A functional axis of mastication and respiration in cognitive function: A narrative review

OBJECTIVE: This review presents an integrative framework of the "Mastication-Respiration Axis," proposing that the masticatory and respiratory systems interact to form a functional axis essential for the development and maintenance of cognitive health in brain circuits. DESIGN: We narratively synthesized studies identified by structured searches of PubMed from inception to September 1, 2025, using predefined keywords related to mastication/chewing, nasal respiration/breathing, and cognition, and including peer-reviewed human and animal studies published in English. RESULTS: Evidence shows that mastication and respiration are coordinated at the brainstem through central pattern generators. Dysfunction in this axis-such as reduced chewing or oral breathing-activates stress and inflammatory pathways. The prefrontal cortex, hippocampus, and cerebellum depend on rhythmic inputs from both systems, with nasal respiration acting as a cortical pacemaker. Animal studies demonstrate that masticatory deficiency impairs hippocampal memory, while respiratory disruption during critical developmental periods causes long-lasting cerebellar and affective-motor deficits, offering a neurobiological basis for clinical links between oral breathing and neurodevelopmental disorders. CONCLUSIONS: Mastication and respiration are not merely peripheral functions but are deeply integrated with the central nervous system, forming a critical axis for brain development, plasticity, and function. Dysfunction in this axis, particularly during sensitive developmental windows, may lead to long-term impairments in memory, motor control, and affective regulation. This integrated model highlights the clinical importance of early interventions in dental, orthodontic, and respiratory health to support lifelong neurological well-being.