Living at high altitude in Nepal is associated not only with higher migraine prevalence but also higher severity of attacks (measured in terms of frequency, duration, and intensity of pain). The prevalence of migraine is very high in Nepal: 34.7% (Manandhar, 2015). In comparison, the global prevalence of migraine is about 11% (Stovner, 2007).
A population-based study among 2100 Nepali showed that migraine prevalence increased from 27.9% to 45.5% with increasing altitude from 0 to 2499 meters. Higher altitude increased the likelihood of having migraine compared to living at under 500 meters (Linde 2017).
At an altitude of 2500 meters or more, the prevalence was slightly lower at 37.9% (although still high in global terms); and headache symptoms were not as bad. The authors suggested that there may be physiological adaptations that kicked in at very high altitudes. However, the lower prevalence and severity of migraine might be due to self-selection. People with really bad headaches might have chosen to live elsewhere.
The association with altitude was not seen in tension-type headache. Participants were selected from among the local population, not among visitors who experience "high-altitude headache," a condition where the body is not given enough time to adjust to rapid ascent to above 2500 meters. The authors also tried to rule out genetic or cultural factors: prevalence was so much higher than in nearby China and India; even in Nepalese districts lying on the border with China.
This research is important because:
- Association with high altitude could explain the high prevalence of migraine in Nepal.
- The body's reactions to living at high altitude might be a key to understanding the causes of migraine.
- Globally, half a billion people live at altitudes above 1500 meters. People with migraine who live at high altitudes might benefit from advice to live at altitudes below 500 meters.
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.
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.
Stovner LJ, Hagen K, Jensen R, Katsarava Z, Lipton RB, Scher AI, Steiner TJ, Zwart J-A. The global burden of headache: a documentation of headache prevalence and disability worldwide. Cephalalgia 2007; 27:193-210.
Photo:
View on Namche Bazar, Khumbu district, Himalayas, Nepal
© Olga Danylenko | Shutterstock
