We are often living longer—far longer—than our ancestors. But we are not always more healthy. Almost a third of all people in the U.S. who reach the age of 85, for instance, will unfortunately be diagnosed with Alzheimer's disease, often combined with other types of dementia. Some 50 million people suffer some form of mental debilitation, according to estimates—and that will worsen in the coming decades, with the global demographic shift continuing its current aging trend. Despite more than 100 current clinical trials, we have no cure.

But as you will learn from this issue's cover story, “A Rare Success against Alzheimer's,” by researchers Miia Kivipelto and Krister Håkansson, the future may not be quite so grim. In fact, studies show that reducing the risk of Alzheimer's and other forms of dementia may include factors as simple as “good diet, exercise, an active social life and the achievement of higher educational levels.”

In addition to a sound mind in our autumn years, we'll want a sound body, of course. Starting here, we present our annual special report on the Future of Medicine. This year the theme is “Transformers,” by journalist Michael Waldholz: microbes whose genetic circuitry has been reshaped by biologists to turn them into medical treatments capable of switching on and off under certain conditions. The modified bacteria can treat genetic diseases, attack tumors and detect antibiotics. It is also just one of the many ways that science can help humanity in solving its most challenging problems.

A Farewell

Scientists are both the subjects and authors of Scientific American's articles, the heart of this 171-year-old magazine. We are sad to report that an author of a feature in this issue, the distinguished NASA scientist Neil Gehrels, passed away after a battle with pancreatic cancer, just as the story was about to go to press. Gehrels, with S. Bradley Cenko, wrote “How to Swallow a Sun,” about supermassive black holes.

During his career, Gehrels was perhaps best known for his transformative studies of gamma-ray bursts, the most powerful and luminous explosions in the cosmos, and the subject of a 2002 article he co-wrote for us; he and colleagues penned a feature, in 1993, about discoveries from the Compton Gamma Ray Observatory. We are truly grateful to him for generously sharing his insights over the years.