Occasional migraine headaches can evolve into chronic migraine attacks in asthma patients, a new study has found.
"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 lead author Vincent Martin, a professor at the University of Cincinnati in US.
Researchers studied about 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 in US.
"Therefore, asthma-related inflammation may lead to migraine progression," said Lipton.
Individuals with chronic migraine have headaches 15 or more days per month; this takes a severe toll on sufferers who often miss work and social events.
The researchers analysed data from the American Migraine Prevalence and Prevention (AMPP) Study. 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.
They were also asked about medication usage, depression and smoking status. The 2008 and 2009 questionnaires included questions about their frequency of headache, which enabled the authors to identify the participants who had progressed to chronic migraine.
Researchers found that after one year of follow-up, new onset chronic migraine developed in 5.4 per cent of participants also suffering from asthma and in 2.5 per cent 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," said Martin.
Researchers have considered various theories as to why asthma may have a predictive role in chronic migraine development for individuals with episodic migraine.
Asthmatic patients are more likely to also have allergies and the researchers have shown in prior studies that patients with allergies might be prone to more frequent headaches particularly if they have hay fever, said Martin.
Another possibility is that patients with asthma may have an overactive parasympathetic nervous system that predisposes them to attacks of both migraine and asthma, said Martin.
It is also possible that asthma may not directly cause chronic migraine, but that a shared environmental or genetic factor, like air pollution, which has been known to trigger both asthma and migraine attacks may play a role, he said.
The study was published in the journal Headache.
