Human Studies in the Pathophysiology of Migraine: Genetics and Functional Neuroimaging

Functional difficulties mediate the association between exposure to adverse childhood experiences and headaches among children: Findings from a population-based study

BACKGROUND

Adverse childhood experiences (ACEs) are commonly observed in the general population and often have lasting neurological and physiological effects. Previous studies have found links between exposure to ACEs, headaches, and functional difficulties in adults. However, little is known about the mechanisms through which exposure to ACEs is associated with headaches among children.

OBJECTIVE

To examine the association between exposure to ACEs and headaches in children, and whether functional difficulties mediate this association.

METHODS

Data for this cross-sectional secondary analysis study came from the 2017-2018 National Survey of Children's Health. The sample analyzed in this study was 40,953 children who were between ages 3 and 17 years. We adjusted for the complexity of the sampling design and used structural equation modeling to examine the mediating effect of functional difficulties in the association between exposure to ACEs and headaches.

RESULTS

Based on parent reports, we found that 4.1% (1697/40,953) of the children reported frequent or severe headaches, and 9.5% (3906/40,953) were exposed to three or more ACEs. About one in four children (23.4%; 9601/40,953) had at least one functional difficulty. The results show that exposure to ACEs was directly positively associated with functional difficulties (β = 0.16, p < 0.001, 95% CI = 0.15-0.17), and functional difficulties were in turn positively associated with headaches (β = 0.17, p < 0.001, 95% CI = 0.12-0.22). The Sobel test of indirect effect showed that functional difficulties partially mediated the association between exposure to ACEs and headaches (β = 0.027, p < 0.001, 95% CI = 0.022-0.029). Also, older children and children with brain injury were more likely to report experiencing headaches.

CONCLUSIONS

The findings from this study suggest an association between exposure to ACEs and headaches among children, and functional difficulties partially mediate this association.

Migraine Headache and Risk of Dementia in the Atherosclerosis Risk in Communities Neurocognitive Study

OBJECTIVE

We aimed to assess the association between migraine headache and incident dementia.

BACKGROUND

Migraine is a risk factor for white matter hyperintensities and ischemic stroke, which are both associated with increased risk of dementia. However, it is unknown whether migraine is independently associated with dementia.

METHODS

History of migraine was ascertained via questionnaire. Adjudicated cases of dementia were identified using cognitive tests, neuropsychological exams, and clinician review of suspected cases. Incident dementia was identified using adjudicated cases, follow-up calls, and surveillance of hospital and death codes. We assessed hazards of incident dementia by migraine status. Sex differences were also examined and stratified results were presented.

RESULTS

Analysis included 12,495 White and African American participants ages 51-70 with a median follow-up time of 21 years. Prevalence of dementia was 18.5% (1821/9955) among those with no migraine history, 15.8% (196/1243) among those with severe non-migraine heading, and 16.7% (233/1397) among migraineurs. There was no association between migraine and incident dementia [hazard ratio: 1.04 (0.91, 1.20)]. There was also no statistically significant interaction between sex and migraine status on risk of dementia.

CONCLUSION

Despite evidence of brain abnormalities in migraineurs, there was no association between migraine and incident dementia in this prospective cohort.

Abnormal functional connectivity under somatosensory stimulation in migraine: a multi-frequency magnetoencephalography study

BACKGROUND

Although altered neural networks have been demonstrated in recent MEG (magnetoencephalography) research in migraine patients during resting state, it is unknown whether this alteration can be detected in task-related networks. The present study aimed to investigate the abnormalities of the frequency-specific somatosensory-related network in migraine patients by using MEG.

METHODS

Twenty-two migraineurs in the interictal phase and twenty-two sex- and age-matched healthy volunteers were studied using a whole-head magnetoencephalography (MEG) system. Electrical stimuli were delivered alternately to the median nerve on the right wrists of all subjects. MEG data were analyzed in a frequency range of 1-1000 Hz in multiple bands.

RESULTS

The brain network patterns revealed that the patients with migraine exhibited remarkably increased functional connectivity in the high-frequency (250-1000 Hz) band between the sensory cortex and the frontal lobe. The results of quantitative analysis of graph theory showed that the patients had (1) an increased degree of connectivity in the theta (4-8 Hz), beta (13-30 Hz) and gamma (30-80 Hz) bands; (2) an increased connectivity strength in the beta (13-30 Hz) and gamma (30-80 Hz) bands; (3) an increased path length in the beta (13-30 Hz), gamma (30-80 Hz) and ripple (80-250 Hz) bands; and (4) an increased clustering coefficient in the theta (4-8 Hz), beta (13-30 Hz) and gamma (30-80 Hz) bands.

CONCLUSIONS

The results indicate that migraine is associated with aberrant connections from the somatosensory cortex to the frontal lobe. The frequency-specific increases in connectivity in terms of strength, path length and clustering coefficients support the notion that migraineurs have elevated cortical networks. This alteration in functional connectivity may be involved in somatosensory processing in migraine patients and may contribute to understanding migraine pathophysiology and to providing convincing evidence for a spatially targeted migraine therapy.

Children with allergic diseases have an increased subsequent risk of migraine upon reaching school age

The association between migraine and allergy has remained a subject of debate for more than a century. To systemically investigate the interaction between children with antecedent allergic diseases and their future risks of migraine on reaching school age, we recruited 16,130 children aged 7-18 with migraine diagnosed between 2000 and 2008, and 64,520 matched controls without a history of migraine. The ORs of migraine were calculated for the association with allergic diseases diagnosed before migraine diagnosis. The allergic diseases included atopic dermatitis, allergic conjunctivitis, allergic rhinitis (AR), and asthma. Children with preceding allergic diseases had a greater subsequent risk of migraine than the controls. Among the four evaluated diseases, AR had the highest adjusted OR (aOR) of 2.17 (95% CI 2.09 to 2.26). Children with all four allergic diseases had the highest aOR of 3.59 (95% CI 2.91 to 4.44). Further, an increasing trend of aORs was observed with more allergic disease-associated medical consulting. Our study indicates that children with allergic diseases are at increased subsequent risk of migraine when they reach school age, and the risk shows a cumulative effect of more allergic diseases and more allergy-related healthcare.

Interictal abnormal fMRI activation of visual areas during a motor task cued by visual stimuli in migraine

Objective

To assess changes in blood-oxygen-level-dependent activity after light deprivation compared to regular light exposure in subjects with migraine in the interictal state and in controls.

Methods

Ten subjects with migraine and ten controls participated in two sessions of functional magnetic resonance imaging. In each session, they performed a finger-tapping task with the right hand, cued by visual stimuli. They were scanned before and after 30 minutes of light deprivation or light exposure. In subjects with migraine, functional magnetic resonance imaging was performed interictally. Analysis of variance was made with the factors time (before or after), session (light deprivation or exposure), and group (migraine or control).

Results

There were significant “group” effects in a cluster in the bilateral cuneus encompassing the superior border of the calcarine sulcus and extrastriate cortex. There were no significant effects of “time”, “session”, or interactions between these factors.

Conclusion

The main result of this study is consistent with aberrant interictal processing of visual information in migraine. Light deprivation did not modulate functional magnetic resonance imaging activity in subjects with or without migraine.

Allergic Conjunctivitis and the Associated Risk of Migraine Among Children: A Nationwide Population-based Cohort Study

PURPOSE

To investigate the risk of migraine in children with allergic conjunctivitis (AC).

METHODS

In this population-based cohort study, 309 138 children with AC and 309 138 non-AC controls were included between 2000 and 2007. By 2008 end, the incidences of migraine in both cohorts, and the AC-to-non-AC cohort hazard ratios (HRs) were measured.

RESULTS

The incidence of migraine during the study period was 1.92-fold higher in the AC cohort than in the non-AC cohort. The risk was greater for boys with AC and children aged <6 years. The mean time-interval between physician-diagnosed AC to physician-diagnosed migraine was 3.67 years (SD = 2.19).The risk of migraine development in the AC cohort increased with follow-up time and was highest during 4-5 years after AC diagnosis. The children with AC more likely had migraine without than with aura.

CONCLUSIONS

Children with AC had a higher incidence and subsequent risk of migraine.

Case-control study of GRIA1 and GRIA3 gene variants in migraine

Background

As the most abundant excitatory neurotransmitter in the central nervous system, glutamate has been accepted to play a major role in the pathophysiology of migraine. The previous studies have reported the glutamate receptor ionotropic GRIA1 and GRIA3 genes variants associated with migraine. The project aims to investigate the polymorphisms in both genes for their association with migraine in the Chinese Han population.

Methods

A Han-Chinese case-control population, including 331 unrelated female migraine patients and 330 matched controls, was studied. Variants in genes (GRIA1 and GRIA3) were genotyped by Multiplex SNaPshot assay.

Results

In the group of patients, the frequency of allele C was 84.1 % (557 C alleles) and allele T was 15.9 % (105 T alleles) for the GRIA1 (rs2195450) in migraineurs, this was significantly as compared with the controls (P = .001, OR = 1.786, 95 % CI: 1.28–2.49). And an association was also seen in the migraine with aura (MA) subtype (P = .012, OR = 2.092, 95 % CI: 1.17–3.76) and migraine without aura (MO) subtype (P = .002, OR = 1.737, 95 % CI: 1.23–2.45). However, no evidence was found that GRIA1 (rs548294) or GRIA3 (rs3761555) is associated with migraine.

Conclusion

Our data of this study confirmed the association of GRIA1 (rs2195450) to female migraine (MA, MO) susceptibility in the Chinese Han population. The result provides evidence that the glutamatergic system is implicated in the pathophysiology of migraine.

Genome wide association study identifies variants in NBEA associated with migraine in bipolar disorder

BACKGROUND

Migraine is a common comorbidity among individuals with bipolar disorder, but the underlying mechanisms for this co-occurrence are poorly understood. The aim of this study was to investigate the genetic background of bipolar patients with and without migraine.

METHODS

We performed a genome-wide association analysis contrasting 460 bipolar migraneurs with 914 bipolar patients without migraine from the Bipolar Genome Study (BiGS).

RESULTS

We identified one genome-wide significant association between migraine in bipolar disorder patients and rs1160720, an intronic single nucleotide polymorphism (SNP) in the NBEA gene (P=2.97 × 10(-8), OR: 1.82, 95% CI: 1.47-2.25), although this was not replicated in a smaller sample of 289 migraine cases.

LIMITATIONS

Our study is based on self-reported migraine.

CONCLUSIONS

NBEA encodes neurobeachin, a scaffolding protein primarily expressed in the brain and involved in trafficking of vesicles containing neurotransmitter receptors. This locus has not previously been implicated in migraine per se. We found no evidence of association in data from the GWAS migraine meta-analysis consortium (n=118,710 participants) suggesting that the association might be specific to migraine co-morbid with bipolar disorder.

Serotonin, 5HT1 agonists, and migraine: new data, but old questions still not answered

PURPOSE OF REVIEW

The serotonergic system has long been linked to migraine but recent studies highlight how much is still unclear about this link. And recent data add to the uncertainty of where/how triptans act and why they are headache specific.

RECENT FINDINGS

Markers of 5HT levels in the brains of migraine patients show no changes between attacks. Several recent meta-analyses show the most convincing data on genetic differences in the serotonergic system for 5HT transporters. Findings of additional triptan actions on peripheral trigeminovascular neurons and in the hypothalamus add more fuel to the debate on where these drugs act. A growing list of studies show efficacy of multiple triptans and other 5HT1b/1d agonists in preclinical models of nonheadache pain arguing for reevaluation of whether these drugs have efficacy in other pain states. Despite these issues, serotonergic drugs continue to be the gold standard for abortive agents with new members on the horizon (5HT1f agonists).

SUMMARY

Given the clear efficacy of serotonergic drugs for migraine, continued study on the role of the endogenous 5HT system may lead to more novel therapies. And with the list of studies demonstrating efficacy triptans in models of nonheadache, clinical studies should address whether these drugs work for other types of pain.

Pharmacogenomics of episodic migraine: time has come for a step forward

Migraine is characterized by heterogeneous behavior in response to drugs. Many resources have been invested in attempting to unravel the genetic basis of migraine, while the role of genetics in responses to currently available drugs has received less attention. We performed a systematic literature search identifying original articles pertaining to pharmacogenomics of episodic migraine. Few primary studies on the pharmacogenomics of symptomatic and preventive medication in episodic migraine were found. The number of patients studied in the individual articles ranged from 40 up to 130. There was a strong heterogeneity among these studies. We believe that pharmacogenomics studies, if properly designed, could contribute towards optimizing the treatment and reducing the burden of migraine, in turn helping patients and optimizing resources. Our knowledge on the pharmacogenomics of migraine is growing too slowly, and concerted measures should be undertaken to speed up the process.

Pediatric migraine: abortive management in the emergency department

Studies suggest that headache accounts for approximately 1% of pediatric emergency department (ED) visits. ED physicians must distinguish between primary headaches, such as a tension or migraine, and secondary headaches caused by systemic disease including neoplasm, infection, or intracranial hemorrhage. A recent study found that 40% of children presenting to the ED with headache were diagnosed with a primary headache, and 75% of these were migraine. Once the diagnosis of migraine has been made, the ED physician is faced with the challenge of determining appropriate abortive treatment. This review summarizes the most recent literature on pediatric migraine with an emphasis on diagnosis and abortive treatment in the ED.

Mitochondrial dysfunction in migraine

Migraine is the most frequent type of headache in children. In the 1980s, scientists first hypothesized a connection between migraine and mitochondrial (mt) disorders. More recent studies have suggested that at least some subtypes of migraine may be related to a mt defect. Different types of evidence support a relationship between mitochondria (mt) and migraine: (1) Biochemical evidence: Abnormal mt function translates into high intracellular penetration of Ca(2+), excessive production of free radicals, and deficient oxidative phosphorylation, which ultimately causes energy failure in neurons and astrocytes, thus triggering migraine mechanisms, including spreading depression. The mt markers of these events are low activity of superoxide dismutase, activation of cytochrome-c oxidase and nitric oxide, high levels of lactate and pyruvate, and low ratios of phosphocreatine-inorganic phosphate and N-acetylaspartate-choline. (2) Morphologic evidence: mt abnormalities have been shown in migraine sufferers, the most characteristic ones being direct observation in muscle biopsy of ragged red and cytochrome-c oxidase-negative fibers, accumulation of subsarcolemmal mt, and demonstration of giant mt with paracrystalline inclusions. (3) Genetic evidence: Recent studies have identified specific mutations responsible for migraine susceptibility. However, the investigation of the mtDNA mutations found in classic mt disorders (mt encephalomyopathy with lactic acidosis and stroke-like episodes, myoclonus epilepsy with ragged red fibers, Kearns-Sayre syndrome, and Leber hereditary optic neuropathy) has not demonstrated any association. Recently, 2 common mtDNA polymorphisms (16519C→T and 3010G→A) have been associated with pediatric cyclic vomiting syndrome and migraine. Also, POLG mutations (eg, p.T851 A, p.N468D, p.Y831C, p.G517V, and p.P163S) can cause disease through impaired replication of mtDNA, including migraine. Further studies to investigate the relationship between mtDNA and migraine will require very large sample sizes to obtain statistically significant results. (4) Therapeutic evidence: Several agents that have a positive effect on mt metabolism have shown to be effective in the treatment of migraines. The agents include riboflavin (B2), coenzyme Q10, magnesium, niacin, carnitine, topiramate, and lipoic acid. Further study is warranted to learn how mt interact with other factors to cause migraines. This will facilitate the development of new and more specific treatments that will reduce the frequency or severity or both of this disease.