Shared genetic basis for migraine and ischemic stroke: A genome-wide analysis of common variants

Association between vertebral artery dominance and basilar artery curvature in migraineurs: an anatomical magnetic resonance imaging study

BACKGROUND AND PURPOSES

Numerous studies demonstrate a link between cerebrovascular alterations and migraine pathogenesis. We investigated the association between migraine and vertebral artery dominance (VAD), basilar artery (BA) curvature, and elongation.

MATERIALS AND METHODS

This cross-sectional MRI study included 74 migraine patients and 74 control subjects aged between 18 and 55 years. Diameters of the intracranial part of the vertebral artery (VA) and BA, height of the BA bifurcation, and total lateral displacement of the BA were measured. In addition, we investigated the directional relationship between VAD and BA curvature.

RESULTS

There were no statistically significant differences between the groups regarding VA and BA diameters and total lateral displacement of the BA. The height of the BA bifurcation was found to be significantly higher in migraine patients compared to controls (p = 0.002). The left-side VAD was more frequent in migraine patients compared to control subjects (60.8% (45/74) vs 41.9% (31/74), p = 0.001). In migraine patients, particularly those with aura (MwA) patients, with left-side VAD, the rate of BA displacement to the right side is significantly higher than those with right-side VAD or non-VAD (p = 0.022). Also, we found that total lateral displacement of the BA is correlated with VA asymmetry in patients with MwA (r = 0.538, p = 0.007).

CONCLUSION

VAD and its opposite-directional relationship with the lateral displacement of the BA may be associated with migraine pathophysiology. Together with aging, this association may contribute to changes in the vertebrobasilar system (VBS) geometry which may result in increased risk for posterior circulation infarction (PCI) in migraineurs.

Genetic causal relationship between immune diseases and migraine: a Mendelian randomization study

Background

Migraine has an increased prevalence in several immune disorders, but genetic cause-effect relationships remain unclear. Mendelian randomization (MR) was used in this study to explore whether immune diseases are causally associated with migraine and its subtypes.

Methods

We conducted a two-sample bidirectional multivariate Mendelian randomization study. Single-nucleotide polymorphisms (SNP) for six immune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes mellitus (T1D), allergic rhinitis (AR), asthma and psoriasis, were used as genetic instrumental variables. Summary statistics for migraine were obtained from 3 databases: the International Headache Genetics Consortium (IHGC), UK Biobank, and FinnGen study. MR analyses were performed per outcome database for each exposure and subsequently meta-analyzed. Reverse MR analysis was performed to determine whether migraine were risk factors for immune diseases. In addition, we conducted a genetic correlation to identify shared genetic variants for these two associations.

Results

No significant causal relationship was found between immune diseases and migraine and its subtypes. These results were robust with a series of sensitivity analyses. Using the linkage disequilibrium score regression method (LDSC), we detected no genetic correlation between migraine and immune diseases.

Conclusion

The evidence from our study does not support a causal relationship between immune diseases and migraine. The mechanisms underlying the frequent comorbidity of migraine and several immune diseases need to be further elucidated.

Towards precision medicine in migraine: Recent therapeutic advances and potential biomarkers to understand heterogeneity and treatment response

After 35 years since the introduction of the International Classification of Headache Disorders (ICHD), we are living in the era of the second great revolution in migraine therapies. First, discoveries of triptans provided a breakthrough in acute migraine treatment utilizing bench-to-bedside research results on the role of serotonin in migraine. Next, the discovery of the role of neuropeptides, more specifically calcitonin gene-related peptide (CGRP) in migraine attack led to the development of anti-CGRP therapies that are effective both in acute and preventive treatment, and are also able to reduce migraine-related burden. Here, we reviewed the most recent clinical studies and real-world data on available migraine-specific medications, including triptans, ditants, gepants and anti-CGRP monoclonal antibodies. Novel drug targets, such as PACAP and amylins were also discussed. To address the main challenges of migraine therapy, the high heterogeneity of people with migraine, the prevalent presence of various comorbid disorders, and the insufficient medical care of migraine patients were covered. Promising novel approaches from the fields of omics, blood and saliva biomarker, imaging and provocation studies might bring solutions for these challenges with the potential to identify further drug targets, distinguish more homogeneous patient subgroups, contribute to more optimal drug selection strategies, and detect biomarkers in association with headache features or predicting treatment efficacy. In the future, the combined analysis of data of different biomarker modalities with machine learning algorithms may serve precision medicine in migraine treatment.

Cross-trait analyses identify shared genetics between migraine, headache, and glycemic traits, and a causal relationship with fasting proinsulin

The co-occurrence of migraine and glycemic traits has long been reported in observational epidemiological studies, but it has remained unknown how they are linked genetically. We used large-scale GWAS summary statistics on migraine, headache, and nine glycemic traits in European populations to perform cross-trait analyses to estimate genetic correlation, identify shared genomic regions, loci, genes, and pathways, and test for causal relationships. Out of the nine glycemic traits, significant genetic correlation was observed for fasting insulin (FI) and glycated haemoglobin (HbA1c) with both migraine and headache, while 2-h glucose was genetically correlated only with migraine. Among 1703 linkage disequilibrium (LD) independent regions of the genome, we found pleiotropic regions between migraine and FI, fasting glucose (FG), and HbA1c, and pleiotropic regions between headache and glucose, FI, HbA1c, and fasting proinsulin. Cross-trait GWAS meta-analysis with glycemic traits, identified six novel genome-wide significant lead SNPs with migraine, and six novel lead SNPs with headache (Pmeta < 5.0 × 10-8 and Psingle-trait < 1 × 10-4), all of which were LD-independent. Genes with a nominal gene-based association (Pgene ≤ 0.05) were significantly enriched (overlapping) across the migraine, headache, and glycemic traits. Mendelian randomisation analyses produced intriguing, but inconsistent, evidence for a causal relationship between migraine and headache with multiple glycemic traits; and consistent evidence suggesting increased fasting proinsulin levels may causally decrease the risk of headache. Our findings indicate that migraine, headache, and glycemic traits share a common genetic etiology and provide genetic insights into the molecular mechanisms contributing to their comorbid relationship.

Neurological and psychiatric comorbidities of migraine: Concepts and future perspectives

BACKGROUND

This narrative review aims to discuss several common neurological and psychiatric disorders that show comorbidity with migraine. Not only can we gain pathophysiological insights by studying these disorders, comorbidities also have important implications for treating migraine patients in clinical practice.

METHODS

A literature search on PubMed and Embase was conducted with the keywords "comorbidity", "migraine disorders", "migraine with aura", "migraine without aura", "depression", "depressive disorders", "epilepsy", "stroke", "patent foramen ovale", "sleep wake disorders", "restless legs syndrome", "genetics", "therapeutics".

RESULTS

Several common neurological and psychiatric disorders show comorbidity with migraine. Major depression and migraine show bidirectional causality and have shared genetic factors. Dysregulation of both hypothalamic and thalamic pathways have been implicated as a possibly cause. The increased risk of ischaemic stroke in migraine likely involves spreading depolarizations. Epilepsy is not only bidirectionally related to migraine, but is also co-occurring in monogenic migraine syndromes. Neuronal hyperexcitability is an important overlapping mechanism between these conditions. Hypothalamic dysfunction is suggested as the underlying mechanism for comorbidity between sleep disorders and migraine and might explain altered circadian timing in migraine.

CONCLUSION

These comorbid conditions in migraine with distinct pathophysiological mechanisms have important implications for best treatment choices and may provide clues for future approaches.

Genetics of migraine: where are we now?

Migraine is a complex brain disorder explained by the interaction of genetic and environmental factors. In monogenic migraines, including familial hemiplegic migraine and migraine with aura associated with hereditary small-vessel disorders, the identified genes code for proteins expressed in neurons, glial cells, or vessels, all of which increase susceptibility to cortical spreading depression. The study of monogenic migraines has shown that the neurovascular unit plays a prominent role in migraine. Genome-wide association studies have identified numerous susceptibility variants that each result in only a small increase in overall migraine risk. The more than 180 known variants belong to several complex networks of "pro-migraine" molecular abnormalities, which are mainly neuronal or vascular. Genetics has also highlighted the importance of shared genetic factors between migraine and its major co-morbidities, including depression and high blood pressure. Further studies are still needed to map all of the susceptibility loci for migraine and then to understand how these genomic variants lead to migraine cell phenotypes.

Migraine genetics: Status and road forward

BACKGROUND

Migraine is considered a multifactorial genetic disorder. Different platforms and methods are used to unravel the genetic basis of migraine. Initially, linkage analysis in multigenerational families followed by Sanger sequencing of protein-coding parts (exons) of genes in the genomic region shared by affected family members identified high-effect risk DNA mutations for rare Mendelian forms of migraine, foremost hemiplegic migraine. More recently, genome-wide association studies testing millions of DNA variants in large groups of patients and controls have proven successful in identifying many dozens of low-effect risk DNA variants for the more common forms of migraine with the number of associated DNA variants increasing steadily with larger sample sizes. Currently, next-generation sequencing, utilising whole exome and whole genome sequence data, and other omics data are being used to facilitate their functional interpretation and the discovery of additional risk factors. Various methods and analysis tools, such as genetic correlation and causality analysis, are used to further characterise genetic risk factors.

FINDINGS

We describe recent findings in genome-wide association studies and next-generation sequencing analysis in migraine. We show that the combined results of the two most recent and most powerful migraine genome-wide association studies have identified a total of 178 LD-independent (r² < 0.1) genome-wide significant single nucleotide polymorphisms (SNPs), of which 99 were unique to Hautakangas et al., 11 were unique to Choquet et al., and 68 were identified by both studies. When considering that Choquet et al. also identified three SNPs in a female-specific genome-wide association studies then these two recent studies identified 181 independent SNPs robustly associated with migraine. Cross-trait and causal analyses are beginning to identify and characterise specific biological factors that contribute to migraine risk and its comorbid conditions.

CONCLUSION

This review provides a timely update and overview of recent genetic findings in migraine.

Migraine attacks are of peripheral origin: the debate goes on

BACKGROUND

Despite the pervasiveness of migraine, the underlying pathophysiological mechanisms initiating migraine attacks are far from well understood and are matter of scientific debate.

OBJECTIVE

In this narrative review, we discuss key evidence for that suggest a peripheral origin or central origin and provide directions for future studies that may provide further clarification.

DISCUSSION

Migraine pathogenesis is considered to involve the trigeminovascular system, a term that encompasses the trigeminal nerve and its axonal projections to the intracranial blood vessels. Beyond any doubt both peripheral and central mechanisms are involved in migraine pathogenesis, but an unresolved question is the how the initial activation occurs in a migraine attack. Evidence favoring a peripheral origin of migraine attacks, i.e., initial events occur outside of the blood-brain barrier, include the importance of sensitization of perivascular sensory afferents early on in a migraine attack. Evidence favoring a central origin include the occurrence of prodromal symptoms, migraine aura, and activation of structures within the central nervous system early in and during a migraine attack.

CONCLUSIONS

Both peripheral and central mechanisms are likely involved in a migraine attack, e.g., peripheral nociceptive input is necessary for pain transmission and cortical activity is necessary for pain perception. Yet, the debate of whether migraine attacks are initiated a peripheral or central site remains unresolved. The increased focus on prodromal symptoms and on the development of a human model of migraine aura will possibly provide key arguments needed to answer this question in the near future. Until then, we cannot draw firm conclusions and the debate goes on.

VIDEO LINK

Video recording of the debate held at the 1st International Conference on Advances in Migraine Sciences (ICAMS 2022, Copenhagen, Denmark) is available at: https://www.youtube.com/watch?v=NC0nlcKohz0 .

Genetics of migraine: Delineation of contemporary understanding of the genetic underpinning of migraine

Migraine is a disabling episodic brain disorder with an increased familial relative risk, an increased concordance in monozygotic twins, and an estimated heritability of approximately 50%. Various genetic approaches have been applied to identify genetic factors conferring migraine risk. Initially, candidate gene associations studies (CGAS) have been performed that test DNA variants in genes prioritized based on presumed a priori knowledge of migraine pathophysiology. More recently, genome-wide association studies (GWAS) are applied that test genetic variants, single-nucleotide polymorphisms (SNPs), in a hypothesis-free manner. To date, GWAS have identified ~40 genetic loci associated with migraine. New GWAS data, which are expected to come out soon, will reveal over 100 loci. Also, large-scale GWAS, which have appeared for many traits over the last decade, have enabled studying the overlap in genetic architecture between migraine and its comorbid disorders. Importantly, other genetic factors that cannot be identified by a GWAS approach also confer risk for migraine. First steps have been taken to determine the contribution of these mechanisms by investigating mitochondrial DNA and epigenetic mechanisms. In addition to typical epigenetic mechanisms, that is, DNA methylation and histone modifications, also RNA-based mechanisms regulating gene silencing and activation have recently gotten attention. Regardless, until now, most relevant genetic discoveries related to migraine still come from investigating monogenetic syndromes with migraine as a prominent part of the phenotype. Experimental studies on these syndromes have expanded our knowledge on the mechanisms underlying migraine pathophysiology. It can be envisaged that when all (epi)genetic and phenotypic data on the common and rare forms of migraine will be integrated, this will help to unravel the biological mechanisms for migraine, which will likely guide decision-making in clinical practice in the future.

Association between migraine and cardiovascular disease: A cross-sectional study

Background

Cardiovascular disease (CVD) poses a tremendous threat to global health, giving rise to exceedingly high morbidity and mortality among patients. A migraine is a common neurological disorder characterized by recurrent attacks of severe headache, while its cardiovascular burden remains unclear. Therefore, this study aims to investigate whether migraine is associated with CVD.

Methods

The cross-sectional data of 5,692 subjects aged 20 or above was obtained from the National Health and Nutrition Examination Survey (NHANES) 1999-2004. To determine whether migraine is associated with CVD, weighted logistic regression models were used. In a subsequent subgroup analysis, several confounding factors were also explored to investigate the association between migraine and CVD.

Results

In total, 5,692 subjects were enrolled in this study, with the prevalence of CVD being 13.3%. Participants with CVD tended to be older, male, non-Hispanic whites, more educated, former smokers, and alcohol drinkers, and had a higher waist circumference, less physical activity, a higher level of triglyceride and creatinine as well as a lower level of high-density lipoprotein cholesterol (HDL-C) and estimated glomerular filtration rate (eGFR) (all P < 0.05). Considering all potential confounders, migraine was associated with a higher risk of CVD [odds ratios (ORs) 2.77; 95% confidence intervals (CIs): 1.56-4.90]. Subgroup analysis showed a higher risk of CVD in females, those older than 60 years, with a lower body mass index (BMI) level (≤ 30 kg/m²), a higher level of eGFR (> 90 mL/min/1.73 m²), hypertension and hyperlipidemia and without diabetes.

Conclusion

In summary, our study revealed a positive association between migraine with CVD in a nationally representative US adult population. Our findings highlighted that migraine should be considered an important risk factor for CVD.

Migraine-Associated Common Genetic Variants Confer Greater Risk of Posterior vs. Anterior Circulation Ischemic Stroke☆

OBJECTIVE

To examine potential genetic relationships between migraine and the two distinct phenotypes posterior circulation ischemic stroke (PCiS) and anterior circulation ischemic stroke (ACiS), we generated migraine polygenic risk scores (PRSs) and compared these between PCiS and ACiS, and separately vs. non-stroke control subjects.

METHODS

Acute ischemic stroke cases were classified as PCiS or ACiS based on lesion location on diffusion-weighted MRI. Exclusion criteria were lesions in both vascular territories or uncertain territory; supratentorial PCiS with ipsilateral fetal posterior cerebral artery; and cases with atrial fibrillation. We generated migraine PRS for three migraine phenotypes (any migraine; migraine without aura; migraine with aura) using publicly available GWAS data and compared mean PRSs separately for PCiS and ACiS vs. non-stroke control subjects, and between each stroke phenotype.

RESULTS

Our primary analyses included 464 PCiS and 1079 ACiS patients with genetic European ancestry. Compared to non-stroke control subjects (n=15396), PRSs of any migraine were associated with increased risk of PCiS (p=0.01-0.03) and decreased risk of ACiS (p=0.010-0.039). Migraine without aura PRSs were significantly associated with PCiS (p=0.008-0.028), but not with ACiS. When comparing PCiS vs. ACiS directly, migraine PRSs were higher in PCiS vs. ACiS for any migraine (p=0.001-0.010) and migraine without aura (p=0.032-0.048). Migraine with aura PRS did not show a differential association in our analyses.

CONCLUSIONS

Our results suggest a stronger genetic overlap between unspecified migraine and migraine without aura with PCiS compared to ACiS. Possible shared mechanisms include dysregulation of cerebral vessel endothelial function.

Genome-wide analysis of 102,084 migraine cases identifies 123 risk loci and subtype-specific risk alleles

Migraine affects over a billion individuals worldwide but its genetic underpinning remains largely unknown. Here, we performed a genome-wide association study of 102,084 migraine cases and 771,257 controls and identified 123 loci, of which 86 are previously unknown. These loci provide an opportunity to evaluate shared and distinct genetic components in the two main migraine subtypes: migraine with aura and migraine without aura. Stratification of the risk loci using 29,679 cases with subtype information indicated three risk variants that seem specific for migraine with aura (in HMOX2, CACNA1A and MPPED2), two that seem specific for migraine without aura (near SPINK2 and near FECH) and nine that increase susceptibility for migraine regardless of subtype. The new risk loci include genes encoding recent migraine-specific drug targets, namely calcitonin gene-related peptide (CALCA/CALCB) and serotonin 1F receptor (HTR1F). Overall, genomic annotations among migraine-associated variants were enriched in both vascular and central nervous system tissue/cell types, supporting unequivocally that neurovascular mechanisms underlie migraine pathophysiology.

Migraine, Stroke, and Cervical Arterial Dissection: Shared Genetics for a Triad of Brain Disorders With Vascular Involvement

BACKGROUND AND OBJECTIVES

Migraine, stroke, and cervical artery dissection (CeAD) represent a triad of cerebrovascular disorders with pairwise comorbid relationships and vascular involvement. Larger samples and recent advances in methodology invite systematic exploration of their shared genetics.

METHODS

Genetic analyses leveraged summary statistics from genome-wide association studies of the largest available samples of each disorder, including subtypes of stroke (ischemic stroke, large artery stroke, small vessel stroke, and cardioembolic stroke) and migraine (with aura and without aura). For each pair of disorders, genetic correlation was assessed both on a genome-wide basis and within independent segments across the genome including known specific loci for each disorder. A cross-trait meta-analysis was used to identify novel candidate loci. Finally, potential causality of migraine susceptibility on stroke and CeAD was assessed by Mendelian randomization.

RESULTS

Among all pairs of disorders, genome-wide genetic correlation was observed only between CeAD and migraine, particularly MO. Local genetic correlations were more extensive between migraine and CeAD than those between migraine and stroke or CeAD and stroke and revealed evidence for novel CeAD associations at rs6693567 (ADAMTSL4/ECM1), rs11187838 (PLCE1), and rs7940646 (MRVI1) while strengthening prior subthreshold evidence at rs9486725 (FHL5) and rs650724 (LRP1). At known migraine loci, novel associations with stroke had concordant risk alleles for small vessel stroke at rs191602009 (CARF) and for cardioembolic stroke at rs55884259 (NKX2-5). Known migraine loci also revealed novel associations but with opposite risk alleles for all stroke, ischemic stroke, and small vessel stroke at rs55928386 (HTRA1), for large artery stroke at rs11172113 (LRP1), and for all stroke and ischemic stroke at rs1535791 and rs4942561 (both LRCH1), respectively. rs182923402 (near PTCH1) was a novel concordant locus for migraine and cardioembolic stroke. Mendelian randomization supported potential causal influences of migraine on CeAD (odds ratio [95% confidence interval] per doubling migraine prevalence = 1.69 [1.24-2.3], p = 0.0009) with concordant risk, but with opposite risk on large artery stroke (0.86 [0.76-0.96], p = 0.0067).

DISCUSSION

The findings emphasize shared genetic risk between migraine and CeAD while identifying loci with likely vascular function in migraine and shared but opposite genetic risk between migraine and stroke subtypes, and a central role of LRP1 in all 3 cerebrovascular disorders.

[Comorbidity in migraine]

Migraine is a common and often disabling disease with a prominent genetic basis. There are many comorbidities associated with migraine which have been identified as risk factors for progression to chronic migraine. Each of these has its own genetic load and shares some common characteristics with migraine. The identification of migraine comorbidities may help clarify common underlying genetic and biological mechanisms of diseases. The treatment of migraine should involve a multifaceted approach, aimed at identifying and reducing possible risk and comorbidity factors. This may prevent the evolution toward a chronic form and then toward pharmacological resistance.

Myocardial infarction, stroke and cardiovascular mortality among migraine patients: a systematic review and meta-analysis

BACKGROUND

An increasing number of studies have shown an association between migraine and cardiovascular disease, in particular cardio- and cerebro-vascular events.

METHODS

Three electronic databases (PubMed, Embase and Scopus) were searched from inception to May 22, 2021 for prospective cohort studies evaluating the risk of myocardial infarction, stroke and cardiovascular mortality in migraine patients. A random effects meta-analysis model was used to summarize the included studies.

RESULTS

A total of 18 prospective cohort studies were included consisting of 370,050 migraine patients and 1,387,539 controls. Migraine was associated with myocardial infarction (hazard ratio, 1.36; 95% CI, 1.23-1.51; p =  < 0.001), unspecified stroke (hazard ratio, 1.30; 95% CI, 1.07-1.60; p = 0.01), ischemic stroke (hazard ratio, 1.35; 95% CI, 1.03-1.78; p = 0.03) and hemorrhagic stroke (hazard ratio, 1.43; 95% CI, 1.07-1.92; p = 0.02). Subgroup analysis of migraine with aura found a further increase in risk of myocardial infarction and both ischemic and hemorrhagic stroke, as well as improved substantial statistical heterogeneity. Migraine with aura was also associated with an increased risk of cardiovascular mortality (hazard ratio, 1.27; 95% CI, 1.14-1.42; p =  < 0.001).

CONCLUSION

Migraine, especially migraine with aura, is associated with myocardial infarction and stroke. Migraine with aura increases the risk of overall cardiovascular mortality.

Migraine and Ischemic Stroke: A Mendelian Randomization Study

Introduction

Previous epidemiological studies have found an increased risk for ischemic stroke in patients with migraine; however, the evidence for a causal relationship between migraine and ischemic stroke is scarce. This study aims to explore the potential causal relationship between migraine and ischemic stroke and its subtypes [including large artery stroke (LAS), small vessel stroke (SVS), and cardioembolic stroke (CES)].

Methods

We used data on genetic variants associated with migraine identified from a genome-wide association study (GWAS) meta-analysis among 889,018 European ancestries. Summary data for ischemic stroke and its subtypes were obtained from the MEGASTROKE consortium including up to 438,847 participants. We performed two-sample Mendelian randomization (MR) analyses using the inverse-variance-weighted method as the primary approach. The MR-Egger, weighted median, simple median, simple mode, and weighted mode methods were also conducted as sensitivity analyses to determine the robustness of our results.

Results

We failed to detect statistically significant associations between migraine and ischemic stroke (OR, 0.935; 95% CI 0.851–1.027; P = 0.159) and its subtypes (LAS: OR, 0.818; 95% CI 0.692–0.967; P = 0.018) (SVS: OR, 0.935; 95% CI 0.781–1.119; P = 0.460) (CES: OR, 1.015; 95% CI 0.867–1.189; P = 0.850). The results were consistent with the sensitivity analyses.

Conclusions

By conducting a series of causal inference approaches, this study supports no causal effect of migraine on ischemic stroke and its subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00310-y.

Migraine and Stroke: In Search of Shared Pathways, Mechanisms, and Risk Factors

Migraines are one of the emerging causes of disabilities experienced worldwide, and strokes are the second leading cause of death globally. Migraines with aura have been reported to be associated with a higher risk of ischemic strokes, whereas hemorrhagic strokes are more closely associated with migraines without aura, possible mechanisms that link migraines to strokes. These can be categorized into vascular mechanisms such as vasospasm, endothelial and platelet dysfunction, and alteration in the vessel wall seen in migraineurs, further perpetrated by vascular risk factors such as hypertension and hyperlipidemias. Cerebral hypoperfusion that occurs in migraines can cause an electrical aberrance, leading to a phenomenon known as "spreading depression" which can contribute to strokes. In this review, we discuss bloodstream elevation in procoagulants such as antiphospholipid antibodies, homocysteine, von Willebrand factor, and prothrombin. Maintaining pregnant women who actively experience migraines with aura under close observation may be of some value in achieving better outcomes. Women who experience migraines after starting hormonal contraception are at a higher risk of experiencing strokes and stand to benefit from being switched to non-hormonal methods. In this article, we discuss the mechanisms linking migraines and strokes, briefly discuss the pathogenesis, and explore the risk factors contributing to the association therein. In addition, we examine the relationship between migraines and ischemic strokes, as well as hemorrhagic strokes, and review management considerations.

Exploring the causal inference of migraine on stroke: A Mendelian randomization study

BACKGROUND AND PURPOSE

Previous observational studies have reported that patients with migraine have an increased risk of stroke. We explored whether migraine has a causal effect on stroke using a two-sample Mendelian randomization approach.

METHODS

Genetic instruments were selected from large genome-wide association studies of migraine and stroke. A two-sample Mendelian randomization analysis was performed, along with sensitivity analysis. We used migraine subtypes (any migraine, migraine with aura, migraine without aura) as risk factors and stroke, ischemic stroke, and hemorrhagic stroke as outcomes for this analysis. Ischemic stroke subtypes were also included to explore the underlying pathogenesis linking migraine to stroke.

RESULTS

Migraine did not show any association with stroke (odds ratio [OR], 0.95; 95% confidence interval [CI], 0.87-1.03), ischemic stroke (OR, 0.93; 95% CI, 0.85-1.02), or hemorrhagic stroke (OR, 1.26; 95% CI, 0.84-1.91), suggesting that the observed association may not be causal. Neither migraine with aura nor without aura showed causal relationship with outcomes. The sensitivity analysis supported the results of the primary analysis. Regarding ischemic stroke subtypes, migraine seemed to have a negative association with large-artery atherosclerosis (OR, 0.81; 95% CI, 0.68-0.95), whereas associations with small-vessel occlusion or cardioembolism were not evident.

CONCLUSIONS

Contrary to previous observational studies, we were unable to find any causal relationship between migraine and stroke. However, the suggested negative association of migraine in large-artery atherosclerosis warrants further research.

Genome-wide association study reveals susceptibility loci for self-reported headache in a large community-based Asian population

BACKGROUND

The genetic substrate for headache in the general population has not been identified in Asians. We investigated susceptible genetic variants for self-reported headache in a large community-based Asian population.

METHODS

We conducted a genome-wide association study in participants recruited from a community-based cohort to identify the genetic variants associated with headache in Taiwanese. All participants received a structured questionnaire for self-reported headache. A total of 2084 patients with "self-reported headache" and 11,822 age- and sex-matched controls were enrolled. Gene enrichment analysis using the Genotype-Tissue Expression version 6 database was performed to explore the potential function of the identified variants.

RESULTS

We identified two novel loci, rs10493859 in TGFBR3 and rs13312779 in FGF23, that are functionally relevant to vascular function and migraine to be significantly associated with self-reported headache after adjusting age, sex and top 10 principal components (p = 8.53 × 10^-11 and p = 1.07 × 10^-8, respectively). Gene enrichment analysis for genes with GWAS suggestive significance (p < 10^-6) demonstrated that the expression of these genes was significantly enriched in the artery (p = 8.18 × 10^-4) and adipose tissue (p = 8.95 × 10^-4).

CONCLUSION

Our results suggest that vascular dysfunction might play important roles in the pathogenesis of self-reported headache in Asian populations.

Stroke and cardiovascular risk factors among working-aged Finnish migraineurs

Background

The aim of our study was to evaluate the risk for comorbid cardio- and cerebrovascular diseases in the working-aged migraine population of Finland.

Methods

A total of 1505 cases who reported diagnosed migraine and 3010 controls from a cohort of 11,596 cases in the Finnish Health and Social Support Study were included. The study material was linked with two registers. ICD diagnoses I63 for ischemic stroke (IS), I21 − I22 for acute myocardial infarction (AMI), and G43 for transient ischemic attack (TIA) among study participants were drawn from the national Finnish Care Register for Health Care at the follow-up in 2012. Reimbursed triptan prescriptions were drawn from the national Social Security Institution (SII) data. The self-reported vascular risk factors were hypertension, high cholesterol values, any diabetes, myocardial infarction, stroke, and TIA. Odds Ratios (OR) with 95% confidence (95% CI) intervals were assessed for diagnosed stroke, myocardial infarction, and TIA.

Results

Migraineurs were mostly female (82%) and ≥ 54 years old (62%). Triptans were reimbursed among 34.7% of migraineurs. A self-reported hypertension (21%), high serum cholesterol (38%), and any diabetes (7%) were more common among migraineurs vs controls (p < 0.05). There was no risk for AMI. The risk for TIA (OR 3.20, 95% CI 1.45–7.05) and IS (2.57, 95% CI 1.28–5.17) among migraineurs vs controls remained high after adjustment for self-reported hypertension, obesity, and smoking. The risk was higher among women in two groups ≥54 years (3.25, 95% CI 1.35–7.84 and 5.0, 95% CI 1.94–12.89, respectively). The average age for IS in migraine was 57.5 years and for TIA 58.2 years among women, and 52.8 years and 50.3 years among men, respectively.

Conclusion

Cardiovascular risk should be screened in the aging migraine population, and hormonal and other migraine-related risk factors should be considered, especially among women. Efficacious attack treatment with triptans should be offered to migraine patients who do not show contraindications.

Risk of Retinal Artery Occlusion in Patients with Migraine

PURPOSE

We sought to determine if migraine is associated with increased risk of retinal artery occlusion (RAO).

DESIGN

Retrospective cohort study.

METHODS

We reviewed a large insurance claims database for patients with migraine and matched control subjects without migraine between 2007 and 2016. Cox proportional hazard regression models were used to investigate the association between migraine and risk of all RAO, central RAO (CRAO), branch RAO (BRAO), and "other" RAO, which includes transient and partial RAO. Primary outcome measures included the incidence of all RAO, including CRAO, BRAO, and other RAO, after first migraine diagnosis.

RESULT

There were 418,965 patients with migraine who met the study criteria and were included in the analysis with the appropriate matched control subjects. Among the 418,965 patients with migraine, 1060 (0.25%) were subsequently diagnosed with RAO, whereas only 335 (0.08%) of the patients without migraine were diagnosed with RAO. The hazard ratio (HR) for incident all RAO in patients with migraine compared with those without migraine was 3.48 (95% confidence interval [CI] 3.07-3.94; P < .0001). This association was consistent across all types of RAO, including CRAO (HR 1.62 [95% CI 1.15-2.28]; P = .004), BRAO (HR 2.09 [95% CI 1.60-2.72]; P < .001), and other types of RAO (HR 4.61 [95% CI 3.94-5.38]; P < .001). Patients with migraine with aura had a higher risk for incident RAO compared with those with migraine without aura (HR 1.58 [95% CI 1.40-1.79]; P < .001). This association was consistent for BRAO (HR 1.43 [95% CI 1.04-1.97]; P < .03) and other types of RAO (HR 1.67 [95% CI 1.45-1.91]; P < .001) but was not statistically significant for CRAO (HR 1.18 [95% CI 0.75-1.87]; P = .475). Significant risk factors for this association included increased age, male sex, acute coronary syndrome, valvular disease, carotid disease, hyperlipidemia, hypertension, retinal vasculitis or inflammation, and systemic lupus erythematosus.

CONCLUSIONS

Migraine is associated with increased risk of all types of RAO and migraine with aura is associated with increased risk of RAO compared with migraine without aura.

Migraine: disease characterisation, biomarkers, and precision medicine

Migraine is a disabling neurological disorder, diagnosis of which is based on clinical criteria. A shortcoming of these criteria is that they do not fully capture the heterogeneity of migraine, including the underlying genetic and neurobiological factors. This complexity has generated momentum for biomarker research to improve disease characterisation and identify novel drug targets. In this Series paper, we present the progress that has been made in the search for biomarkers of migraine within genetics, provocation modelling, biochemistry, and neuroimaging research. Additionally, we outline challenges and future directions for each biomarker modality. We also discuss the advances made in combining and integrating data from multiple biomarker modalities. These efforts contribute to developing precision medicine that can be applied to future patients with migraine.

Ischemic Stroke in Young Adults

PURPOSE OF REVIEW

This article reviews current knowledge on epidemiology, risk factors and causes, diagnostic considerations, management, and prognosis of ischemic stroke in young adults (those 55 years old and younger).

RECENT FINDINGS

The incidence of ischemic stroke in young adults has been increasing since the 1980s, which has occurred in parallel with increasing prevalence of vascular risk factors and substance abuse among the younger population. Young adults have a considerably wider range of risk factors than older patients, including age-specific factors such as pregnancy/puerperium and oral contraceptive use. Behavioral risk factors such as low physical activity, excess alcohol consumption, and smoking are factors as well. More than 150 identified causes of early-onset ischemic stroke exist, including rare monogenic disorders. Several recent advances have been made in diagnosis and management of stroke in young adults, including molecular characterization of monogenic vasculitis due to deficiency of adenosine deaminase 2 and transcatheter closure of patent foramen ovale for secondary prevention. Compared with the background population of the same age and sex, long-term mortality in patients remains fourfold higher with cardiovascular causes underlying most of the deaths. The cumulative rate of recurrent stroke extends up to 15% at 10 years. Patients with atherosclerosis, high-risk sources of cardioembolism, and small vessel disease underlying their stroke seem to have the worst prognosis regarding survival and recurrent vascular events. Young stroke survivors also often have other adverse outcomes in the long term, including epilepsy, pain, cognitive problems, and depression.

SUMMARY

Systematic identification of risk factors and causes and the motivation of patients for long-term prevention and lifestyle changes are of utmost importance to improve the prognosis of early-onset ischemic stroke.

Migraine and risk of stroke

Migraine and stroke are two common and heterogeneous neurovascular disorders responsible for a significant burden for those affected and a great economic cost for the society. There is growing evidence that migraine increases the overall risk of cerebrovascular diseases. In this review, based on available literature through a PubMed search, we found that ischaemic stroke in people with migraine is strongly associated with migraine with aura, young age, female sex, use of oral contraceptives and smoking habits. The risk of transient ischaemic attack also seems to be increased in people with migraine, although this issue has not been extensively investigated. Although migraine appears to be associated with haemorrhagic stroke, the migraine aura status has a small influence on this relationship. Neuroimaging studies have revealed a higher prevalence of asymptomatic structural brain lesions in people with migraine. They are also more likely to have unfavourable vascular risk factors; however, the increased risk of stroke seems to be more apparent among people with migraine without traditional risk factors. The mechanism behind the migraine-stroke association is unknown. In light of the higher risk of stroke in people with migraine with aura, it is important to identify and modify any vascular risk factor. There is currently no direct evidence to support that a migraine prophylactic treatment can reduce future stroke in people with migraine.

Migraine, headache, and mortality in women: a cohort study

BACKGROUND

Migraine carries a high global burden, disproportionately affects women, and has been implicated as a risk factor for cardiovascular disease. Migraine with aura has been consistently associated with increased risk of cardiovascular mortality. However, published evidence on relationships between migraine or non-migraine headache and all-cause mortality is inconclusive. Therefore, we aimed to estimate the effect of non-migraine headache and migraine as well as migraine subtypes on all-cause and cause-specific mortality in women.

METHODS

In total, 27,844 Women's Health Study participants, aged 45 years or older at baseline, were followed up for a median of 22.7 years. We included participants who provided information on migraine (past history, migraine without aura, or migraine with aura) or headache status and a blood sample at study start. An endpoints committee of physicians evaluated reports of incident deaths and used medical records to confirm deaths due to cardiovascular, cancer, or female-specific cancer causes. We used multivariable Cox proportional hazards models to estimate the effect of migraine or headache status on both all-cause and cause-specific mortality.

RESULTS

Compared to individuals without any headache, no differences in all-cause mortality for individuals suffering from non-migraine headache or any migraine were observed after adjustment for confounding (HR = 1.01, 95%CI, 0.93-1.10 and HR = 0.96, 95% CI: 0.89-1.04). No differences were observed for the migraine subtypes and all-cause death. Women having the migraine with aura subtype had  a higher mortality due to cardiovascular disease (adjusted HR = 1.64, 95%CI: 1.06-2.54). As an explanation for the lack of overall association with all-cause mortality, we observed slightly protective signals for any cancer and female-specific cancers in this group.

CONCLUSIONS

In this large prospective study of women, we found no association between non-migraine headache or migraine and all-cause mortality. Women suffering from migraine with aura had an increased risk of cardiovascular death. Future studies should investigate the reasons for the increased risk of cardiovascular mortality and evaluate whether changes in migraine patterns across the life course have differential effects on mortality.

Advance in genetics of migraine

Purpose of review

Migraine is a primary headache disorder and one of the most common and disabling neurological diseases worldwide. Genome-wide association studies have identified ≈40 genetic loci associated with migraine. How these and other genetic findings are used to expand our knowledge on the pathophysiological mechanism of common migraine and rare migraine variants will be discussed.

Recent findings

The genetic load, based on common polygenic variation, is higher in familial migraine cases than in nonfamilial cases, and higher for migraine with aura and hemiplegic migraine. Migraine shares common genetic variant risks with depression. Specific clinical features of common migraine seem to be determined by genetic factors. A stronger family history of migraine is associated with lower age-at-onset, higher frequency and number of medication days and the migraine with aura subtype. Mild hemiplegic migraine is likely caused by complex polygenic interaction of multiple gene variants and environmental factors, like in common migraine subtypes. Phenotypical features in hemiplegic migraine patients may guide physicians in providing adequate genetic counseling.

Summary

Integration of genetic, phenotypic and epigenetic data will help to identify the biological mechanisms by which genetic factors contribute to migraine pathogenesis. Recent studies show the impact of genetics on clinical features and comorbidities in migraine and may guide clinicians to an adequate genetic advice for patients.

Mouse Models of Familial Hemiplegic Migraine for Studying Migraine Pathophysiology

Migraine, an extremely disabling neurological disorder, has a strong genetic component. Since monogenic mi-graines (resulting from mutations or changes in a single gene) may help researchers discover migraine pathophysiology, transgenic mice models harboring gene mutations identified in Familial Hemiplegic Migraine (FHM) patients have been gen-erated. Studies in these FHM mutant mice models have shed light on the mechanisms of migraine and may aid in the identifi-cation of novel targets for treatment. More specifically, the studies shed light on how gene mutations, hormones, and other factors impact the pathophysiology of migraine. The models may also be of relevance to researchers outside the field of mi-graine as some of their aspects are relevant to pain in general. Additionally, because of the comorbidities associated with mi-graine, they share similarities with the mutant mouse models of epilepsy, stroke, and perhaps depression. Here, we review the experimental data obtained from these mutant mice and focus on how they can be used to investigate the pathophysiology of migraine, including synaptic plasticity, neuroinflammation, metabolite alterations, and molecular and behavioral mecha-nisms of pain.

A Comprehensive Assessment of Vascular and Nonvascular Risk Factors Associated with Migraine

Introduction: Migraine is a chronic disabling neurological disease, with an estimated expense of $15-20 million/year. Several studies with a small number of patients have studied risk factors for migraine such as cardiovascular disorders, stroke, smoking, demographic, and genetic factors but this is the first comprehensive study for evaluation of vascular and nonvascular risk factors. It is important to evaluate all the risk factors that help to prevent the healthcare burden related to migraine. 

Methodology: We performed a retrospective cross-sectional analysis of the Nationwide Inpatient Sample (NIS) (years 2013-2014) in adult (>18-years old) hospitalizations in the United States. Migraine patients were identified using ICD-9-CM code to determine the demographic characteristics, vascular, and nonvascular risk factors. Univariate analysis was performed using the chi-square test and a multivariate survey logistic regression analysis was performed to identify the prevalence of the risk factors and evaluate the odds of prevalence of risk factors amongst migraine patients compared to nonmigraine patients, respectively.

Results: On weighted analysis, after removing missing data of age, gender and race, from years 2013 to 2014, of the total 983,065 (1.74%) migraine patients were identified. We found that younger (median age 48-years vs. 60-years), female (82.1% vs. 58.5%; p<0.0001), white population (76.8% vs. 70.5%; p<0.0001), and privately insured (41.1% vs. 27.4%; p<0.0001) patients were more likely to have migraine than others. Cerebral atherosclerosis, diabetes mellitus, ischemic heart disease, atrial fibrillation, and alcohol abuse were not significantly associated with migraine. Migraineurs had higher odds of having hypertension [odds ratio (OR): 1.44; 95% confidence interval (CI): 1.43-1.46; 44.49% vs. 52.84%], recent transient ischemic attack (TIA) (OR: 3.13; 95%CI: 3.02-3.25; 1.74% vs. 0.67%), ischemic stroke (OR: 1.40; 95%CI: 1.35-1.45; 2.06% vs. 1.97%), hemorrhagic stroke (OR: 1.11; 95%CI: 1.04-1.19; 0.49% vs. 0.46%), obesity (OR: 1.46; 95%CI: 1.44-1.48; 19.20% vs. 13.56%), hypercholesterolemia (OR: 1.33; 95%CI: 1.30-1.36; 5.75% vs. 5.54%), substance abuse (OR: 1.51; 95%CI: 1.48-1.54; 7.88% vs. 4.88%), past or current consumption of tobacco (OR: 1.40; 95%CI: 1.38-1.41; 31.02% vs. 27.39%), AIDS (OR: 1.13; 95%CI: 1.04-1.24; 0.33% vs. 0.41%), hypocalcemia (OR: 1.09; 95%CI: 1.03-1.14; 0.77% vs. 0.89%), and vitamin D deficiency (OR: 1.93; 95%CI: 1.88-1.99; 2.47% vs. 1.37%) than patients without migraine. Female patients were at a higher risk of migraine (OR: 3.02; 95%CI: 2.98-3.05) than male.

Conclusion: In this study, we have identified significant risk factors for migraine hospitalizations. Early identification of these risk factors may improve the risk stratification in migraine patients. 

Association of rs2651899 Polymorphism in the Positive Regulatory Domain 16 and Common Migraine Subtypes: A Meta-Analysis

BACKGROUND

Migraine is a neurovascular disease with recurrent headache attacks. A polymorphism (rs2651899) of the PRDM16 gene, which is associated with migraine, was identified in recent genome-wide association studies. The potential role of the PRDM16 rs2651899 polymorphism in migraine is still unknown. Therefore, we conducted this systematic review and meta-analysis to examine this issue.

METHODS

We performed a comprehensive literature search of the PubMed, Embase, and Google Scholar databases to identify eligible studies published before October 2018. Individual odds ratio and 95% confidence interval was used to estimate the pooled strength of the association between the PRDM16 rs2651899 polymorphism and common migraine subtypes, including migraine with aura (MA) and migraine without aura (MO).

RESULTS

Six studies with 2853 cases and 9319 controls that fulfilled the inclusion and exclusion criteria were selected for this meta-analysis. Of the 6 included studies, 4 studies had available data for MWA and another 4 studies had data for MWoA. Overall, significant migraine risks of 1.257, 1.305, and 1.419 were found under allele model (C vs T), dominant model (C/C+T/C vs T/T), and recessive model (C/C vs T/C+T/T), respectively. In the recessive model, significantly increased risks of 1.454 and 1.546 were found for MA and MO, respectively.

CONCLUSION

Our major findings suggest that PRDM16 rs2651899 polymorphism is associated with the risk of migraine. Furthermore, we found that PRDM16 rs2651899 polymorphism is significantly related to common migraine subtypes (MA and MO).

Migraine Genetic Variants Influence Cerebral Blood Flow

Objective

To investigate the association of migraine genetic variants with cerebral blood flow (CBF).

Background

Migraine is a common disorder with many genetic and non‐genetic factors affecting its occurrence. The exact pathophysiological mechanisms underlying the disease remain unclear, but are known to involve hemodynamic and vascular disruptions. Recent genome‐wide association studies have identified 44 genetic variants in 38 genetic loci that affect the risk of migraine, which provide the opportunity to further disentangle these mechanisms.

Methods

We included 4665 participants of the population‐based Rotterdam Study (mean age 65.0 ± 10.9 years, 55.6% women). Cross‐sectional area (mm²), flow velocity (mm/s), and blood flow (mL/min) were measured in both carotids and the basilar artery using 2‐dimensional phase‐contrast magnetic resonance imaging. We analyzed 43 previously identified migraine variants separately and calculated a genetic risk score (GRS). To assess the association with CBF, we used linear regression models adjusted for age, sex, and total brain volume. Hierarchical clustering was performed based on the associations with CBF measures and tissue enrichment.

Results

The rs67338227 risk allele was associated with higher flow velocity and smaller cross‐sectional area in the carotids (P_minimum = 3.7 × 10⁻⁸). Other variants were related to CBF with opposite directions of effect, but not significantly after multiple testing adjustments (P < 1.4 × 10⁻⁴). The migraine GRS was not associated with CBF after multiple testing corrections. Migraine risk variants were found to be enriched for flow in the basilar artery (λ = 2.39).

Conclusions

These findings show that genetic migraine risk is complexly associated with alterations in cerebral hemodynamics.

Advances in genetics of migraine

Background

Migraine is a complex neurovascular disorder with a strong genetic component. There are rare monogenic forms of migraine, as well as more common polygenic forms; research into the genes involved in both types has provided insights into the many contributing genetic factors. This review summarises advances that have been made in the knowledge and understanding of the genes and genetic variations implicated in migraine etiology.

Findings

Migraine is characterised into two main types, migraine without aura (MO) and migraine with aura (MA). Hemiplegic migraine is a rare monogenic MA subtype caused by mutations in three main genes - CACNA1A, ATP1A2 and SCN1A - which encode ion channel and transport proteins. Functional studies in cellular and animal models show that, in general, mutations result in impaired glutamatergic neurotransmission and cortical hyperexcitability, which make the brain more susceptible to cortical spreading depression, a phenomenon thought to coincide with aura symptoms. Variants in other genes encoding ion channels and solute carriers, or with roles in regulating neurotransmitters at neuronal synapses, or in vascular function, can also cause monogenic migraine, hemiplegic migraine and related disorders with overlapping symptoms. Next-generation sequencing will accelerate the finding of new potentially causal variants and genes, with high-throughput bioinformatics analysis methods and functional analysis pipelines important in prioritising, confirming and understanding the mechanisms of disease-causing variants.

With respect to common migraine forms, large genome-wide association studies (GWAS) have greatly expanded our knowledge of the genes involved, emphasizing the role of both neuronal and vascular pathways. Dissecting the genetic architecture of migraine leads to greater understanding of what underpins relationships between subtypes and comorbid disorders, and may have utility in diagnosis or tailoring treatments. Further work is required to identify causal polymorphisms and the mechanism of their effect, and studies of gene expression and epigenetic factors will help bridge the genetics with migraine pathophysiology.

Conclusions

The complexity of migraine disorders is mirrored by their genetic complexity. A comprehensive knowledge of the genetic factors underpinning migraine will lead to improved understanding of molecular mechanisms and pathogenesis, to enable better diagnosis and treatments for migraine sufferers.

Aura and Stroke: relationship and what we have learnt from preclinical models

BACKGROUND

Population-based studies have highlighted a close relationship between migraine and stroke. Migraine, especially with aura, is a risk factor for both ischemic and hemorrhagic stroke. Interestingly, stroke risk is highest for migraineurs who are young and otherwise healthy.

MAIN BODY

Preclinical models have provided us with possible mechanisms to explain the increased vulnerability of migraineurs' brains towards ischemia and suggest a key role for enhanced cerebral excitability and increased incidence of microembolic events. Spreading depolarization (SD), a slowly propagating wave of neuronal depolarization, is the electrophysiologic event underlying migraine aura and a known headache trigger. Increased SD susceptibility has been demonstrated in migraine animal models, including transgenic mice carrying human mutations for the migraine-associated syndrome CADASIL and familial hemiplegic migraine (type 1 and 2). Upon experimentally induced SD, these mice develop aura-like neurological symptoms, akin to patients with the respective mutations. Migraine mutant mice also exhibit an increased frequency of ischemia-triggered SDs upon experimental stroke, associated with accelerated infarct growth and worse outcomes. The severe stroke phenotype can be explained by SD-related downstream events that exacerbate the metabolic mismatch, including pericyte contraction and neuroglial inflammation. Pharmacological suppression of the genetically enhanced SD susceptibility normalizes the stroke phenotype in familial hemiplegic migraine mutant mice. Recent epidemiologic and imaging studies suggest that these preclinical findings can be extrapolated to migraine patients. Migraine patients are at risk for particularly cardioembolic stroke. At the same time, studies suggest an increased incidence of coagulopathy, atrial fibrillation and patent foramen ovale among migraineurs, providing a possible path for microembolic induction of SD and, in rare instances, stroke in hyperexcitable brains. Indeed, recent imaging studies document an accelerated infarct progression with only little potentially salvageable brain tissue in acute stroke patients with a migraine history, suggesting an increased vulnerability towards cerebral ischemia.

CONCLUSION

Preclinical models suggest a key role for enhanced SD susceptibility and microembolization to explain both the occurrence of migraine attacks and the increased stroke risk in migraineurs. Therapeutic targeting of SD and microembolic events, or potential causes thereof, will be promising for treatment of aura and may also prevent ischemic infarction in vulnerable brains.

Association of migraine with calcification in major vessel beds: The Rotterdam Study

BACKGROUND

To explore the role of large-artery atherosclerosis in migraine, we investigated the association between migraine and arterial calcification in different intracranial and extracranial vessels.

METHODS

1856 participants were included, mean age (standard deviation) 67.4 (5.8) years, from the population-based Rotterdam Study cohort. Migraine was assessed by validated questionnaire and vascular calcification was assessed by computed tomography (expressed in Agatston score for the coronary arteries and volume in mm³ for the aortic arch, intracranial, and extracranial carotid arteries). Per vessel, the association of migraine with calcification was investigated by linear regression, adjusted for age, sex, cardiovascular risk factors, and calcification in other vessels.

RESULTS

Of the participants, 279 (15%) were identified as persons with lifetime migraine. In multivariable adjusted models, migraine was associated with smaller intracranial carotid artery calcification volume (difference in log-transformed calcification volume in persons with migraine compared to persons without migraine: -0.19[-0.29, -0.08]). While subjects with migraine also showed a lower calcification burden in the remaining arterial beds, those associations did not reach statistical significance.

CONCLUSIONS

Persons with migraine, compared to those without, had less arterial calcification in the intracranial carotid artery, but not in other arterial beds. Future studies are needed to confirm these findings.

Risk of ischaemic stroke in patients with migraine: a longitudinal follow-up study using a national sample cohort in South Korea

OBJECTIVE

Accumulating evidence has supported the association between migraine and stroke, but the causative association remains unclear. We aimed to investigate the risks of different types of stroke in patients with migraine.

DESIGN

A longitudinal follow-up study.

SETTING

Data collected from a national cohort between 2002 and 2013 by the South Korea Health Insurance Review and Assessment.

PARTICIPANTS

We extracted the data from patients with migraine (n=41 585) and 1:4 matched controls (n=1 66 340) and analysed the occurrence of ischaemic and haemorrhagic strokes. The migraine group included participants treated for migraine (International Classification of Disease-10 (ICD-10): G43)≥2 times. Haemorrhagic stroke (I60-I62) and ischaemic stroke (I63) were determined based on the admission histories. The crude and adjusted HRs were calculated using Cox proportional hazard models, and the 95% CI were determined. Subgroup analyses stratified by age and sex were also performed.

RESULTS

Higher rates of ischaemic stroke were observed in the migraine group (2.3% [964/41,585]) than in the control group (2.0% [3294/166 340], P<0.001). The adjusted HR for ischaemic stroke was 1.18 (95% CI=1.10 to 1.26) in the migraine group (P<0.001). Compared with control subjects, participants who reported migraine with aura and migraine without aura had increased adjusted HRs of 1.44 (95% CI=1.09 to 1.89) and 1.15 (95% CI=1.06 to 1.24), respectively, for ischaemic stroke, but no increased risk of haemorrhagic stroke. In our subgroup analysis, a strong association between migraine and ischaemic stroke was observed in young patients, specifically young women. The contribution of migraine to the occurrence of ischaemic stroke was also observed in middle-aged women and old women (each P<0.05). The risk of haemorrhagic stroke did not reach statistical significance in any age group.

CONCLUSION

Migraine is associated with an increased risk of ischaemic stroke, but not haemorrhagic stroke.

Targeting MTHFR for the treatment of migraines

INTRODUCTION

Migraine is a common neurovascular disorder classified by the World Health Organization as one of the most debilitating diseases. Migraine is a complex disease and is a consequence of an interaction between genetic, epigenetic and environmental factors. The MTHFR gene is one of the few replicated genetic risk factors for migraine and encodes an enzyme that is crucial for the folate and the methionine cycles. Individuals carrying the T allele of the MTHFR C677T polymorphism have increased plasma concentrations of homocysteine which leads to endothelial cell injury and alterations in coagulant properties of blood. Areas covered: This review focuses on the recent advances in genetics and the role of the MTHFR gene and homocysteine metabolism in migraine etiopathogenesis. The article summarizes the potential of targeting MTHFR and homocysteine for disease prevention. Expert opinion: Determination of MTHFR C677T polymorphisms as well as measurement of homocysteine concentrations may be useful to migraine patients, particularly those suffering from migraine with aura. Preliminary studies support the use of folate, vitamin B6 and vitamin B12 for the prevention of migraine. However, the results of these studies await replication in larger randomized controlled clinical trials.

Using a Genetic Risk Score Approach to Predict Headache Response to Triptans in Migraine Without Aura

A large meta-analysis of genome-wide association studies has recently identified a number of risk loci for migraine without aura (MwoA). In this study, we tested the hypothesis that a genetic risk score based on single-nucleotide polymorphisms (SNPs), previously reported to be associated with MwoA at genome-wide significance, may influence headache response to triptans in patients with migraine without aura. Genotyping of rs9349379, rs2078371, rs6478241, rs11172113, rs1024905, and rs6724624 was conducted with a real-time PCR allelic discrimination assay in 172 MwoA patients, of whom 36.6% were inconsistent responders to triptans. Each genetic risk score model was constructed as an unweighted score, calculated by adding the number of risk alleles for MwoA across each SNP at selected loci. The association with headache response to triptans was evaluated by logistic regression analysis adjusted for triptan, and the P values were corrected for the false discovery rate. The genetic risk score including susceptibility risk alleles at TRPM8 rs6724624 and FGF6 rs1024905 was found to be inversely associated with risk of inconsistent response to triptans (OR, 0.62; 95%CI, 0.43-0.89; false discovery rate q value, 0.045). In addition, adding this genetic risk score to the triptan-adjusted logistic regression model significantly improved (P = .037) the discrimination accuracy, from 0.57 (95%CI, 0.50-0.65) to 0.64 (95%CI, 0.57-0.72). A modest but significant effect on risk of inconsistent response to triptans was identified for a genetic risk score model composed of 2 known risk alleles for MwoA, suggesting its potential utility in predicting headache response to triptan therapy.

Risk factors and mechanisms of stroke in young adults: The FUTURE study

Incidence of ischemic stroke and transient ischemic attack in young adults is rising. However, etiology remains unknown in 30-40% of these patients when current classification systems designed for the elderly are used. Our aim was to identify risk factors according to a pediatric approach, which might lead to both better identification of risk factors and provide a stepping stone for the understanding of disease mechanism, particularly in patients currently classified as "unknown etiology". Risk factors of 656 young stroke patients (aged 18-50) of the FUTURE study were categorized according to the "International Pediatric Stroke Study" (IPSS), with stratification on gender, age and stroke of "unknown etiology". Categorization of risk factors into ≥1 IPSS category was possible in 94% of young stroke patients. Chronic systemic conditions were more present in patients aged <35 compared to patients ≥35 (32.6% vs. 15.6%, p < 0.05). Among 226 patients classified as "stroke of unknown etiology" using TOAST, we found risk factors in 199 patients (88%) with the IPSS approach. We identified multiple risk factors linked to other mechanisms of stroke in the young than in the elderly . This can be a valuable starting point to develop an etiologic classification system specifically designed for young stroke patients.

Polygenic risk score: use in migraine research

BACKGROUND

The latest Genome-Wide Association Study identified 38 genetic variants associated with migraine. In this type of studies the significance level is very difficult to achieve (5 × 10^- 8) due to multiple testing. Thus, the identified variants only explain a small fraction of the genetic risk. It is expected that hundreds of thousands of variants also confer an increased risk but do not reach significance levels. One way to capture this information is by constructing a Polygenic Risk Score. Polygenic Risk Score has been widely used with success in genetics studies within neuropsychiatric disorders. The use of polygenic scores is highly relevant as data from a large migraine Genome-Wide Association Study are now available, which will form an excellent basis for Polygenic Risk Score in migraine studies.

RESULTS

Polygenic Risk Score has been used in studies of neuropsychiatric disorders to assess prediction of disease status in case-control studies, shared genetic correlation between co-morbid diseases, and shared genetic correlation between a disease and specific endophenotypes.

CONCLUSION

Polygenic Risk Score provides an opportunity to investigate the shared genetic risk between known and previously unestablished co-morbidities in migraine research, and may lead to better and personalized treatment of migraine if used as a clinical assistant when identifying responders to specific drugs. Polygenic Risk Score can be used to analyze the genetic relationship between different headache types and migraine endophenotypes. Finally, Polygenic Risk Score can be used to assess pharmacogenetic effects, and perhaps help to predict efficacy of the Calcitonin Gene-Related Peptide monoclonal antibodies that soon become available as migraine treatment.

Genome-wide DNA methylation profiling in whole blood reveals epigenetic signatures associated with migraine

Background

Migraine is a common heritable neurovascular disorder typically characterised by episodic attacks of severe pulsating headache and nausea, often accompanied by visual, auditory or other sensory symptoms. Although genome-wide association studies have identified over 40 single nucleotide polymorphisms associated with migraine, there remains uncertainty about the casual genes involved in disease pathogenesis and how their function is regulated.

Results

We performed an epigenome-wide association study, quantifying genome-wide patterns of DNA methylation in 67 migraine cases and 67 controls with a matching age and sex distribution. Association analyses between migraine and methylation probe expression, after adjustment for cell type proportions, indicated an excess of small P values, but there was no significant single-probe association after correction for multiple testing (P < 1.09 × 10^− 7). However, utilising a 1 kb sliding window approach to combine adjacent migraine-methylation association P values, we identified 62 independent differentially methylated regions (DMRs) underlying migraine (false discovery rate < 0.05). Migraine association signals were subtle but consistent in effect direction across the length of each DMR. Subsequent analyses showed that the migraine-associated DMRs were enriched in regulatory elements of the genome and were in close proximity to genes involved in solute transportation and haemostasis.

Conclusions

This study represents the first genome-wide analysis of DNA methylation in migraine. We have identified DNA methylation in the whole blood of subjects associated with migraine, highlighting novel loci that provide insight into the biological pathways and mechanisms underlying migraine pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4450-2) contains supplementary material, which is available to authorized users.

Migraine and risk of stroke: a national population-based twin study

Numerous studies have indicated an increased risk for stroke in patients with migraine, especially migraine with aura; however, many studies used self-reported migraine and only a few controlled for familial factors. We aimed to investigate migraine as a risk factor for stroke in a Swedish population-based twin cohort, and whether familial factors contribute to an increased risk. The study population included twins without prior cerebrovascular disease who answered a headache questionnaire during 1998 and 2002 for twins born 1935-58 and during 2005-06 for twins born between 1959 and 1985. Migraine with and without aura and probable migraine was defined by an algorithm mapping on to clinical diagnostic criteria according to the International Classification of Headache Disorders. Stroke diagnoses were obtained from the national patient and cause of death registers. Twins were followed longitudinally, by linkage of national registers, from date of interview until date of first stroke, death, or end of study on 31 Dec 2014. In total, 8635 twins had any migraineous headache, whereof 3553 had migraine with aura and 5082 had non-aura migraineous headache (including migraine without aura and probable migraine), and 44 769 twins had no migraine. During a mean follow-up time of 11.9 years we observed 1297 incident cases of stroke. The Cox proportional hazards model with attained age as underlying time scale was used to estimate hazard ratios with 95% confidence intervals for stroke including ischaemic and haemorrhagic subtypes related to migraine with aura, non-aura migraineous headache, and any migraineous headache. Analyses were adjusted for gender and cardiovascular risk factors. Where appropriate; within-pair analyses were performed to control for confounding by familial factors. The age- and gender-adjusted hazard ratio for stroke related to migraine with aura was 1.27 (95% confidence interval 1.00-1.62), P = 0.05, and 1.07 (95% confidence interval 0.91-1.26), P = 0.39 related to any migraineous headache. Multivariable adjusted analyses showed similar results. When stratified by gender and attained age of ≤50 or >50 years, the estimated hazard ratio for stroke was higher in twins younger than 50 years and in females; however, non-significant. In the within-pair analysis, the hazard ratio for stroke related to migraine with aura was attenuated [hazard ratio 1.09 (95% confidence interval 0.81-1.46), P = 0.59]. In conclusion, we observed no increased stroke risk related to migraine overall but there was a modestly increased risk for stroke related to migraine with aura, and within-pair analyses suggested that familial factors might contribute to this association.

Shared genetic risk between migraine and coronary artery disease: A genome-wide analysis of common variants

Migraine is a recurrent pain condition traditionally viewed as a neurovascular disorder, but little is known of its vascular basis. In epidemiological studies migraine is associated with an increased risk of cardiovascular disease, including coronary artery disease (CAD), suggesting shared pathogenic mechanisms. This study aimed to determine the genetic overlap between migraine and CAD, and to identify shared genetic risk loci, utilizing a conditional false discovery rate approach and data from two large-scale genome-wide association studies (GWAS) of CAD (C4D, 15,420 cases, 15,062 controls; CARDIoGRAM, 22,233 cases, 64,762 controls) and one of migraine (22,120 cases, 91,284 controls). We found significant enrichment of genetic variants associated with CAD as a function of their association with migraine, which was replicated across two independent CAD GWAS studies. One shared risk locus in the PHACTR1 gene (conjunctional false discovery rate for index SNP rs9349379 < 3.90 x 10⁻⁵), which was also identified in previous studies, explained much of the enrichment. Two further loci (in KCNK5 and AS3MT) showed evidence for shared risk (conjunctional false discovery rate < 0.05). The index SNPs at two of the three loci had opposite effect directions in migraine and CAD. Our results confirm previous reports that migraine and CAD share genetic risk loci in excess of what would be expected by chance, and highlight one shared risk locus in PHACTR1. Understanding the biological mechanisms underpinning this shared risk is likely to improve our understanding of both disorders.

Migraine and Stroke: What's the Link? What to Do?

Migraine and stroke are common, disabling neurologic disorders, with a high socioeconomic burden. A link between them has been proposed years ago, and various theories have been proposed to explain this bidirectional relation. However, the precise causes remain unclear. We briefly summarize existing hypotheses of this correlation seeking for recommendations for stroke prevention in migraineurs, if any exist. Among the strongest suggested theories of migraine-stroke association are cortical spreading depression, endovascular dysfunction, vasoconstriction, neurogenic inflammation, hypercoagulability, increased prevalence of vascular risk factors, shared genetic defects, cervical artery dissection, and patent foramen ovale. There is no evidence that any preventive therapy in migraineurs should be used to decrease stroke risk, even in most predisposed subset of patients. However, a woman with migraine with aura should be encouraged to cease smoking and avoid taking oral contraceptives with high estrogen doses. We need further investigation to better understand the complexity of migraine-stroke association and to make firm recommendations for the future.