In the midst of an attack, migraine sufferers may find themselves asking: why them? What about their bodies makes them more susceptible to this painful condition than others? According to research, the microbiome may be a point of distinction, an insight which could lead not only to the improvement of diagnosis and treatment, but perhaps the prevention of this debilitating disorder as well.
Gut Microbiome Differences
The bacteria in the gut microbiome help defend against pathogens, regulate the immune system, absorb nutrients, produce vitamins and protect against disease. When a healthy gut microbiome is perturbed, health issues can ensue, and it’s this dysbiosis which may play a role in migraine.
Differences in the gut microbiome have been observed in a study of elderly women with migraine (1). In the migraine group, there was a significant reduction in highly abundant bacteria known to play an important role in health compared to the healthy controls. Conversely, bacterial species thought to be detrimental to human health were found to be more abundant in migraineurs. In general, the gut of control subjects contained more beneficial and more diverse microorganisms than migraineurs, suggesting a healthier microbiome.
As well as differences in composition, the study also showed differences in vital metabolic functions in the gut microbiota of migraine suffers and healthy subjects including increased GABA synthesis (an important neurotransmitter in the brain) in the migraine group, higher glutamate degradation (the main excitatory neurotransmitter in the healthy brain) in the healthy group and higher quinolinic acid degradation (a metabolite that has a potent neurotoxic effect) also in the healthy group.
Oral Microbiome Differences
Nitric oxide is a chemical which has been linked to the development of migraine (2) and it turns out that people who suffer migraines are more likely to harbour nitric oxide producing bacteria in their mouths than non-migraneurs.
A study conducted by Rob Knight and his team (3) looked into the types of microbes in the mouth and the levels of nitric oxide they produce.
Certain bacterial genes such as nitrate reductase, nitrite reductase and nitric oxide reductase are involved in the modulation of nitric oxide. Healthy participants submitted oral and faecal samples for sequencing. A connection was determined between the presence and abundance of nitrate, nitrite and nitric oxide reductase genes in the samples and the self-reported migraine status of participants. Results showed that migraine sufferers had a higher amount of these genes than non-migraineurs indicating that nitrate-reducing bacteria in the mouth could be contributing to migraine-triggering levels of nitric oxide in the body.
It’s not known yet why some people have more of these nitrate-reducing bacteria than others, but it’s an interesting area of research offering insight into the impact of the microbiome on disease.
Treatment
Understanding that differences exist between the microbiomes of migraneurs and non-migraineurs leads us to ask if anything can be done to ameliorate these microbial differences and thus improve migraine status?
One suggestion made by researchers (1) is that monitoring harmful bacteria in the gut could be a new strategy for early diagnosis and prevention of migraine. Also, probiotics could be administered to migraineurs to treat dysbiosis of the gut and thus prevent the onset of migraine attacks.
Conclusion
The microbiome is now offering a new arena in which to better understand the ways in which migraines occur. The more we know about how microbes interact with our body, the better we can support this important symbiotic relationship, and perhaps one day prevent the onset of migraines through strategies targeting the microbiome.
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Refernces
(1) Chen J, Wang Q, Wang A, Lin Z. Structural and Functional Characterization of the Gut Microbiota in Elderly Women With Migraine. Front Cell Infect Microbiol. 2020 Jan 29;9:470. doi: 10.3389/fcimb.2019.00470. PMID: 32083024; PMCID: PMC7001586.
(2) Gallai, V., Sarchielli, P. Nitric oxide in primary headaches. J Headache Pain 1, 145–154 (2000). https://doi.org/10.1007/s101940070036
(3) Knight, Rob. “Migraines Are Correlated with Higher Levels of Nitrate-, Nitrite-, and Nitric Oxide-Reducing Oral Microbes in the American Gut Project Cohort.” mSystems, vol. 2, no. 2, 2017, pp. 17-23, https://msystems.asm.org/content/1/5/e00105-16.
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