WEDNESDAY, Jan. 19 (HealthDay News) -- Across the United States,
suicide risk appears to be significantly higher among people who
live in higher altitudes, new research suggests.
The latest observation seems to confirm the findings of previous
research that unearthed a complex and as-yet not fully explained
relationship between higher than average suicide rates and
residency in higher elevations.
"Once you get to somewhere between 2,000 and 3,000 feet, you start seeing the suicide rates increase," explained study author Dr. Barry E. Brenner, a professor of emergency medicine and internal medicine, as well as program director, in the department of emergency medicine at University Hospital Case Medical Center in Cleveland. "The correlation is very, very, very high, and it happens in every single region of the U.S."
"And yet as you go up in altitude the overall death rate, or all-cause mortality, actually decreases," Brenner noted. "So, the fact that suicide rates are increasing at the same time is a really significant and really striking finding."
Brenner and his colleagues discuss their results in the Jan. 18
online issue of
High Altitude Medicine & Biology.
The authors noted that data collected earlier this decade
indicates that, globally, suicide is the 14th most common cause of
death, amounting to 1.5 million fatalities every year.
Brenner's new evidence of a linkage between suicides and high
altitudes stem from an analysis of two decades worth of mortality
data (1979-1998) obtained from the U.S. Centers for Disease Control
The CDC figures covered deaths that occurred in all 2,584
counties across the United States in that timeframe. At the same
time, the authors obtained countywide elevation statistics from the
U.S. Geologic Survey.
The research team determined that over the course of the 20-year
period, suicides accounted for 1.4 percent of all American deaths,
with an average county-wide suicide rate of 14 out of every 100,000
Even after adjusting for traditional risk factors such as age,
race, household income, population density, and gender, the authors
found that suicide rates (whether involving a firearm or not) were
significantly higher than average in those counties with higher
Even after adjusting for greater isolation, lower income and
greater access to firearms, the findings remained statistically
significant, the authors said.
In contrast, those same locales defined by relatively high
not home to the highest rates of death due to any and all
causes. In fact, higher altitude counties actually registered lower
than average death rates due to all causes.
This latter finding actually highlighted the strength of the
apparent connection between suicide risk and high altitudes, the
research team said.
For the time being, Brenner and his colleagues cautioned that
attempts to explain the association are "speculative."
"It may be related to obesity levels and sleep apnea that may be more common in higher altitudes," Brenner suggested. He and his colleagues also noted that hypoxia -- inadequate oxygen supply to the body's cells and tissues -- is more common at high altitudes, and is thought to increase mood disturbances, especially among emotionally unstable patients.
"It could be that hypoxic environments may lead to higher levels of depression or higher tendencies among the depressed to take suicidal action," he said. "It's an area that is rife for further investigation."
Meanwhile, the research team suggested that their findings might
help draw attention to residents of higher elevations who could
benefit from relocation to lower altitudes and/or suicide
monitoring and prevention services.
Last fall, Dr. Perry F. Renshaw, a professor of psychiatry at
the Utah School of Medicine and an investigator with the Utah
Science Technology and Research (USTAR) initiative, led a similar
study that reported a correlation between high altitudes and higher
His work -- published in the
American Journal of Psychiatry -- also crunched 20 years'
worth of data provided by the CDC. That effort revealed that nine
states in the so-called "Intermountain West" region of the country
(Montana, Idaho, Wyoming, Utah, Colorado, Nevada, New Mexico,
Arizona and Oregon) all ranked among the top 10 states in the
nation in terms of suicide rates.
Noting that these states have some of the highest altitudes in
the country, Renshaw's analysis concluded that high altitude seems
to be an independent risk factor for suicide, particularly among
people already prone to depression and mood disorders.
"So my take on this new study is that it's wonderful that independently of each other we got to the same point," Renshaw said. "Because within the suicidology world, we are always concerned that we are missing something, or that this isn't relevant. But here, this group is probably even more methodologically sophisticated than we are, so the fact that we did much the same thing and they have replicated our finding is a very good thing."
"I'm also not surprised that they found that suicide rates differ from the overall mortality experience in high altitude places," he added. "Because many people do seem to adapt quite well to living in a higher altitude, and there's something about committing suicide that's clearly very different from mortality risk."
"But for those people with pre-disposing factors to suicide, like depression and emotional distress, there really appears to be something quite pernicious about living at a higher altitude," he concluded. "And this confirming finding puts us all in a better position to further explore the subject and get a better understanding of what's going on."
The U.S. Centers for Disease Control and Prevention has more on