Masticatory Dysfunction and Hippocampal Volume in Ageing Adults: An MRI-Based Scoping Review

Area of Science:

• Neuroimaging
• Gerontology
• Oral Health

Background:

• Preclinical studies suggest tooth loss accelerates brain degeneration.
• Human neuroanatomical evidence linking mastication and brain health is lacking.
• This study synthesizes structural MRI findings in older adults.

Purpose of the Study:

• To map and critically appraise structural MRI studies.
• To investigate associations between masticatory function and medial-temporal lobe morphology.
• Focus on adults aged 60 years and older.

Main Methods:

• Systematic literature search (PubMed, Embase, etc.) from 1995 to June 2025.
• Included studies on adults ≥60 years with quantitative masticatory indicators and structural neuroimaging.
• Data extraction and quality appraisal using JBI adaptation for neuroimaging.

Main Results:

• Eight studies (2016-2024) from Japan, Taiwan, and Sweden were included.
• Six studies reported inverse associations between poorer mastication and smaller hippocampal/parahippocampal volumes.
• Dose-response relationships were observed, with tooth loss correlating with reduced brain volume.

Conclusions:

• Evidence suggests an inverse relationship between masticatory function and medial-temporal lobe integrity in older adults.
• Causality cannot be inferred from current structural MRI data.
• Longitudinal studies with standardized metrics are needed to determine temporality and the impact of oral rehabilitation.