By Lisa Rapaport

(Reuters Health) - A common gene variant linked to migraine headaches may have proliferated because it made it easier for early humans adapt to cold weather in northern climates, a new study suggests.

Migraines have long been more common in people of European descent than those from Africa, and both genetics and environment are thought to play a role. For the current study, researchers focused on TRPM8, a gene involved in regulating the ability to detect cold that's also associated with vulnerability to migraines.

Researchers discovered that a genetic variant upstream from this gene, which may regulate it, became increasingly common in populations living in cold climates. For example, 88 percent of people of Finnish ancestry carry the variant, compared with just 5 percent of people of Nigerian ancestry.

"The direct link between cold sensation and migraine is unknown; however, both are related to pain which provides a possible, but speculative, link," said lead study author Felix Key of the Max Planck Institute for the Science of Human History in Leipzig, Germany.

Within the last 50,000 years, some humans left the warm climate of Africa to colonize colder locales in Asia, Europe, and other parts of the world, researchers note in PLoS Genetics. Genetic adaptations to help humans respond to cold temperatures may have helped people survive this migration.

The gene TRPM8 helps control the only known receptor that enables people to detect and respond to cold temperatures. Variants found in people whose ancestors lived in cold climates thousands of years ago might help shut off or reduce the ability to detect cold or feel pain from the cold.

The researchers found that a variant of this gene became increasingly common in populations living in higher latitudes and colder climates during the past 25,000 years.

While this gene has been linked to migraines in previous research, the current study authors speculate that adaptation to cold temperatures in early human populations may at least partially explain the variation in migraine prevalence among different groups of people.

"Most genetic variants have very similar frequencies across human populations," said senior study author Aida Andres of University College London in the UK.

"So it was surprising that this (variant) is at very low frequency in some populations, say Yoruba, Nigeria, and very high frequency in others, for example Finnish in northern Europe," Andres said by email.

But the exact molecular cause of migraines remains unknown, and even in populations where most people are of northern European descent, only about 10 to 15 percent suffer from migraines, said Andy Weyer, a researcher at Pacific University in Forest Grove, Oregon, who wasn't involved in the study.

"Just because a person's DNA contains this variant does not mean that they will suffer from migraines," Weyer said by email.

While drugmakers are currently exploring whether it's possible to develop migraine medicines that work by targeting TRPM8, the current study findings won't change how people are currently treated for these headaches, Weyer added.

People may manage migraines by trying to avoid triggers like stress, lack of sleep or poor diet that can make the headaches more likely. Some patients may also take painkillers or antidepressants for acute migraines.

Cold is can be a trigger, noted Greg Dussor, a researcher at the University of Texas at Dallas who wasn't involved in the study.

"Stressors, or deviations from normal patterns, seem to be triggers for migraine attacks and exposure to cold is a stressor that the body doesn't like," Dussor said by email. "The migraine might be a warning sign that the stressor, in this case cold, could be dangerous and the person should protect themself from the temperature."

SOURCE: https://bit.ly/2Kw2Hps PLoS Genetics, online May 3, 2018.