The thin air of America's higher-elevation regions may reduce the risk of attention-deficit/hyperactivity disorder (ADHD), a new study suggests.
ADHD decreases with altitude
Researchers reported that the occurrence of ADHD decreases substantially as altitude increases. For example, Utah has an average state elevation of 6,100 feet. That state's ADHD rate is half that of states at sea level, they said.
It's important to note though that the current study's design can only show a link between altitude and a lower incidence of ADHD. It can't prove a cause-and-effect relationship.
Still, the researchers suspect that brain chemistry may be affected by the lower oxygen levels at higher elevations.
In particular, levels of dopamine – one of the brain's chemical messengers (neurotransmitters) – increase as someone adapts to oxygen-depleted air, said Dr. Douglas Kondo, a child psychiatrist and brain imaging researcher at the University of Utah's Brain Institute and University Neuropsychiatric Institute.
One of dopamine's jobs is to help regulate emotional responses. Previous research has associated lower levels of the hormone with ADHD, Kondo said. Most drugs used to treat ADHD work through the dopamine system.
Read: Causes of ADHD
Kondo and his colleagues have theorized that as dopamine levels increase with elevation, the risk for developing ADHD diminishes.
"The idea is that if your symptoms are on the borderline of clinical ADHD – it's affecting your family life and your academic life – the effects of high altitude are beneficial," Kondo said.
So, should parents in low-lying states pack up their ADHD kids and set out for a Rocky Mountain high? Not necessarily, Kondo added.
"That kind of very life-changing clinical recommendation, we're not there yet," he said. "We're just asking the question at this point."
Visits to higher altitudes not advised
Kondo doesn't even recommend visiting places like Utah or Nevada solely to see whether the high altitude can positively affect an ADHD kid.
Just the novelty of being in the mountains or being on vacation, along with the additional physical activity involved, likely would improve a child's symptoms, he said.
The research was published online in the Journal of Attention Disorders.
For the study, the research team relied on elevation data gathered during a NASA space shuttle mission. This mission created a highly detailed topographical map of the 48 contiguous United States.
The investigators then paired that with data on ADHD collected during two surveys conducted by the U.S. Centres for Disease Control and Prevention.
Read: Treating ADHD
Researchers found that for every 1-foot increase in elevation, the likelihood of being diagnosed with ADHD by a health care provider decreased by 0.001 percent.
North Carolina, with an average elevation of 869 feet above sea level, had the highest percentage of children diagnosed with ADHD – nearly 16 percent.
Delaware, Louisiana and Alabama, all states with an average elevation of less than 1,000 feet, followed closely behind North Carolina with high percentages of ADHD.
Nevada has an average elevation of more than 5,500 feet above sea level, and the lowest percentage of ADHD children at less than 6 percent. Utah also had one of the lowest rates of ADHD, at less than 7 percent, the findings showed.
All of the western mountain states rated well below average for the percentage of children diagnosed with ADHD.
That was true even after the researchers adjusted the data to control for other factors that could affect ADHD risk, such as birth weight, ethnic background and gender.
Interesting and provocative
Mark Stein, a clinical paediatric psychologist at Seattle Children's Hospital, called the findings "very interesting and provocative".
"A clear implication is that youth with ADHD should be encouraged to participate in outdoor activities, including higher altitude ones if available and safe, as opposed to sedentary activities. More summer treatment programmes and physical exercise," Stein suggested.
Stein agreed that dopamine provides the most likely explanation for the altitude effect. He said that the neurotransmitter "is associated with many of the symptoms of ADHD, including motivation, activity level and self-control".
Read: Symptoms of ADHD
Kondo pointed out that an altitude change may not be the panacea parents are wishing for. The same altitude that benefits ADHD kids with a dopamine surge also has been shown to increase levels of depression and suicide in people, Kondo said, possibly by affecting levels of the neurotransmitter serotonin. Families might wind up trading one emotional problem for another.
"We know that in animal models, if you subject experimental lab animals to simulated altitude, their serotonin levels in the brain go down, which might account for increased depression at altitude," he said.
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