By: Claire Sandoe, MD, MSc, Women’s College Hospital Centre for Headache, University of Toronto

Why do some people have more disabling forms of migraine than others? Why is my migraine disease getting worse? Is there anything I can do to reduce my risk of migraine becoming chronic?

These are important questions, and we currently have some but not all the answers. 

The International Classification of Headache Disorders (ICHD-3) defines chronic migraine as having at least 15 headache days per month, of which at least 8 are migraine days, for at least 3 months. The 15-day cutoff is under debate for a few reasons, including the fact that many people have fluctuations in headache days from month to month, and people with 8-14 migraine days per month can find migraine just as disabling as people who have 15 or more days per month.

Migraine is Genetic

Migraine often has a genetic component, but the extent to which this contributes to risk of chronic migraine for most people is not clear. 

Regardless, we do know that there are several risk factors for migraine disease worsening. Some of these are so-called modifiable risk factors, or things people may have some control over, such as smoking, obesity, sleep issues, and medication overuse. Unfortunately, some other risk factors are considered non-modifiable, such as adverse childhood experiences, stressful life events, and being female. Some conditions such as depression straddle the lines between modifiable and non-modifiable – there is likely a genetic component to these as well, but treatment of these modifiable risk factors can reduce their impact on migraine and reduce the risk of migraine disease worsening.

Research also suggests that migraine treatments can be important in reducing the risk of migraine disease progression. For example, people who do not have an acute treatment that works for them, and people who do not find triptans effective, are at higher risk of developing chronic migraine. We do not yet know whether this is because these individuals have a more disabling version of migraine disease, but we are starting to think that migraine treatments can slow the progression of migraine and reduce risk. 

We also think that the risk of chronic migraine goes up once people have 4 or more migraine days per month. The idea is as follows: the brain walks on a migraine path. This path may start out looking different from person to person for genetic reasons, for example some people may be born in a forest with a tiny migraine path, while others are born in a city that is covered in huge migraine highways. At any rate, the more often the path is traveled, the easier it is for the brain to find it the next time, and the more likely the brain is to walk on the migraine path again. Trying to let the plants grow over the path might keep the path from getting bigger over time. This could include both acute treatments, taken as needed to turn off the migraine attack process as quickly as possible, and preventive treatments, trying to reduce the number of attacks and increase the amount of time that the brain spends off of the migraine path. A recent review suggested that medication “underuse” could therefore also lead to migraine disease progression. 

Reducing Risk

So, what should people living with migraine do to reduce their risk of chronic migraine? Consider visiting the AMF guide to lifestyle changes for migraine management and resource library for suggestions on tackling some of the modifiable risk factors, and talk to your healthcare professional about a treatment plan that will be best tailored to you. You can also visit the AMF find a doctor tool here.

References
Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd edition (beta version). Cephalalgia 2013;33(9):629-808. doi:10.1177/0333102413485658

Ishii R, Schwedt TJ, Dumkrieger G, et al. Chronic versus episodic migraine: The 15-day threshold does not adequately reflect substantial differences in disability across the full spectrum of headache frequency. Headache 2021; 61: 992–1003. https://doi.org/10.1111/head.14154

Lipton RB, Buse DC, Nahas SJ, et al. Risk factors for migraine disease progression: a narrative review for a patient-centered approach. J Neurol 2023;270(12):5692-5710. doi:10.1007/s00415-023-11880-2

Rattanawong W, Rapoport A, Srikiatkhachorn A. Medication “underuse” headache. Cephalalgia 2024;44(4):3331024241245658. doi:10.1177/03331024241245658

Scher AI, Stewart WF, Ricci JA, Lipton RB (2003) Factors associated with the onset and remission of chronic daily headache in a population-based study. Pain 106:81–89. https://doi.org/10.1016/s0304-3959(03)00293-8