The BBC and The Guardian reported today that there are differences between the brains of people who get migraines and those who don’t. They say that the part of the brain that deals with pain and touch sensation is 21% thicker in people who have migraine, and that "this may explain why people with migraines often also have other pain disorders”. Both sources mention that the researchers are unsure if the differences are the cause - or the result - of migraine attacks.
These stories are based on a study that used magnetic resonance imaging (MRI) scans to examine and compare the brains of people who get migraines with people who don’t. The study only looked at a relatively small number of people, and so its findings will need to be confirmed in a larger sample of people before it can be concluded that these brain changes are a common phenomenon in people with migraine.
Where did the story come from?
Alexandre DaSilva and colleagues from the Harvard Medical School and the Massachusetts Institute of Technology in the US carried out this research. The study was funded by the US National Institutes of Health, the Swiss Heart Foundation, and the Harvard School of Dental Medicine. The study was published in the peer-reviewed medical journal: Neurology.
What kind of scientific study was this?
This was a cross sectional study comparing the brains of people with and without a history of migraine.
The researchers recruited 24 people who had migraine from headache clinics in the Boston area and asked them detailed questions about their headaches. They recruited 12 people who experienced sensory phenomena (called auras) when they had their migraines, for example, having visual changes (such as seeing lights or spots) or numbness; and 12 people who had migraines without auras. All the subjects had suffered from migraines for 20 years on average.
They also picked 12 volunteers who did not get migraines to act as controls. These people were as similar as possible to the people who suffered from migraines in age and sex. None of the participants had any major health problems or other serious pain conditions.
The researchers then used magnetic resonance imaging (MRI) to look at the brains of the participants. They took measurements of different areas of the brain, including those areas involved in sensing touch and pain (the somatosensory cortex), and compared these measurements between people with a history of migraine and those without.
What were the results of the study?
On average, the region of the brain involved in sensing touch and pain (the somatosensory cortex) was thicker in people who experienced migraine (with or without auras) than in the people who didn’t. In people who experienced migraines with auras, this area was 21% thicker than in healthy controls. The differences in thickness were evident in the areas that are associated with sensations in the head and face.
What interpretations did the researchers draw from these results?
The researchers conclude that their findings suggest that the migraines are associated with changes in the somatosensory cortex, but that they cannot yet say whether these changes are cause or effect. They also suggest that these changes may explain why people with migraine also often have other problems with pain and touch, such as back pain or unusually sensitive skin.
What does the NHS Knowledge Service make of this study?
This is an interesting study that has given us the beginning of an idea of the changes in the brain that might occur with migraine. The study is small, and the results obtained with this small sample of people who have a long history of migraine may not be representative of all people with migraine. It is also too early to conclude that these changes are responsible for other pains experienced by people with migraine, especially as this study only looked at people who had no other major pain disorders.
Sir Muir Gray adds...
MRI is so powerful it reveals many phenomena whose meaning is hard to understand.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Guardian, 20 November 2007
BBC News, 20 November 2007
Links to the science
Neurology 2007; 69: 1990-1995