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 Nov. 21, 2016, 8:37 PM GMT / Updated Nov. 21, 2016, 8:37 PM GMT By Maggie Fox 
 
 Rates of Alzheimer’s disease and other types of dementia appear to have fallen considerably since 2000, and better education may be partly responsible, researchers reported Monday. 
 
 Better treatment for diabetes and cardiovascular disease may also be helping, the researchers reported in the Journal of the American Medical Association. 
 
 Elderly woman covering face with her hands. Westend61 / Getty Images 
 
 Dr. Kenneth Langa of the University of Michigan and colleagues studied records from 21,000 people with an average age of 75. 
 
 While 11.6 percent of Americans aged 65 and older had dementia, based on standardized tests, the rate fell to 8.8 percent in 2012. 
 
 “More years of education was associated with a lower risk for dementia, and average years of education increased significantly,” they wrote. 
 
 “Rising levels of education among U.S. adults over the past 25 years may also have contributed to decreased dementia risk." 
 
 In 2000, the average amount of education was 11.8 years — just short of a full high school education. By 2012, the average was 12.7 years. 
 
 “Our study, along with prior studies, supports the notion that ‘cognitive reserve’ resulting from early life and lifelong education and cognitive stimulation may be a potent strategy for the primary prevention of dementia in both high- and low-income countries around the world,” they wrote. 
 
 And while obesity, a lack of exercise and poor diet can all raise the risk of Alzheimer’s, rates went down as more people got heavier, developed high blood pressure and diabetes, Langa’s team found. 
 
 More than 5 million Americans have Alzheimer's disease. The Alzheimer's Association says more than 28 million baby boomers will develop the disease between now and 2050, and the cost of caring for them will consume nearly 25 percent of Medicare spending in 2040. 
 
 Related: Could Brain Games Help Alzheimer's Risk? 
 
 Research has shown that increased physical activity, eating a heart-healthy diet, social engagement and keeping the brain active with puzzles or games can help prevent Alzheimer’s or at least delay it, and a whole industry has arisen out of that research, with mixed success. 
 
 The findings fit in with other recent reports that have shown a fall in dementia rates. But the Alzheimer's Association says that doesn't necessarily mean fewer people with Alzheimer's. 
 
 "There is an important difference between prevalence rate (number of people with the disease divided by the total population) and the prevalence number (number of people with the disease)," the group said in a statement. 
 
 "Although these recent findings indicate that a person's risk of dementia at any given age may be decreasing slightly, it should be noted that the total number of Americans with Alzheimer's and other dementias is expected to continue to increase dramatically." 
 
 Nonetheless, it’s welcome news in an aging world. There is no cure for dementia, and trials of various treatments have been far from successful. 
 
 Treating other diseases associated with aging may help. There’s plenty of evidence that the same damage that happens as blood vessels get clogged and stiff may underlie dementia. 
 
 Related: Exercise May Help Alzheimer's 
 
 “Intensity of treatment for diabetes, hypertension and high cholesterol level has increased with more patients achieving treatment goals, and a significant decline in the vascular complications of diabetes such as heart attack, stroke and lower-extremity amputations, suggesting that there could be a ‘spill-over’ benefit of a decline in the vascular-related risk for dementia,” Langa’s team wrote. 
 
 “Intensity of treatment for diabetes, hypertension, and high cholesterol level has increased." 
 
 “Rising levels of education among U.S. adults over the past 25 years may also have contributed to decreased dementia risk. The proportion of adults 65 years or older with a high school diploma increased from 55 percent in 1990 to 80 percent in 2010, while the proportion with a college degree increased from 12 percent to 23 percent,” they wrote. 
 
 It’s not clear what better education does, but experts note there may be several effects. Better-educated people may have a better ability to adapt to the lost brain function caused by dementia; they may be healthier in general; and they may have better medical care. 
 
 People who are underweight had a higher-than-usual risk of dementia, the team found. 
 
 It’s possible that weight loss is an early symptom of dementia, Dr. Sanjay Asthana of the University of Wisconsin School of Medicine and Public Health said in a commentary accompanying the study. 
 
 “There is evidence that weight loss may precede the onset of dementia by many years,” Asthana and his colleague Ozioma Okonkwo wrote. 
 
 Dementia can affect the sense of taste and smell and may cause people to eat far too little, they said. ||||| Dementia Risk Declines, And Education May Be One Reason Why 
 
 Enlarge this image toggle caption Alfred Pasieka/Science Photo Library/Getty Images Alfred Pasieka/Science Photo Library/Getty Images 
 
 Some encouraging news in the battle against Alzheimer's disease and other forms of dementia: The rate at which older Americans are getting these conditions is declining. That's according to a study published Monday in JAMA Internal Medicine. Researchers say one reason for the improved outlook is an increase in education. 
 
 The study used data gathered in two snapshots, one in 2000 and another in 2012, that each looked at more than 10,000 Americans who were at least 65 years old. In the first snapshot, 11.6 percent of them had some form of dementia. In the second snapshot, it was 8.8 percent. 
 
 Put in more human terms, "that's well over a million people who don't have dementia, who would have had it if the rates had stayed the same as 2000 rates," says John Haaga, who directs the Division of Behavioral and Social Research at the National Institute on Aging, which funded the study. 
 
 While the prevalence of dementia cases dropped, the average amount of education in the study population increased. In 2000, the average amount of education was 11.8 years, just shy of the 12 years it usually takes to graduate from high school. In 2012, the average amount of education was 12.7 years — in other words, high school plus a little bit of college. 
 
 Researchers don't know why education should be a protector against dementia, says Dr. Kenneth Langa, a professor of medicine at the University of Michigan and the lead author of the study. But they have some theories. 
 
 "One is that education might actually change the brain itself," Langa says. "We think that it actually creates more, and more complicated, connections between the nerve cells so that you're able to keep thinking normally later into life." 
 
 Education can not only change the brain, it can change your whole life, says Haaga. 
 
 "It affects what kind of work you do, of course. It also affects who your friends are, who you're married to, whether you're married. All aspects of life are affected by educational attainment," he says. 
 
 But the study doesn't say that education alone is the "X factor" in preventing dementia. There are medical factors, too. 
 
 Cardiovascular conditions believed to increase the risk of dementia — things like high blood pressure, high cholesterol, obesity, diabetes — are becoming more common, says Haaga. But they're also being treated more aggressively. 
 
 "So it could well be that we're getting better at managing the bad effects of these risk factors," he says. "But they are still risk factors." 
 
 This study fits a recent trend. In the past decade or so, other researchers have found similar declines in dementia risk in wealthier nations. But the populations they examined haven't been very diverse. This study is different. It draws on the ongoing Health and Retirement Study that follows about 20,000 older Americans of all backgrounds nationwide. 
 
 Langa says the ethnic, geographic and economic diversity of the subjects makes the trend shown in all these studies more convincing. "The fact that our study also shows a decline [in the prevalence of dementia], provides additional evidence that this phenomenon seems to be going on across the United States and not in one particular geographic region." 
 
 But while the risk of dementia is declining, the number of cases is still expected to rise. That's because the population of older adults in this country is increasing. The number of people 65 and older is expected to nearly double by 2050. ||||| Researchers have found a small piece of good news for people at high risk of some kinds of dementia: it might be possible to delay it or even prevent it. 
 
 They found falling rates of vascular dementia in people who also happened to improve their heart health. The findings, published in the New England Journal of Medicine, support the idea that what’s good for the heart is good for the head. 
 
 "Our study offers cautious hope that some cases of dementia might be preventable or at least delayed," Claudia Satizabal of the Boston University Schools of Medicine and colleagues wrote in their report. 
 
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 They looked at more than 5,000 people who have been having their health tracked in minute detail as part of the Framingham Heart Study. The multi-generational study has been going on since 1948 and in 1971 children of the original volunteers signed up. Their memory has been tested since 1975. 
 
 "On average, since 1977, there has been a decline in the incidence of dementia of 20 percent per decade," the researchers wrote. The decrease in rates of vascular dementia has been 29 percent per decade. 
 
 "The decline in the incidence of Alzheimer’s disease was not significant, whereas the decline in the incidence of vascular dementia appeared to be more rapid than that of Alzheimer’s disease," they added. 
 
 “Our study offers cautious hope that some cases of dementia might be preventable or at least delayed." 
 
 Keith Fargo, director of scientific programs for the Alzheimer's Association welcomed the findings. 
 
 "The incidence rates for dementia in the Framingham heart study appear to be decreasing over the past few decades and that's good news. It's probably not everything that needs to be done, but it's good news and it points us in a couple of directions about what we might be able to do to decrease the risk for dementia as people age," Fargo told NBC News. 
 
 "We know that things like increasing your physical activity, eating a heart-healthy diet, making sure that you stay socially active, making sure that you stay cognitively engaged, if you smoke, stop smoking — all of these things are going to reduce your likelihood of cognitive decline as you age and may even delay or prevent dementia," Fargo said. 
 
 Related: Here's a Recipe for Preventing Dementia 
 
 But the news only applies to the mostly white people taking part in the study. A second study found dementia rates are highest in African Americans and lowest in Asian Americans. 
 
 And the Boston team’s findings only applied to people with a high school education or more. That supports other research that shows education can protect against dementia, probably by keeping the brain active and growing. 
 
 Vascular dementia is the second most common cause of dementia after Alzheimer’s disease. 
 
 One person who’s doing her best to stave off dementia is Cynthia Huling Hummel, a retired pastor in Elmira, New York. She was diagnosed with mild cognitive impairment, which can progress to Alzheimer’s, in 2011. 
 
 "I was preparing for my doctorate, I was preparing to defend my dissertation and I couldn't remember any of the classes I had been taking," Hummel, who is 61, told NBC News. 
 
 "I couldn’t remember the material I had read. I couldn’t remember the teachers or the students I had interfaced with so I knew there was a problem," she added. 
 
 "It’s frustrating. It’s embarrassing. By Wednesday I would forget what I had preached on Sunday," she said. 
 
 Hummel retired, but she got busy trying to do what she could to prevent the dementia from worsening. 
 
 "Getting more physically active, engaging myself more socially, challenging myself with more learning opportunities, being mindful of what I was eating, all those things," she said. 
 
 "I take classes at Elmira College. I’m now taking my 28th class in almost 4 ½ years," Hummel added. 
 
 "You want to pump that blood and stay physically active and again, what is good for the heart is good for the brain and so I swim three times a week at the Y." 
 
 “You want to pump that blood and stay physically active." 
 
 It appears to be working. 
 
 "I went to see my neurologist last month and he said, 'Whatever you’re doing continue to do it because it’s working.' And so that is good news," she said. 
 
 More than 5 million Americans have Alzheimer's disease. The Alzheimer's Association says more than 28 million baby boomers will develop the disease between now and 2050, and the cost of caring for them will consume nearly 25 percent of Medicare spending in 2040. It's worse in women. 
 
 A second study looked at just who gets dementia. 
 
 Dementia rates in African Americans are 65 percent higher than among Asian Americans, the study found. 
 
 "Our projections indicate that in every racial and ethnic group, over one in four people who survive to age 65 can expect to be diagnosed with dementia in their lifetime," said Rachel Whitmer, an epidemiologist at Kaiser Permanente Northern California, who led the study published in an Alzheimer's Association journal. 
 
 Her team’s study of 274,000 members of Kaiser Permanente found dementia incidence over the 14-year study period ranged from an average annual rate of 26.6 cases of dementia per 1,000 people for African-Americans, to 15.2 cases per 1,000 people for Asian-Americans. In between were Latinos and Pacific Islanders with an average annual rate of 19.6 cases per 1,000 people, and whites with 19.3 per 1,000. 
 
 Various studies have given people hints at what can prevent Alzheimer’s. Regular exercise and eating plenty of fruits and vegetables helps. 
 
 Others have shown that people who are socially engaged are less likely to develop memory loss. Still others have shown that keeping the brain active with puzzles or games can help, and a whole industry has arisen out of that research.
– Good news for older Americans: A new study suggests that their odds of getting dementia are shrinking despite predictions to the contrary. While standardized tests showed 11.6% of Americans 65 and older had dementia in 2000, only 8.8% did in 2012, reports NBC News. What's more, people are getting dementia later, with the average age at diagnosis increasing from 80.7 to 82.4 over the same period, reports the New York Times. One possible factor: A person's average education increased during that period from 11.8 years to 12.7 years, say University of Michigan researchers. "Education might actually change the brain itself," lead author Kenneth Langa tells NPR. "We think that it actually creates more, and more complicated, connections between the nerve cells so that you're able to keep thinking normally later into life." Another potential factor: While health ailments linked to dementia such as diabetes, high blood pressure, and high cholesterol increased, people were treating them with better medications. The study draws on long-range data about 20,000 Americans from all kinds of backgrounds, and Langa says it suggests that dire predictions about the nation's dementia problem might have been been overstated. The Alzheimer's Association isn't so sure: Though dementia rates may be falling, "the total number of Americans with Alzheimer's and other dementias is expected to continue to increase dramatically" as the number of older adults climbs," it says. In the US, the number of people 65 and older is projected to double by 2050, notes NPR. (A game could reduce your dementia risk.)