Should high school kids get a genetic test for the risk for Alzheimer’s disease before they’re allowed to play football? Two prominent scientists who study both Alzheimer’s and the traumatic brain injury suffered by some football players raise that ethically charged question in an editorial out Wednesday in the journal Science Translational Medicine. We all carry a gene called APOE which comes in three forms. If we carry one copy of the form called E4, it triples our lifetime risk for Alzheimer’s. About 10 percent of the U.S. population falls in that category. If we have two copies of E4, the lifetime Alzheimer’s risk is 15 times greater. About 2 percent of us have that genetic makeup.

It's easy enough to understand the ghastly accident that befell poor Phineas Gage in Cavendish, Vermont on Sept. 13, 1848: the 25-year-old railroad worker was using an iron rod to tamp down blasting powder when the stuff exploded, sending the 43-inch-long, 13-pound rod through his left cheek and out the top of his head. What's not so easy to understand is why Gage survived the accident--or the precise reason for the dramatic change in his personality afterward. John Harlow, the doctor who treated the once-affable Gage, wrote that he "could not stick to plans, uttered 'the grossest profanity' and showed 'little deference for his fellows,'" Smithsonian magazine reported in 2010.