Migraine: Sex-influenced trait model?

Headache-a challenge across medical students' life: a systematic review and meta-analysis

BACKGROUND

Headache is a disabling disease that affects psychosocial factors. Medical students are recognized to be more susceptible to psychological stress than other. Quantitative summaries of prevalence studies on this subject are limited. The aim of this study was to quantify and comprehend the variance in prevalence at the global and regional levels.

METHODS

We used a comprehensive search approach to find studies on headaches prevalence in the medical literature published between November 1990 and May 5, 2022. Database searched were PubMed, Scopus, EMBASE, and Google Scholar. Studies that reported headaches (unspecified, migraine, or tension-type headache (TTH)) in medical students were included. Subgroup analysis and meta-regression were applied to investigate heterogeneity, with the risk of bias tool employed to assess study quality. PROSPERO number CRD42022321556 was assigned to the study protocol.

RESULTS

Out of 1561 studies, 79 were included. The pooled prevalence estimates of unspecified headache, migraine, and TTH were 70.44% (95% CI: 63.32-77.57), 18.9% (95% CI: 15.7-22.0), and 39.53% (95% CI: 31.17-47.90), respectively. TTH and migraine were more prevalent in Eastern Mediterranean and American region. TTH and migraine were less prevalent in higher income countries.

CONCLUSION

Although the prevalence of headaches among medical students varies in different countries, it is higher than the general population of the same age. Higher stressors and overwork in these students may contribute to this condition. The well-being of medical students should be a priority for the relevant authorities.

Sex Differences in Migraine: A Twin Study

Migraine is a neurological disorder with a prominent sex difference such that two thirds of sufferers are female. The mechanisms behind the preponderance of migraine in women have yet to be elucidated. With data on 51,872 participants from the Swedish Twin Registry, we report results from two distinct analyses intended to clarify the degree to which genetic and environmental factors contribute to sex differences in migraine. First, we fit a sex-limitation model to determine if quantitative genetic differences (i.e., is migraine equally heritable across men and women) and/or qualitative genetic differences (i.e., are different genes involved in migraine across men and women) were present. Next, we used a multilevel logistic regression model to compare the prevalence of migraine in individuals from opposite-sex and same-sex twin pairs to determine whether differences in the prenatal hormone environment contribute to migraine risk. In the final analytic sample, women were found to have a significantly higher rate of migraine without aura relative to men (17.6% vs. 5.5%). The results from an ADE sex-limitation model indicate that migraine is equally heritable in men and women, with a broad sense heritability of 0.45, (95% CI = 0.40-0.50), while results from a reduced AE sex-limitation model provide subtle evidence for differences in the genes underlying migraine across men and women. The logistic regression analysis revealed a significant increase in migraine risk for females with a male co-twin relative to females with a female co-twin (OR = 1.51, 95% CI = 1.26-1.81). These results suggest that the prominent sex difference in migraine prevalence is not entirely accounted for by genetic factors, while demonstrating that masculinization of the prenatal environment may increase migraine risk for females. This effect points to a potential prenatal neuroendocrine factor in the development of migraine.

Prevalence of Migraine in General Spanish Population; Factors Related and Use of Health Resources

Migraine is a common neurological disorder considered the second most disabling condition worldwide. Its prevalence ranges from 2.6% to 21.7% in population studies. This study aimed to know the prevalence of diagnosed and undiagnosed migraine in the general Spanish adult population, their health care use, and factors related. A descriptive cross-sectional study was undertaken with 23,089 individuals >15 years from the 2017 Spanish National Health Survey. Three groups were defined: people diagnosed with migraine (DM), people reporting undiagnosed migraine (UM) and people without migraine. Sociodemographic, clinical and use of health resources data were collected. The scales Duke Social Support Index (DSSI) and General Health Questionnaire (GHQ-12) were used. Prevalence of DM and UM were determined with 95% confidence intervals. To determine the factors associated with DM and UM, a multinomial logistic regression model was used. The prevalence of DM was 8.6% (95%CI: 8.2–9), and UM, 0.9% (95%CI: 0.8–1). People with DM more frequently visited healthcare professionals (47.8%), required more supplementary tests (86.8), had a higher percentage of hospitalization (11.3%), and used emergency services (45.1%). Women had nearly three times the risk of DM and UM. Worse mental health was a risk factor for UM (OR = 1.20) and DM (OR = 1.18). The greater the work stress, the greater the risk of DM (OR = 1.12). An adequate monitoring and management of migraine in people with these characteristics could contribute to improving their quality of life and reducing costs in the system.

Sex Differences of Migraine: Results of a Nationwide Home-based Study in Turkey

Introduction

The prevalence of migraine was found to be more than three-fold higher in women as compared with men, and in addition to differences in prevalence rates, the characteristics and associated features might also differ between the sexes. The aim of this study was to compare sex-specific features of migraine and demographic parameters in a nationwide population-based study in Turkey.

Methods

Among 5323 subjects, a total of 871 patients who were diagnosed as having definite migraine according to the diagnostic criteria of the International Classification of Headache Disorders-III (ICHD-III) were included in our study. The demographic characteristics, associated features, and triggers of migraine were examined with regard to sex.

Results

The study group comprised 640 women (73.5%) and 231 men (26.5%), with a female to male ratio of 2.8:1. Attack duration, mean migraine disability assessment scores (MIDAS), frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were found significantly different between women and men. When we compared these parameters between men and postmenopausal women, all these parameters were still significant except nausea. Odor was statistically more frequent as a reported trigger in women, whereas excessive sleep was a statistically more frequent triggering factor in men. The rates of depression and allergy were significantly higher in women when compared with men.

Conclusion

Longer attack duration, higher MIDAS scores, and the frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were more significant in women and this variance in sex persisted after menopause. Also, some trigger factors and co-morbidities differed between the sexes. These findings might result from complex genetic factors besides sociocultural influences, biologic, and sociocultural roles. Future studies should continue to explore biologic and genetic factors with respect to sex in migraine.

Untangling the Association Between Migraine, Pain, and Anxiety: Examining Migraine and Generalized Anxiety Disorders in a Canadian Population Based Study

OBJECTIVE

The aims of this study were to investigate: (1) the prevalence and unadjusted and adjusted odds of 12-month generalized anxiety disorder (GAD) among adults with migraine in comparison to those without migraine; (2) If debilitating pain and/or limitations in instrumental activities of daily living (IADLs) are mediators of the migraine-GAD association; and (3) Factors associated with past year GAD among adults with migraine.

METHODS

Secondary data analysis of the nationally representative 2012 Canadian Community Health Survey-Mental Health (CCHS-MS), a population-based survey of community dwellers with a response rate of 68.9%. The first subsample included those with (n = 2232) and without migraine (n = 19,270), and the second subsample was restricted to those with migraine (n = 2232). GAD was based on the WHO-CIDI scale.

RESULTS

Fully, 6% of those with migraines had past year GAD in comparison of 2.1% of those without migraine (P < .001). The socio-demographically adjusted odds of past year GAD were two and a half times higher among those with migraine than those without (OR= 2.46; 95% CI = 2.00, 3.02). A path analysis indicated that debilitating pain and limitations in IADLs were mediators in the relationship between migraine and GAD. In the sample restricted to migraineurs, the factors associated with higher odds of 12-month GAD included having a university degree, having low income, being without a confidant, and being male.

CONCLUSIONS

Generalized anxiety disorder is robustly associated with migraine and targeted outreach and interventions are warranted.

Sex differences in the epidemiology, clinical features, and pathophysiology of migraine

Migraine is two to three times more prevalent in women than men, and women report a longer attack duration, increased risk of headache recurrence, greater disability, and a longer period of time required to recover. Conditions recognised to be comorbid with migraine include asthma, anxiety, depression, and other chronic pain conditions, and these comorbidities add to the amount of disability in both sexes. Migraine-specifically migraine with aura-has been identified as a risk factor for vascular disorders, particularly in women, but because of the scarcity of data, the comparative risk in men has yet to be established. There is evidence implicating the role of female sex hormones as a major factor in determining migraine risk and characteristics, which accounts for sex differences, but there is also evidence to support underlying genetic variance. Although migraine is often recognised in women, it is underdiagnosed in men, resulting in suboptimal management and less participation of men in clinical trials.

Sex-related differences in migraine

This paper reviews sex-related differences in migraine epidemiology, symptoms, natural history and co-morbid disorders. Migraine is more than twice as common in females as in males, and women experience more frequent, longer lasting and more painful attacks, have more disability and a risk of transition from episodic to chronic migraine greater than men, but the mechanisms behind these differences are still poorly understood. The role of sex hormones, genes, and the differences in brain function and structure are discussed. Finally, we evaluate the many gender-related questions about treatment of migraine in women. In future research data should be analyzed separately for men and women to ensure that differences between the sexes could be identified.

Studies on the pathophysiology and genetic basis of migraine

Migraine is a neurological disorder that affects the central nervous system causing painful attacks of headache. A genetic vulnerability and exposure to environmental triggers can influence the migraine phenotype. Migraine interferes in many facets of people's daily life including employment commitments and their ability to look after their families resulting in a reduced quality of life. Identification of the biological processes that underlie this relatively common affliction has been difficult because migraine does not have any clearly identifiable pathology or structural lesion detectable by current medical technology. Theories to explain the symptoms of migraine have focused on the physiological mechanisms involved in the various phases of headache and include the vascular and neurogenic theories. In relation to migraine pathophysiology the trigeminovascular system and cortical spreading depression have also been implicated with supporting evidence from imaging studies and animal models. The objective of current research is to better understand the pathways and mechanisms involved in causing pain and headache to be able to target interventions. The genetic component of migraine has been teased apart using linkage studies and both candidate gene and genome-wide association studies, in family and case-control cohorts. Genomic regions that increase individual risk to migraine have been identified in neurological, vascular and hormonal pathways. This review discusses knowledge of the pathophysiology and genetic basis of migraine with the latest scientific evidence from genetic studies.

Sex matters: evaluating sex and gender in migraine and headache research

Significant sex differences exist in migraine and other headache disorders. Several hypotheses have been proposed to explain these differences, including fluctuations in sex hormones and receptor binding, genetic factors, differences in exposure to environmental stressors, as well as differences in response to stress and pain perception; but how valid are some of these findings and can we improve the quality of research in this field? It is notable that the preponderance of animal pain studies use male subjects to study a predominantly female disorder. Furthermore, with respect to headache and migraine sex differences, limited data have been derived from animal models. Additionally, although sex differences (based on the categorization of male vs female) may be more routinely evaluated in clinical headache research than in the basic science research, greater attention to potential differences across the life cycle of women (ie, premenopausal vs postmenopausal differences) and menstrual cycle is warranted. In this manuscript we define the differences between "sex" and "gender" and highlight the importance of their application and use in headache research. The enhanced recognition and implementation of attention to sex differences throughout the hormonal and life-cycle phase in both human and animal research will only help to strengthen and further our understanding of migraine and may help guide the direction of future headache research.

Assessing risk factors for migraine: differences in gender transmission

Aim

Our aim was to assess which specific factors are contributing to an increased risk of migraine in a group of 131 Portuguese families.

Methods

We studied 319 first-degree relatives, using a multilevel approach to account for the dependency among members from the same family. We included in the model relative’s gender, the proband’s gender and age-at-onset, to evaluate if any of these variables were associated with relative’s affection status. We also included in the model proband’s migraine subtype. We further assessed female and male transmissions within the proband nuclear family.

Results

Relatives’ gender was found to be a risk factor for migraine (Odds Ratio = 2.86; 95% CI = 1.75–4.67), with females at a higher risk. When splitting probands according to their migraine subtype, we found that none of the variables studied contributed to relatives of MA-probands affection-status. Our results also show a significant difference between proband’s transmission and the gender of the parents and offspring.

Conclusions

With this study, we showed that gender is truly a risk factor for migraine and that a gender-biased transmission is also observed. This reinforce the importance of identifying genes associated with migraine that are modulated by genes located in the sex chromosomes and the study of mitochondrial DNA or X-chromosome and hormonal-related effects associated with migraine susceptibility.

Development of visual contour integration in children with migraine without aura

Introduction: As migraine attacks pose insult to cerebral circulation and ion homeostasis, migraine has the potential to interfere with the development of different brain structures, producing functional deficits. It is known that visual contour integration (CI) is a function with a protracted development. Therefore, we sought to establish whether migraine interferes with its development.

Methods: Forty-eight migraineurs (without aura) and 48 age- and sex-matched controls participated in the study, divided into three cohorts by age. Stimuli were presented on cards with a contour consisting of Gabor patches embedded in random noise. Difficulty was varied by the manipulation of relative noise density. The task was to identify and show the contour.

Results: A significant difference was found between the performance of migraineurs and controls in the 10–14-year-old and 15–18-year-old cohorts ( p < 0.05). Development between all three cohorts was significant in the control group ( p < 0.017), while it was not significant in migraineurs between 6 and 14 years. Correlation between age and CI threshold was stronger in controls than in migraineurs.

Conclusion: Children with paediatric migraine exhibited a less marked development in the Gabor patch-based CI task.

Migraine as a sex-conditioned inherited disorder: evidences from China and the world

Migraine is a complex and heterogeneous disorder. Although several genetic models has been proposed including autosomal-dominant/autosomal recessive, sex-linked, sex-limited, mitochondrial, and multi-gene, none of these models can well-explain the transmission of the disease. We hypothesied that migraine is a sex-conditioned inherited disorder (autosomal dominant in females and autosomal recessive in males). This hypothesis is supported by the evidence such as the locations of genes associated with familial hemiplegic migraine, possibly "typical" migraine as well (dominantly on chromosome 19p, 1q, and 2q), male:female ratio of prevalence (1:2-1:4), the mostly youth-onset, the provocation by the contraceptives, the induction by menstruation, and the self-limitation after menopause. Female sex-hormones appear to be the key contributor to a higher prevalence of migraine in female. Socio-environmental factors may also play an important role.