Thursday, August 10, 2023

The Gut-Brain Connection: A New Horizon in Neurological Health

The human body is a complex system, and one of its most fascinating connections is the gut-brain axis. This bidirectional communication between the gastrointestinal (GI) tract and the central nervous system (CNS) has recently gained traction in the scientific community, especially concerning acute neurological diseases like stroke, multiple sclerosis, Alzheimer's disease, and migraine.

The gut-brain axis is not just a physical connection between the gut and the brain; it's a complex network involving proinflammatory cells, gut metabolites, hormones, and neural pathways. Key metabolites include trimethylamine N-oxide (TMAO) and short-chain fatty acids (SCFAs), which are believed to play a central role in gut-brain axis dysfunction. 

Over 50% of ischemic stroke survivors experience GI complications, with dysphagia, constipation, and GI bleeding being the most common. Diarrhea, constipation, and gastroesophageal reflux are also more frequent in patients with migraine. These complications are not merely side effects but may contribute to poor functional neurologic outcomes. It is postulated that the propagation of proinflammatory cells and gut metabolites (including trimethylamine N-oxide and short-chain fatty acids) from the GI tract to the central nervous system play a central role in gut-brain axis dysfunction. In fact, plasma trimethylamine N-oxide (TMAO) levels might predict early neurological deterioration (END) in individuals with acute ischemic stroke. 

Stroke itself can lead to gut dysbiosis, alterations in the normal host intestinal microbiome. This dysbiosis may further perpetuate neurological impairments, creating a vicious cycle that challenges recovery.

Cognition is one of the most evaluated neurologic subjects linked to the gut microbiome. Cognitive impairment is particularly prevalent in patients with multiple sclerosis (MS), a chronic neurological disorder.

Referenced reviews discuss the known GI complications in acute ischemic stroke and multiple sclerosis, emerging therapeutics and lifestyle modifications that target the gut-brain axis. 


Yong HYF, Ganesh A, Camara-Lemarroy C. Gastrointestinal Dysfunction in Stroke. Semin Neurol. 2023 Aug 10. doi: 10.1055/s-0043-1771470. Epub ahead of print. PMID: 37562458.

Ghadiri F, Ebadi Z, Asadollahzadeh E, Moghadasi AN. Gut microbiome in multiple sclerosis-related cognitive impairment. Multiple Sclerosis and Related Disorders. 2022 Sep 7:104165.

La Rosa G, Lonardo MS, Cacciapuoti N, Muscariello E, Guida B, Faraonio R, Santillo M, Damiano S. Dietary Polyphenols, Microbiome, and Multiple Sclerosis: From Molecular Anti-Inflammatory and Neuroprotective Mechanisms to Clinical Evidence. International Journal of Molecular Sciences. 2023 Apr 14;24(8):7247.

He Q, Wang W, Xiong Y, Tao C, Ma L, Ma J, You C. A causal effects of gut microbiota in the development of migraine. The Journal of Headache and Pain. 2023 Dec;24(1):1-7.