I don't know (and I'm obviously too young to know yet) but I see it in my parents. My dad especially. He would remember everything, and I mean everything. Could tell you in detail every hotel room he's ever been in, what exit number to take to get to a restaurant he's only been to once, and could always find his way around without a map or compass. Just intuited it. Well, everywhere except Knoxville, Iowa. He'd always get turned around there.
He's got a GPS now and appears to be incapacitated without it. I want to tell him to turn the damn thing off and figure it out without his fancy toys. I think as my parents have gotten older, and wealthier, they've become too reliant on technology. They are both engineers so their brains are wired to find the simplest and easiest solution to a problem. As of late, that's meant they buy gadgets to make life simpler and easier. I'm not sure it works though.
I think some of it is natural. As we get older the connections in our brains begin to break down, and that's fine. That's the way it is supposed to work. But I think we can accelerate the process by being lazy and letting machines do the work that we are more than capable of.