Pre-existing asthma may be a strong predictor of future chronic migraine attacks in individuals experiencing occasional migraine headaches, according to researchers from the University of Cincinnati (UC) in the US.
"If you have asthma along with episodic or occasional migraine, then your headaches are more likely to evolve into a more disabling form known as chronic migraine," said author Vincent Martin from the UC.
A study was conducted of 4,500 individuals who experienced episodic migraine or fewer than 15 headaches per month in 2008.
"Migraine and asthma are disorders that involve inflammation and activation of smooth muscle either in blood vessels or in the airways," said Richard Lipton director of Montefiore Headache Centre.
"Therefore, asthma-related inflammation may lead to migraine progression," Lipton added.
Study participants completed written questionnaires both in 2008 and 2009.
Based on responses to the 2008 questionnaire, they were divided into two groups — one with episodic migraine and coexisting asthma and another with episodic migraine and no asthma.
About 12 percent of the US population experiences migraine, which is almost three times more common in women than in men, according to Martin.
They were also asked about medication usage, depression and smoking status.
After follow-up of one year, the researchers found that new onset chronic migraine developed in 5.4 percent of participants also suffering from asthma and in 2.5 percent of individuals without asthma.
"In this study, persons with episodic migraine and asthma at baseline were more than twice as likely to develop chronic migraine after one year of follow-up as compared to those with episodic migraine but not asthma," Martin explained.
There can be a possibility that patients with asthma may have an overactive parasympathetic nervous system that predisposes them to attacks of both migraine and asthma, Martin stated.
It is also possible that asthma may not directly cause chronic migraine, but that a shared environmental or genetic factor, like air pollution, which can trigger both asthma and migraine attacks, he noted.
The findings were published online in the journal Headache.