What pain looks like

Why do certain paintings, patterns and light effects cause headaches? Debbie Ayles, an artist and migraine sufferer, helped researchers find out

Art lovers prone to migraines should stick to Turner, as well as avoiding cheese, flashing lights and stress and keeping the headache pills handy on Saturdays. The English artist's paintings are not just easy on the eye; they're also less likely to trigger headaches than many other works of art.

Research shows that unnatural patterns, stripes and contrasts in some paintings are uncomfortable to view, and can literally be a pain. Professor Arnold Wilkins, who led the research at Essex University, says: "We have shown for the first time that the discomfort from looking at complex images like paintings can be predicted, and our test could be used to avoid putting stressful images in public places where they could cause problems for some people."

The work was carried out after the artist Debbie Ayles, who creates paintings inspired by her migraines, approached the researchers because some people had complained of discomfort after viewing her paintings.

Migraine was first described almost 4,000 years ago, but much about the condition is still not understood. What is known is that the throbbing, usually one-sided headache affects an estimated 18 per cent of women and 6 per cent of men, and that migraine is preceded in one in six sufferers by an aura, where there can be flashes of light or blind spots, difficulty with focusing and seeing things as though through a broken mirror, which last 15 to 60 minutes.

The difficulties with the condition are that it is triggered by so many things in different people; that it may have links with other conditions, from depression and breast cancer to stroke and heart disease; and that it responds to medication in different ways.

Common triggers include caffeine and cheese, bright or flickering light, changes in the weather, stress, the contraceptive pill, sleeping tablets and lack of sleep. It's known, too, that women are prone to migraine at different times of the month, and that attacks are more common after stress rather than during it – the so-called weekend or evening effect. Most sufferers probably have a genetic predisposition, as about eight in 10 sufferers have a family history of migraines.

Migraines have been linked to increased risk of heart disease and stroke, and a reduced risk of breast cancer. People with migraine plus aura are more likely to have a patent foramen ovale – a hole in the wall between left and right heart atria. Treatments used include Botox, beta-blockers, antidepressants and anticonvulsants.

Until relatively recently, the general view was that, whatever the trigger, the migraine pain and aura were linked to blood vessels contracting and then expanding – the vascular theory. But another theory – that it is due to an underlying central nervous system disorder – has emerged, suggesting that symptoms are caused by changes in the activity of nerve cells in the brain, which lead to changes in blood vessels.

It's suggested that the brain chemical serotonin, whose levels drop during an attack, is implicated. One idea is that the low levels cause blood vessels to contract, causing the aura. Dopamine may be involved, and low levels of magnesium have been linked to the aura. Hormones may be involved, and may be why some women migraineurs are more likely to have an attack around the time of their period. Monthly changes in hormone levels may also explain why women are more prone to migraines.

According to University of Maryland researchers, the central nervous disorder theory can be used to pull together many of the events that occur in migraine. "Stress or some other factor triggers the release of peptides, which dilate blood vessels and produce an inflammatory response that triggers over-excitation of the cells in the trigeminal nerve, which runs from the brain stem to the head and face. This spreads to the meninges, the membrane covering of the brain. While the brain itself is insensitive to pain, the meninges and blood vessels around the brain are sensitive to pain. Some experts suggest that pain occurs when blood drains from the centre of the head to the blood vessels around the brain," they say.

And auras, they add, may be a reaction to the changes in blood flow that cause a rapid reduction in brain activity washing across the brain over a period of 15 to 60 minutes. "This spreading depression effect can be seen as an electrical wave spreading through the brain, just as a wave of water is caused by the dropping of a pebble," they say.

The exact way migraines are triggered is also unclear. How can things as diverse as diet (more than 100 foods have been implicated), the weather, stress, bright lights, travel motion, strong smells and the contraceptive pill trigger the same cascade of events?

The art research at Essex University is producing some clues as to how visual triggers may work. In the research, reported in the journal Perception, Professor Wilkins and Dr Dominic Fernandez carried out a series of studies to pinpoint the specific causes of the uncomfortable sensation and headaches when viewing some paintings.

The artist Debbie Ayles says: "It was something that I became aware of as my work progressed. I am a migraineur and I began, inadvertently at first, to replicate some of the visual auras I experienced. Other migraineurs looking at the work recognised some of the auras within the paintings themselves. Once I realised that this is what I was doing, I explored this further in my paintings and prints. Since my migraines have become under control, I now in fact paint in a slightly different manner."

Study volunteers were asked to rate a number of paintings using a seven-point scale for both artistic merit and visual comfort, and the images were then analysed. This showed revealed factors unique to the uncomfortable images. In particular, there were strong contrasts between light and dark, combined at specific points where vision is most sensitive. Simple patterns of stripes with a specific spatial frequency induce headaches.

The researchers then developed computer software primed with the features they detected. They took images of works, analysed them with the software, and found that they were able to predict which would be the most uncomfortable to view. The more unnatural the structure of the paintings, the greater the discomfort.

Just why these images are uncomfortable isn't clear. One theory is that the brain has evolved to process natural images rapidly, and that it is confused or disturbed by some unnatural patterns. That results in a feeling of discomfort that can trigger headaches, migraines or epileptic seizures in people vulnerable to such attacks.

The researchers also compared photographic images of urban and rural scenes and found that the latter caused less discomfort, possibly because urban areas have more man-made structures with more unnatural patterns. The finding could explain other visual triggers, such as flickering and bright lights.

Wilkins and his team have looked at other stimuli and found the same kind of effects in photographs, typefaces and other images. One of the most uncomfortable images of all, they say, was found to be the lines on the treads on the London Underground escalators.

However, the research is not conclusive. "There is a huge number of myths and old wives' tales, and a huge amount that is still not known which helps to allow people to have those myths," says Dr Andrew Dowson, the chairman of Migraine Action's medical advisory board and head of headache services at King's College Hospital, London. "Is it, for example, a myth or a truth that food always causes migraine? A study in the US found that chocolate made no difference at all to migraine. It may be that people in the early stages crave and eat convenience foods such as chocolate and cheese. So it may be part of the migraine to want to eat those things rather than that they actually cause it."

He adds: "Many have realised that the sensory system is 'sensitised' within, and also often between, attacks. It has proved more difficult to confirm the suspicion that red and blue wavelengths of light, for example, are actual triggers, and I guess this work is of a similar nature. It would be interesting to see if exposure to one type of image had a different resultant migraine rate, but it is hard to design such a study."

Anatomy of an attack: The five stages

1. Prodromal Telltale mood, appetite and other changes, including non-specific aches and pains, can occur hours before an attack.

2. Aura For one in six people, the pain is preceded by an aura that lasts, on average, 20 to 30 minutes.

3. Headache A pulsating or throbbing pain on one side of the head, which may be accompanied by nausea, extreme sensitivity to bright light and loud sounds, and a strong desire to lie down in a dark room.

4. Resolution Most attacks gradually fade away. They can last up to 72 hours.

5. Postdromal The recovery phase, where there is often a feeling of exhaustion.

Migraine and the body: The latest research

Depression

According to research at the University of Manitoba, evidence is emerging that migraines are associated with mental disorders. They found that having a migraine in the previous year was significantly associated with depression, bipolar disorder, panic attacks, panic disorder and phobia "The present study adds to a growing body of literature that suggests a strong association between migraines and mood and anxiety disorders," the researchers say.

Heart attack and stroke

According to a report from the Mount Sinai School of Medicine in New York, migraine with aura raises the risk of a heart attack in women by 91 per cent, and of a stroke by 108 per cent. Migraine without aura raised the level of both risks by about 25 per cent. "It would be prudent for women who suffer migraine with aura to seek medical advice and consider lifestyle changes in order to improve their cardiovascular risk profile," the report says.

Menstrual migraine

Changing hormone levels may also be a factor. According to research conducted at the University of Cincinnati, a trigger thought to be partially responsible is a significant drop in circulating oestrogen two to three days prior to the onset of menses. "It is estimated that approximately 50 per cent of women have an increased risk of experiencing migraine during the premenstrual phase of decreasing oestrogen levels," researchers say.

Breast cancer

Women who have migraines may be less likely to develop breast cancer. The frequency of migraine headache changes at various times during a woman's reproductive cycle, and research at the Fred Hutchinson Cancer Research Center, Seattle shows that a history of migraine is associated with a decreased risk of breast cancer. For some types of breast cancer, women with mirage had a 35 per cent lower risk.