The effects of migraines are well known, but the causes are less clear. Now scientists think they may have found a link between the neurological condition and a part of the brain called the visual cortex.
It's the bit of the brain that handles visual information as it comes in, and based on a study of 60 volunteers, an over-excitable visual cortex could have some relationship with the risk of migraines.
In the study, in the 29 volunteers who suffer from migraines (migraineurs), the visual cortex was found to be more excitable and more responsive in a series of tests. That could give us clues to the causes of migraines – and ways of treating them.
"Most migraineurs also report experiencing abnormal visual sensations in their everyday life, for example, elementary hallucinations, visual discomforts and extra light sensitivity," says psychologist Terence Chun Yuen Fong from the University of Birmingham in the UK.
"We believe this hints at a link between migraine experiences and abnormalities in the visual cortex. Our results provide the first evidence for this theory, by discovering a specific brain response pattern among migraineurs."
The study participants were shown a striped grating pattern (like those already known to give migraine sufferers problems) and then asked to rate how uncomfortable it was to look at, and to log any other visual phenomena associated with looking at it.
Further electroencephalogram (EEG) tests were used to track and record the brain waves of the volunteers. The migraineurs showed a larger response in their visual cortices during both the pattern and EEG experiments.
What's more, a subgroup of non-migraineurs who reported seeing additional visual disturbances also showed hyper-excitability in their visual cortex responses.
On its own, the study isn't enough to prove a definitive link between migraines and brain over-excitability, but the results fit in with previous studies, and offer up an interesting avenue for further investigation.
Work to unlock the secrets of migraine sources continues. A study from 2017 found a link between the chronic headaches and a jaw condition, perhaps suggesting some underlying biological cause, and we know migraines are much more common in women too.
Around one in seven people are thought to have problems with migraines – just about a billion of us across the planet – so finding better ways of targeting the root causes of the condition is going to bring a lot of relief to a lot of people.
"Our study provides evidence that there are likely specific anomalies present in the way the visual cortex of migraine sufferers processes information from the outside world," says neuroscientist Ali Mazaheri, from the University of Birmingham.
"However, we suspect that is only part of the picture, since the same patterns of activity can also be seen in non-migraineurs who are sensitive to certain visual stimuli."
The research has been published in Neuroimage: Clinical.