A surprising connection between altitude and ADHD

Study: A surprising connection between altitude and ADHD

 

Who would have thought that children living at higher altitudes are at reduced risk for the development of ADHD? As the
research described below suggests, however, this may be the case.

 

The impetus for this study is the well-documented regional variation in the prevalence of ADHD in youth. For example,
national data for the years 2007-2009 indicate that ADHD prevalence rates were approximately 10% in the south and
midwest but only 5% in the western US. How can such substantial regional variation be explained?

 

The authors of a recently published study [Huber et al., (2016). Association between altitude and regional variation of
ADHD in youth. Journal of Attention Disorders] suggest that living at altitude reduces ADHD risk because diminished
oxygen levels present at high altitudes results in mild hypobaric hypoxia, i.e., less oxygen reaching the brain, which,
in turn, stimulates the production of dopamine. This hypothesis is plausible because youth with ADHD show decreased
dopamine activity relative to other youth, and stimulant medications used to treat ADHD increase brain dopamine
activity. Thus, if ADHD is associated with reduced dopamine activity, and living at high altitudes ‘naturally’ increases
brain dopamine levels, perhaps ADHD would be less common among youth living at higher elevations.

 

The authors examined the association between ADHD prevalence and altitude in 2 nationally representative data sets that
include tens of thousands of children; one data set was from 2007 and the second from 2010. The data sets include ADHD
diagnostic information so that the prevalence of ADHD in all 50 states could be calculated. The average altitude for
each state was calculated using data obtained from NASA.

 

If living at high altitudes protected against the development of ADHD, then ADHD rates should be lower in state with
higher altitude higher in states at lower altitude, i.e., there would be a negative correlation between states’ ADHD
prevalence rate and average altitude.

 

 

Results – This negative correlation is exactly what was found. In one sample, the correlation between average state
altitude and ADHD prevalence was -0.53; in the second sample, the correlation was -0.54. These results are remarkably
consistent and the magnitude of the association is impressive.

 

In a more fine-grained analysis, the researchers reexamined the link between altitude and ADHD prevalence after
controlling for other variables related to ADHD prevalence across states. These included the percent of youth in each
state from different racial/ethnic groups, the percent of low birth rate babies, the percent uninsured, the percent
living in a two-parent household, and the percent ever diagnosed with depression and anxiety.

 

After controlling for these factors, mean state altitude remained a significant predictor of ADHD prevalence rate.
Specifically, results indicated that for each additional foot in altitude, ADHD prevalence decreased by an average of
0.001%. While .001% is small, the average altitude rate across states is large, ranging from 60 feet above sea level in
Delaware to 6700 feet above sea level in Washington. Based on study results, that would lead to a predicted ADHD
prevalence rate in Delaware that is 6.6% higher than for Washington, a non-trivial difference.

 

 

Summary and implications – Because this is a correlational study, one cannot conclude with certainty that variations in
altitude play a causal role in the development of ADHD. However, in 2 large and nationally representative data sets, a
clear and consistent association between altitude and ADHD prevalence was evident. This association remained after
controlling for multiple other factors linked to variation in state-wide prevalence of ADHD and may help explain the
geographic variation in ADHD prevalence that has been reported. While this demonstrated link between ADHD risk and
altitude is surprising, there is also a plausible theoretical mechanism, i.e., living at higher altitude promotes
increases in dopamine activity, that may explain it.

 

This study adds to other work on how natural factors may play a role in the development of ADHD. For instance, several
years ago I reviewed a study in which a link between ADHD and exposure to sunlight was reported – you can find this
review at http://www.helpforadd.com/2013/may.htm

In other related research, exposure to natural outdoor environments has also reported to reduce ADHD symptoms – you can
find summaries of this work at http://www.helpforadd.com/2009/february.htm

 

Results such as these are surprising and interesting, and highlight the complexity of factors that may be involved in
the development and expression of ADHD symptoms.

 

Several aspects of the current work are important to keep in mind. First, the results highlight a potential linkage
between altitude and ADHD at the population level; while interesting to say the least, one can’t conclude from
population-level data that living at lower altitude causes the development of ADHD for any individual child. Instead,
variations in altitude may be one factor among many that modifies the risk of ADHD and additional work is needed both to
replicate the current findings and to better understand the mechanism by which altitude may modify ADHD risk.

 

Second, it is difficult to know what the practical implications of these findings may be. The authors speculate that
conducting summer camps for children with ADHD at high altitudes may help alleviate symptoms. They also suggest that
spending time in devices that mimic high altitudes by creating a hypobaric environment – and which have been shown to be
safe and effective in the training of endurance athletes – might be helpful for youth with ADHD. Theoretically, this
could be an alternative to stimulant drugs for increasing dopaminergic activity. This may be an interesting approach to
test, although even if benefits were found, one wonders what the duration would be.

 

Based on these findings alone, it would certainly be premature to suggest that moving to a high altitude state would
improve a child’s ADHD symptoms. However, the findings highlight the value of keeping an open mind in efforts to
understand the development of ADHD and the role natural environments may play in potentially alleviating it. Also
highlighted is the value of future research into the biological mechanism that is affected by altitude for individuals
with ADHD.

Copyright © 2020 by David Rabiner

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