Too much caffeine may trigger migraine, but how much is too much?
Migraine is a form of primary headache disorder.
The term "primary" refers to the fact that the underlying causes are unclear.
In the United States, 12% of the population (39 million people) experience migraine. This includes adults and children.
When it comes to caffeine, the amount a person drinks may be the central factor in whether or not it is a trigger. According to the American Migraine Foundation, some people find it helpful to use a small amount of caffeine to stop some of their migraine headaches. Others may have more frequent migraine headaches with regular caffeine consumption.
Although there is anecdotal evidence of caffeine's potential Jekyll-and-Hyde nature, clinical data from migraineurs is rare.
A new study paper, which now appears in The American Journal of Medicine, sheds some light on this conundrum.
Elizabeth Mostofsky, from the Department of Epidemiology at Harvard T.H. Chan School of Public Health in Boston, MA, is the first author of the study.
Together with her collaborators, Mostofsky set out to investigate if caffeine consumption is linked to the onset of migraine on the same day in people living with the condition.
3 or more caffeinated drinks may be a trigger
For her study, Mostofsky recruited 98 volunteers who experience migraine with or without aura. The study participants filled in electronic diaries every morning and evening for 6 weeks. In these diaries, they recorded a variety of factors, including exercise, caffeine and alcohol consumption, stress, sleep quality, and headaches.
Specifically, the team asked the participants about total daily caffeine intake from coffee, tea, soda, or energy drinks.
They then compared how likely each participant was to experience migraine on a day when they consumed caffeine with the likelihood on a day when they didn't.
Using a statistical model, the team estimated that drinking one or two caffeinated beverages did not change the odds of experiencing a migraine headache on the same day. However, when the volunteers consumed three or more caffeinated drinks, the odds were significantly higher.
The results were similar when the team reanalyzed the data to take alcohol intake, stress, sleep quality, exercise, and female participants' menstrual cycles into account.
Mostofsky also looked at the potential of reverse causation, meaning that the volunteers may have consumed more caffeine to help cope with the onset of a migraine headache.
However, the data showed that people who drank three or more caffeinated beverages had higher odds of developing a headache on the following day, meaning that this amount of caffeine didn't stop migraine in its tracks.
"To date, there have been few prospective studies on the immediate risk of migraine headaches with daily changes in caffeinated beverage intake," says principal study investigator Dr. Suzanne M. Bertisch, an assistant professor of medicine at Harvard Medical School.
"In this study, there was a nonlinear association between caffeinated beverage intake and the odds of migraine headache on that day. This suggests that high levels of caffeinated beverage intake may be a trigger of migraine headaches on that day."
"Additional research is needed to examine the potential effect of caffeine on symptom onset in the subsequent hours and the interplay of sleep, caffeine, anxiety, environmental factors, and migraine," the authors conclude in their paper.