Fast food is causing the dementia boom—and it’s projected to get worse. Almost 3.8 million people 71 or older have dementia, according to a study published today in the New England Journal of Medicine. The rise in Alzheimer’s is partly due to the aging of baby boomers. But there is another reason. When these senior citizens were teenyboppers, the fast-food craze was just taking off: The first KFC franchise opened in 1952, the first Burger King in 1954, and the first McDonald’s and Dunkin’s Donuts in 1955. As these foods caught on, America’s meat and cheese intake soared. Today’s dementia boom can be attributed to the saturated fats and trans fats that began inundating the American diet with the rise of fast food. Saturated fats—in Big Macs, fried chicken, and other meat and dairy products—appear to encourage the production of beta-amyloid plaques within the brain. The Chicago Health and Aging Study reported in the Archives of Neurology in 2003 that people consuming the most saturated fat had more than triple the risk of developing Alzheimer’s disease, compared with people who generally avoided these foods. Trans fats, found in doughnuts, snack pastries, and often in french fries, have been shown to increase Alzheimer’s risk more than fivefold. These “bad fats” raise cholesterol levels and apparently increase production of the beta-amyloid protein that collects in plaques in the brain as Alzheimer’s disease begins. There’s no sign that fast-food restaurants will stop slash-and-burn growth tactics. Today, McDonald’s has more than 34,000 restaurants in 119 countries. While McDonald’s and other fast-food corporations make billions, they leave Americans paying a huge health toll. The total cost of dementia in 2010 was $215 billion. By 2040, 9.1 million people in America alone will suffer from dementia and it will cost the country $511 billion. Now that generations have been raised on Whoppers and glazed donuts, what can we do? Put down the fast food, as well as other sources of meaty, cheesy, fat-laden fare. People who generally avoid saturated and trans fats—skipping the cheese, bacon, and doughnuts—have had remarkably low rates of Alzheimer’s disease in research studies. Alzheimer’s is incurable. But there’s time for the Millennial Generation—and even Baby Boomers—to halt it before it starts.