My wife, Clare, and I love to travel. Upon retirement, we flew across the Arctic Circle, strolled across the Great Wall of China and through Red Square in Moscow, and meandered among the giant tortoises in the Galapagos. But on one of our trips, I noticed Clare forgetting things, and these weren't mere "senior moments." She'd talk about two grandchildren, although we have four. Or she'd talk about our trip to France, though we'd never been there.