Migraine Prevalence, Severity Linked to Higher Altitude

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Previous research has indicated a higher prevalence of migraines in Nepal, with a 60% increased likelihood of migraines once above 1000 m.
Previous research has indicated a higher prevalence of migraines in Nepal, with a 60% increased likelihood of migraines once above 1000 m.

People who live at high altitudes may experience increased migraine prevalence, duration, and severity of symptoms, according to results from a population-based study conducted in Nepal and published in the European Journal of Neurology.1

Worldwide, migraine is the third most prevalent disorder and the sixth leading cause of disability.2 Although the etiology of migraine is not fully understood, environmental factors including chronic exposure to high altitude have been linked to migraine development.3

Nepal provides an ideal geography to study the association of altitude and migraine because areas range from 60 to more than 8000 m above sea level. Previous research has indicated a higher prevalence of migraines in Nepal, with a 60% increased likelihood of migraines once above 1000 m.4

Professor Mattias Linde, MD, PhD, from the Norwegian University of Science and Technology in Trondheim, and colleagues sought to further explore the association between altitude and migraine. The investigators conducted a cross-sectional population-based study of Nepali-speaking adults. A cluster sampling was obtained to ensure balanced representation from the population. Data were obtained by unannounced visits to participants' homes to administer a culturally adapted questionnaire.

The study included 2100 participants (mean age, 36.4 years; 59.0% women). More than 52% of participants lived above 1000 m, and 22.4% lived at or above 2000 m.

Overall, migraine prevalence increased with altitude, going from 27.9% at <500 m to 45.5% at 2000 to 2499 m. Interestingly, migraine prevalence decreased to 37.9% above 2500 m. Compared with altitudes <500 m, the adjusted odds ratios (aORs) were significantly greater for increasing altitudes of 1000 to 1499 m (aOR, 1.5; P =.001), 1500 to 1999 m (aOR, 1.9; P <.001), and 2000 to 2499 m (aOR, 2.22; P <.001).

Likewise, the median frequency of migraine increased with increasing altitude, from 1.3 days per month at <500 m above sea level to 3 days per month at 2000 to 2499 m (P <.001). Further, both migraine duration and pain intensity increased significantly with rising altitude, from 9.0 hours' duration at <500 m to 24.0 hours' duration at 2000 to 2499 m, and from 35.5% of participants reporting high-intensity pain to 56.9% (P <.001 and P =.011).

The investigators suggested altitude can have a "migraine-aggravating" effect leading to increase in frequency, duration, and intensity of the headaches. They noted that high-altitude headaches are unlikely to be a factor in this study because the participants were fully adapted to this environment to be able to maintain tissue oxygenation.

"Migraine prevalence and indices of migraine severity are strongly associated with altitude. The mechanisms are unknown, but require investigation," they wrote. "A very large number of people might benefit from possible treatments that target these mechanisms."1

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References

  1. Linde M, Edvinsson L, Manandhar K, Risal A, Steiner TJ. Migraine associated with altitude: results from a population-based study in Nepal. Eur J Neurol. 2017;24(8):1055-1061.
  2. Global Burden of Disease Study 2013 Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2015;386(9995):743-800.
  3. Arregui A, Cabrera J, Leon-Velarde F, Paredes S, Viscarra D, Arbaiza D. High prevalence of migraine in a high-altitude population. Neurology. 1991;41:1668-1669.
  4. Manandhar K, Risal A, Steiner TJ, Holen A, Linde M. The prevalence of primary headache disorders in Nepal: a nationwide population-based study. J Headache Pain. 2015;16:95.
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