Migraines affect women more often than men. Could estrogen be to blame?
Migraine is the third most prevalent illness in the world. An estimated 1 in 4 American households include someone who experiences migraine.
Women are three times more likely to experience migraine than men, with the condition arising in 18 percent of women, compared with 6 percent of men.
Researchers believe that the increased risk in women is probably due to both biological and psychosocial factors.
However, because this gender difference is most pronounced in women of reproductive age, many scientists believe that hormone levels might be a significant part of the problem.
Estrogen levels and migraine
Researchers, led by Dr. Jelena Pavlović at Albert Einstein College of Medicine/Montefiore Medical Center in Bronx, NY, set out to investigate the role of estrogen further. They set out to uncover the links between estrogen fluctuations and an individual's likelihood of experiencing migraine.
The theory they wanted to test was that women whose estrogen levels drop more swiftly in the days just before menstruation might be more at risk of developing migraine.
The results are published this week in the American Academy of Neurology's journal - Neurology.
The team of scientists used data from 114 women with a history of migraine and 223 women with no previous migraine experience. The women had an average age of 47.
The participants kept a headache diary and monitored their hormone levels across one monthly cycle.
Hormones were measured through urine samples; the investigators charted peak hormone levels and average daily levels. They also measured day-to-day rates of decline, calculated over the 5 days following each hormone peak in their cycles.
The part of the cycle that was of particular interest to the team was the 2 days following the peak estrogen level in the luteal phase of the cycle. This is the time after ovulation but before menstruation.
Significantly greater estrogen drop
The team found that, for women with migraine, estrogen levels dropped by 40 percent, compared with 30 percent for women without a history of migraine.
Although other hormone levels were measured, the only significant changes were found in estrogen.
"These results suggest that a 'two-hit' process may link estrogen withdrawal to menstrual migraine. More rapid estrogen decline may make women vulnerable to common triggers for migraine attacks such as stress, lack of sleep, foods, and wine."
Although the investigation used a relatively large sample size and the effect that they found was of a substantial size, there were some limitations to the study. There were a disproportionate number of Japanese and Chinese women in the non-migraine group and too many white and black women in the migraine sample. Because levels of sex hormones might vary within different ethnic groups, this could have had an impact on the results.
A review of current research into migraine and estrogen, published in Current Opinion in Neurology, concluded that, although estrogen does appear to play a substantial role, the overall picture is a complex one.
Studies investigating the factors involved in migraine have unearthed interesting differences in a number of aspects, including differences in the central nervous system.
The review also noted that estrogen's role seems to be pivotal and suggests that hormone treatment might help decrease the frequency of migraines for some women, especially if their migraine appears to be menstrually related.
Further research will be necessary to firm up these findings. However, the study acts as yet another strand of evidence pointing in the direction of estrogen and its role in migraine. The next questions that researchers will need to answer are why and how estrogen has this impact in some women.