A study using a colon tumor mouse model suggested that environmental enrichment could decrease tumor growth through enhanced microbiota diversity (Bice et al., 2017), and a study using a Parkinson's disease mouse model (mice overexpressing the complete human SNCA gene) found that enrichment reduced gut inflammatory markers and was able to modify the gut microbiome composition (Singh et al., 2019). This evidence concerns the gene SNCA and colonic neoplasm.