 In 1985, a Swiss pathologist noted Alzheimer's disease-like changes, plaques, and tangles. In the brains of about three-quarters of a small group of men and women in their 50s and 60s who had died from other causes. Whereas most brains collected under age 30 were clean, but these studies just involved a few dozen people, based on thousands of autopsies. One can see what appears to be the first satellite stages starting even in our 20s, and about 10% of the population, and about 50% by age 50, just as the first malignant cells in cancer fail to produce any clinically detectable symptoms, but represent a larger, more potentially life-threatening disease process, the presence of these tangles in the brain may constitute a true threat. The high prevalence of the first stage of the disease, even in the young, and it's extraordinarily long duration. Most people don't get diagnosed with Alzheimer's until their 70s, had not been fully appreciated until now. We now understand that neurodegenerative brain changes begin by middle age, and so does cognitive decline. We start losing brain function in our 40s. Before people are diagnosed with Alzheimer's, they're diagnosed with what's called MCI, mild cognitive impairment. That's when cognitive decline becomes clinically apparent. A few years later, Alzheimer's may be diagnosed, which then results in death. But we never knew what was happening before mild cognitive impairment was diagnosed until now. There appears to be a slow decline in brain function, the buildup of plaques and tangles in the brain for decades before Alzheimer's is diagnosed. This finding potentially has profound implications for the prevention of dementia. We have to start early before marked brain loss has occurred. The good news is that brain disease is not inevitable, even after age 100. Oldest woman in the world, retaining the brain power of those practically half her age had she not died from stomach cancer, she could have kept on thriving. Turns out there's no such thing as dying from old age. 42,000 consecutive autopsies were studied, and centenarians, those living past 100, though most were perceived to have been healthy just prior to death, even by their physicians succumbed to diseases in 100% of the cases examined. Not one died of old age. Until recently, advanced age was considered kind of a disease in and of itself. But people don't die as a consequence of old age, as commonly assumed, from diseases, most commonly heart attacks. But not in our 115-year-old, one of the most intriguing findings was that her body showed no significant atherosclerosis, and the arteries in her brain were clear as well. And that may have actually been one of the secrets to her mental clarity. There is emerging consensus that what is good for our hearts is also good for our heads, which I'll cover next.