Sex differences in clinical characteristics of migraine and its burden: a population-based study.

BACKGROUND AND PURPOSE: Understanding migraine in a sex-specific manner is crucial for improving clinical care, diagnosis and therapy for both females and males. Here, data on sex differences are provided in the presentation of migraine in a large European-based population cohort, which is representative of the general population. METHODS: A population-based study of 62,672 Danish blood donors (both present and previous donors), of whom 12,658 had migraine, was performed. All participants completed a 105-item diagnostic migraine questionnaire sent via an electronic mailing system (e-Boks) between May 2020 and August 2020. The questionnaire allowed for correct diagnosis of migraine according to the International Classification of Headache Disorders, third edition. RESULTS: The migraine questionnaire was in-cohort validated and had a positive predictive value of 97% for any migraine, a specificity of 93% and a sensitivity of 93%. There were 9184 females (mean age 45.1 years) and 3434 males (mean age 48.0 years). The 3-month prevalence of migraine without aura was 11% in females and 3.59% in males. The 3-month prevalence of migraine with aura was 1.72% in females and 1.58% in males. In females, the age-related 3-month prevalence of migraine without aura increased markedly during childbearing age. In males, migraine both with and without aura showed less age variation. Females had a higher frequency of migraine attacks (odds ratio [OR] 1.22) but a lower frequency of non-migraine headaches (OR = 0.35). Females also had a greater intensity of pain, more unilateral and pulsatile pain, and exacerbation by physical activity (OR = 1.40-1.49) as well as more associated symptoms (OR = 1.26-1.98). Females carried 79% of the total migraine disease burden, which was almost exclusively driven by migraine without aura (77%), whilst there was no sex difference in the disease burden of migraine with aura. CONCLUSION: Females have more severe disease, resulting in a much higher migraine disease burden than indicated by prevalence alone.

Population-based prevalence of cranial autonomic symptoms in migraine and proposed diagnostic appendix criteria.

BACKGROUND: Migraine with cranial autonomic symptoms is well described in the literature, but its prevalence in previous studies varies enormously. A precise estimate of the prevalence in a population-based material is important because migraine with cranial autonomic symptoms might represent an endophenotype, in which genetic and pathophysiological features differ from those without cranial autonomic features. The aim of the present study, therefore, was to estimate the prevalence in a big population-based sample using both questionnaire-based diagnosis (N = 12,620) and interview-based diagnosis (N = 302). We validate questionnaire-based diagnosis of migraine with cranial autonomic symptoms and develop the first diagnostic criteria for future research of this possible endophenotype. METHODS: The Danish Blood Donor Study included 127,802 persons who all received a migraine diagnostic questionnaire. Participants who had answered the diagnostic questionnaire constituted the Danish Migraine Population Cohort (N = 62,677) of whom 12,620 had migraine. The diagnostic migraine questionnaire included questions about the following cranial autonomic symptoms: Facial/forehead sweating, lacrimation, ptosis, conjunctival injection, rhinorrhea, nasal congestion, and miosis. Validation was performed by a follow-up semi-structured, purpose-built interview of 302 participants with migraine, where detailed questions were asked to ascertain the validity of the symptoms. RESULTS: The questionnaire-based prevalences of one, respectively two cranial autonomic symptoms were 57% and 31%. The semi-structured interview-based prevalences of one, respectively two symptoms were 44% and 22%. The most common symptoms were facial/forehead sweating (39%) and lacrimation (24%). The specificity of the questionnaire was 80% and the sensitivity was 68%. Correlation analysis showed a weak correlation between symptoms ranging from 0.07 - 0.41, and no clear clustering of symptoms was detected. We suggest the first diagnostic appendix criteria for genetic and epidemiological studies and tighter criteria for clinical and pathophysiological studies. We encourage further studies of severity and consistency of symptoms. CONCLUSION: Migraine with cranial autonomic symptoms is prevalent in the general population. Suggested diagnostic appendix criteria are important for future studies of this possible migraine endophenotype.

Familial analysis reveals rare risk variants for migraine in regulatory regions.

The most recent genome-wide association study of migraine increased the total number of known migraine risk loci to 38. Still, most of the heritability of migraine remains unexplained, and it has been suggested that rare gene dysregulatory variants play an important role in migraine etiology. Addressing the missing heritability of migraine, we aim to fine-map signals from the known migraine risk loci to regulatory mechanisms and associate these to downstream genic targets. We analyzed a large cohort of whole-genome sequenced patients from extended migraine pedigrees (1040 individuals from 155 families). We test for association between rare variants segregating in regulatory regions with migraine. The findings were replicated in an independent case-control cohort (2027 migraineurs, 1650 controls). We report an increased burden of rare variants in one CpG island and three polycomb group response elements near four migraine risk loci. We found that the association is independent of the common risk variants in the loci. The regulatory regions are suggested to affect different genes than those originally tagged by the index SNPs of the migraine loci. Families with familial clustering of migraine have an increased burden of rare variants in regulatory regions near known migraine risk loci, with effects that are independent of the variants in the loci. The possible regulatory targets suggest different genes than those originally tagged by the index SNPs of the migraine loci.