Studies on the roundworm C. elegans have revealed that the molecules required for learning and memory are the same from C. elegans to mammals, suggesting that the basic mechanisms underlying learning and memory are ancient, and that this animal can serve as a testing ground for treatments for age-related memory loss. Intriguingly, a comparison of two known regulators of longevity — reducing calorie intake and reducing activity in the insulin-signaling pathway (achieved through genetic manipulation) — has found that these two treatments produce very different effects on memory. While dietary restriction impaired memory in early adulthood, it maintained memory with age. On the other hand, reduced insulin signaling improved early adult memory performance but failed to preserve it with age. These different effects appear to be linked to expression of CREB, a protein known to be important for long-term memory. Young roundworms with defective insulin receptors had higher levels of CREB protein, while those worms genetically altered to eat less had low levels, but the level did not diminish with age. These findings add to our understanding of why memory declines with age.
(2010). Insulin Signaling and Dietary Restriction Differentially Influence the Decline of Learning and Memory with Age.
PLoS Biol. 8(5), e1000372 - e1000372.