An estimated 400 million people—myself included—live at elevations higher than 1,500 meters above sea level. The beautiful scenery, rugged mountains and clean air are part of the appeal to many of us. But interesting changes in the body seem to occur as a response to living at high altitude. Scientists from all over the world are working hard to understand these changes and how and why they happen.

At increasing altitudes, air pressure in the atmosphere (atmospheric pressure) decreases. Atmospheric pressure helps us get air into our lungs and blood. As the air pressure decreases, we inhale less oxygen with each breath, throwing off our normal breathing patterns,which means we don’t get enough oxygen to use for energy. As a result, the blood flow to the brain increases. This is called hypoxia. Carbon dioxide in the blood also decreases (hypocapnia), which causes decreased blood flow in the brain. Two researchers presented posters at the Experimental Biology 2018 meeting in San Diego that explore the role of genetics, cerebral blood flow and altitude on our bodies.

Hailey Lafave presents her poster, “Tracking cerebral blood flow regulation during incremental ascent to altitude: Effect of superimposed hypoxia and hypocapnia” at Experimental Biology 2018. Credit: Nathalie Fuentes

Hailey C. Lafave, of Mount Royal University in Alberta, Canada, studied hikers who trekked 4,370 meters above sea level over seven days in the Nepal Himalayas. The hikers’ vital signs were measured at 1,400 meters on day 1; 3,440 meters on day 3; and 4,370 meters on day 7. The study found that the hikers’ blood oxygen levels and blood pressure decreased at higher altitudes. Blood flow increased on the seventh day of hiking (at an elevation of 4,370 meters), but not at lower elevations (3,440 meters) on the third day. This novel finding could be used as a metric to detect hypocapnia on cerebral blood flow regulation at altitude.

Elijah Lawrence’s poster, “Genetic missense variants at the EGLN1 locus associated with high-altitude adaptation in Tibetans are rare in Andeans” at Experimental Biology 2018. Credit: Nathalie Fuentes

Elijah S. Lawrence, of the University of California, San Diego, collaborated with researchers at the Universidad Peruana Cayetano Heredia in Peru to study why people who live at high altitude full-time experience hypoxia. The results demonstrate one of the most rapid evolution observations in humans. Lawrence found differences in the DNA of people living in high versus low altitudes. Genetic variations associated with hypoxia may be why some populations living at high altitude are particularly adapted to their environment and suffer from less severe hypoxia-induced complications.

As we continue to learn how hypoxia and hypocapnia affect the body and how we genetically adapt to our environment, remember to breathe slowly and deeply when you’re at high altitude to decrease your heart rate. This will help your body take in the oxygen it needs.

Nathalie Fuentes is a PhD candidate in the biomedical sciences program at Penn State College of Medicine. Her studies in Dr. Patricia Silveyra’s lab include the development of sex-specific therapies to treat lung diseases, sex differences in asthma-related lung inflammation triggered by ground-level ozone and the role of male and female sex hormones in lung disease. Nathalie is originally from Caguas, Puerto Rico.

Nathalie served as a meeting blogger for Experimental Biology 2018.