Rapamycin, a drug that keeps the immune system from attacking transplanted organs, was recently found to extend the life span of aged research mice. Now a study involving genetically engineered mice has found that 10 weeks of taking the drug improved learning and memory and reduced Alzheimer's-like damage in the brain.
Rapamycin rescues memory in Alzheimer's mice
 Molecular interplay between mTOR, A and tau: Effects on cognitive impairments. Journal of Biological Chemistry.(2010).