The Anatomy of a Migraine

A migraine can come on like a sledgehammer—with a pain so intense, you feel like you need to hole up in a dark room. If you deal with migraine attacks regularly, you might have a sense of what triggers them, but maybe not so clear a picture of what’s going on in your body when they occur. What’s happening in your head that makes it hurt so much? And is there anything you can do to prevent it?

If you really want to make sense of your migraine, you first have to understand that this isn't your average headache. Migraine is often accompanied by nausea, light sensitivity, and other symptoms that are not typical of regular head pain. "It's more than just a headache," says Brian McGeeney, M.D., M.P.H., a staff neurologist at the John R. Graham Headache Center at Brigham and Women's Faulkner Hospital in Boston, MA.

Still, considering how common migraine is (an estimated 39 million Americans live with this disabling condition), the jury is still out on definitely what causes it. Theories have changed over the years, and while scientists are still not certain on some specifics, the latest thinking is helping researchers formulate better and more effective treatments. Let’s take a closer look at what scientists currently think is happening in your head during a migraine attack.

What’s Happening in the Brain When You Have Migraine

Back in the 1940s, neurologist and researcher Harold Wolff hypothesized that migraine headaches happen when blood vessels in the brain relax and stretch the nerves running through them. That idea, termed the "vascular hypothesis," led to the advent of triptan medications, which relieve headaches by narrowing blood vessels.

The thinking about migraine has evolved in recent years. Blood vessels are still involved—and they do become more sensitive during migraine attacks, which is one reason why you feel throbbing pain, says Dr. McGeeney. But they don't drive the process.

Instead, the latest thinking is that migraine is the result of a more complex interaction, says Chantel Strachan, M.D., a headache specialist and general internist at Columbia University Irving Medical Center in New York City. First, a trigger—either hormonal or in the environment—leads to the release of calcitonin gene-related peptide (CGRP) in your body, a protein involved in the transmission of pain. "That triggers the pathway that ultimately relays signals back to the brain and increases the perception of pain," Dr. Strachan says.

Next, the lining of the brain and its blood vessels, both of which contain a lot of nerves, become hypersensitive to the pain signals being released. "That system starts to fire off autonomously, as if damage is being done. But damage is not being done," Dr. McGeeney adds. Extra sensitive nerves are why even the slightest head movement can produce pain when you're in the throes of a migraine attack.

Other migraine symptoms, like nausea and light sensitivity, have to do with the interconnected nature of the brain. "The activation of pain pathways in the brain also activates other systems and centers," explains Dr. McGeeney. So, for example, if the part of your brain that processes vision information is involved, you'll be extra-sensitive to light during a migraine.

How Genes Affect Your Migraine Risk

Genetics plays a major role in the occurrence of migraine, factoring into up to 60% of the cases. Usually, there isn’t one specific gene that you inherit that causes migraine. Instead, your parents pass down a variety of genes that make you more susceptible to this type of head pain. For most people with migraine, more than 100 genes are involved, according to the latest research.

The exception is a very rare type called hemiplegic migraine that affects only one in 10,000 people. This variety of migraine produces a collection of sensory symptoms known as aura, plus weakness on one side of the face or body during flare-ups. Three specific genes cause hemiplegic migraine, and they impact the ion channels—proteins that make nerves hypersensitive.

Sometimes genes aren't involved at all—so it’s possible to be the only one in your family with migraine. And of course, some people have genes that put them at risk for migraine and yet don’t have the condition. That’s because even if you’re predisposed, migraine is usually brought on by a trigger—something in your environment that flips a switch and turns it on. Fortunately, many of these triggers are within your control.

The Most Common Migraine Triggers

Migraine is the byproduct of “a mix of genetic baggage and the environment, and that includes lifestyle," according to Dr. McGeeney. Anything from throwing back a few too many beers at your local bar to oversleeping can set off one of these flare-ups.

Everyone's triggers are different, but these are some of the most common migraine-starters, according to the American Migraine Foundation.

Stress: This is a big one. Nearly 70% of people who get migraine say that stress triggers their headaches. Ironically, the stress of having migraine can lead to more headaches, which is why relaxation techniques like meditation are an important management tool.

Sleep: It goes both ways: Both too much and too little rest can lead to migraine. The sleep-wake cycle is very precisely balanced. Anything that throws off that balance, including waking up many times at night or sleeping extra late on the weekend, can result in migraine.

Food and drink: Meals are peak times for migraine because so many foods and beverages are on the trigger list. Alcohol and chocolate are the most common ones, but cheeses, processed or cured meats, artificial sweeteners (think aspartame), and food additives like MSG are also problematic. Caffeine is a "double-edged sword" when it comes to migraine, says Dr. McGeeney. On the one hand it has an anti-headache effect, which is why you'll find it on the ingredient list of some over-the-counter migraine meds. But too much caffeine can also cause migraine.

Dehydration: One in three people with migraine say that dehydration, or lack of fluid, makes their head pound. Your brain, just like the rest of you, needs adequate hydration to function optimally. When you're dehydrated, your brain tissues contract and put pressure on nerves in your head. Hence the headache.

Hormones: Women are three times more likely than men to get migraine. For this, we can blame hormones. Changes in estrogen and progesterone levels, especially during menstruation, are why women tend to get far more of these headaches around their period.

Medication: Ironically, the same medication you take to stop a migraine could bring on headaches if you use them too often. Doctors call this rebound phenomenon "medication overuse headaches." Researchers think that drugs like triptans, ergotamine, and over-the-counter pain relievers change your brain in ways that can make it more sensitive to pain.

Improving Migraine Treatment

Understanding the processes that give rise to migraine is helping researchers find new ways to treat the condition. The hope is that going forward, researchers will unearth even more information about migraine and begin to chip away at that 39 million number.

In the meantime, if you’re dealing with migraine and haven’t found a treatment that works for you, try tracking your lifestyle habits closely in an effort to identify triggers and eliminate them. And keep working with your doctor to find a medication that provides relief. The trial and error process can be frustrating, but with the options available today, you’re bound to find one that works for you.