Researchers at the University of Edinburgh have conducted tests on a compound that slowed age-related memory loss in mice. An enzyme called 11 beta-hydroxysteroid dehydrogenase type 1 generates glucocorticoids, a class of hormones, that enhance memory formation:
Link via Glenn Reynolds | Photo (unrelated) via Flickr user jepoirrier used under Creative Commons license
The Edinburgh team showed that knocking out either one or both copies of the gene for this enzyme in mice preserved the animals' memory into old age. To determine whether blocking the enzyme could improve memory in already aged animals, researchers then developed a compound designed to cross into the brain and inhibit the enzyme. Just 10 days of treatment in two-year-old mice--the maximum lifespan for a typical lab mouse--was enough to improve the animals' performance on a test of spatial memory.
Link via Glenn Reynolds | Photo (unrelated) via Flickr user jepoirrier used under Creative Commons license
You have a point.
Spatial memory is by far the easiest type of memory to demonstrate in animals, with lots of spatial memory mazes being specially developed for rats. The question is whether we can generalise findings of spatial memory to general memory.
I did an experiment myself with rats in mazes, but I was careful to only apply my findings to spatial memory.