Migraine is the most common type of chronic, episodic headache, affecting 10%-12% of the adult population. It is more prevalent among women, and, for both sexes, it develops in the second and third decades and often persisting into late middle age, but declines thereafter. Two primary types of migraine can be distinguished: migraine without aura (MO) and migraine with aura (MA). MO, the most common form of migraine, is characterized by unilateral pulsating pain of moderate to severe intensity, aggravated by physical activity and lasting 4 -72 h. The attacks are associated with nausea, vomiting, photophobia, and phonophobia. MA shares the same headache qualities, but the headache attack is usually preceded by transient focal neurological aura symptoms, usually visual, that develop gradually within 5-20 min and that persist for <60 min. Frequency, duration, and severity of the attacks vary substantially among patients and also in the same patients. Moreover, approximately one-third of individuals with migraine experience both types of migraine during their lifetimes, but usually one type of attack prevails.
Although the pathophysiology of migraine remains largely unknown, there are clearly genetic, vascular and neural mechanisms involved. Migraine episodes are frequently triggered by several factors like emotional stress, hypoglycemia, lack of or excessive sleep, certain foods, hormonal changes in women, sensorial stimulation (loud noise, light, strong odor) and sympathetic stimulation (sport, physical exercise). The diagnosis is based on clinical criteria, since biochemical or instrumental tests are not available. Symptoms can be difficult to control and quality of life may deteriorate substantially. Management includes modification of diet, and recommendations for sleep, exercise, and stress reduction through bio-behavioral interventions as well as the use of a range of medications for prevention and acute treatment of migraine.
Family-, twin-, and population-based studies strongly suggest that both genetic and environmental factors are involved in the two types of migraine, most likely with a multifactorial mode of inheritance, but that genetic factors are more influential in MA than in MO. The inheritance of migraine is estimated between 34-57%. Moreover, approximately 50% of migraine sufferers have an affected first-degree relative. Despite that, the mode of transmission of the disorder is not clear. However, in some families, a Mendelian pattern of inheritance cannot be excluded.
Migraine exhibits genetic heterogeneity. Multiple loci have been identified for both MA and MO (MGR1- MGR12). Familial hemiplegic migraine (FHM), which is a type of autosomal dominant MA, has been known to occur due to mutations in the CACNA1A (Calcium Voltage-Gated Channel Subunit Alpha1 A) gene, ATP1A2 (ATPase Na+/K+ Transporting Subunit Alpha 2) gene, and SCN1A (Sodium Voltage-Gated Channel Alpha Subunit 1) gene. Additionally, variations in the ESR1 (Estrogen Receptor 1) gene, and TNF (Tumor Necrosis Factor) gene has been reported to confer susceptibility to migraine.
Bessisso et al. (2005) studied the prevalence of headache and migraine and associated factors among school children in the State of Qatar through a cross-sectional study conducted over a period from March 2001 to April, 2003. A total of 1000 school children ranging from 6-17 years old, selected by a multi-stage stratified cluster sampling method, were interviewed by means of a questionnaire. Of these, 851 school children (27.7% males, and 72.3% females) responded to the questionnaire. This study showed that the prevalence rate of migraine was 11.9%. Of the total subjects, 43.6% experienced unilateral headache and 4.2% of them had migraine with aura.
Bener (2006) used the International Headache Society (HIS) diagnostic criteria to study the prevalence of migraine and headache and its associated factors in the Qatari population through a cross-sectional study conducted during the period from October to December 2004 in Qatar. A total of 1,200 Qatari subjects (above 15 years of age), selected by a multi-stage stratified cluster sampling method, were interviewed by means of a questionnaire. Of these, 76.1% (913 subjects; 54.9% males, and 45.1% females) responded to the questionnaire. The prevalence of headache amounted to be 72.5% and migraine 7.9% of the studied subjects. The study revealed that the prevalence of headache was higher among women (78.2%) than men (67.9%). Subjects aged 25-34 years had higher prevalence of headache comparing to other age groups (27.3%). Subjects with less than a high school education had higher frequency of headache (49.1%) comparing to educated subjects (graduate level; 14%), but monthly income did not show any association with headache. The most common warning symptoms prior to headache were found to be abnormal vision (53.0%) and weakness (30.4%). Moreover, stress (71.8%) and weather (49.5%) made headache worse in subjects. Furthermore, the study revealed that there was a strong association between hemoglobin level and headache and its severity. Bener (2006) also found that family history of migraine and recurrent headache influenced the prevalence of headache and migraine (13.8% in men and 21.4% in women). Bener (2006) found that the prevalence of headache and migraine in Qatar is higher than in Western and African countries. Bener (2006) suggested that fast urbanization is the reason for the high prevalence of headache and migraine in Qatar.
Bener et al. (2000) studied the prevalence of migraine and headache in school children in the United Arab Emirates and the genetic and environmental factors associated with these conditions through a cross-sectional population study conducted in Al-Ain, Dubai, and Sharjah over a period from October 1995 to June 1996. A total of 1400 schoolchildren of UAE nationality aged from 6 to 14 years, selected by a multistage stratified cluster sampling method, were collected by screening questionnaires followed by clinical interviews. Of these, 1159 schoolchildren (594 boys and 565 girls) were included in the study for analysis due to losses from school absence and incomplete questionnaires, resulting in a response rate of 82.7%. The estimated prevalence rates for headache and migraine were found to be 36.9% and 13.7%, respectively. The prevalence of headache was found to be increased with age, the highest prevalence being in 13-year-old children (17.5%). No significant difference was found between boys and girls with respect to the prevalence of headache. Of the 159 (13.7%) children who fulfilled the diagnostic criteria for migraine, 76 were boys whose mean age (+/- SD) was 10.3 +/- 2.8 years, and 83 were girls (mean age 9.9 +/- 2.5 years). Of the children who had migraine, 20 (12.6%) had migraine without aura, and 13 (8.2%) had migraine with aura. The most common migraine symptoms in schoolchildren had been aggravated by physical activity (47.2%; in boys, 39.5%, and in girls, 54.2%) and a positive family history of migraine (46.5%; in boys, 40.8%, and in girls, 51.8%). The most common illnesses were found to be infectious illnesses (41.5%). A strong relationship was found between migraine and the timing of examinations (46.5%), followed by too much homework (40.3%). The most common environmental exposure for migraine was found to be playing on a computer (45.9%), followed by loud noise (41.5%), and a hot climate (37.1%). In familial occurrence of headache among immediate relatives, the most frequently affected relative was the mother (17.6%), followed by father (6.9%), the maternal aunt (3.8%), and the paternal uncle and sister (both 3.1%). Bener et al. (2000) concluded that headache and migraine are common in childhood and may be influenced by social, familial, environmental, and psychological factors.