A number of studies suggest that enriched environments ameliorate the effects of traumatic brain injury; neurodevelopment and ageing; neurodegenerative diseases such as Alzheimers and Huntington's; depression, fear and stress; addictions; epilepsy... and seem to function via increase of cognitive reserve.
Benefits include increase in synaptic density, neurotrophic support, glial proliferation, neurogenesis, vasculature support. Several studies have been done in our labs (Subicular lesion studies by Anandh and Bindu B; Restraint stress by Ramkumar and Veena; Fear conditioning by Preethi; Depression by Mahati and now on Epilepsy as well).