Myriam Penninckx was having lunch at a restaurant in Brussels when her right arm began to shake. This was just the latest in a string of signs that something might be amiss. Her handwriting had suddenly become impossible to decipher, and she had noticed herself slowing down, physically and mentally. “I had always been Speedy Gonzales, doing a lot of things at the same time,” she says. “But that was becoming less possible.”