Genetics play a major role in your chance of developing migraines.

©iStockphoto/Don Bayley

Anatomy of a Migraine

Nobody is completely sure of what causes some people to have migraines and some not to. Doctors do know that they run in families. If one of your parents has migraine problems, you have a 50 percent chance of developing them. If both of your parents have migraines, you chances jump to about 70 percent.

Likewise, doctors don't know for sure what happens when a trigger causes a migraine, or what exactly happens in the brain. Right now they think that migraine is caused by a progression of several things:

  1. Pain-sensing cells in your brain stem (nociceptors) pick up on this change in your routine and release a chemical (neuropeptides).
  2. This chemical attacks other pain-sensing cells nearby, making them more sensitive to pain. They also release neuropeptides.
  3. Some of these chemicals begin to work on the muscles surrounding the blood vessels near the surface of your brain. Those muscles relax, making the blood vessels dilate and causing more blood to flow. This is where doctors think the aura in a classic migraine comes from.
  4. Some of the neuropeptide chemicals cause the cranial (skull) vessels to begin leaking, making the tissue around the area swell.

Doctors now think that the combination of these factors -- increased sensitivity, swelling brain tissues and swelling of blood vessels -- is the cause of migraines.