NEW ORLEANS (AP) - Actor Billy Crystal, tennis star Martina Navratilova and singers Stevie Nicks, Gladys Knight and Melissa Etheridge are among celebrities headed to New Orleans this week to champion life after 50.

More than a dozen celebrities will host discussions and activities for aging Americans at the national conference of the AARP. The conference runs Thursday through Saturday at the Ernest N. Morial Convention Center and is expected to attract about 20,000 attendees.

The conference will be a presidential campaign stop for Republican Mitt Romney's running mate, Wisconsin Rep. Paul Ryan. President Barack Obama is expected to answer questions via satellite on Friday.

Ryan and Obama are expected to discuss such issues as Social Security, Medicare and financial security for older Americans.