Ralph Rehbock, age 91 and a Holocaust survivor, has a lot on his calendar. Every month, he attends group meetings for MEL: Men Enjoying Leisure. Every Friday, he performs with the Meltones, the club’s singing group. And over the years, he’s engaged with thousands of students and educators to share his story of escape from Nazi Germany. Rehbock is considered a “super-ager,” people 80 and up who have the same memory ability as someone 20 to 30 years younger. Scientists at Northwestern University have been studying this remarkable group since 2000, in the hopes of discovering how they’ve avoided typical age-related cognitive decline, as well as more serious memory disorders like Alzheimer’s disease. Super-agers are a diverse bunch; they don’t share a magic diet, exercise regimen or medication. But the one thing that does unite them is “how they view the importance of social relationships,” said Sandra Weintraub, a professor at Northwestern University. Can socializing help protect agai...