Does Altitude Affect ADHD Risk?

In contrast to recent studies linking patients who reside in higher elevations with increased rates of depression and suicide, a new study suggests that the prevalence of attention-deficit hyperactivity disorder (ADHD) appears to decrease as altitude increases.

For the University of Utah-based study, researchers found that the average rate of diagnosed ADHD cases in the university’s home state—with an average elevation of 6,100 feet—was about 50% lower than the rate found in states at sea level. Diagnosed ADHD prevalence was about 38% lower in Salt Lake City, with an elevation of 4,300 feet, when compared with cities at sea level.

The study authors speculated that their finding may be the result of higher levels of dopamine produced in response to hypobaric hypoxia, which occurs when people breathe air with low oxygen levels at higher elevations. As decreased dopamine levels are associated with ADHD, it may be that when levels of dopamine increase with elevation, the risk for getting ADHD diminishes.

“Our previous studies of mood disorders and suicide consistently suggest that hypobaric hypoxia associated with altitude may serve as a kind of environmental stressor,” said senior author Douglas G. Kondo, MD, assistant professor of psychiatry, University of Utah. “But these results raise the question of whether, in the case of ADHD, altitude may be a protective factor.”

Data for the study came from information on average state elevations taken from NASA’s Shuttle Radar Topography Mission and the National Geospatial-Intelligence Agency, as well as data from two national health surveys. The 2007 National Survey of Children’s Health contacted nearly 92,000 households and found that more than 73,000 children aged 4 to 17 had been diagnosed with mild, moderate, or severed ADHD by a physician or other healthcare provider. The National Survey of Children with Special Healthcare Needs contacted more than 372,000 households in 2010 and found that more than 40,000 children in the same age range had been diagnosed with full ADHD.

With this data, the study investigators correlated the number of cases of diagnosed ADHD with average elevations in the continental United States to determine rates of ADHD. Then, they derived data on ADHD rates at sea level and above and found that the likelihood of being diagnosed with ADHD by a healthcare provider decreased by 0.001% for every 1-foot increase in elevation.

For example, North Carolina, with an average elevation of 869 feet above sea level, had the highest percentage of children diagnosed with ADHD (15.6%). Other states with average elevations below 1,000 feet above sea level (DE, LA, AL) followed closely behind North Carolina, with higher percentages of ADHD.

At the other end of the spectrum, Nevada, with an average elevation of 5,517 feet above sea level, had the lowest percentage of children diagnosed with ADHD (5.6%). All of the Mountain West states had percentages of children diagnosed with ADHD that were well below the average.

Whereas the study findings don’t mean that people who move to the mountains to avoid developing ADHD, they do have potential implications for treating the disorder, according to co-author Perry F. Renshaw, MD, PhD, MBA, professor of psychiatry, University of Utah.

“To treat ADHD, we very often give someone medication that increases dopamine,” said Renshaw. “Does this mean we should be increasing medications that target dopamine? Parents or patients might want to take this information to their healthcare providers to discuss it with them.”