- In a 2010 study published in High Altitude Medicine and Biology, the Case Western group analyzed suicide rates across 2,584 counties in 16 states and found that suicides start increasing between 2,000 and 3,000 feet in all U.S. regions. The U.S. isn't a special case — analysis of suicide rates in other countries, including South Korea and Austria, bore similar results.
- So why do some people enjoy the benefits of the Utah air's impact on increased dopamine levels, which should make us happier, and some fall victim to the impact on decreased levels of serotonin, which would make us more depressed?
The answer lies in how changes in neurotransmitter levels affect our individual brain chemistry.
As Renshaw's theory goes, serotonin deficiency exacerbates symptoms of pre-existing anxiety and depression, increasing the likelihood of becoming suicidal (mental illness is a factor in about 90% of suicides). People with an existing mood disorder, or a predisposition to mental illness, would be more sensitive to the effects of waning serotonin levels.