Triggers and premonitory symptoms – which come first?

By: Paula Sureda Gibert, PhD Candidate in Basic and Clinical Neuroscience, King’s College London

11th August 2021

One of the helpful features of migraine is the possibility of knowing when an attack might come on. People with migraine often describe several things which can trigger their attack. These triggers can vary from person to person, and include factors such as: stress, skipping meals, certain foods, irregular meals, weather changes and changes in sleep patterns.

It is clear that some of these things, such as changes in sleep patterns, can increase the likelihood of an attack. For other triggers (such as chocolate), it is less clear if they genuinely increase the likelihood of a migraine, or if they are an early symptom of an attack.

These early symptoms are known as the “premonitory phase” and can last for up to 72 hours, acting as an early warning that a person may be at an increased risk of an attack. For example, research identified that individuals who reported light as a migraine trigger, were more likely to report light sensitivity (photophobia) during their premonitory phase. In a similar way, if you consider specific foods or skipping meals as a trigger, it is possible that these are actually pre-existing food cravings or a loss of appetite during the premonitory phase.

It is now thought that a lot of potential triggers may actually be premonitory symptoms of migraine. Learning to recognize these may help to identify when you are likely to have a migraine attack.

How cautious should I be about triggers?

Our understanding of the basic biology of migraine and its associated symptoms is developing rapidly. Many so-called triggers are now understood to be early migraine symptoms. Keeping a headache diary can help, so you can monitor particular symptoms and find those that may predict an attack.

These symptoms might include tiredness, yawning, neck stiffness, food cravings, lack of concentration and increased light sensitivity (photophobia). While it is a good idea to maintain regular sleep patterns, (as sleep disruption is considered a key trigger), if you can recognize your premonitory symptoms you may be able to avoid potential triggers when you are more likely to be vulnerable to them.

This might be useful for you and it can also help in your discussion with your doctor when considering the best treatment options for you.

The hypothalamus and migraine

Research is revealing the hypothalamus as a key area involved in migraine. The hypothalamus is an area of the brain that plays a role in balancing several bodily functions. For example, by sensing energy supply and demand it can regulate an individual’s appetite. It also plays a key role in regulating several other factors such as fatigue, sleep-wake cycles and hormones. Importantly, we know that this region is activated during the premonitory phase of migraine and scientists have shown that it can also control head pain, both decreasing and increasing the pain signals arriving in the brain.

While a stable lifestyle during the premonitory phase can be key to avoiding a migraine attack, it isn’t always possible to control our activities. Scientists are also working to develop new treatments that can help to “normalise” or stabilise these early symptoms. The ultimate goal would be to rebalance the system and reduce the likelihood of an attack developing. While not exhaustive, these targets include the specific signaling molecules: orexin, dopamine, noradrenaline and serotonin, which are all thought to be altered in migraine.

New research aims to understand how the hypothalamus changes prior to and during a migraine attack. It also looks at how the interaction of these molecules might increase the likelihood of a migraine attack. With migraine being such a complex disorder, scientists hope that by gaining a detailed understanding of the biology involved in the start of an attack, they can make and advance the development of new treatments and improve the impact of migraine.