Mycobiome–Brain Interactions: Emerging Role of Gut Fungi in Neurodegeneration

Abstract

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, are increasingly linked to disruptions in the gut-brain axis. While most research is focusing on bacterial microbiota, the gut mycobiome, or fungal population of the gastrointestinal tract, has emerged as a potentially essential but understudied contributor to neurological health. Gut fungi interact with human immunology, metabolic processes, and microbial networks, and an imbalance (fungal dysbiosis) can cause systemic inflammation, blood-brain barrier disruption, and neuroinflammatory reactions. Microglial activation, oxidative stress, and neuronal damage can be influenced by fungal metabolites and cell wall components, indicating ways in which the mycobiome may contribute to neurodegeneration. Patients with multiple sclerosis, Alzheimer's disease, Parkinson's disease, and several mental disorders have been shown to have altered fungal profiles, suggesting potential involvement in the course of the disease and the severity of its symptoms. The complexity of gut microbial control of brain function is further highlighted by interactions between fungal and bacterial communities. This review summarizes current evidence on gut mycobiome composition, mechanisms of mycobiome–brain communication, and associations with neurodegenerative diseases. Understanding these interactions may reveal novel biomarkers and therapeutic targets, emphasizing the need for longitudinal studies and mycobiome-focused interventions to clarify the clinical significance of gut fungi in neurodegeneration.