Migraine is a form of severe headache accompanied with sensory disturbances. Various environmental conditions can temporarily increase the risk of initiation of migraine headache.
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What is migraine?
Migraine is a complex condition characterized by intense and recurrent headaches, which is often accompanied by nausea, vomiting, and light and sound sensitivity. An episode of migraine attack generally lasts for 4 – 72 hours.
Some people experience a more severe symptom called an aura, which mainly includes visual problems, including light flashes or blind spots. In addition, an aura may be associated with other disturbances, such as tingling sensation or weakness/numbness in one side of the face or body, speaking difficulty, and uncontrollable jerking.
Although the exact etiology is not known, the onset of migraine is believed to be associated with changes in the brain pain pathways. Moreover, brain chemicals that are responsible for regulating pain sensation, such as serotonin, may play a role in migraine headache. Regarding predisposing aspects, both genetic and environmental factors play significant roles in triggering migraine headaches.
Can weather changes trigger a migraine attack?
Several studies have examined weather-related conditions, such as barometric pressure, ambient temperature, and relative humidity, in relation to migraines.
People with migraine are more likely to be affected by a changing weather. Weather-related factors that affect the people most include bright sunlight, sun glare, extreme heat/cold, windy weather, high relative humidity, dry air, and low barometric pressure.
In this context, one study involving migraine patients has claimed that there is a 7.5% higher risk of transiently triggering migraine headache with a temperature rise of 5°C. The same study have also revealed that lower barometric pressure is another important trigger for migraine.
Another study on migraine showed that higher relative humidity is associated with a higher risk of migraine headache onset only in warm climates. However, it is believed that low barometric pressure does not trigger migraine alone; other related factors, such as warm climate, dust, wind, cloud cover, and precipitation work together to create conditions that make migraine more likely in certain persons.
Regarding mechanism of migraine headache onset, a neurovascular event called cortical spreading depression is known to trigger migraine headache by activating prevascular trigeminal nerves. Moreover, a small change in barometric pressure causes dilation of cerebral blood vessels and increased release of serotonin from platelets. This further leads to serotonin-induced vasoconstriction and onset of migraine with aura. Afterward, a reduction in blood serotonin level causes rapid expansion of cerebral blood vessels, leading to onset of migraine.
Does air pollution cause migraines?
Growing evidence suggests that air pollution can trigger migraines. Various air pollutants, including lead, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matters (PM10 and PM2.5), are known to have positive association with migraine intensity, frequency, and duration, as well as the rate of doctor visit due to migraine attack.
Among various air pollutants, nitrogen dioxide and PM have the highest effect on migraine. Given the well-documented association between alteration in blood flow and onset of migraine, it is believed that PM2.5 may activate the sympathetic nervous system, which is the primary regulator of the vascular system. In addition, traffic-related pollutants, such as ozone precursors and carbon monoxide, are known to induce migraine headache, particularly in cold climates.
Taken together, pollutants and certain weather conditions can increase the risk of migraine attack, which can eventually lead to emergency department visits and even hospitalization.