The first of a new class of drugs to prevent migraines was approved last week. The medication, called Aimovig, reduces the frequency of migraines among those severely afflicted, but the drug rarely prevents these episodes altogether. One expert called it “progress but not a panacea.” Migraine is the most disabling neurological disease in the world among people under age 50, beating epilepsy, strokes and chronic back pain. Yet many who have migraines don’t realize it or ever mention their symptoms to a doctor.

How do you know if you have migraines?

Migraines are not just headaches. It is diagnosed in patients only if they have had a minimum of five attacks, each lasting four to 72 hours. Each attack has to include at least two of the following symptoms: throbbing headache with pain that is moderate to severe, that worsens with activity, and is only on only one side of the head. Also, a person suffering a migraine attack is nauseated or abhors sound or noise.

What about auras? Are they part of a migraine?

Sometimes, but not always. About 20 percent of migraine patients get an aura before the headache. Auras involve distortions of vision. People see jagged lights or have blind spots in their visual field. But auras can take other forms as well: a prickling pins-and-needles feeling on parts of the body, speech disturbances, distortions of sounds. Some get auras without a headache or only a mild headache. Auras actually involve different areas of the brain than migraines, and it is not clear why they are linked to migraine headaches.

How common are migraines?

They can start in childhood, although they usually begin in adolescence or young adulthood. They strike nearly one in five women worldwide, one in 16 men and one in 11 children. One out of four households has at least one member with migraine. The condition seems to spring from a combination of genetic and environmental factors. There is nothing a person can do to reduce the odds of developing migraine.