The impact of mastication on cognition: Evidence for intervention and the role of adult hippocampal neurogenesis

Abstract

Adult hippocampal neurogenesis (AHN) in the dentate gyrus of the hippocampus has been shown to affect mood, cognition, learning ability and memory. A growing area of interest is whether mastication or chewing also affects AHN. This article aims to collect the evidence from animal and human studies to ascertain whether mastication is an oral environment enrichment capable of having a modulatory effect on AHN and associated behaviors. Current data point toward a causal relationship between masticatory ability and cognitive function. Experimental studies on mice and rats have consistently shown that impairing masticatory function results in physical and behavioral changes. A recurring theme of decreased neural stem cells proliferation in the hippocampus was seen in most of the studies found. Human population study has shown that tooth loss and masticatory difficulty are positively correlated with having greater odds of cognitive impairment. However, no causal mechanism has yet been found to explain the effects of mastication on AHN. Further clinical studies, in humans, are currently conducted to ascertain whether mastication could be used as a potential health intervention to slowdown cognitive decline in the aging population or delay the onset of diseases such as dementia.