For millions of people, migraines are not “just headaches.” They can be crushing, disabling attacks that interrupt daily life and leave people unable to function normally for hours or days.
Some migraine sufferers become sensitive to light and sound, feel sick to their stomach, or experience strange visual symptoms before the pain begins.
Now, scientists at Stanford Medicine say migraines may actually exist in at least two biologically different forms, according to a major new brain imaging study published in the journal Cephalalgia.
The discovery could eventually help doctors move beyond the current system of treating migraines largely through trial and error.
Migraine headaches affect more than one in 10 Americans and are among the leading causes of disability around the world. Yet doctors still do not fully understand why migraines vary so much between patients.
Some people have occasional attacks, while others suffer frequent, disabling episodes. Certain patients respond well to medications, while others try treatment after treatment with little success.
At present, migraine diagnosis depends almost entirely on symptoms described by patients. Doctors classify migraines as either episodic or chronic based mainly on how many headache days occur each month.
Patients with headaches on more than 15 days monthly are considered to have chronic migraine. These patients are more likely to receive preventive medications designed to reduce migraine frequency.
However, researchers have increasingly questioned whether headache frequency alone truly reflects the biology of migraine disease.
To explore this issue, Stanford researchers conducted the largest functional MRI migraine study ever performed.
The study included 111 migraine patients and 51 healthy volunteers who did not suffer from migraines. Scientists gathered detailed information about symptoms, age, medical history, and disability levels.
Participants then underwent two forms of brain imaging. One type examined brain structure, while the second type, called functional MRI or fMRI, measured patterns of brain activity and communication.
Rather than starting with a fixed theory, researchers used computer analysis to search for natural groupings hidden within the imaging data.
The computer identified two distinct migraine clusters.
One group appeared much closer to healthy volunteers in their brain activity patterns. These patients generally experienced less severe migraines.
The second group showed major changes in communication between different brain regions, especially areas involved in sensory processing and pain responses.
Researchers believe these patients may process everyday sensory signals differently from other people.
Normally, the brain uses pain as a warning system to protect the body from danger. But in severe migraine patients, the brain may overreact to ordinary sensory experiences such as light, sound, movement, or smells.
This overreaction may help explain why migraines can feel overwhelming and disabling even without obvious external triggers.
Patients in the second cluster also had several important differences. They tended to be older, experienced longer migraine attacks, and were more likely to suffer serious disability from their condition.
Surprisingly, however, the two groups did not differ much in how often migraines occurred.
This finding suggests that migraine biology may be more complicated than the current chronic-versus-episodic classification system.
Dr. Robert Cowan, senior author of the study and a headache specialist at Stanford Medicine, said current migraine treatment often feels uncertain because doctors lack reliable biological markers.
Today, many treatment decisions are based on guesswork. Patients may spend years trying different medications before finding one that works.
Researchers hope the new biological subtype system could eventually allow doctors to make more personalized treatment decisions.
For example, some patients who technically have episodic migraines may still belong to the more severe biological subtype and could benefit from preventive medications earlier.
This could become especially important because insurance companies often restrict coverage for preventive migraine treatments to patients classified as chronic migraine sufferers.
The researchers are now working to identify blood markers and clinical symptom patterns linked to the brain imaging subtypes. Their goal is to eventually classify patients without requiring expensive brain scans.
Functional MRI remains too expensive and impractical for routine migraine diagnosis in most hospitals and clinics.
Still, scientists believe the findings may represent an important shift in migraine research.
For many years, migraine was mainly studied as a single disorder with varying severity. This new work suggests migraines may instead involve different biological pathways affecting the brain in different ways.
If confirmed in future studies, this could lead to more targeted therapies and better prediction of which patients are likely to develop disabling migraines.
Researchers also hope future studies may show whether certain biological migraine subtypes respond better to specific medications.
The findings are important because they challenge the traditional way migraines are classified and treated. Instead of focusing mainly on how often headaches occur, doctors may someday use biological markers to better understand the underlying disease process in each patient.
However, researchers caution that the study is still early, and more work is needed before these findings change routine medical care. Larger studies will be necessary to confirm the brain imaging patterns and determine how useful they will be in predicting treatment outcomes.
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The study was published in Cephalalgia.
Source: Stanford Medicine.
