September 18, 2010
Higher Altitute Increases Suicide Risk?
Move downhill if you are thinking of offing yourself.
SALT LAKE CITY—The Intermountain West is renowned for the beauty of its towering mountains and high deserts, but according to new research from an investigator with the University of Utah Brain Institute the region's lofty altitudes significantly influence a deadly problem: the high prevalence of suicides in this part of the country.
In the Sept. 15, 2010, online edition of the American Journal of Psychiatry, Perry F. Renshaw, M.D., Ph.D., MBA, professor of psychiatry at the U School of Medicine and an investigator with Utah Science Technology and Research (USTAR) initiative, and colleagues report that the risk for suicide increases by nearly one-third at an altitude of 2,000 meters, or approximately 6,500 feet above sea level.
In the United States the Western states have the highest suicide rates. What's with Alaska? Vitamin D deficiency? Or just the bitter cold?
In 2006, the latest year for which national data was available, Montana, Idaho, Wyoming, Utah, Colorado, Nevada, New Mexico, Arizona, and Oregon accounted for nine of the 10 highest suicide rates in the country. Alaska also was in the top 10 in suicide rates.
The researchers analyzed data at the level of individual counties to reach their conclusion.
After analyzing data from a U.S. Centers for Disease Control and Prevention (CDC) database with information on 3,108 counties in the lower 48 states and District of Columbia, Renshaw and his colleagues from the University of Utah Brain Institute, Veteran Affairs Salt Lake City Health System, and Case Western Reserve University concluded that altitude is an independent risk factor for suicide, and that "this association may have arisen from the effects of metabolic stress associated with mild hypoxia (inadequate oxygen intake)" in people with mood disorders. In other words, people with problems such as depression might be at greater risk for suicide if they live at higher altitudes.
What I want to know: Does high altitude living also correlate with earlier onset of dementia or Alzheimer's Disease? Mild hypoxia has got to be bad for you.
What I also want to know: Does the link between altitude and suicide risk become greater with age as lung capacity declines? More hypoxia in old age and hence more suicide?
The pattern holds for South Korea as well.
To verify the study conclusions, Namkug Kim, Ph.D., the study's first author and a former post-doctoral fellow under Renshaw, conducted a similar data study in South Korea and found that the suicide rate in areas at 2,000 meters increased by 125 percent in that country.
The pattern might break down for Tibetans and other populations that are genetically adapted to high altitude living.
A likely example of reversed cause and effect. This longtime resident of the intermountain West suspects that people who are poorly socialized move to places where there are fewer people, which would include places with less air (the mountains) or water (the desert). Not mentioned is whether Renshaw noticed high suicide rates in low altitude sparsely populated desert counties. Another confounding factor would be higher concentrations of American Indians at > 2000 m.
The bit about "mild hypoxia" suggests Renshaw et al. don't know much about high altitude physiology. The difference in blood O2 saturation between 0 m and 2000 m is hard to measure after one is acclimated, and is compensated by an increase in red blood cell count. There is a chronic mountain sickness (Munge's disease) but that really doesn't kick in until > 3000 m and is rare in the US. It is probably caused not by hypoxia but by increased blood viscosity caused by higher RBC count.
I'm sympathetic to Hugh Jass's suggestion. I would add that these are also states that saw many immigrants moving in from California over the past 10-15 years. That's bound to increase the level of mental illness anywhere. Would be interesting to see if these correlated in fact with new arrivals or not.
IIRC total life expectancy is higher in cities like Denver. I would not be surprised if higher altitude reduces free-radical damage from oxygen. If it affects some people's mood negatively, there are many solutions (including technical ones, like breathing enriched air).
Surprisingly, there are no settlements in Alaska at high elevations, due to intense winter conditions. the population is mostly at sea level in Anchorage, the coastal towns in southeast, Kodiak, Dutch Harbor, etc. most Native villages are either on the seacoast or the lower stretches of major rivers. the only settlement of Native away from the water is the Inupiat village at Anuktuvuk Pass, which is about 2,000 feet elevation in a major pass through the Brooks Range. I think the high suicide level in Alaska is linked to Native population [about 15% of the total] and high levels of socially unattached whites. drug and alcohol abuse rates are quite high in all racial groups, with Native leading the way.
There is not enough information given for any reader to decide if these conclusions are statistically significant or not. The numbers are small enough that small variances could overwhelm any conclusions, nor are standard deviations//statistical conclusions provided. Known suicide contributing confounding factors like average cloud cover per year are not mentioned and may not have been considered.
Judging from the mention of how they determined "average" elevation rings my bullcrap alarm. People do not live at "average" elevation. It is not a difficult task to determine the actual weighted average elevation of populations within a reasonable accuracy, although it would take some effort.
These kinds of correlations cast as causes are almost always suspect. Just look at CO2 and global warming as another example of inference gone wild. LOL
> This longtime resident of the intermountain West suspects that people who are poorly socialized move to places where there are fewer people, which would include places with less air (the mountains) or water (the desert).
I agree. One place with fewer people, less rules, more distracting dreams and visions is the American west itself, in general. It's not hard to imagine 4% of happy easterners moving west between year x and year y, and 5% of dysthymic easterners doing so. To be sure, there are listless dysthymics who would be less likely to go than normals, but there are also many restless dysthymics. The restless type might be more likely to sign off before their natural span. Or a lot of people destined for major depression might have an restless prodrome first. Or gun owners might be slightly more likely to sign off even if they are otherwise identical to others.
Or it could be any other of dozens of prima facie plausible things, or combinations thereof.
I'm not sure how often RP has taken one of these vaunted new papers (or five or six of em that he has posted years back) and traced out what happens to the thesis as it runs the gauntlet of replication attempts. I suspect he would be frustrated and no longer flock to these alleged pearls of wisdom with the same intensity. Probably the majority of papers on minute advances in molecular bio are true. Cell bio, little less so. But some entire fields with hundreds of papers have been meaningfully accused of being completely fallacious. Epidemiology strikes me as an awfully soft and squishy field where you can't do randomized controlled interventions very easily, without epistemologically troubling drop-out rates. Best you can often do is regressions. I haven't read many of em, but I would suspect that most new epidemiology papers are false, probably 80% of them or more, in terms of the most favored one or two interpretations of the data they offer (though somewhat fewer would have false data to start with). That's a bit of a guesstimate considering my small reading in the particular field, but I have read maybe 25,000 disease biology abstracts and a lot of papers.