Diet and the microbiome-gut-brain axis: implications for clinical neuropsychology

To synthesize current evidence on the microbiome-gut-brain axis, with a specific focus on dietary modulation, and to outline its relevance and practical implications for clinical neuropsychology.

This narrative review synthesizes literature on mechanistic pathways linking diet, the gut microbiome, and brain health, including interoception and vagal signaling, immune education within the gut-associated lymphoid tissue, microbial metabolites such as short-chain fatty acids, and hypothalamic-pituitary-adrenal axis regulation. Content is based on the author's invited National Academy of Neuropsychology lecture and considers methodological limitations of the field, including variability in sequencing pipelines, reliance on preclinical models, and limited clinical translation.

The gut microbiome plays a critical role in bidirectional communication between the gastrointestinal tract and central nervous system, influencing cognition, mood, behavior, and neurodegenerative processes. Diet is one of the most powerful and modifiable determinants of gut microbiome composition and function, with downstream effects on immune regulation, neuroendocrine signaling, and neural activity relevant to brain health.

Diet represents a foundational, adjunctive strategy for supporting brain health and cognitive resilience across the lifespan. Neuropsychologists can meaningfully incorporate evidence-based dietary discussion into assessment, patient education, and interdisciplinary care coordination, reinforcing established public health guidance rather than providing individualized medical nutrition therapy.