Psychoneurogastroenterology: The Abdominal Brain, the Microbiome, and Psychiatry: Neuropsychiatric Researchers Have Long Ignored the Enteric Nervous System and the Microbiome; It's Time for Them to Focus on How to Exploit These Entities
Bibliographic record
Abstract
Existence of a gastrointestinal (GI) nervous system, distinct from the CNS that comprises the brain and spinal cord, has been recognized for more than a century (1)--yet it has been ignored by psychiatry and rarely is included in residency training. This nervous system is located inside the wall of the GI tract, extending from the esophagus to the rectum. Technically, it is known as the enteric nervous system, or ENS, but it has been given labels, too: second brain, (2) brain, other brain, and back-up Its neurologic disorders include abdominal epilepsy, abdominal migraine, and autism with intestinal symptoms, such as chronic enterocolitis. (3) Impressive brain-like features The ENS includes 100 million neurons (same as the spinal cord) with glia-like support cells. It contains >30 neurotransmitters, including several closely linked to psychopathology (serotonin, dopamine, [gamma]-aminobutyric acid, and acetylcholine). The ENS is not part of the autonomic nervous system. It communicates with the brain via the vagus nerve. A vast system of gut bacteria The ENS maintains close links with, and is influenced by, the microbiome, an extensive universe of commensal (that is, symbiotic) bacteria in the gut that play a vital role in immune health, brain function, and signaling systems within the CNS. The role of the microbiome in neuropsychiatric disorders has become a sizzling area of research. The numbers of the microbiome are astonishing, including approximately 1,000 species of bacteria; 100 trillion total bacterial organisms (outnumbering cells of the body by 100-fold); 4 million bacterial genes (compared with 26,000 genes in the host human genome); and a density as high as 1 trillion bacteria in a cubic milliliter--higher than any known microbial system. (4) Significant Gl-brain connections It is of great relevance to psychiatry that 90% of the body's serotonin and 50% of dopamine are found in the GI brain. Selective serotonin reuptake inhibitors often are associated with GI symptoms, such as nausea and diarrhea; antipsychotics, which are dopamine antagonists, are known for antiemetic effects. Clozapine's potent anticholinergic effects can cause serious ileus. Things get more interesting when one considers the association of GI disorders and psychiatric symptoms: Irritable bowel syndrome is associated with panic disorder, generalized anxiety disorder, social phobia, dysthymia, and major depression. Inflammatory bowel disease (IBD)--such as Crohn's disease and ulcerative colitis (prevalence ranging from 6% in Canada to 14% in the United States to 46% in Mexico (5))--is commonly associated with mood and anxiety disorders and personality changes. The psychiatric manifestations of IBD are so common that the authors of a recent article in World Journal of Gastroenterology urged gastroenterologists to collaborate with psychiatrists when managing IBD. (6) Celiac disease has been repeatedly associated with several neuropsychiatric disorders, including ataxia, epilepsy, peripheral neuropathy, headache, anxiety, attention-deticit/hyperactivity disorder, autism spectrum disorder, and schizophrenia. …
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.004 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.003 | 0.006 |
| Insufficient payload (model declined to judge) | 0.016 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".