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New research into the genetic underpinnings of Alzheimer’s disease offers fresh evidence that the devastating brain disorder may gain a foothold years before dementia sets in, and takes a key step toward earlier detection of the disease. In a study that scoured the genes of healthy young people for the presence of variants linked to Alzheimer’s disease, researchers have found that those who carried many of the telltale gene variations had a smaller hippocampus -- a brain structure that is crucial to memory-formation – than did their peers with few of the genetic variations. (Healy, 7/6)

Such experiments are one of medicine’s oldest traditions. Many a vaccine or poison was first tested on its developer; most of the earliest work on psychedelic drugs was conducted by intrepid scientists tripping in the name of research. As medicine has progressed, however, self-experimentation has become less popular in academic labs, to be taken up instead by a growing biotech industry. Those changes have given rise to a new breed of self-tester: the guinea pig CEO. (Preston, 7/7)

The fallout from nuclear bomb testing decades ago is now helping researchers better understand knee joints. By tracking radioactive carbon absorbed in knees, a team of Danish researchers has found that the structure of cartilage is determined by early adolescence and doesn’t change later in life. They published their findings Wednesday in Science Translational Medicine. (Wessel, 7/6)

Lenny and Amy’s 5-year-old son has epilepsy. When conventional medications caused terrible side effects, they started giving him a daily drop of cannabis oil, with dramatic results. But it’s a calculated risk: While there is anecdotal evidence of cannabis’ effectiveness, scientists face research roadblocks because it’s a schedule 1 controlled substance. (O'Brien, 7/6)