The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatryAug 17, 2026

How Vagus Nerve Signals Between the Gut and Brain May Affect Mental Health and Thinking

Gut-Brain Axis Weekly Brief ↗PubMed ↗DOI ↗

Updated Aug 18, 2026

Abstract

The vagus nerve is a key pathway connecting the central nervous system with peripheral organs and is involved in gut-brain communication.

Vagal signaling may influence stress regulation, affective processing, cognition, and the brain's ability to adapt.
Current knowledge emphasizes the role of vagal pathways in modulating various neurotransmitter systems, including noradrenergic, serotonergic, and cholinergic circuits.
Vagus nerve stimulation could serve as a neuromodulatory strategy for several neurological and psychiatric disorders.
Evidence suggests potential benefits of vagus nerve stimulation in conditions such as epilepsy, mood disorders, cognitive impairment, and neurodegenerative diseases.
Variability in stimulation methods and outcome measures may hinder the ability to compare results across studies.

Simplified

The vagus nerve constitutes a core bidirectional pathway linking the central nervous system with peripheral organs and plays a fundamental role in gut-brain communication. Beyond its classical autonomic functions, accumulating evidence positions vagal signaling as a candidate integrative mechanism through which visceral, immune, and microbial inputs may modulate stress regulation, affective processing, cognition, and neuroplasticity. This narrative review synthesizes current anatomical and physiological knowledge of vagal pathways, with emphasis on afferent projections to the nucleus tractus solitarius and downstream modulation of noradrenergic, serotonergic, and cholinergic circuits involving the locus coeruleus, hippocampus, and prefrontal cortex. We further examine vagus nerve stimulation, including invasive and noninvasive approaches, as a neuromodulatory strategy for neurological and psychiatric disorders. Evidence is reviewed for its effects in epilepsy, mood and anxiety disorders, cognitive impairment, and neurodegenerative conditions, highlighting mechanisms such as synaptic plasticity enhancement, neuroimmune modulation, and regulation of hypothalamic-pituitary-adrenal axis activity. While findings support the translational relevance of vagal modulation, variability in stimulation parameters and outcome measures limits cross-study comparison. Greater methodological standardization and integration of neurocognitive endpoints are required to clarify its clinical and neuroscientific significance.