Migraine is a very common, but very particular, type of headache. Most people who have migraine experience repeated attacks of headaches that occur over many years. The typical migraine headache is throbbing or pulsating, and often is associated with nausea and changes in vision. While many migraine headaches are severe, not all severe headaches are migraines, and some episodes can be quite mild.
Up to 20% of people in the United States will experience migraine headaches at some point in life. In about half of those, migraine headaches first appear during childhood or adolescence. Two-thirds of people who get migraines are women, probably because of the influence of hormones. Migraines also tend to run in families.
Despite years of research, scientists do not know exactly why migraines occur. The pain of migraines is associated with swelling in blood vessels and irritation of nerves that surround the brain. But most experts don't think that this is the direct cause of migraines.
The brain doesn't have pain receptors. But it processes pain signals from other parts of the body. It's the pain processing networks, or centers, in the brain that are overly reactive or dysfunctional in migraine.
The brain chemical serotonin may play an important role in this process as it does in other conditions, including depression and eating disorders.