I have reported previously on research suggesting that rapamycin, a bacterial product first isolated from soil on Easter Island and used to help transplant patients prevent organ rejection, might improve learning and memory. Following on from this research, a new mouse study has extended these findings by adding rapamycin to the diet of healthy mice throughout their life span. Excitingly, it found that cognition was improved in young mice, and abolished normal cognitive decline in older mice.
Anxiety and depressive-like behavior was also reduced, and the mice’s behavior demonstrated that rapamycin was acting like an antidepressant. This effect was found across all ages.
Three "feel-good" neurotransmitters — serotonin, dopamine and norepinephrine — all showed significantly higher levels in the midbrain (but not in the hippocampus). As these neurotransmitters are involved in learning and memory as well as mood, it is suggested that this might be a factor in the improved cognition.
Other recent studies have suggested that rapamycin inhibits a pathway in the brain that interferes with memory formation and facilitates aging.
 Chronic inhibition of mammalian target of rapamycin by rapamycin modulates cognitive and non-cognitive components of behavior throughout lifespan in mice. Neuroscience [Internet]. Submitted . Available from: http://www.sciencedirect.com/science/article/pii/S0306452212006720
 . Inhibition of mTOR by Rapamycin Abolishes Cognitive Deficits and Reduces Amyloid-β Levels in a Mouse Model of Alzheimer's Disease. PLoS ONE [Internet]. 2010 ;5(4):e9979 - e9979. Available from: http://dx.doi.org/10.1371/journal.pone.0009979
 . Selective pharmacogenetic inhibition of mammalian target of Rapamycin complex I (mTORC1) blocks long-term synaptic plasticity and memory storage. Proceedings of the National Academy of Sciences [Internet]. 2011 ;108(9):3791 - 3796. Available from: http://www.pnas.org/content/108/9/3791.abstract