Migraines may cause lasting changes to the structure of a suffering person’s brain, according to a new study.

Scientists still aren’t sure exactly what predisposes some people to suffer from recurring migraine headaches, which tend to be concentrated on one side of the head. Some migraines are heralded by an “aura,” a pre-headache sensory disturbance that often manifests as visual hallucinations -- sparkling lights, gray areas or zigag lines -- nausea, or sensitivity to light and sound.

A team of scientists from the University of Copenhagen and the Albert Einstein College of Medicine in New York analyzed 19 other studies to see if migraine patients were more likely to have abnormalities in their brains. They found that people with migraines have more abnormalities in the white matter of the brain, more brain lesions and altered brain volumes than people that do not suffer from the disorder. Brain abnormalities are even more likely to occur in people who suffer from migraines with aura, the researchers wrote in the journal Neurology.

Study co-author Richard Lipton, a neurologist at Montefiore Medical Center and a professor of neurology at Albert Einstein, said in a phone interview that the connection between aura and brain damage might be the underlying mechanism of the aura itself. It’s thought that the aura that precedes a migraine results from a phenomenon called a cortical spreading depression, where a wave of electric activity passes over the surface of the brain. This wave first excites, then inhibits, certain brain activities.

“It’s a pretty dramatic event in the brain that involves reductions in activity of nerve cells and reductions in blood flow,” Lipton says. “In the overwhelming majority of cases, these reductions in blood flow don’t cause brain damage, but it looks like in a minority of cases those auras might cause damage to the brain.”

But what about the brain damage seen in people without auras? Lipton speculated that some patients classified as having migraines without auras might actually be experiencing the same effect, but in a different part of the brain. A spreading cortical depression might affect areas associated with critical thinking as well as the area responsible for vision. And while people might readily remember that they saw zigzag lines right before a migraine, they might not necessarily report or even notice that they had clouded intuition before a headache struck.

While the significance of these brain abnormalities still isn’t clear, “these abnormalities are reported to increase with migraine frequency, which may represent a form of anatomic progression of the disorder,” Lipton and his colleagues wrote in their paper.

One positive takeaway from the study is that migraine patients may not need to be particularly alarmed if a brain scan shows some white matter lesions – small patches of dead cells in parts of the brain. Such phenomena, it turns out, are not themselves an abnormal symptom.

“The fact that white matter lesions are so common with migraines ought to reassure patients; it’s not necessarily associated with any bad outcome,” Lipton says.

But the study also found that migraine patients with aura are more likely to show signs of infarct-like lesions in the brain, which resemble tiny strokes. These infarct-like lesions are all the more reason for migraine patients to do what they can to reduce their stroke risk, Lipton says.

To reduce stroke risk, Lipton advises quitting smoking, watching one’s blood pressure and keeping a diary of migraine attacks, which could illuminate a pattern behind the headaches. Some people will find that red wine brings on a migraine; for others, it’s aspartame artificial sweeteners or stress.

Whatever a patient’s particular situation is, “if you can manage your triggers, you might reduce your frequency of headaches,” Lipton says.

SOURCE: Bashir et al. “Migraine and structural changes in the brain: A systematic review and meta-analysis.” Neurology, 28 August 2013.