Social contact influences histological and behavioral outcomes following cerebral ischemia: http://www.ncbi.nlm.nih.gov/pubmed/19733169 Social isolation alters neuroinflammatory response to stroke: http://www.ncbi.nlm.nih.gov/pubmed/19307557 Environmental enrichment enhances cellular plasticity in transgenic mice with Alzheimer-like pathology: http://www.ncbi.nlm.nih.gov/pubmed/19118549 Long-term assessment of enriched housing and subventricular zone derived cell transplantation after focal ischemia in rats: http://www.ncbi.nlm.nih.gov/pubmed/18675262 Environmental enrichment counteracts Alzheimer's neurovascular dysfunction in TgCRND8 mice: http://www.ncbi.nlm.nih.gov/pubmed/17924982 Environmental enrichment augments the efficacy of idiotype vaccination for B-cell lymphoma: http://www.ncbi.nlm.nih.gov/pubmed/17589292 Social interaction improves experimental stroke outcome: http://www.ncbi.nlm.nih.gov/pubmed/16100018 Loss of Environmental Enrichment Increases Vulnerability to Cocaine Addiction: http://www.ncbi.nlm.nih.gov/pubmed/22334125 Everything from Stroke recovery, to vaccination, to cocaine addiction. And here's the one I was looking for!: Environmental and genetic activation of a brain-adipocyte BDNF/leptin axis causes cancer remission and inhibition: http://www.ncbi.nlm.nih.gov/pubmed/20603014 Cancer is influenced by its microenvironment, yet broader, environmental effects also play a role but remain poorly defined. We report here that mice living in an enriched housing environment show reduced tumor growth and increased remission. We found this effect in melanoma and colon cancer models, and that it was not caused by physical activity alone. -That's an environmental affect (namely, one that stimulates mental activity) upon tumor progression. Cell is a very difficult journal to get into, so it's very likely that there is something behind this study.