Although we don’t know the precise biochemical mechanism of migraine, we certainly know a lot about the things that trigger it. The following things are all known to trigger off attacks in some patients. They are in no particular order.
Food
There’s a very complex relationship between migraine and food. Insufficient food – such as missing or delaying a meal, or fasting – may trigger a migraine in susceptible people, and about one in five migraine sufferers claims that a particular food or foods will trigger an attack. Chocolate and cheese are high on the list of culprits, but alcohol, citrus fruits and dairy products are all well known triggers.
There are three completely distinct mechanisms by which food can cause problems.
• A drop in glucose levels in the blood, caused by a sudden lack of food.
• Direct stimulation of cells in the brain from the lyramine content of certain foods. Tyramine is an amino acid (a chemical compound found in protein) and it is present in high concentrations in some foods – particularly chocolate and cheese. The effect of tyramine is directly related to the close the patient receives. A smal dose might have a small triggering effect, and a larger close gives a correspondingly larger effect on the brain. Tyramine and related chemicals are thought to trigger migraine’s because people who are susceptible to tyramine don’t have the enzymes to remove these chemicals as quickly from the body; they remain for longer, affecting the blood vessels and triggering an attack.
Stress
Stress is probably the most common trigger for migraine. Stress is a blanket term which can also include excitement and anticipation. Like food allergies, stress can also trigger migraine when it is removed; for example, causing a ‘weekend migraine’, when you’re away from the busy office. Migraines can also be brought on by the stress of social situations – such as parties, travel, and going to the cinema or dancing.
There is also the stress brought on by a fear of what the migraines might mean (for example, fear of an underlying brain tumour). This merely serves to multiply whatever stress you have, bringing on more migraines.
Too much or too little sleep can precipitate a migraine; for example, lying in bed at the weekend may start off an attack. There is an increased frequency of migraine in anxiety and depression.
Anything which causes excitement – particularly in children – can trigger migraines. Certain types of physical stress, such as jogging or lovemaking can act as triggers, too.
If it is erratic, exercise can trigger migraine. On the other hand, regular exercise is beneficial. Bending or stooping (as in gardening) can trigger attacks, as can lifting heavy weights and straining, as well as physical or mental fatigue.
Car journeys
Car journeys can trigger migraines. A lot of other triggers can be involved, too -the stress and fatigue of the journey; motion sickness; flashing lights at night as cars zoom past in the other direction; windscreen wipers flicking across your field of view, especially where there are bright lights in front (causing flicker). And, when the sun is low and to one side, travelling through a treelined avenue can create immense flicker.
Hormonal changes
This is exclusively confined to women. Migraines may be triggered by the drop in oestrogen at the time of the monthly period and may be improved (but sometimes worsen) during pregnancy; often improve (but sometimes worsen) at the menopause, and can be made worse by the Pill, which in rare cases can trigger off a most dangerous type of migraine attack.
Environment
Heat, cold, light and noise can all precipitate migraine. The weather can also act as a trigger. The most famous account of this is Dr Edward Wilson, who was on Captain Scott’s doomed expedition to the South Pole. He invariably suffered a migraine attack ten to twelve hours before a blizzard started.
In most migraineurs it is probably the increased glare which does the damage. This is made worse by high-altitude thin cloud, which heralds a cold front; the cloud causes the glare, and the rain follows the front.
Bright light and especially high contrast can trigger attacks. Even something as simple as sitting talking to a friend who is silhouetted in front of a sunlit window can bring on a migraine. Some people get migraines from staring at computer screens, particularly when they are not set up very well.
Sunlight reflecting or shimmering off water can act as a trigger. Polarised glasses, which selectively cut out reflected light, can help greatly in reducing the amount of reflected flicker.
Positive ions in the atmosphere can also trigger migraines. These ions occur in large quantities before a thunderstorm. As the storm passes, the charge changes from positive to negative, but by then the migraine may have started. Sprays of water fill the air with negative ions, so having a shower may help counter the effects of thundery weather.
Positive ions are also present in large quantities in centrally heated and air-conditioned offices; there are many ions in the air, but the metal ducting used in air conditioning systems tends to attractive negative ions more quickly than positive ones, thereby stripping the air of negative ions and leaving positive ones behind. Opening the windows, or using an ioniser, may help. Hot baths can trigger migraines in some people.
Dental causes
It is now recognisd that some types of dental problems can trigger migraines. One particularly strange one is that alterations of the bite can lead to different tensions in the muscles on either side of the head, and this in turn can cause migraines. Sometimes the problem occurs when so many teeth have been lost that the jaw over-closes. Altering the angle of the bite can stop the provocative effects.
Unconscious grinding of the teeth often occurs during sleep, causing tension in the muscles that form the cheeks; this may also prompt an attack. Relaxation therapy may help to reduce the over-all level of stress.
Neck pain
Spasm of the muscles in the neck, which often occurs as a result of minor malpositioning of the vertebrae, can set off migraines. Improvement in the care of the neck – sometimes by manipulation, sometimes by better ergonomic planning – may bring dramatic improvements.
Smoking
Smoking can generate migraines, too. There is a cross-over effect with a food allergy to potatoes, tobacco and tomatoes, as these plants are all closely related.
Body clock
Changes to the body clock such as jet-leg, or going on to night shift may trigger migraines; also, holidays and weekends (with relaxation from stress, late rising, and erratic bedtimes) may do the same.
Anaemia
Anaemia can both worsen migraine attacks, and increase their frequency. Why Me?
Only one form of migraine is known to be completely genetic in origin. This is familial hemiplegic migraine, a specific (and rare) type of migraine. In this form of migraine, the migraineur suffers from transient paralysis of one side of the body; and other close members of the family suffer from an identical type of migraine.
Although a direct genetic link hasn’t been established in other types of migraine, migraine does seem to run in families. Nearly half of migraine sufferers have a near relative with the disease, compared to one-sixth of non-migraineurs.
There may be several reasons for this. Firstly, some people have migraines because of food allergies. The tendency to be allergic is probably a single inherited gene, but the allergen to which you are sensitive and how it manifests itself depends on many other things – such as what substances you’ve been exposed to, especially at certain vulnerable times of your life. Therefore, migraines caused by food allergies are not solely genetic in origin.
The second reason is that there are probably several different genes involved in migraine, and whether you tend to get migraines or not depends upon what mix of genes you receive in your own genetic make-up.
The third reason migraines run in families is that stressed parents often teach their children stressful behaviour by example. Or, more relevantly, they don ‘/teach them how to cope with stress, because they don’t know how to do so themselves. Stress therefore runs in families, but in a non-genetic way.
There is no relationship between migraines and class, race or intelligence.
A slight statistical relationship exists between migraine and epilepsy. Both share a number of neurological features, such as visual symptoms, and a spread of the effect within the movements of the brain. In particular, temporal lobe epilepsy can share some features with migrainous attacks; and in those with both migraine and epilepsy, a high proportion started their epilepsy in the years immediately after the migraines started.
There is also a relationship with Meniere’s disease (one-sided deafness, dizziness and tinnitus); people with Meniere’s disease have a higher-than-average incidence of migraine.
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