How do they work?

Most preventive migraine medications were initially developed to treat other diseases, such as seizures, depression, or hypertension. You may wonder, How can these drugs help to prevent migraine? Although scientists aren't exactly sure what causes migraine -or how the medications used to treat it work - recent breakthroughs have led to a better understanding of the mechanisms at work in the human body.

There are several theories. One widely held belief comes from the strong link between a chemical in the brain, called serotonin, and migraine. As the level of brain serotonin rises and falls, it can disturb normal brain function and cause or relieve migraines, depending on whether the level increases or decreases. But the link between migraine and serotonin, even though it is powerful, does not fully explain the disease. If it did, then serotonin-type drugs would be effective in all migraine patients, which they are not. In fact, serotonin levels have been linked to other common diseases, such as anxiety and depression.

Imagine the brain as a large series of switches, where each switch controls a specific biological activity. Turning certain combinations of switches on or off affects specific activities. As scientists develop new drugs that are specialized to work on specific chemicals and areas in the brain, they are learning which switches control which activities. Sometimes, switches other than those originally intended are affected. When this happens, a drug that was initially designed to treat seizures, for example, may prove to be equally effective in preventing migraine.