In a new study, researchers found five big predictors of chronic migraine.
The research was conducted by a team at the Albert Einstein College of Medicine and elsewhere.
Chronic migraine is defined by the International Classification of Headache Disorders—ICHD-3 as having headaches for—15 days per month, for—3 months, which—8 days/month are linked to migraine.
Several factors have been linked to migraine chronification, such as depression, anxiety, sleep disorders, obesity, other pain disorders comorbidities, allodynia, female sex, medication overuse, coffee, major life events, and low income.
However, these studies are not devoid of biases and limitations that may underestimate or overestimate these factors.
In this study, the team pointed out the main factors contributing to the evolution of episodic migraine to the chronic form.
Excluding biases and poor-quality studies, they showed that, significantly, only the following factors were associated with chronic migraine:
Depression
Suffering from depression increases the chances of progressing to chronic migraine by 58%. This is, in fact, a psychiatric comorbidity widely observed in many other migraine studies.
High Frequency of Attacks
Having—5 attacks per month increases 3.1 times, while—10 attacks per month lead to a 5.9-fold increase in the risk for chronic migraine.
In fact, these findings raise a permanent debate surrounding the chronic migraine diagnostic criteria.
From the functional and emotional disability perspective, patients with—10 attacks per month show no difference from chronic migraine patients.
Drug Overuse
Medication overuse increases the odds of developing chronic migraine by 8.8 times.
At this point, the researchers stress the need for more vigilance by clinicians on failures of acute medications and medication overuse.
Allodynia
Allodynia is a sensory disorder where innocuous (harmless) stimuli turn out to cause pain.
The best-known example is cutaneous allodynia on the scalp when combing becomes a painful act because of scalp sensitivity.
In the study, having allodynia increased the chances of progressing from episodic migraine to chronic migraine by 40%.
Allodynia results from a neurophysiological process called central sensitization, where 2nd and 3rd order neurons in the central nervous system are activated producing exaggerated sensory stimuli, which can make normal stimuli such as touch into painful sensations.
Although the magnitude of the allodynia effect was small in this meta-analysis, it makes sense from the pathophysiological viewpoint.
Income
Having an income of—US$ 50,000 reduces the chances of progressing to chronic migraine by 35%.
A likely explanation for this fact is that a higher income allows access to information and treatments that prevent migraine chronification.
The team says healthcare professionals should remain vigilant for factors that may increase risk the risk of progression to chronic migraines in people with high-frequency headaches, medication overuse, and depression, and treat these conditions when they encounter them.
The lead author of the study is Dr. Dawn Buse from the Department of Neurology.
The study is published in the journal Cephalalgia.
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