People with migraines may feel like time passes a bit more slowly than it actually does, if a small study is correct.
The difference in time perception seems subtle - it's seen in people's perception of milliseconds. But the findings help validate the common complaint of migraine sufferers that they feel a bit "off" at times, according to a headache specialist not involved in the study.
The new research, reported in the journal Headache, involved 27 adults with migraines and the same number of headache-free adults the same age. All of them took a test of time perception in which they estimated the amount of time a series of rectangles appeared on their computer screen.
Sometimes the image appeared for 600 milliseconds (six tenths of a second), sometimes for three seconds and other times five seconds.
In general, the researchers found, people with migraines overestimated the 600-millisecond time window. They thought it lasted twice as long - about 1.2 seconds, on average - while the non-migraine group gave an estimate of about 0.9 seconds.
That's a small gap. But the findings support the idea that "migraine does indeed affect cognitive function," write Kai Wang and colleagues at Anhui Medical Center in Hefei, China.
Dr. Jennifer Kriegler, an associate professor of neurology at the Cleveland Clinic Lerner College of Medicine, agreed.
"A lot of people who have migraines report that when they are in a bad headache period, they just feel like they are in a fog," said Kriegler, who was not involved in the current study. "They don't feel like they're processing information as clearly."
An extreme and very rare version of this effect, dubbed Alice in Wonderland Syndrome, has been seen in migraine and epilepsy sufferers. It involves distorted time perception and a sense of disconnection from reality and even self.
The current time perception study was small, Kriegler said, but it was well done. And it suggests that the foggy feeling migraine sufferers report is not just due to the pain.
"It may be because of differences in brain processing," Kriegler said.
Worldwide, it's thought that 11 percent of the population has had a migraine in the past year. In the U.S. alone, migraines cost an estimated $20 billion a year in medical care and lost work productivity.
Migraines typically cause an intense throbbing sensation in one area of the head, plus sensitivity to light and sound, and nausea or vomiting in some cases.
About 30 percent of people with recurrent migraines also have sensory disturbances shortly before their headache hits. Those disturbances, known as aura, are usually visual - like seeing flashes of light or blind spots.
It's not completely clear what causes migraines, but they do appear to involve abnormal brain activity. And like the current study, some others have linked migraines - particularly those with aura - to differences in memory, reaction times and certain other cognitive abilities.
In this study, migraine sufferers were different in their perception of the 600-millisecond time frame, but not the longer, three- to five-second windows.
It's not clear what to make of that. Kriegler said that since the study was so small more research is needed to see whether it really is only the millisecond arena where people with migraines differ.
She also said it was "significant" that study participants with migraines were not actively having headaches during the testing. So even in between migraines, Kriegler said, there's a difference in brain functioning.
What does that mean for people in real life?
"Is this something that's going to affect people's daily functioning? Probably not," Kriegler said. Or at least not in the short term, she added.
One unanswered question is what kind of treatment people with migraines in the study were taking.
The researchers note that 21 patients "received medicine," and the majority took painkillers after their head pain set in.
But there is no indication they were on drugs that prevent migraines - which people with recurrent migraines often take. (Wang, the senior researcher, did not respond to an email seeking comment.)
So it's not clear whether preventive medications might have any effect on time perception, according to Kriegler.
Also unclear is whether any cognitive differences might have implications for migraine sufferers' long-term brain health. Right now, there is no evidence that people with migraines have, for example, a faster mental decline as they age or a higher risk of Alzheimer's, Kriegler said.
The current findings, she said, offer some "validation" to people who have felt their migraines put them "off their game."
Doctors, she noted, may brush off such complaints. "But," she said, "that patient knows there's something wrong."