Migraines have long thought to be caused by fluctuations in the chemicals of the brain - specifically when the level of serotonin decreases.

But as no one really knows why the level of serotonin is decreasing, a new study has shed light on another possibility - people who get migraines may have differences in the blood vessel structure of their brains.

"These differences seem to be associated with changes in blood flow in the brain, and it's possible that these changes may trigger migraine, which may explain why some people, for instance, notice that dehydration triggers their headaches," study researcher Dr. Brett Cucchiara, MD, associate professor of neurology at the University of Pennsylvania Perelman School of Medicine, explained in a statement.

migraine

Over 8 million people in the UK suffer from migraines, and the low levels of serotonin can make blood vessels in one part of your brain suddenly contract, which makes them narrower. The NHS adds: "Soon after the blood vessels dilate, which is thought to cause the headache."

There are several ways to raise serotonin - reducing stress, exercise and being in direct sunlight are three - but you can make an immediate start with your diet.

Avoid white sugar and simple carbs (white bread, pasta and rice) as these will raise your blood sugar and then send it crashing down. Make sure you're also eating plenty of protein. Chatelaine.com says: "The production of serotonin is closely linked to the availability of vitamin B6 and the amino acid tryptophan. If our diet lacks sufficient protein and vitamins, we run a greater risk of serotonin deficiency."

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  • Sleeping In

    It may not be surprising that skimping on shut-eye can cause a migraine -- but so can binging on sleep on your days off. "The migraine brain likes things to be as normal and reliable and routine as possible," Buse says. And that includes your sleep schedule -- getting too much or too little sleep, or experiencing jet lag, can trigger a migraine attack. "We always advise people to try to wake up at the same time every day, even on Saturday and Sunday," she says. It sounds tough, but it's worth it -- not only can you stave off headaches by keeping your weekend bedtime and wake-time within an hour or so of your weekday schedule, but it also will help your sleep. Shifting your body clock several hours at the end of every week forces the body into a <a href="http://www.huffingtonpost.com/2012/05/11/social-jet-lag-weekend-harm-health_n_1507396.html" target="_blank">so-called social jet lag</a>, or stationary jet lag, that can cause sleep and health problems down the line.

  • The Letdown After Stress

    It makes sense that stress is a migraine trigger for many people -- but, turns out, so is the period of relaxation right after. The body's stress response increases levels of various chemicals that then drop off once we calm down. That chemical change could be what causes the so-called "letdown" or "weekend" migraines. This explains why an attack might strike on the first day of vacation, the day after you quit a stressful job or the beginning of your honeymoon, Buse says. In fact, according to research she presented at the 2011 American Neurological Association's annual meeting, people have a 20 percent increased likelihood of having a migraine in the 12 to 24 hours after their mood shifts from "sad" or "nervous" to "happy" or "relaxed." This underscores the importance of managing stress effectively as it's happening, Buse says: "It's really tough to do, but incredibly important."

  • Rain

    While there hasn't yet been any definitive research linking migraines with the weather, anecdotally speaking, patients often report getting more migraines on rainy days, Silberstein says. While you can't control the weather, you <em>can</em> take extra care to avoid other triggers on rainy days.

  • Estrogen Fluctuations

    Fluctuations in estrogen -- whether that be menstruation, coming off birth control pills, pregnancy, the time right after delivering a baby, menopause or taking oral contraceptives with changing doses throughout the month -- can trigger migraines. What's more, they can also lower your migraine threshold, meaning you're more susceptible to <em>other</em> triggers. If you find you're getting migraines between ovulation and menses, you might want to talk to your doctor about taking an extended oral contraceptive, Buse suggests, which can eliminate 75 percent of these hormonal periods.

  • Food

    The jury is still out on many of the foods people report triggering migraines. But while the science isn't conclusive, Buse says foods containing tyramine (including red wine, aged cheeses, certain processed meats and pork, to name a few) and tannins (including red wine, tea, coffee and apple juice), <em>may</em> cause an attack. Other food additives, including MSG, aspartame and nitrites, could be headache culprits, though, again, much of the data is anecdotal and not scientific at this point. In people with celiac disease or an allergy, gluten can also cause migraines. Keeping a diary can help you to pinpoint what foods you think could be setting off headaches for you. "One person will have one food be a problem and another person will say that doesn't happen with them," Buse says. But while avoiding a suspected trigger food might be helpful, she advises speaking to your doctor before making any extreme diet changes in the name of migraines.

  • Your Co-Worker's Perfume

    That strong scent is more than annoying -- for some migraine sufferers, it's enough to set off an attack. Sensory stimuli like bright lights (including the sun, computer screen or movie theater screen glare), strong smells (like perfume or cigarette smoke) and loud noises can all be headache culprits, Buse says. Some stimuli you can't do much about, but she suggests wearing sunglasses outdoors year-round if light is a problem and asking friends and co-workers to go easy on the perfume, if possible.

  • Drinking Coffee (And Not Drinking Coffee)

    This one works both ways: Too much caffeine can trigger a headache and, for heavy drinkers, <em>not</em> getting your fix can also set off your migraines. This might also be the culprit for your weekend headaches if you're guzzling coffee all week at the office and skipping it at home (or sleeping past your morning jolt), Silberstein says. To avoid caffeine-related migraines, Buse recommends people cap their daily intake at 200 mg (about the amount in a cup of coffee). Drinking more than that now? Taper off slowly to avoid withdrawal headaches.

  • Happy Hour

    The body metabolizes alcohol into acetate, which might cause a migraine, Silberstein says. To avoid the morning-after pain, he suggests drinking only in moderation, taking an an Aleve or Motrin before you drink and consuming food with your alcohol. While all alcohol can trigger migraines, Buse says dark-colored liquors, such as tequila and bourbon, and red wine anecdotally seem to be worse -- though there isn't hard data to back that up.

  • Sex

    According to Buse, physical exertion -- including sex -- can trigger a headache. While the exact cause of exercise-induced migraines isn't totally understood, it could be a chemical change in the brain, especially among those who are out of shape, or it could be that the very early stages of the attack have already begun, meaning the nervous system might be extra sensitive, she explains. The good news is that <em>regularly</em> breaking a sweat can often be a successful way to reduce the number of migraine attacks you experience. "If you exercise on a regular basis, the body makes its own painkillers," Silberstein says. (Even better, <a href="http://www.huffingtonpost.com/2013/03/13/sex-migraine-pain-study_n_2819196.html" target="_blank">one study published earlier this year</a> found that sex can relieve migraine pain for some people.) If the impact that comes with some exercise seems to be the problem, Buse suggests trying swimming, biking or yoga instead.

  • Skipping Lunch

    Again, routine is key for migraine sufferers. Skipping a meal or fasting can set off a headache, Silberstein says. We don't know exactly why, he explains, but it might have something to do with low glucose levels. Either way, it's important to eat regularly when possible to avoid an attack.

The new study, published in the journal PLOS ONE, included 170 people who fit into one of three categories: those who didn't get any migraines, those who got them with aura, and those who got them without aura. Researchers looked at the structure of blood vessels in the study participants' brains, as well as changes in cerebral blood flow. They specifically looked at the "circle of Willis," which is the term used for a system of arteries responsible for delivering blood to the brain.

The researchers found that people with migraines were more likely to have an "incomplete" circle of Willis than those who didn't get migraine headaches. Specifically, 73 percent of those who get migraines with aura had an incomplete circle of Willis, and 67 percent of those who get migraines without aura had an incomplete circle of Willis. Meanwhile, 51 percent of those who didn't get migraines had an incomplete circle of Willis.

MIGRAINE FACTS:
  • In the UK, there are an estimated 190,000 migraine attacks every day (Steiner et al, Cephalalgia, 2003)
  • Women are more likely to have migraine attacks than men – 18% of women and 8% of men (Steiner et al, Cephalalgia, 2003)
  • Among adults of all ages, migraine is one of the top 20 causes of disability expressed as years of healthy life lost to disability (The World Health Report 2001, WHO)
Source: Migraine Trust

"Abnormalities in both the circle of Willis and blood flow were most prominent in the back of the brain, where the visual cortex is located. This may help explain why the most common migraine auras consist of visual symptoms such as seeing distortions, spots, or wavy lines," senior author of the study, Dr. John Detre, MD, a professor of neurology and radiology at the university, said in a statement.