Believe it or not, those who'd had the "old" words in their quizzes were about 30% slower-moving than those who didn't. Simply reading certain words "aged" them, albeit temporarily.
The reverse experiment was organized by Ellen Langer of Harvard, who gathered a group of elderly patients in a nursing-home like environment; but surrounded them with the decor, clothing, and music of their twenties. The researchers went so far as to pipe in the radio programs & TV shows from that time; and the magazines all around were from that era. Even the fridge was stocked with long-discontinued foods.
In the ensuing weeks, physical exams showed tighter skin, better eyesight, less joint pain, increased muscle strength and even higher bone density than before and compared to the control group.
As Benazir cautions: if elements of ourselves as fundamental as bone density and eyesight are affected by what we see, hear, and thus what we think; can you imagine what it's likely to be doing within our minds? The New York Times has a fascinating "who's minding the mind?" article with more startling experiments.
Some mental food is health food. Some mental food is junk food. Pay close attention what you're pouring into your mind.