Perhaps you've noticed you're less likely to forget where you parked your car after a brisk tennis match than after a trip to the library. There's a reason for that, says a new study: in healthy seniors and those with emerging memory problems, even a single brief bout of vigorous exercise and the release of norepinephrine that comes with it can enhance memory of what came just before it.
The phenomenon is one of evolution's cleverest memory-enhancing tricks: when an event triggers high emotion -- the unexpected sight of a snake, for instance, and the fear reaction that comes with it -- we tend to remember longer and better the details surrounding that event. For the young and inexperienced, the ability to remember those details -- where and when one saw that snake, and how exactly it behaved -- increases the odds that one will live long enough to reproduce.
But do those who have already survived into old age also benefit from the norepinephrine effect, and can it help compensate for memory impairment? Researchers at UC Irvine set out to explore those questions.
To do so, they recruited 31 healthy older adults with an average age of 69, and 23 subjects who had been diagnosed with "amnestic" mild cognitive impairment -- memory loss that is problematic but which falls short of Alzheimer's disease. All were shown a series of 20 emotionally positive images -- beautiful landscapes, baby animals, sports scenes. And then, half of those in each group were put on treadmills to exercise for six minutes at 70% of their aerobic maximum. Subjects in the other half of each group were allowed to sit quietly.