This decrease in IL-4 with dementia severity may help explain the rapid cognitive decline seen in later stages of dementia as IL-4 can protect against amyloid-beta (Aβ)-induced neuronal toxicity while inducing a microglial phenotype that favours brain homeostasis and neuronal protection and repair (Szczepanik et al., 2001; Cherry et al., 2015). This evidence concerns the gene IL4 and Mental deterioration.