Americans over 50 are a boon to, not a drain on, the economy. And while researchers have long known that maintaining social connections is critical to mental health, it is also linked to a stronger immune system, lower blood pressure and a longer life. These findings and more are featured in The Second Fifty: Answers to the 7 Big Questions of Midlife and Beyond (W. W. Norton & Company), the new book from Debra Whitman, AARP Executive Vice President and Chief Public Policy Officer.