An excellent review has just been published in Nature Reviews Neuroscience on the relationship between enriched environments and the onset and severity of nervous system diseases. A consensus seems to be emerging: putting rodents in enriched environments – cages with space for foraging, toys and social interaction – not only delays disease but reduces the symptoms. The list of diseases for which this effect has been verified is staggering. It reads like a who’s who of neural nightmares: Alzheimers, Huntington’s, Parkinson’s, epilepsy, stroke, traumatic brain injury, Fragile X syndrome and Down syndrome.
How do enriched environments help mitigate the effects of disease? No one quite knows, but scientists are learning that more complex environments create more complex brains. The mind is like a muscle:
Studies investigating the effects of differential housing showed that enrichment altered cortical weight and thickness. Subsequently, various studies have shown that enrichment increases dendritic spines and the size of synapses on some neuronal populations. Furthermore, enrichment increases hippocampal neurogenesis and the integration of these newly born cells into functional circuits.
One leading theory is that having more neuronal connections and dendritic spines simply means that you are able to lose more neurons before you notice the loss. Enriched environments, then, act like a buffer. While they don’t prevent disease, they do slow the damage.
It’s also worth noting that many of these enriched environment studies show more profound and consistent benefits than just about any drug that has been approved by the FDA for these brain diseases. If we had a pill that could do half of what enriched environments can do, I’m sure we would all be popping them like candy. Unfortunately, it’s much easier to prescribe a pill than fix our public schools.