It isn't necessarily that the body needs oxygen, but that key neurotransmitters in the brain change when one goes to altitude —Dr. Perry Renshaw
SALT LAKE CITY — Increased suicide rates in high altitude locations like Utah led researchers to study whether depression is being treated the right way in the state, specifically in women.
What they found was that popular selective serotonin reuptake inhibitors (SSRIs) — such as Prozac, Zoloft and Paxil — may not be addressing the problem correctly here.
The new research isolates hypobaric hypoxia, or the reduced oxygen experienced at high altitude, as "a distinct risk factor for depression" for people living at high altitudes, said Shami Kanekar, a research assistant professor of psychiatry at the University of Utah and the lead author of the study, which was published online in the March edition of High Altitude Medicine and Biology.
She said low oxygen levels at high altitudes could be the reason for higher levels of depression among the Intermountain West states of Utah, Colorado, Wyoming, Montana, Idaho, Nevada, Arizona and New Mexico.
Those states, according to the American Foundation for Suicide Prevention, also have suicide rates exceeding 18 per 100,000 people, compared with the national average of 12.5 per 100,000 people.
"It isn't necessarily that the body needs oxygen, but that key neurotransmitters in the brain change when one goes to altitude," said Dr. Perry Renshaw, a Utah Science Technology and Research Initiative professor of psychiatry at the U. and senior author of the study.
Previous research shows that suicide rates increase above altitudes of 2,000 feet, which "is exactly the point where our bodies have trouble getting enough oxygen to meet our needs," he said. "Most of Utah is above 2,000 feet."
Renshaw said that because females have less serotonin to begin with, they are more vulnerable to high-altitude induced changes in the brain that can lead to depression.
To track changes in the brain, researchers housed rats for a week at simulated altitudes reflecting conditions at sea level, 10,000 feet and 20,000 feet, as well as local conditions at 4,500 feet. Then the rats were placed in a cylinder filled with water and forced to swim.
It's a test that is widely used by drug companies developing antidepressant medications because it exhibits motivation levels following controlled stimuli.
Some of the rats gave up more quickly than others, opting to do just enough to stay afloat, which is a similar characteristic of depression, the researchers said.
Because rats are not subject to the same psychological and societal pressures as people, the current study bolsters the argument that physiological changes triggered by hypobaric hypoxia can contribute to depression.
Future studies will address what the changes are and whether they occur in people, too.
"Depression is not going to go away even if we could magically move Salt Lake City to sea level," Renshaw said. But determining changes imposed by altitude may help develop more effective treatment methods.
Utah has not only the highest use rates of antidepressant use in the country, but the highest depression index, according to a National Mental Health Survey in 2007.
"The fact that both depression and suicide rates increase with altitude implies that current antidepressant treatments are not adequate for those suffering from depression at altitude, leading to high levels of unresolved depression that can contribute to higher levels of suicidal ideation and suicide attempts," Kanekar said.
Other prevalent and potential risk factors of depression, including poverty, rural living, low population density, gun ownership and psychiatric disorders, are also common in the Intermountain West region.
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