Association between gut microbiota and migraine has been confirmed

An altered gut microbiota composition has already been reported in metabolic, cardiovascular, oncological, neurological and psychiatric disorders. According to the results of a study published in early 2023 by a South Korean team, we can now add migraine to this long list. The researchers studied the stools of 42 individuals with episodic migraine, 45 individuals with chronic migraine (sidenote: Chronic form of migraine Headache for ≥ 15 days per month with ≥ 8 migraine features (increased sensitivity to light, sound or smells, nausea, vomiting…) for > 3 months.  Weatherall MW. The diagnosis and treatment of chronic migraine. Ther Adv Chronic Dis. 2015 May;6(3):115-23. ) and 43 healthy controls, all aged between 19 and 65 years.  The researchers excluded patients undergoing medical or psychiatric treatment other than for anxiety, depression, or fibromyalgia, those who had significantly changed their dietary habits in the previous six months, and those who had taken probiotics or antibiotics in the previous year.

However, all patients took migraine treatment in the case of an episode and 60% were taking disease-modifying treatments (anti-epileptics, beta-blockers, etc.), which may represent a bias (impact on the microbiota) and was taken into account in the analysis of the results.

Microbiota varies according to the study group

No significant differences were observed between the three groups in terms of alpha (sidenote: α diversity A measure indicating the diversity of a single sample, i.e. the number of different species present in an individual. Hamady M, Lozupone C, Knight R. Fast UniFrac: facilitating high-throughput phylogenetic analyses of microbial communities including analysis of pyrosequencing and PhyloChip data. ISME J. 2010;4:17-27. https://www.nature.com/articles/ismej200997 ) and beta (sidenote: β diversity A measure indicating the species diversity between samples, it allows to assess the variability of microbiota diversity between subjects. Hamady M, Lozupone C, Knight R. Fast UniFrac: facilitating high-throughput phylogenetic analyses of microbial communities including analysis of pyrosequencing and PhyloChip data. ISME J. 2010;4:17-27. https://www.nature.com/articles/ismej20099 ) diversity in their gut microbiota. However, the composition of the gut microbiota differed significantly:

• the class Tissierellia and the order Tissierellales  were overrepresented in the 87 individuals with migraine compared to the 43 controls. At the genus level, Roseburia, Eubacterium_g4, Agathobacter, PAC000195_g, and Catenibacterium were more abundant in the migraine groups.
• the class Bacilli and the orders Selenomonadales and Lactobacillales were less abundant in the chronic migraine group compared to the episodic migraine group, as were the classes Selenomonadaceae and Prevotellaceae. At the genus level, the bacterium PAC001212_g predominated in the chronic migraine group, whereas Prevotella, Holdemanella, Olsenella, Adlercreutzia, and Coprococcus characterized the episodic migraine group.

^{Sources (sidenote: Burch RC, Buse DC, Lipton RB. Migraine: Epidemiology, Burden, and Comorbidity. Neurol Clin. 2019 Nov;37(4):631-649. )}

Bacteria linked to headache frequency or intensity

Additional analyses show a link between certain bacterial genera and the clinical characteristics of migraine: a higher composition of PAC000195_g was significantly associated with lower headache frequency; whereas Agathobacter revealed a significant negative association with severe headache intensity.
While these results provide evidence of gut dysbiosis in individuals with migraine, only longitudinal studies will allow us to better understand the relationship between the gut microbiota and migraine (causes and consequences) and, ultimately, the potential to find prophylactic treatments against migraines via the gut microbiota.