one in seven people around the world suffer from migraine. In the UK, migraine has a crippling economic effect, with approximately 25m days lost every year, costing the country £2.3bn. But while the condition has been studied since the time of the ancient Greeks – who attempted to treat it with trepanning, by drilling a hole into the skull to release evil spirits – it remains poorly understood with few adequate treatments.
What is it?
Migraine is an inherited disorder characterised by episodes of throbbing head pain. Many patients also report nausea, sensory hyperactivity, with ordinary volumes of sound or light seeming intolerably loud or bright. Others experience aura or neurological abnormalities such as vertigo, temporary blindness and numbness. Some rare types, such as hemiplegic migraine, are single gene disorders, with a particular mutation predisposing individuals to neuronal hyperactivity, meaning that areas of the brain involved in interpreting sensory events can be easily activated. But most common forms are polygenic – in which a constellation of genes contribute. Various environmental triggers are also strongly associated with migraine, including stress, skipping meals and lack of adequate sleep.
Our understanding of the neurological processes are still limited, but scientists are starting to put some of the pieces together. “We know that dilation of blood vessels may play a role and some of the newer treatments try to inhibit this,” says Elizabeth Loder, professor of neurology at Harvard medical school.
Why don’t we know more?
Serious research into migraine began only relatively recently, as for a long time many doctors believed that it was a psychosomatic condition produced by people being unable to deal with stress. “It was a disorder that most obviously affected women and so wasn’t taken as seriously,” Loder says. “And it’s a pain disorder. Pain is subjective: we don’t have any way of measuring it, which can make it very hard for people to believe it’s real. Plus, on top of all of that, it’s episodic, so between attacks, sufferers may look perfectly well.”
The fact that migraine is researched at all owes a lot to the development of the medication methysergide in 1960, which was found to eliminate headaches in weeks. The drug is no longer commercially available as it was found to have serious side-effects, but its legacy remains. What had been perceived as a psychological condition clearly had a biological basis. “The market is, of course, very big,” Loder says. “It’s a common disorder, it lasts decades. So, that made pharmaceutical companies sit up and take notice; money poured into the field; it improved and professionalised research.”
However, migraine receives much less funding, compared with similarly debilitating conditions. Studies looking at money allocated by the US National Institute of Health, for example, have shown that migraine is considerably underfunded.
Are women more prone to migraine?
Migraine is extremely common in both sexes but statistics suggest that it is more prevalent in women. Reports in the US estimate that, while 12% of the population has had an attack in the past year, this rises to 18% when women alone are considered.
Scientists suspect that cycling ovarian steroid hormones, in particular the drop in oestrogen that occurs during the menstrual cycle, are particularly provocative, especially for those genetically susceptible to the disorder. The dissipation of these hormones with age explains why some women find that migraine attacks become less common as they get older.
“I think women with the disorder are more likely than men to be accurately diagnosed with migraine,” Loder says. “Women see doctors more and are less likely to be hesitant to complain about head pain than men are. Some research shows that men with the disorder tend to be investigated for other causes of headache, suggesting that doctors have a cognitive bias and they don’t think of migraine as readily as they do with women.”