DAVID GREENE, HOST:
The Mountain West is home to some of the happiest states in the country. That's according to a recent Gallup poll. Paradoxically, they also have some of the highest rates of depression and suicide, and some researchers believe altitude may be playing a role here. Reporter Rae Ellen Bichell starts with an odd experiment.
RAE ELLEN BICHELL, BYLINE: Back in 1991, a crew of eight people stepped into a series of sealed glass rooms in Arizona. They didn't come out for two years and 20 minutes. One of them was Mark Nelson.
MARK NELSON: It was pretty radical experiment.
BICHELL: It was called Biosphere 2, and it was a privately funded experiment to recreate a mini version of our ecosystem.
NELSON: We fell in love with our world. Everything made sense in Biosphere 2.
BICHELL: Except there was a problem. As the months went by, the oxygen levels started dropping. A lot of it got trapped in the building's concrete. It got down to about 14%, which is about the oxygen availability you'd expect on top of a 13,000 foot mountain.
NELSON: You know, we kind of were like the lobsters in the pot.
BICHELL: But eventually, they started feeling pretty bad. They were low energy. Several developed sleep apnea. Three started talking to therapists on the phone. Finally, Mission Control injected a bunch of oxygen into the building.
GREENE: Suddenly, I found myself running and laughing and - party time.
BICHELL: There are a lot of obvious reasons that Nelson and his crew members' experience is not at all representative of the real world, from their specialized diet to the fact that this was a group of people that basically said sure, we'll live in a box for two years. But in terms of oxygen having real effects on their bodies, they might be a good example of something researchers think is happening across the Mountain West.
BRENT KIOUS: I think that's a totally appropriate example.
BICHELL: Brent Kious is a psychiatrist with the University of Utah. He's among a group of researchers who think that the lack of oxygen at altitude could actually be messing with people's mental health. The thinking goes something like this - the brain needs oxygen in order to function, and it needs more oxygen to do things like communicate between the parts of the brain that handle reasoning and emotion.
KIOUS: There are very close, very complicated connections between those parts. And we know from a lot of other studies that they're disrupted in many people with depression.
BICHELL: He says lack of oxygen could contribute to that in a few ways. Withholding energy from the reasoning part of our brains could affect the ability to regulate emotions. Or maybe it messes with serotonin production, also important for mood. Still, none of this is certain.
KIOUS: It is still a fairly controversial hypothesis.
BICHELL: It's controversial because depression and suicide are really complicated. Even if altitude does impact a person's suicide risk, it's probably only a little sliver of the picture.
EMMY BETZ: It's not going to be responsible for 100% of it.
BICHELL: Emmy Betz is an emergency physician and researcher at the University of Colorado School of Medicine. She also just wrapped up a stint on the Colorado Suicide Prevention Commission. She says it's really important to look at other factors.
BETZ: Things like access to firearms, access to behavioral health care, the sort of potential stigma in the society around asking for help.
BICHELL: Or the types of people who choose to live in often-remote areas. Betts took a closer look at the people who died by suicide at low and high altitude in 15 states, and she found that they were different in a lot of ways - from race and ethnicity to firearm use to the likelihood that they'd recently had some sort of crisis like losing their job.
BETZ: Suggesting that it wasn't just the altitude explaining the difference in suicide rates.
BICHELL: But a growing number of studies backup the idea that oxygen could be involved, like one in Peru on electrical workers. The ones stationed at about 10,000 feet had more symptoms of depression and anxiety than their sea-level colleagues. Or the study on a small group of Marines before, during and after a month of altitude training. They showed more symptoms of depression. So did medical students who moved higher up for residency.
Given all these pieces of information, there's something Emmy Betz and Brent Kious are very certain of - this is worth a much closer look. And who knows, maybe it'll reveal something about how to treat people with depression at whatever their altitude. For NPR News, I'm Rae Ellen Bichell.
GREENE: That story comes from the Mountain West News Bureau, a public radio collaboration. And let's remember; suicide can be prevented. If you are in crisis, call the National Suicide Prevention Lifeline at 1-800-273-TALK, or you can text TALK to 741741. Transcript provided by NPR, Copyright NPR.