, according to Fargo. He said:
“Alzheimer’s is going to remain the public health crisis of our time, even with modestly reduced rates.”
Dr. Sam Gandy, director of the Center for Cognitive Health at Mount Sinai Hospital in New York City, said:
“What we need now is to educate middle-aged people, since that’s where the risk factors are most important. Unfortunately, as the baby boomers turn 80, I worry that the silver tsunami will swamp this benefit.”