| Therapeutic strategy | Description | Mechanism of action | Potential benefits |
| Probiotics | Live microorganisms that are similar to the beneficial bacteria that are naturally found in the gut. | Probiotics can help to restore the balance of gut bacteria and improve gut health. | Probiotics have been shown to be effective in treating a variety of neurological and psychiatric disorders, including depression, anxiety, autism, and Alzheimer’s disease [45] . |
| Prebiotics | Non-digestible fibers that feed the beneficial bacteria in the gut. | Prebiotics help to promote the growth of beneficial bacteria in the gut. | Prebiotics have been shown to improve gut health and reduce inflammation. Prebiotics are also being investigated as a potential treatment for a variety of neurological and psychiatric disorders [46] . |
| Fecal microbiota transplantation (FMT) | A procedure in which fecal matter from a healthy donor is transplanted into the gut of a person with a diseased microbiome. | FMT can help to restore the balance of gut bacteria and improve gut health. | FMT has been shown to be effective in treating recurrent Clostridium difficile infection. FMT is also being investigated as a potential treatment for a variety of other conditions, including neurological and psychiatric disorders [47] . |
| Vagus Nerve Stimulation | Non-invasive or surgically implanted device that stimulates the vagus nerve, influencing brain activity and gut function. | Reduces inflammation, improve mood and emotional regulation, potentially modulate gut microbiota. Left cervical VNS is an approved therapy for refractory epilepsy and for treatment resistant depression. | May offer benefits for treatment-resistant depression, epilepsy, and chronic pain. The relationship between depression, inflammation, metabolic syndrome, and heart disease might be mediated by the vagus nerve [11] . |