Gut-brain Axis and migraine headache: a comprehensive review

Systematic review and meta-analysis of calculating degree of comorbidity of irritable bowel syndrome with migraine

BACKGROUND

Irritable bowel syndrome (IBS) and migraines are often comorbid each other. These disorders are likely to be bidirectionally linked through the gut-brain axis and share several underlying mechanisms including central nervous system sensitization. However, quantitative analysis of comorbidity was not reported enough. The aim of this systematic review and meta-analysis was to calculate the present degree of comorbidity of these two disorders.

METHODS

A literature search was performed searching for articles describing IBS or migraine patients with the same inverse comorbidity. Pooled odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (CIs) were then extracted. The total effect estimates were determined and presented by random effect forest plots for the group of articles with IBS patients with migraine and the group of articles on migraine sufferers with comorbid IBS separately. The average results of these plots were compared.

RESULTS

The literature search resulted in initial 358 articles and final 22 articles for the meta-analysis. The total OR values obtained were 2.09 [1.79 - 2.43] in IBS with comorbid migraine or headache, 2.51 [1.76 - 3.58] for migraineurs with comorbid IBS and an overall HR of 1 .62 [1.29 - 2.03] was found for cohort studies of migraine sufferers with comorbid IBS. A similar expression of a selection of other comorbidities was found in IBS and migraine patients, especially for depression and fibromyalgia a strong similarity was found in their expression rate.

CONCLUSIONS

This systematic review with meta-analysis was the first to combine data on IBS patients with comorbid migraine and migraineurs with comorbid IBS. The fact that closely related existential rates were observed between these two groups should be used as motivation for future research to further investigate these disorders for why this similarity occurs. Mechanisms involved in central hypersensitivity such as genetic risk factors, mitochondrial dysfunction and microbiota are particularly good candidates. Experimental designs in which therapeutic methods for these conditions can be exchanged or combined may also lead to the discovery of more efficient treatment methods.

Neuroendocrine and neuroimmune mechanisms underlying comorbidity of pain and obesity

Pain and obesity, as well as their associated impairments, are major health concerns. Understanding the relationship between the two is the focus of a growing body of research. However, early researches attribute increased mechanical stress from excessive weight as the main factor of obesity-related pain, which not only over-simplify the association, but also fail to explain some controversial outcomes arising from clinical investigations. This review focuses on neuroendocrine and neuroimmune modulators importantly involved in both pain and obesity, analyzing nociceptive and anti-nociceptive mechanisms based on neuroendocrine pathways including galanin, ghrelin, leptin and their interactions with other neuropeptides and hormone systems which have been reported to play roles in pain and obesity. Mechanisms of immune activities and metabolic alterations are also discussed, due to their intense interactions with neuroendocrine system and crucial roles in the development and maintenance of inflammatory and neuropathic pain. These findings have implications for health given rising rates of obesity and pain-related diagnoses, by providing novel weight-control and analgesic therapies targeted on specific pathways.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Perspectives on Neuronutrition in Prevention and Treatment of Neurological Disorders

The term neuronutrition has been proposed as part of nutritional neuroscience, studying the effects of various dietary components on behavior and cognition. Other researchers underline that neuronutrition includes the use of various nutrients and diets to prevent and treat neurological disorders. The aim of this narrative review was to explore the current understanding of the term neuronutrition as the key concept for brain health, its potential molecular targets, and perspectives of its nutritional approach to the prevention and treatment of Alzheimer's and Parkinson's diseases, multiple sclerosis, anxiety, depressive disorders, migraine, and chronic pain. Neuronutrition can be defined as a part of neuroscience that studies the influence of various aspects of nutrition (nutrients, diet, eating behavior, food environment, etc.) on the development of nervous disorders and includes nutrition, clinical dietetics, and neurology. There is evidence that the neuronutritional approach can influence neuroepigenetic modifications, immunological regulation, metabolic control, and behavioral patterns. The main molecular targets in neuronutrition include neuroinflammation, oxidative/nitrosative stress and mitochondrial dysfunction, gut-brain axis disturbance, and neurotransmitter imbalance. To effectively apply neuronutrition for maintaining brain health, a personalized approach is needed, which includes the adaptation of the scientific findings to the genetic, biochemical, psycho-physiological, and environmental features of each individual.

Probiotics as functional foods: How probiotics can alleviate the symptoms of neurological disabilities

Neurological disorders are diseases of the central nervous system with progressive loss of nervous tissue. One of the most difficult problems associated with neurological disorders is that there is no clear treatment for these diseases. In this review, the physiopathology of some neurodegenerative diseases, etiological causes, drugs used and their side effects, and finally the role of probiotics in controlling the symptoms of these neurodegenerative diseases are presented. Recently, researchers have focused more on the microbiome and the gut-brain axis, which may play a critical role in maintaining brain health. Probiotics are among the most important bacteria that have positive effects on the balance of homeostasis via influencing the microbiome. Other important functions of probiotics in alleviating symptoms of neurological disorders include anti-inflammatory properties, short-chain fatty acid production, and the production of various neurotransmitters. The effects of probiotics on the control of abnormalities seen in neurological disorders led to probiotics being referred to as "psychobiotic. Given the important role of the gut-brain axis and the imbalance of the gut microbiome in the etiology and symptoms of neurological disorders, probiotics could be considered safe agents that positively affect the balance of the microbiome as complementary treatment options for neurological disorders.

Migraine, inflammatory bowel disease and celiac disease: A Mendelian randomization study

OBJECTIVE

To assess whether migraine may be genetically and/or causally associated with inflammatory bowel disease (IBD) or celiac disease.

BACKGROUND

Migraine has been linked to IBD and celiac disease in observational studies, but whether this link may be explained by a shared genetic basis or could be causal has not been established. The presence of a causal association could be clinically relevant, as treating one of these medical conditions might mitigate the symptoms of a causally linked condition.

METHODS

Linkage disequilibrium score regression and two-sample bidirectional Mendelian randomization analyses were performed using summary statistics from cohort-based genome-wide association studies of migraine (59,674 cases; 316,078 controls), IBD (25,042 cases; 34,915 controls) and celiac disease (11,812 or 4533 cases; 11,837 or 10,750 controls). Migraine with and without aura were analyzed separately, as were the two IBD subtypes Crohn's disease and ulcerative colitis. Positive control analyses and conventional Mendelian randomization sensitivity analyses were performed.

RESULTS

Migraine was not genetically correlated with IBD or celiac disease. No evidence was observed for IBD (odds ratio [OR] 1.00, 95% confidence interval [CI] 0.99-1.02, p = 0.703) or celiac disease (OR 1.00, 95% CI 0.99-1.02, p = 0.912) causing migraine or migraine causing either IBD (OR 1.08, 95% CI 0.96-1.22, p = 0.181) or celiac disease (OR 1.08, 95% CI 0.79-1.48, p = 0.614) when all participants with migraine were analyzed jointly. There was some indication of a causal association between celiac disease and migraine with aura (OR 1.04, 95% CI 1.00-1.08, p = 0.045), between celiac disease and migraine without aura (OR 0.95, 95% CI 0.92-0.99, p = 0.006), as well as between migraine without aura and ulcerative colitis (OR 1.15, 95% CI 1.02-1.29, p = 0.025). However, the results were not significant after multiple testing correction.

CONCLUSIONS

We found no evidence of a shared genetic basis or of a causal association between migraine and either IBD or celiac disease, although we obtained some indications of causal associations with migraine subtypes.

The microbiota-gut-brain axis and three common neurological disorders: a mini-review

Neurological disorders are an important cause of disability and death globally. Recently, a large body of research shows that the gut microbiome affects the brain and its conditions, through the gut-brain axis. The purpose of this mini-review is to provide a brief overview of the relationship between the microbiota-gut-brain axis in three neurological disorders: epilepsy, Parkinson's disease, and migraine. The authors chose these three disorders because of their burdensome and great effect on health care. We live on a microbial planet. Before humans, microorganisms existed for a hundred million years. Today, there are trillions of these microbes living in our bodies, it is called human microbiota. These organisms have a crucial role in our homeostasis and survival. Most of the human microbiota live in the gut. The number of gut microbiota is much more than the number of body cells. Gut microbiota has been regarded as a crucial regulator of the gut-brain axis. The discovery of the microbiota-gut-brain axis is described as a major advancement in neuroscience because it influences the pathophysiology of several neurological and psychiatric disorders. From this, more studies of the microbiota-gut-brain axis are needed in the future, to provide a better understanding of brain disorders and so that better treatment and prognosis.

Serum Zonulin Levels in Pediatric Migraine

BACKGROUND

Migraine is a complex neurogenic inflammatory disorder. There are strong neuronal, endocrine, and immunologic connections between the brain and gastrointestinal system. Damage to the intestinal barrier is thought to cause systemic immune dysregulation. Zonulin is a protein produced by the small intestine epithelium in humans that regulates intestinal permeability through intracellular tight junctions and is a potential marker for inflammation. Zonulin increases in positive correlation with permeability. In our study, we aimed to research the correlation between serum zonulin levels in the period between attacks in pediatric patients with migraine.

METHODS

The study included 30 patients with migraine and 24 healthy controls, matched in terms of sex and age. Demographic and clinical characteristics were recorded. Serum zonulin levels were studied with the enzyme-linked immunosorbent assay method.

RESULTS

Patients had a mean of 5.6 ± 3.5 attacks per month. The mean serum zonulin was 5.68 ± 1.21 ng/mL in the migraine group and 5.72 ± 2.1 ng/mL in the control group with no significant difference found (P = 0.084). In the migraine group, no correlations were identified between serum zonulin levels and age, body mass index, pain frequency, pain duration, onset time, visual analog scale score, and presence of gastrointestinal systems apart from nausea-vomiting.

CONCLUSIONS

More than 50 proteins were identified to affect the intestinal permeability apart from zonulin. There is a need for prospective studies encompassing the time of attack, but our study is important as it is the first study about zonulin levels in pediatric migraine.

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

Helicobacter pylori Infection in Children: A Possible Reason for Headache?

(1) Background: The correlation between infection with Helicobacter pylori (H. pylori) and headache has been argued and explored for a long time, but a clear association between the simultaneous presence of the two in children has not been established yet. In this study, we aimed to explore this relationship in children from the Northeast region of Romania. (2) Methods: A retrospective study exploring the correlation between children having H. pylori infection and headache or migraine was conducted on a batch of 1757 children, hospitalized over 3 years in a pediatric gastroenterology department in Northeast Romania. (3) Results: A total of 130 children of both sexes had headache. From 130 children, 54 children (41.5%) also presented H. pylori infection. A significant association between headache and H. pylori infection (χ2; p < 0.01) was noticed. (4) Conclusions: More studies are needed on this relationship, and we emphasize the importance of further analyses, as they present great clinical importance for both prompt diagnosis and treatment.

Gut microbiota mediated the individualized efficacy of Temozolomide via immunomodulation in glioma

BACKGROUND

Temozolomide (TMZ) is the preferred chemotherapy strategy for glioma therapy. As a second-generation alkylating agent, TMZ provides superior oral bio-availability. However, limited response rate (less than 50%) and high incidence of drug resistance seriously restricts TMZ's application, there still lack of strategies to increase the chemotherapy sensitivity.

METHODS

Luci-GL261 glioma orthotopic xenograft model combined bioluminescence imaging was utilized to evaluate the anti-tumor effect of TMZ and differentiate TMZ sensitive (S)/non-sensitive (NS) individuals. Integrated microbiomics and metabolomics analysis was applied to disentangle the involvement of gut bacteria in TMZ sensitivity. Spearman's correlation analysis was applied to test the association between fecal bacteria levels and pharmacodynamics indices. Antibiotics treatment combined TMZ treatment was used to confirm the involvement of gut microbiota in TMZ response. Flow cytometry analysis, ELISA and histopathology were used to explore the potential role of immunoregulation in gut microbiota mediated TMZ response.

RESULTS

Firstly, gut bacteria composition was significantly altered during glioma development and TMZ treatment. Meanwhile, in vivo anti-cancer evaluation suggested a remarkable difference in chemotherapy efficacy after TMZ administration. Moreover, 16s rRNA gene sequencing and non-targeted metabolomics analysis revealed distinct different gut microbiota and immune infiltrating state between TMZ sensitive and non-sensitive mice, while abundance of differential gut bacteria and related metabolites was significantly correlated with TMZ pharmacodynamics indices. Further verification suggested that gut microbiota deletion by antibiotics treatment could accelerate glioma development, attenuate TMZ efficacy and inhibit immune cells (macrophage and CD8α⁺ T cell) recruitment.

CONCLUSIONS

The current study confirmed the involvement of gut microbiota in glioma development and individualized TMZ efficacy via immunomodulation, hence gut bacteria may serve as a predictive biomarker as well as a therapeutic target for clinical TMZ application.

[The state of the oropharyngeal microbiome in patients with migraine]

OBJECTIVE

To determine a role of changes in the oropharyngeal microbiome in the development and clinical manifestations of migraine.

MATERIAL AND METHODS

Seventy patients with migraine, aged 21-56 years, and 15 healthy subjects matched for age and sex were examined using headache diary, MIDAS and VAS, the Gastrointestinal Symptom Rating Scale (GSRS), microbiological smear examination from the mucous membrane of the posterior wall of the oropharynx with evaluation by the method of mass spectrometry of microbial markers (MSMM) with determination of 57 microorganisms.

RESULTS

The following changes in the oropharynx of individuals with migraine compared with the group of healthy individuals (control group) were found: a) a significant increase in the content of markers of resident (conditionally pathogenic) microorganisms characteristic of chronic diseases of the upper respiratory tract (strepto- and staphylococci); b) the appearance of markers of transient microorganisms normally absent, characteristic of the intestinal microflora (clostridia, gram-negative rods, enterobacteria, anaerobes); c) the appearance of viral markers of cytomegaloviruses, Herpes group, Epstein-Barr; d) a significant decrease in the content of bifidobacteria and lactobacilli). All people with migraine had a history or were found on examination to have chronic diseases of the upper respiratory tract (sinusitis in 48%, pharyngitis in 43%, tonsillitis in 25% of people), and gastrointestinal diseases. Dyspepsia was the most frequent and pronounced of the gastrointestinal syndromes on the GSRS in people with migraine (87%). This corresponds to the data on the extremely frequent occurrence of IBS (70% of patients) and other gastrointestinal pathology obtained from the patient history.

CONCLUSION

In our work, the microbiota of the oropharynx in patients with migraine was studied for the first time using a new MSMM method. Disturbance of the oropharyngeal microbiome compared to the norm was detected in 100% of people with migraine. The changes characteristic of most patients included a significant decrease in the content of normal flora, an increase in the concentration of conditionally pathogenic microorganisms and the appearance of pathogenic microflora characteristic of chronic diseases of the upper respiratory tract and gastrointestinal tract, which may indicate their role in the pathogenesis of migraine.

Associations between the Gut Microbiome and Migraines in Children Aged 7-18 Years: An Analysis of the American Gut Project Cohort

BACKGROUND

The gut microbiome seems to play a role in migraines through increasing intestinal epithelial permeability and pro-inflammatory processes. The associations between the gut microbiome and migraines are uncertain in children.

AIM

The purpose of this quantitative study was to examine the associations between the gut microbiome and migraines in children aged 7-18 years from the American Gut Project (AGP).

METHOD

A cohort of children aged 7-18 years from the AGP was analyzed. 16S rRNA V4 gene sequences for the gut microbiome, migraines, and demographics were obtained from the AGP Public Repository. After quality control of 16S rRNA gene sequences, α-diversity (Shannon, Faith's_PD, and evenness) and β-diversity metrics (Bray-Curtis and weighted-UniFrac distances), taxonomy, and abundance analyses were implemented using QIIME 2.

RESULTS

In total, 381 children (341 without migraines; 40 with professional or self-diagnosed migraines) were analyzed with a mean age of 11.5 years. Compared with those without migraines, children with migraines showed lower estimates in Shannon and Faith's_PD (p < .01). Both Bray-Curtis and weighted-UniFrac distances displayed the gut microbial dissimilarities between these two groups (p = .001). Children with migraines had higher abundances in genus of phylum Bacteroidetes (Bacteroides, Parabacteroides, Odoribacter), Actinobacteria (Eggerthella, Varibaculum), Firmicutes (SMB53, Lachnospira, Dorea, Veillonella, Anaerotruncus, Butyricicoccus, Coprobacillus, Eubacterium), and Proteobacteria (Sutterella) than children without migraines.

CONCLUSIONS

Associations of the gut microbiome diversity and abundances with migraines in children indicated potential biological mechanisms of migraines. Future work needs to confirm our findings in children.

Altered gut microbiota in individuals with episodic and chronic migraine

Emerging evidence reveals a close association between gut microbiota and human neurological disorders. The present study aimed to assess whether the composition of gut microbiota in participants with episodic migraine (EM) and chronic migraine (CM) was altered in comparison to that of the controls. This study was a cross-sectional, case-control study. The gut microbiota were evaluated by the partial, targeted sequencing of the 16S rRNA V3-V4 region. This study enrolled 42 and 45 participants with EM and CM, respectively, and 43 controls. Alpha and beta diversities revealed no significant difference among the three groups; however, the microbiota composition at the class, order, family, and genus levels differed significantly between EM and the control, CM and the control, and the EM and CM groups. Moreover, higher composition of PAC000195_g was significantly associated with a lower headache frequency among the five genera that exhibited significantly different microbiota composition in EM and CM. Agathobacter revealed a significant negative association with severe headache intensity. The findings of the present study provide evidence of altered gut microbiota in EM and CM. These findings will help in understanding the course and treatment of migraine.

The Microbiota-Dependent Treatment of Wuzhuyu Decoction for Chronic Migraine Model Rat Associated with Anxiety-Depression Like Behavior

We previously found that Wuzhuyu Decoction (WZYD) could affect central and peripheral 5-HT to relieve hyperalgesia in chronic migraine (CM) model rats, possibly related to gut microbiota. However, the exact role of gut microbiota has not been elucidated. Accumulating evidence points to the possibility of treating central nervous system disease via the gut-brain axis. In our study, the inflammatory soup-induced CM model rats presented depression- and anxiety-like behaviors which both related to insufficient 5-HT. It was found that antibiotic administration caused community dysbiosis, and proteobacteria became the main dominant bacteria. The bacteria related to short-chain fatty acids and 5-HT generation were reduced, resulting in reduced levels of 5-HT, tryptophan hydroxylase, and secondary bile acids. Functional prediction-revealed sphingolipid signaling pathway in CM rats was significantly decreased and elevated after WZYD treatment. The effect of WZYD could be weakened by antibiotics. The CM rats exhibited anxiety- and depression-like behavior with 5-HT and number of neurons decreased in the CA1 and CA2 regions of hippocampal. The treatment of WZYD could recover to varying degrees. Antibiotics combined with WZYD attenuate the effect of WZYD on increasing the 5-HT content and related protein expression in the brain stem, plasma and colon, reducing CGRP, c-Fos, and inflammatory factors. And antibiotics also led to colon length increasing and stool retention, so that the antimigraine effect was weakened compared with WZYD. This experiment revealed that gut microbiota mediated WZYD treatment of CM rats with anxiety-depression like behavior.

Nutrition and Calcitonin Gene Related Peptide (CGRP) in Migraine

Targeting calcitonin gene-related peptide (CGRP) and its receptor by antibodies and antagonists was a breakthrough in migraine prevention and treatment. However, not all migraine patients respond to CGRP-based therapy and a fraction of those who respond complain of aliments mainly in the gastrointestinal tract. In addition, CGRP and migraine are associated with obesity and metabolic diseases, including diabetes. Therefore, CGRP may play an important role in the functioning of the gut-brain-microflora axis. CGRP secretion may be modulated by dietary compounds associated with the disruption of calcium signaling and upregulation of mitogen-activated kinase phosphatases 1 and 3. CGRP may display anorexigenic properties through induction of anorexigenic neuropeptides, such as cholecystokinin and/or inhibit orexigenic neuropeptides, such as neuropeptide Y and melanin-concentrating hormone CH, resulting in the suppression of food intake, functionally coupled to the activation of the hypothalamic 3',5'-cyclic adenosine monophosphate. The anorexigenic action of CGRP observed in animal studies may reflect its general potential to control appetite/satiety or general food intake. Therefore, dietary nutrients may modulate CGRP, and CGRP may modulate their intake. Therefore, anti-CGRP therapy should consider this mutual dependence to increase the efficacy of the therapy and reduce its unwanted side effects. This narrative review presents information on molecular aspects of the interaction between dietary nutrients and CGRP and their reported and prospective use to improve anti-CGRP therapy in migraine.

The association between dietary fiber intake and severe headaches or migraine in US adults

Background

The data on the effect of dietary fiber on severe headaches or migraine are limited. Therefore, this study aimed to investigate the association between dietary fiber intake and the prevalence of severe headaches or migraine.

Methods

We conducted a cross-sectional study involving 12,710 participants, all data collected from NHANES 1999-2004. A multivariable logistic regression model was used to analyze the relationship between dietary fiber intake (as an independent variable) and severe headaches or migraine (as outcome variable). We also performed sensitivity analyses, including multiple sensitivity analyses.

Results

The overall incidence of severe headache or migraine in the study was 2527/12,710 (19.9%). After adjusting for correlation covariates, we found a significant inverse association between dietary fiber intake and severe headache or migraine, with lowest prevalence in the fifth quintile (OR: 0.74, 95% CI: 0.61-0.90). Our study also revealed that for every 10 g/day increase in dietary fiber intake, the prevalence of severe headache or migraine decreased by 11%. However, no such inverse association was found among Mexican Americans, other races, or those with a body mass index (BMI) of 25-30. E-value analysis suggested robustness to unmeasured confounding.

Conclusion

Increasing the intake of fiber-rich foods might protect from severe headache or migraine. More prospective studies should be conducted to confirm their association before dietary recommendations.

Migraine and obesity: what is the real direction of their association?

INTRODUCTION

In recent decades, studies have addressed the issue of how migraine and obesity are related and have suggested obesity as a risk factor for migraine headache. However, the exact direction of this relationship remains under debate. In this review, the authors summarize the evidence that have suggested migraine as a risk factor for obesity and overweightness.

AREAS COVERED

This article reviews the results of the previous research published on PubMed and Scopus databases (from 2000 to 2020) concerning the association between migraine and obesity to determine the actual direction of their association. Special attention has been given to the common mechanistic pathways involved in the pathophysiology of migraine and obesity.

EXPERT OPINION

The majority of research conducted thus far has considered obesity as a risk factor for migraine. However, because of the cross-sectional design of available research, we cannot be certain of the proposed direction of this association. There is evidence supporting the hypothesis that obesity can serve as a consequence of migraine through the effects of neuropeptides, inflammatory mediators, adipokines, gut microbiota and modifications in eating behavior and lifestyle. However, the real direction of the relationship between migraine and obesity should be further investigated in large prospective studies.

Primary headache disorders in Latin America and the Caribbean: A meta-analysis of population-based studies

BACKGROUND

In this manuscript, we aim to systematically estimate the pooled prevalence and incidence of primary headaches and its subtypes (migraine, tension-type headache, and chronic headaches) in Latin America and the Caribbean, describing its epidemiological profile and associated factors.

METHODS

We systematically searched PubMed/MEDLINE, Scopus, and LILACS (From conception to March 2021), for populational studies reporting the epidemiology of primary headaches and their associated factors in Latin America and the Caribbean. The data extraction was conducted independently. We performed random-effect model meta-analysis of prevalence (overall primary headaches and by subtypes) and associated factors, assessed potential sources of heterogeneity, the risk of bias, publication bias, and the evidence certainty (GRADE methodology).

RESULTS

We included 32 populational studies (38 subpopulations, n = 63,813). The prevalence of primary headaches was 41.4% (95% CI 31.1-52.2%; n = 54,357), 15% for migraine (95% CI 12.0-18.3; n = 53,658 individuals), 20.6% for tension-type headache (95% CI 12.4-30.2; n = 25,840), and 6% for chronic headaches (95% CI 3.3-9.6; n = 21,720), with high between-study heterogeneity. No incidence data was found. Female sex, white ethnicity, high BMI, comorbid mental health disorders, and low-back pain were associated with higher prevalence of primary headaches. The prevalence was less in rural areas.

CONCLUSION

In Latin America and the Caribbean, primary headaches are highly prevalent affecting young females disproportionally. The prevalence of chronic headaches is higher than in other systematic global and regional estimations. The presence of comorbidities as modifiable risk factors should encourage their integration as targets for community-based preventive and therapeutic interventions.

PROTOCOL REGISTRATION NUMBER

CRD42018105116.

Case report: Look at my eyes

The comorbidity of migraine and Autism Spectrum Disorder (ASD) still remain unclear. In spite of plausible evidences of such comorbidity, there is a scarcity of populational studies focusing this hypothesis. The diagnosis of migraine in children with ASD is very challenge due to the large clinical heterogeneity and limited communication skills, particularly verbal abilities in young children and those with intellectual disability. ASD and migraine are chronic prevalent disorders sharing some pathophysiological changes (neurotransmission dysregulation, altered immune response, abnormal findings in the cortical minicolumn organization, and dysfunctions in the gut–brain axis), susceptibility genes (including calcium channel mutations and polymorphisms), and atypical sensory processing. Herein, we take advantage of a prototypical case of an adolescent with episodic migraine transformed to chronic, not responsive to preventive treatment, to explore the diagnostic workup and successful personalized clinical and therapeutical management.

The contribution of gut-brain axis to development of neurological symptoms in COVID-19 recovered patients: A hypothesis and review of literature

The gut microbiota undergoes significant alterations in response to viral infections, particularly the novel SARS-CoV-2. As impaired gut microbiota can trigger numerous neurological disorders, we suggest that the long-term neurological symptoms of COVID-19 may be related to intestinal microbiota disorders in these patients. Thus, we have gathered available information on how the virus can affect the microbiota of gastrointestinal systems, both in the acute and the recovery phase of the disease, and described several mechanisms through which this gut dysbiosis can lead to long-term neurological disorders, such as Guillain-Barre syndrome, chronic fatigue, psychiatric disorders such as depression and anxiety, and even neurodegenerative diseases such as Alzheimer's and Parkinson's disease. These mechanisms may be mediated by inflammatory cytokines, as well as certain chemicals such as gastrointestinal hormones (e.g., CCK), neurotransmitters (e.g., 5-HT), etc. (e.g., short-chain fatty acids), and the autonomic nervous system. In addition to the direct influences of the virus, repurposed medications used for COVID-19 patients can also play a role in gut dysbiosis. In conclusion, although there are many dark spots in our current knowledge of the mechanism of COVID-19-related gut-brain axis disturbance, based on available evidence, we can hypothesize that these two phenomena are more than just a coincidence and highly recommend large-scale epidemiologic studies in the future.

Migraine management: Non-pharmacological points for patients and health care professionals

Migraine is a highly prevalent disorder with an enormous burden on societies. Different types of medications are used for controlling both acute attacks and prevention. This article reviews some non-pharmacological recommendations aiming to manage migraine disorder better and prevent headache attacks. Different triggers of migraine headache attacks, including environmental factors, sleep pattern changes, diet, physical activity, stress and anxiety, some medications, and hormonal changes, are discussed. It is advised that they be identified and managed. Patients should learn the skills to cope with the trigger factors that are difficult to avoid. In addition, weight control, management of migraine comorbidities, lifestyle modification, behavioural treatment and biofeedback, patient education, using headache diaries, and improving patients' knowledge about the disease are recommended to be parts of migraine management. In addition, using neuromodulation techniques, dietary supplements such as riboflavin, coenzyme Q10 and magnesium, and acupuncture can be helpful. Non-pharmacological approaches should be considered in migraine management. Furthermore, the combination of pharmacological and non-pharmacological approaches is more effective than using each separately.

Alteration of gut microbiota in migraine patients with irritable bowel syndrome in a Chinese Han population

Objective

Migraine is frequently reported in patients with irritable bowel syndrome (IBS), and emerging evidence suggests that gut microbiota plays a role in migraine and IBS. However, alterations in the gut microbiome in migraine patients with IBS remain unknown. This study aimed to explore the compositions of gut microbiota in migraine patients with IBS in a Chinese Han population.

Methods

Sixteen migraine patients with IBS and thirteen age- and gender-matched IBS patients with similar dietary and lifestyle habits were enrolled in this pilot study. Demographic data, clinical data, eating habits, lifestyle habits, comorbidities, and medications were recorded using a unified case registration form. Questionnaires for the Migraine Disability Assessment (MIDAS), Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Scale (HAMA), and Hamilton Depression Scale (HAMD) were completed. Fecal samples were collected, and microbial DNA was extracted. Gut microbiota 16S ribosomal RNA (16S rRNA) gene sequencing targeting the V4 region was performed using the Illumina HiSeq 2500 high-throughput sequencing platform. The relationships between gut microbiota and clinical characteristics of migraine were analyzed.

Results

The structure of gut microbiota differed between migraine patients with IBS and patients with IBS, while the richness and diversity of gut microbiota in migraine patients with IBS showed no significant difference from that of patients with IBS. We found a higher relative abundance of the genus Parabacteroides and a lower relative abundance of the genera Paraprevotella, Lachnospiraceae_UCG-010, Lactococcus, Collinsella, and Comamonas in migraine patients with IBS than in patients with IBS. According to random forest predictive models, the phylum Bacteroidota shows the most important role in migraine patients with IBS. Furthermore, no statistical correlation was found between significantly different taxa at the genus level and migraine clinical data.

Conclusion

This study identified that altered gut microbiota occurred in Chinese Han migraine patients with IBS, but no correlation was found between gut microbiota and the clinical characteristics of migraine. Further study is needed to better understand the role of gut microbiota in the pathogenesis of migraine in IBS.

Brain-gut axis and psychiatric disorders: A perspective from bibliometric and visual analysis

BACKGROUND

The Brain-Gut Axis, a bidirectional signaling pathway that connects the intestinal and central nervous systems, plays an important role in the development of psychiatric disorders. However, the overall research trends in this field are unclear. This study explored the patterns of research on the brain-gut axis and psychiatric disorders from a bibliometric perspective.

METHODS

Relevant data were retrieved from the Web of Science Core Collection, with search terms on psychiatric disorders and the brain-gut axis. R (version 4.2.0), VOSviewer (version 1.6.17), CiteSpace software, and the online bibliometric platform were used in the data analysis.

RESULTS

A total of 2,298 articles published between 1993 and 2022 were identified, showing an increasing trend over time. China (1,859; 20.70%) was the country that contributed the most publications. The journal Nutrients (95; 4.13%) published the most publications. Cryan JF (153; H-index=73) and University College Cork (559; 22.54%) were the most influential author and the most productive institution, respectively. The high-frequency keywords were clustered into six themes, including neurodegenerative diseases, stress-related diseases, immune, brain behavior, depression, and probiotic-related topics; of which, depression (880; 2019), anxiety (207; 2018) and autism (191; 2019) were the most studied psychiatric disorders in the past 5 years. "Depressive symptom" (2019-2020) and "probiotic treatment" (2019-2020) were the main areas addressed in recent years.

CONCLUSION

Research on the brain-gut axis and psychiatric disorders has attracted increasing attention in the past decade, with most publications originating from high-income level countries. This study provides a useful perspective on understanding the research trends, key hot topics, and research gaps in this expanding field.

Association between Migraines and Prior Proton Pump Inhibitor Use: A Nested Case-Control Study Using a National Health Screening Cohort

The effect of proton pump inhibitor (PPI) use on migraine risk remains controversial. We explored the odds of migraines in relation to prior PPI use and treatment duration. Data from the Korean National Health Insurance Service-Health Screening Cohort (2002−2015) were analyzed in this nested case-control study involving 28,159 participants with incident migraines and 112,636 controls (1:4 matched by sex, age, income, and residential region). The baseline covariates were balanced by performing propensity score overlap weighting-based adjustments, and the effect of prior PPI use (past vs. current) and treatment duration (<30 and 30−365 days vs. ≥365 days) on incident migraines was evaluated using logistic regression. In past and current PPI users, prior PPI use raised the likelihood of migraines (adjusted odds ratio [95% confidence interval]: 2.56 [2.36−2.79] and 4.66 [4.29−5.06], respectively). Participants who used PPI for <30, 30−365, or ≥365 days exhibited high odds of migraines (2.49 [2.29−2.72], 4.41 [4.05−4.79], and 4.14 [3.77−4.54], respectively). Incident migraines with or without aura also increased independently of PPI use history or duration. In summary, prior PPI use, irrespective of the elapsed time since use and the duration of use, is possibly associated with incident migraines with or without aura.

Role of Calcitonin Gene-Related Peptide on the Gastrointestinal Symptoms of Migraine-Clinical Considerations: A Narrative Review

Calcitonin gene-related peptide (CGRP) is involved in several of the pathophysiologic processes underpinning migraine attacks. Therapies that target CGRP or its receptor have shown efficacy as preventive or acute treatments for migraine. Two small-molecule CGRP receptor antagonists (rimegepant and ubrogepant) are approved for the acute treatment of migraine, and 4 monoclonal antibodies (eptinezumab, erenumab, fremanezumab, and galcanezumab) are approved for migraine prevention; erenumab targets the canonical CGRP receptor, the others CGRP ligand. CGRP plays a role in gastrointestinal nociception, inflammation, gastric acid secretion, and motility. Nausea and vomiting are among the gastrointestinal symptoms associated with migraine, but individuals with migraine may also experience functional upper and lower gastrointestinal comorbidities, such as gastroesophageal reflux disease, gastroparesis, functional diarrhea or constipation, and irritable bowel syndrome. Although gastrointestinal symptoms in migraine can be treatment-related, they may also be attributable to increased CGRP. In this review, we summarize the epidemiologic evidence for associations between migraine and gastrointestinal disorders, consider the possible physiologic role of CGRP in these associations, and review the clinical occurrence of gastrointestinal events in patients with migraine receiving CGRP-based therapies and other migraine treatments. Because patients with migraine are at an increased risk of comorbid and treatment-related gastrointestinal effects, we also propose a patient-management strategy to mitigate these effects.

The Role of the Human Microbiome in the Pathogenesis of Pain

Understanding of the gut microbiome's role in human physiology developed rapidly in recent years. Moreover, any alteration of this microenvironment could lead to a pathophysiological reaction of numerous organs. It results from the bidirectional communication of the gastrointestinal tract with the central nervous system, called the gut-brain axis. The signals in the gut-brain axis are mediated by immunological, hormonal, and neural pathways. However, it is also influenced by microorganisms in the gut. The disturbances in the gut-brain axis are associated with gastrointestinal syndromes, but recently their role in the development of different types of pain was reported. The gut microbiome could be the factor in the central sensitization of chronic pain by regulating microglia, astrocytes, and immune cells. Dysbiosis could lead to incorrect immune responses, resulting in the development of inflammatory pain such as endometriosis. Furthermore, chronic visceral pain, associated with functional gastrointestinal disorders, could result from a disruption in the gut microenvironment. Any alteration in the gut-brain axis could also trigger migraine attacks by affecting cytokine expression. Understanding the gut microbiome's role in pain pathophysiology leads to the development of analgetic therapies targeting microorganisms. Probiotics, FODMAP diet, and fecal microbiota transplantation are reported to be beneficial in treating visceral pain.

Ambient NO2 exposure induces migraine in rats: Evidence, mechanisms and interventions

Migraine is a complex neurological disorder with a high disability rate. Although the precipitating factors of migraine remain unclear, previous studies suggest that when there is excess nitrogen dioxide (NO₂) pollution in the atmosphere, the medical demand due to migraine attacks increases sharply. However, the main role of NO₂ as a trigger for migraine is not yet well understood. The purpose of this study was to explore the relationship between NO₂ exposure and the occurrence of migraine as well as the possible underlying mechanisms. We first investigated whether repeated short-term NO₂ exposure could induce behavioural and biological migraine phenotypes in rats. Next, capsazepine (CZP) was used to block transient receptor potential cation channel subfamily V member 1 (TRPV1) in vivo, and CZP and vitamin E (VE) were used to verify the role of reactive oxygen species (ROS)-TRPV1 signalling in NO₂-induced migraine in primary trigeminal neurones in vitro. We demonstrated that short-term repeated NO₂ exposure can significantly induce migraine in rats, and its key molecular mechanism may be related to ROS burst and its downstream TRPV1 channel activation. The findings of this study will enhance the understanding of the neurotoxic mechanism of NO₂, provide new clues for identifying the aetiology of migraine, and lay a new experimental basis for implementing migraine-related preventive and therapeutic control measures.

Role of Calcitonin Gene-Related Peptide on the Gastrointestinal Symptoms of Migraine-Clinical Considerations: A Narrative Review

Calcitonin gene-related peptide (CGRP) is involved in several of the pathophysiological processes underpinning migraine attacks. Therapies that target CGRP or its receptor have shown efficacy as preventive or acute treatments for migraine. Two small-molecule CGRP receptor antagonists (rimegepant and ubrogepant) are approved for the acute treatment of migraine, and four monoclonal antibodies (eptinezumab, erenumab, fremanezumab, and galcanezumab) are approved for migraine prevention; erenumab targets the canonical CGRP receptor, the others CGRP ligand. CGRP plays a role in gastrointestinal nociception, inflammation, gastric acid secretion, and motility. Nausea and vomiting are among the gastrointestinal symptoms associated with migraine, but individuals with migraine may also experience functional upper and lower gastrointestinal comorbidities, such as gastroesophageal reflux disease, gastroparesis, functional diarrhea or constipation, and irritable bowel syndrome. Although gastrointestinal symptoms in migraine can be treatment-related, they may also be attributable to increased CGRP. In this review, we summarize the epidemiological evidence for associations between migraine and gastrointestinal disorders, consider the possible physiological role of CGRP in these associations, and review the clinical occurrence of gastrointestinal events in patients with migraine receiving CGRP-based therapies and other migraine treatments. Because patients with migraine are at an increased risk of comorbid and treatment-related gastrointestinal effects, we also propose a patient-management strategy to mitigate these effects.

Dietary ω-3 intake for the treatment of morning headache: A randomized controlled trial

Morning headache (MH) is a frequent condition with a not fully explained pathogenesis. During the past years, several studies have been performed to identify a better diet therapy to reduce the frequency and intensity of headaches. Our study aims to determine if an adequate omega-3 (ω-3) intake in a Modified Mediterranean Diet (MMD) can improve the frequency and intensity of MH and, subsequently, the quality of life. Of the 150 enrolled subjects, 95 met the inclusion criteria (63.3%). Patients were included in the study and randomized into two groups: group A following MMD A and group B following MMD B. The MMD A group was designed to arise at least a 1.5:1 ω-6/ω-3 ratio; the MMD B group was designed to derive at least a 4:1 ω-6/ω-3 ratio. Eighty-four subjects completed the 6 weeks intervention (56%). After 6 weeks (t1), group A showed a significant reduction in both Headache Impact Test-6 and Visual Analog Scale scores (p < 0.001, p < 0.001, respectively). During dietary treatment, group A progressively dismissed ketoprofen-based pharmacological treatment (p = 0.002) from baseline to t1. Furthermore, a decrease in the platelet-to-lymphocyte ratio and neutrophil-to-lymphocyte ratio at t1 in group A (p = 0.02) was observed compared to group B. Concluding, this study provides evidence of a positive impact of ω-3-enriched MMD regimen on the inflammatory status and MH.

Clinical trial registration:https://clinicaltrials.gov/ct2/show/NCT01890070, identifier: NCT01890070.

Dysbiosis and Migraine Headaches in Adults With Celiac Disease

One of the most significant illnesses associated with gluten is celiac disease, which encompasses many conditions. It is generally recognized that neurological manifestations can occur either at the time of the disease onset or as the illness continues to develop. One of the main clinical presentations of celiac disease is headache, either in the form of migraine or in an unspecific form. Migraine pathophysiology is intricate and still poorly understood. Several mechanisms involving the gut-brain axis have been proposed to explain this association. These include the interaction of chronic inflammation with inflammatory and vasoactive mediators, the modulation of the intestinal immune environment of the microbiota, and the dysfunction of the autonomic nervous system. However, further research is required to fully comprehend the fundamental mechanisms and pathways at play. This review aims to give a narrative summary of the literature on celiac disease's neurological symptoms, particularly migraines, and to assess any potential associations to dysbiosis, an imbalance in the microbiome.

The Pathogenetic Role of Melatonin in Migraine and Its Theoretic Implications for Pharmacotherapy: A Brief Overview of the Research

Migraine is a chronic disease of global concern, regardless of socio-economic and cultural background. It most often and intensely affects young adults, especially women. Numerous mechanisms of a migraine attack have been identified (disturbances in the reaction of vessels, functions of neurotransmitters, cortical neurons, ion channels, receptors, the process of neurogenic inflammation), and many of its symptoms can be explained by activation of the hypothalamus and disturbances in its communication with other brain regions (including the brainstem). Numerous neuropeptides and neurochemical systems also play a role in migraine. One of them is melatonin, a hormone that allows the body to adapt to cyclically changing environmental and food conditions. In this article, we present the pathophysiological basis of melatonin release from the pineal gland and other tissues (including the intestines) under the influence of various stimuli (including light and food), and its role in stimulating the brain structures responsible for triggering a migraine attack. We analyze publications concerning research on the role of melatonin in various headaches, in various stages of migraine, and in various phases of the menstrual cycle in women with migraine, and its impact on the occurrence and severity of migraine attacks. Melatonin as an internally secreted substance, but also present naturally in many foods. It is possible to supplement melatonin in the form of pharmaceutical preparations, and it seems, to be a good complementary therapy (due to the lack of significant side effects and pharmacological interactions) in the treatment of migraine, especially: in women of childbearing age, in people taking multiple medications for other diseases, as well as those sensitive to pharmacotherapy.

Abdominal massage: A review of clinical and experimental studies from 1990 to 2021

OBJECTIVE

To systematically review the current state and holistic application of abdominal massage (AM).

DESIGN

A systematic review of qualitative evidence was conducted. All English articles exploring the topic of AM that had been published until the end of June 2021 were retrieved.

DATA SOURCES

The PubMed, Cochrane library, and Embase databases were accessed. Some original texts were obtained from Google Scholar.

DATA EXTRACTION AND SYNTHESIS

Two authors independently evaluated all search data to identify relevant studies. Disagreements were settled by discussion with a third author. Results were independently extracted into standardized sheets and checked for accuracy.

MAIN RESULTS

A total of 107 full-text reports were eligible for inclusion. Adult digestive disorders, pediatric disorders, gynecological disorders, obstetric disorders, metabolic disorders, psychological disorders, the side effects of AM, and animal experiments accounted for 49.53%, 14.02%, 7.48%, 7.48%, 4.67%, 4.67%, 5.61%, and 6.54% of all these papers, respectively, with most reports focusing on clinical studies.

CONCLUSION

The variety of diseases treated with AM is gradually increasing, and the treatment programs of AM for many diseases are being gradually optimized. Different forms of AM, especially mechanical AM, have been widely studied; the side effects of AM have also been considered; and the possible mechanisms of AM therapy continue to be discovered. In general, AM is an effective and safe therapy and can be widely used in various diseases, but further studies are necessary to clarify the mechanism of AM for different diseases. In the future, AM could become an even safer, more popular, and more modern therapy.

Unlocking the Potential of the Human Microbiome for Identifying Disease Diagnostic Biomarkers

The human microbiome encodes more than three million genes, outnumbering human genes by more than 100 times, while microbial cells in the human microbiota outnumber human cells by 10 times. Thus, the human microbiota and related microbiome constitute a vast source for identifying disease biomarkers and therapeutic drug targets. Herein, we review the evidence backing the exploitation of the human microbiome for identifying diagnostic biomarkers for human disease. We describe the importance of the human microbiome in health and disease and detail the use of the human microbiome and microbiota metabolites as potential diagnostic biomarkers for multiple diseases, including cancer, as well as inflammatory, neurological, and metabolic diseases. Thus, the human microbiota has enormous potential to pave the road for a new era in biomarker research for diagnostic and therapeutic purposes. The scientific community needs to collaborate to overcome current challenges in microbiome research concerning the lack of standardization of research methods and the lack of understanding of causal relationships between microbiota and human disease.

On the Association between Gastrointestinal Symptoms and Extragastric Manifestations

The aim of this study was to investigate the relationship between gastrointestinal (GI) symptoms and extragastric manifestations such as headache, fatigue, and dizziness. A prospective cohort study was conducted in a tertiary hospital in Athens, where patients with GI problems and extragastric symptoms were treated only for their GI problems, and improvement in extragastric manifestations was recorded. Inclusion criteria were an age older than 18 years, the presence of at least one of the three extragastric symptoms investigated in this study (headache, dizziness, and fatigue), and the concomitant presence of at least one gastrointestinal symptom (e.g., nausea, belching, abdominal tenderness, epigastric pain, halitosis, flatulence, diarrhea, bad odor of flatulence, flatulence, and constipation). A standardized questionnaire was used to collect demographic data (such as age, weight, and height), patients' symptoms, laboratory findings (gastric biopsy, gastroscopy, and colonoscopy), and intensity/frequency of GI and extragastric symptoms. Statistically significant associations were found between GI symptoms (nausea, constipation, halitosis, and belching) and dizziness, fatigue, and headache (frequency, intensity, and duration). Treatment of GI problems resulted in a significant improvement in extragastric symptoms within one month of treatment initiation. It should be emphasized that the actual reason for the improvement in extragastric symptoms was solely the resolution of the GI problems, as patients did not receive specific treatments for headache, dizziness or fatigue, or other changes in daily life. This study demonstrates the association between extragastric manifestations and GI disorders.

Repeated inflammatory dural stimulation-induced cephalic allodynia causes alteration of gut microbial composition in rats

BACKGROUND

Gut microbial dysbiosis and gut-brain axis dysfunction have been implicated in the pathophysiology of migraine. However, it is unclear whether migraine-related cephalic allodynia could induce the alteration of gut microbial composition.

METHODS

A classic migraine rat model was established by repeated dural infusions of inflammatory soup (IS). Periorbital mechanical threshold and nociception-related behaviors were used to evaluate IS-induced cephalic allodynia and the preventive effect of topiramate. The alterations in gut microbial composition and potential metabolic pathways were investigated based on the results of 16 S rRNA gene sequencing. Microbiota-related short-chain fatty acids and tryptophan metabolites were detected and quantified by mass spectrometry analysis.

RESULTS

Repeated dural IS infusions induced cephalic allodynia (decreased mechanical threshold), migraine-like behaviors (increased immobility time and reduced moving distance), and microbial composition alteration, which were ameliorated by the treatment of topiramate. Decreased Lactobacillus was the most prominent biomarker genus in the IS-induced alteration of microbial composition. Additionally, IS infusions also enhanced metabolic pathways of the gut microbiota in butanoate, propanoate, and tryptophan, while the increased tryptophan-related metabolites indole-3-acetamide and tryptophol in feces could be the indicators.

CONCLUSIONS

Inflammatory dural stimulation-induced cephalic allodynia causes the alterations of gut microbiota profile and microbial metabolic pathways.

Endometriosis and irritable bowel syndrome: similarities and differences in the spectrum of comorbidities

STUDY QUESTION

Do the spectrum and prevalence of comorbidities of endometriosis and irritable bowel syndrome (IBS) overlap?

SUMMARY ANSWER

Despite several overlapping symptoms, the most significantly associated comorbidities of endometriosis and IBS are different and are rather related to the organ systems primarily involved in the index diagnosis.

WHAT IS KNOWN ALREADY

Endometriosis and IBS both have several similar unspecific symptoms, such as recurrent abdominal pain, cramping and anxiety, and both diseases affect young women and are associated with a number of comorbidities causing a poor quality of life. However, a detailed study, revealing the full spectrum of endometriosis and IBS comorbidities in the same study population, is lacking.

STUDY DESIGN, SIZE, DURATION

This article presents a retrospective in silico analysis of the data from a large nationwide biobank-based cohort consisting of 121 773 women. After excluding all first- and second-degree relatives, the data of up to 65 421 women were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

International Classification of Disease-10 diagnosis main codes associated with endometriosis (N80) and IBS (K58) diagnoses were identified from the Estonian Biobank dataset by linking with the Estonian Health Insurance Fund and other relevant registries. The associations between N80 and K58 and other diagnosis codes were tested using logistic regression, adjusting for age at recruitment and 10 genetic principal components to account for potential population stratification. Bonferroni correction was applied to account for multiple testing.

MAIN RESULTS AND THE ROLE OF CHANCE

Both women with endometriosis and IBS suffered from more conditions compared to the control group, with 226 and 428 diagnosis codes statistically significantly more frequent in women with respective diagnosis compared to controls. Women suffering from both conditions had 275 significantly associated comorbidities. A remarkable proportion of women with IBS or endometriosis suffered also from endometriosis (9.0%) or IBS (13.6%), respectively. In endometriosis, the most prevalent diagnoses were related to diseases of the genitourinary system (33 N-category codes) and in women with IBS, the most associated diagnoses were related to digestive disorders and gastrointestinal tract (52 codes from K-category). Among the most significant diagnoses in endometriosis were uterine leiomyomas (D25), menstrual disorders (N92) and infertility (N97) (P < 1 × 10-315 for all), and in IBS, lactose intolerance (E73), gastritis and duodenitis (K29) and functional dyspepsia (K30) were in the top list of most significant comorbidities (P < 1 × 10-315 for all).

LIMITATIONS, REASONS FOR CAUTION

The information about the severity stages of endometriosis and subtypes of IBS was not available for analysis. The findings may not be fully extrapolated to all female populations, because all participants were from one geographic area and had good access to health services.

WIDER IMPLICATIONS OF THE FINDINGS

These findings support previous studies that have found a high prevalence of pre-selected comorbidities in women with endometriosis and IBS. However, taking into account the differences in the full spectrum of comorbidities of endometriosis and IBS may aid in diagnosing these disorders. Women and healthcare providers need to be aware that women with endometriosis are at high risks of complications during pregnancy and should be carefully monitored.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by the Estonian Research Council (grant PRG1076), Horizon 2020 innovation grant (ERIN, grant no. EU952516), Enterprise Estonia (grant no. EU48695), MSCA-RISE-2020 project TRENDO (grant no. 101008193) and by the European Union through the European Regional Development Fund (Projects no. 2014-2020.4.01.15-0012 and no. 2014-2020.4.01.16-0125). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

The potential impact of nutritional intake on symptoms severity in patients with comorbid migraine and irritable bowel syndrome

Background

Specific dietary recommendations for migraine patients with comorbid irritable bowel syndrome (IBS) are lacking. This work aimed to study the severity scores of such two common pain-related disorders in relation to various macronutrients and micronutrients intake.

Methods

A cross-sectional study was conducted on patients with concomitant migraine and IBS. The frequency and intensity of migraine attacks and the severity of IBS were evaluated. Data on dietary intake were collected using food frequency questionnaires and 24-hour dietary recall.

Results

One-hundred patients with a median age of 36 years participated. The severity scores for migraine and IBS were positively correlated with fat and copper and negatively correlated with fiber and zinc intake. Copper intake was an independent predictor of the severity of both migraine and IBS (P 0.033, < 0.001). Patients with episodic migraine (n = 69) had a significantly higher frequency of cooked, fresh vegetables, and wheat bran bread intake (P 0.009, 0.004, 0.021) and lower frequency of hydrogenated oils intake (P 0.046), in comparison to patients with chronic migraine (n = 31). Patients with moderate intensity of migraine (n = 37) had a significantly higher frequency of herbal drinks intake (P 0.014) than patients with a severe intensity of migraine (n = 63). Patients with mild (n = 13) and moderate IBS (n = 41) had a significantly higher frequency of wheat bran bread and sen bread intake (P 0.003, 0.022) than patients with severe IBS (n = 46).

Conclusion

Patients with comorbid migraine and IBS are advised to adhere to a diet low in fat and copper and rich in fiber and zinc.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02723-0.

The Effects of Probiotics on Inflammation, Endothelial Dysfunction, and Atherosclerosis Progression: A Mechanistic Overview

INTRODUCTION

The relationship between the intestinal microbiota dysbiosis, inflammation, and cardiovascular disorders (CVDs) has become evident, based on a growing body of literature from animal models and human studies. On the other hand, probiotics are believed to have promising effects on modifying dysbiosis and protecting against CVDs.

OBJECTIVE

This narrative review provides an overview of the link between gut microbiota, inflammation, endothelial dysfunction, and atherosclerosis. The influences of probiotic supplementation on biomarkers contributing to these conditions as the primary underlying risk factors for developing CVDs are also discussed.

METHODS

An up-to-date review was performed of the available evidence from experimental studies, clinical trials, and meta-analyses, considering their challenges and limitations. It also aimed to provide mechanistic insight into the likely mechanisms of probiotics that could prevent atherosclerosis initiation and progression.

RESULTS

Probiotic supplementation seems to be associated with reduced levels of inflammation and oxidative stress biomarkers (C-reactive protein, tumour necrosis factor-α, interleukin (IL)-6, IL-12, and malondialdehyde). Further, these agents might enhance antioxidant factors (IL-10, total antioxidant status, total antioxidant capacity, glutathione, and nitric oxide). Probiotics also appear to improve intestinal barrier integrity, reduce leakage of harmful metabolites (e.g., lipopolysaccharides), inhibit pro-inflammatory signalling pathways, and possibly suppress the formation of trimethylamine/trimethylamine oxide. Probiotics have also been found to enhance endothelial function and halter thrombosis.

CONCLUSION

The current clinical evidence underlines belief that probiotics might be associated with reduced levels of inflammation biomarkers. Experimental evidence reports that the beneficial effects of probiotics seem to be mainly imposed by triggering the secretion of short-chain fatty acids and bile acids, in addition to suppressing the NF-κB signalling pathway. However, the current studies are still in their infancy and it is of high priority to design further research on the topic.

Headaches and obesity

Obesity and headache disorders are two very common conditions in the general population that have been increasing in incidence over the last decades. Recent studies have shown a significant relationship between obesity and headaches, particularly migraine, with an important role in whether the disease is chronic. On the other hand, no such association was found with tension-type headaches. Studies showing an overlapping of hunger-control pathways and those involved in the pathophysiology of migraine may justify the close association between obesity and migraine. Moreover, a secondary headache for which obesity is a strong risk factor is idiopathic Intracranial Hypertension (pseudotumor cerebri), with several studies showing the impact of weight reduction/bariatric surgery in the treatment of the disease. In conclusion, since obesity is a modifiable risk factor, it is important for physicians treating patients with headaches, and particularly migraine, to be aware of the association between these two disorders.

Supplementation with SCFAs Re-Establishes Microbiota Composition and Attenuates Hyperalgesia and Pain in a Mouse Model of NTG-Induced Migraine

Migraine is a common brain-disorder that affects 15% of the population. Converging evidence shows that migraine is associated with gastrointestinal disorders. However, the mechanisms underlying the interaction between the gut and brain in patients with migraine are not clear. In this study, we evaluated the role of the short-chain fatty acids (SCFAs) as sodium propionate (SP) and sodium butyrate (SB) on microbiota profile and intestinal permeability in a mouse model of migraine induced by nitroglycerine (NTG). The mice were orally administered SB and SP at the dose of 10, 30 and 100 mg/kg, 5 min after NTG intraperitoneal injections. Behavioral tests were used to evaluate migraine-like pain. Histological and molecular analyses were performed on the intestine. The composition of the intestinal microbiota was extracted from frozen fecal samples and sequenced with an Illumina MiSeq System. Our results demonstrated that the SP and SB treatments attenuated hyperalgesia and pain following NTG injection. Moreover, SP and SB reduced histological damage in the intestine and restored intestinal permeability and the intestinal microbiota profile. These results provide corroborating evidence that SB and SP exert a protective effect on central sensitization induced by NTG through a modulation of intestinal microbiota, suggesting the potential application of SCFAs as novel supportive therapies for intestinal disfunction associated with migraine.

Topiramate-Induced Suicidal Ideation and Olfactory Hallucinations: A Case Report

Antiepileptic drugs prescribed in the context of migraine have been reported to be potentially linked with an increased risk of suicidal ideation and behavior. Meta-analyses support the evidence that amongst antiepileptic drugs, Topiramate has the greatest potential for facilitating the occurrence of suicidal ideation and behavior. Studies indicate that this occurs via the increased incidence of mood disorders amongst the population with migraines using Topiramate as a treatment, with a slow and progressive onset of suicidal ideation (if any). We discuss the unique case of a 43-year-old man known to have chronic migraines, who presented with intense rapid-onset suicidal ideation and olfactory hallucinations, three weeks after the introduction of Topiramate for chronic migraines. After a negative extensive investigation panel to rule out common organic diseases, Topiramate was ceased. The suicidal ideation and olfactory hallucinations resolved in less than 24 h without further interventions. This case report highlights that rapid-onset suicidal ideation and olfactory hallucinations could be linked as an unusual side effect to the introduction of Topiramate. The removal of Topiramate from the patient’s pharmacological treatments prevented further psychological distress linked to ego-dystonic suicidal ideation and a resolution of olfactory hallucinations. He was discharged 48 h later.

A road map for happiness: The psychological factors related cell types in various parts of human body from single cell RNA-seq data analysis

Massive evidence from all sources including zoology, neurobiology and immunology has confirmed that psychological factors can raise remarkable physiological effects. Researchers have long been aware of the potential value of these effects and wanted to harness them in the development of new drugs and therapies, for which the mechanism study is a necessary prerequisite. However, most of these studies are restricted to neuroscience, or starts with blood sample and fall into the area of immunity. In this study, we choose to focus on the psychological factor of happiness, mining existing publicly available single cell RNA sequencing (scRNA-seq) data for the expression of happiness-related genes collected from various sources of literature in all types of cells in the samples, finding that the expression of these genes is not restricted within neuro-regulated cells or tissue-resident immune cells, on the opposite, cell types that are unique to tissue and organ without direct regulation from nervous system account for the majority to express the happiness-related genes. Our research is a preliminary exploration of where our body respond to our mind at cell level, and lays the foundation for more detailed mechanism research.

The association between gastro-oesophageal reflux and migraine in the paediatric population: a multicentre case-control study

Infantile regurgitation is one of the most common discomforts in the first months of life. Infantile colic and, in older children, functional dyspepsia have been linked to migraine. To date, this is the first study to investigate a possible association between infantile regurgitation and primary headaches in children. This is a case-control study of 195 children aged 6-17 years, with primary headache (migraine, or tension type headache) in 5 European paediatric hospitals. The control group is composed of 240 same-aged children attending with minor injuries during the same period - February 1st 2020 to December 1st 2020. A structured questionnaire identified a history of infantile regurgitation and other functional gastrointestinal disorders for case and control participants. The outcome was the difference in the prevalence of infantile regurgitation among children with or without a diagnosis of primary headache. The analysis showed a significant association between infantile regurgitation and migraine (OR = 1.88, CI 95 = 1.01-3.4, p = 0.04). No association was found between infantile regurgitation and tension type headache (p = 0.33). Subgroup analysis confirmed that the association was only significant for migraine without aura (OR = 2.3, CI 95 = 1.2-4.4, p = 0.01). In a further subgroup analysis, the presence of functional dyspepsia, irritable bowel syndrome and abdominal migraine was associated with migraine without aura.

CONCLUSION

The presence of migraine among children aged 6-17 was associated with a history of infantile regurgitation. Additional longitudinal studies are required to confirm whether infantile regurgitation could be considered as a precursor of migraine.

WHAT IS KNOWN

• Children suffering from functional gastrointestinal disorders are more likely to be suffering from migraine and tension-type headache as well. • Children suffering from primary headache are more likely to have had infantile colic in their first six month of life.

WHAT IS NEW

• It is the first study to find an association between migraine and infantile regurgitation in children. • These findings could have an impact on the diagnosis and therapeutics of both migraine and infantile regurgitation.

Dural Immune Cells, CGRP, and Migraine

Migraine is the most common neurological disorder in the world, affecting 12% of the population. Migraine involves the central nervous system, trigeminal nerves and meninges. Recent advances have shown that targeting calcitonin gene-related peptide (CGRP) through either antibodies or small molecule receptor antagonists is effective at reducing episodic and chronic migraine episodes, but these therapeutics are not effective in all patients. This suggests that migraine does not have a singular molecular cause but is likely due to dysregulated physiology of multiple mechanisms. An often-overlooked part of migraine is the potential involvement of the immune system. Clinical studies have shown that migraine patients may have dysregulation in their immune system, with abnormal plasma cytokine levels either during the attack or at baseline. In addition, those who are immunocompromised appear to be at a higher risk of migraine-like disorders. A recent study showed that migraine caused changes to transcription of immune genes in the blood, even following treatment with sumatriptan. The dura mater is densely packed with macrophages, mast and dendritic cells, and they have been found to associate with meningeal blood vessels and trigeminal afferent endings. Recent work in mice shows activation and morphological changes of these cells in rodents following the migraine trigger cortical spreading depression. Importantly, each of these immune cell types can respond directly to CGRP. Since immune cells make up a large portion of the dura, have functional responses to CGRP, and interact with trigeminal afferents, CGRP actions on the dural immune system are likely to play key roles in migraine.

Association between Gastrointestinal Diseases and Migraine

Migraine is a common disease worldwide, and recent studies showed that the incidence of migraine was increased in patients with gastrointestinal (GI) diseases. In addition, preclinical evidence suggested a bidirectional relationship between the GI nervous system and the central nervous system called the gut−brain axis. This study aimed to determine the association between several high-prevalence GI diseases and migraine. Patients diagnosed with migraine or GI diseases were classified as the patient group at least twice a year. We included peptic ulcer disease, dyspepsia, inflammatory bowel disease, irritable bowel syndrome, and gastroesophageal disease as GI diseases. A total of 781,115 patients from the HIRA dataset were included in the study. The prevalence of migraine was about 3.5 times higher in patients with one or more GI diseases after adjusting for age, gender, and insurance type (adjusted odds ratio (ORadj = 3.46, 95% CI: 3.30−3.63, p < 0.001). In addition, the prevalence of migraine was increased as the number of comorbid GI diseases increased. The prevalence of GI disease was also higher in patients with medication for migraine, both preventive and acute treatment, compared to patients with either acute preventive or acute treatment. There was a statistically significant association between the prevalence of GI diseases and migraine, and the higher the number of accompanying GI diseases, the higher the correlation was in patients using both preventive and acute treatment drugs for migraine.

Migraine: A Review on Its History, Global Epidemiology, Risk Factors, and Comorbidities

Migraine affects more than one billion individuals each year across the world, and is one of the most common neurologic disorders, with a high prevalence and morbidity, especially among young adults and females. Migraine is associated with a wide range of comorbidities, which range from stress and sleep disturbances to suicide. The complex and largely unclear mechanisms of migraine development have resulted in the proposal of various social and biological risk factors, such as hormonal imbalances, genetic and epigenetic influences, as well as cardiovascular, neurological, and autoimmune diseases. This review presents a comprehensive review of the most up-to-date literature on the epidemiology, and risk factors, as well as highlighting the gaps in our knowledge.