It is well established that mice living in an environment that is rich in sensory stimuli, social contact, and cognitive stimulation are better able to learn and remember than mice in a relatively impoverished environment. Enriched mice also show physical signs of a healthier brain, including more synaptic connectivity, more new neurons, and less neuron death. On the other hand, it is generally believed that once a significant amount of neurodegeneration has occurred, such as in Alzheimer’s disease, it is too late for an enriched environment to have much impact.
Yesterday, MIT researchers in the Li-Huei Tsai lab published groundbreaking work arguing that it is not too late to improve learning and recover lost memories even after substantial, Alzheimer’s-like brain degeneration. A richly stimulating environment or a histone deacetylase inhibitor can have this dramatic effect on mice.
In this study, mice first learned to navigate a maze using spatial memory. By genetically manipulating the expression of a particular protein,
p25, the researchers then induced the symptoms and neural pathology of Alzheimer’s in these mice. Over several weeks, their brains atrophied and they lost their ability to navigate the maze they had previously learned. Some of these mice then began living in a much more interesting cage, which included toys, tunnels, running wheels, other mice… you name it, it was an exciting time for these privileged animals.
When compared with mice that lived in a standard boring lab cage, the enriched mice were better able to learn new things and had more synaptic connections between their neurons. Incredibly, they also recovered the ability to navigate the maze and other tasks they had learned before the symptoms and neural degeneration took place.
According to Tsai, “…our mouse model shows that even when there has been a significant loss of neurons, it is still possible to improve learning and memory.”
While these results are very exciting, an important caveat is that rodents are different than people, and the p25 manipulation is not exactly the same thing as Alzheimer’s disease. Thankfully, I’m sure we’ll see more research like this soon. In the meantime, it can’t hurt to live more like privileged rodents: challenge your brain, be social, and always wear close-toed shoes on the running wheel.
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