In the US and world populations, migraine prevalence is two to three times higher in women [
6]. According to the most recent iteration of the Global Burden of Diseases Study (2019), migraine is the most disabling condition affecting young women [
7]. In the USA, migraine epidemiology data are drawn primarily from the two largest longitudinal epidemiology studies of episodic and chronic migraine: American Migraine Prevalence and Prevention (AMPP, 2004–2009) and Chronic Migraine Epidemiology and Outcomes (CaMEO, 2012–2013). Among people with migraine, episodic migraine has been reported as far more prevalent than chronic migraine (AMPP 93%, CaMEO 91%). Headache-related disability assessed by the Migraine Disability Assessment (MIDAS) questionnaire was greater in women than men for both episodic and chronic migraine [
8]. In the AMPP, sex differences in multiple domains were identified for migraine in general (defined as migraine or probable migraine according to the then current International Classification of Headache Disorders, 2
nd edition (ICHD-2) criteria, not stratified by episodic vs chronic). Of note, the CaMEO studies reference gender; however, the methodology suggests participant sex was actually elicited [
9]. For the AMPP, gender is the prevailing term used; however, sex is also referenced [
10]. In addition to migraine being more common among women, women were more likely to have MIDAS Grade IV headache-related disability, utilize prescription and non-prescription headache medications, and utilize a prescription medication for depression or anxiety. Higher emergency department or urgent care utilization was also observed [
11]. Hypothesized reasons for these differences in disability grade may include persistent inequity in household labor; despite advances in education and career attainment, women (including those who work full time) continue to perform the majority of household tasks [
12,
13]. Other reasons include the contribution of menstrual migraine, which can be more intense and therefore more disabling [
14]. The CaMEO study revealed interesting patterns in men, including differences in diagnosis of migraine (less likely to be diagnosed in men) and co-morbidities (favoring higher rates of co-morbid cardiac disease and stroke, emphysema, and hypertension in men vs allergies, asthma, temporomandibular disorders, anxiety, and Raynaud’s in women). Attack features also differed, with men generally exhibiting a lower frequency of attacks, less allodynia, and fewer aura symptoms. Interestingly, men with episodic migraine were more likely to transition to chronic migraine. As history of head trauma (which is more common in men) was not assessed, its degree of influence on migraine progression is unknown. Gender differences in seeking migraine care or potentially undiscovered prognostic factors in men were cited as possible contributors [
15]. Further study in this area is warranted to corroborate these findings. A comparison of these two large studies, CaMEO and AMPP, can be found in Table 1 of Lipton et al. [
8].
The Migraine in America Symptoms and Treatment (MAST) study intends to update epidemiologic knowledge of migraine, and began collecting data in 2016 with a prospective, longitudinal, cross-sectional, online survey design with the broad goal of assessing migraine symptoms, diagnosis, management, and co-morbid conditions. In 2018, data on sex differences revealed findings consistent with prior epidemiologic investigations, with higher disability and more frequent headache days in women compared to men. Importantly, the study did not collect inclusive data (elicited as male/men or female/women, sex/gender used interchangeably). Approximately 63% of the sample had a headache frequency consistent with episodic migraine (1–4 monthly headache days (MHD)) and ~ 10% had at least 15, consistent with chronic migraine. Women were over-represented in the chronic migraine and high-frequency episodic migraine (10–14 MHD) groups [
16].
Adding to these epidemiologic studies, the ObserVational survey of the Epidemiology, tReatment and Care Of MigrainE (OVERCOME) Study is a prospective online survey study that began enrollment in 2018. Thus far, the Spring 2019 sample of over 20,000 people meeting criteria for migraine demonstrated that optimal acute migraine treatment is associated with lower disability and improved health related quality of life [
17]. Sex and gender-specific findings are not yet published, but according to the study methodology, data on gender minorities were not collected.
Our understanding of the epidemiology of migraine in GM populations is significantly limited. A 2021 scoping review of SGM literature in neurology identified only 6 headache articles published from 1960–2020: 4 case reports and 2 cross-sectional studies [
18••]. Of these, only the cross-sectional studies examined migraine, and only one included transgender individuals. Using data from The Gender Team Clinic in The Netherlands, Pringsheim and Gooren found that migraine prevalence in transgender women taking gender affirming hormone therapy was similar to that of cisgender women in population estimates, approximately 26% [
19]. As this is a single center with only 50 respondents, generalizability is limited. Given limited data sources inclusive of gender identity, we do not yet know the prevalence of migraine in the broader GM community. Future research efforts may help to illuminate these epidemiologic data gaps.