There are a great many ways to work at maintaining and even improving your memory functions as you get older, and there's no question that both mental and physical stimulation keep your brain sharp. But the simple truth is that our memories may not be fading as quickly as we think.
Why don't the schools and universities teach design thinking for thinking? We teach physical fitness. But rather than brain fitness we emphasize cramming young heads with information and testing their recall.
With external electronic devices replacing our internal memory systems, we are asking our brains to do less memory-work, and thus, it is likely that our brains have become less efficient or skilled at memory-work.