Attention Research Update

September 2004

"Helping parents, professionals and educators stay informed about new research on ADHD"

David Rabiner, Ph.D.  Senior Research Scientist, Duke University



CAN EXPOSURE TO NATURE REDUCE CHIDLREN'S SYMPTOMS OF ADHD?

Is it possible that increasing children's time spent in natural green settings could be an effective method for diminishing ADHD symptoms?

This question was addressed in a study published in a recent issue of the American Journal of Public Health (Kuo, F.E., & Faber Taylor, A. (2004). A potential natural treatment for ADHD: Evidence from a national study. AJPH, 94, 1580-1586).

This provocative study is based upon research conducted with non-ADHD populations in which it has been shown that inattention and impulsivity are reduced after exposure to natural views and settings.  An explanation for this finding proposed by environmental psychologists is that tasks and situations that require one to direct attention or inhibit unwanted stimuli, thoughts, or impulses cause the attention system to fatigue.

Natural environments are suggested to assist in the recovery from "attention fatigue", in part, because they "engage the mind effortlessly, providing a respite from having to deliberately direct attention."  This may explain the feelings of freshness and rejuvenation that is commonly experienced after one spends times in natural settings.

The authors of this study reasoned that if exposure to natural settings enhances attention and focus in those without ADHD, it could potentially play a role in diminishing inattentive behavior in children with ADHD.  They cite preliminary work (reviewed in Attention Research Update at www.helpforadd.com/2002/july.htm ) in which 96 parents rated a variety of leisure activities  with respect to whether their child's ADHD symptoms were "better than", "worse than", or the "same as usual" after engaging in those activities.  Results indicated that symptoms were better than usual (i.e., less problematic) after the child engaged in activities in relatively green settings. 


RESEARCH DESIGN

The current study built on this prior work by collecting data from a large, national sample using a web-based survey.  Participants were 452 parents of children ages 5 to 18 who were recruited through ads in national newspapers and a posting on the CHADD website.  (CHADD is the national support organization for children and adults with ADHD).  These parents represented approximately 60% of those who visited the survey site, and who met the eligibility criteria to participate (i.e., the child had been formally diagnosed with ADHD by a physician, psychologist, or psychiatrist).  The parents who participated were diverse in terms of their socioeconomic status, age of their child, community type they lived in, and region of the country they were from.  The severity of their children's ADHD symptoms was also diverse, and both males (80%) and females (20%) were represented.

In the survey, parents rated 49 common after-school and weekend activities in terms of whether it made their child's symptoms "much worse than usual", "worse than usual", "same as usual", "better than usual", or "much better than usual" for an hour or so after the activity ended.  The symptoms that parents were asked about were:

  • Difficulty remaining focused on unappealing tasks;
  • Difficulty completing tasks;
  • Difficulty in listening and following directions;
  • Difficulty in resisting distractions;
Activities were described as occurring in either green outdoor settings (i.e., any mostly natural area - a park, a farm, or just a green backyard of neighborhood space), "built" outdoor settings (i.e., mostly human made space - parking lots, downtown areas, or just a neighborhood space that doesn't have much greenery) or indoor settings.  The after effects of several activities were rated when they occurred in different settings.  For example, "reading" could take place indoors, in a relatively green outdoor setting, or in a built outdoor setting.

Parents knew nothing about the purpose of the study.  Thus, their ratings are unlikely to have been biased by the knowledge that the authors were interested in documenting that spending time in natural settings is associated with a reduction in children's ADHD symptoms. 


RESULTS

The authors examined the aftereffects of activities conducted in green settings with those occurring in built or indoor settings.  The analysis controlled for children's gender, income, and severity of ADHD symptoms.  The authors also controlled for whether children lived in rural vs. urban settings.

For the sample as a whole, parents' ratings indicated that children's ADHD symptoms were significantly better (i.e., less problematic) after participating in green outdoor activities compared to activities that occurred indoors, or in build outdoor spaces.  This pattern of results was found for virtually all subgroups the authors examined (i.e., boys vs. girls, older vs. younger children, higher vs. lower income families, etc.).  It was also evident regardless of which region of the country children were from and whether they lived in rural or urban environments.

One possible explanation for the apparent superiority of "green" activities in reducing ADHD symptoms may be the nature of the activities themselves.  That is, activities that occur in natural settings may systematically differ from those that occur in other settings, and it may be the type of activity rather than where it takes place that accounts for the findings reported above.

To examine this possibility, the authors examined differences in parent ratings for activities that occurred in both green and other settings.  Results from this supplemental analysis indicated that even when the activities were identical, they were associated with greater reduction in attention problems when they took place in green settings. 


SUMMARY AND IMPLICATIONS


Results from this study suggest that exposure to ordinary natural settings in the course of common after-school and weekend activities may be helpful in reducing attention difficulties in children with ADHD.  This advantage of green outdoor activities over activities conducted in other settings was consistent for children across a wide range of individual and residential characteristics, and was found even when the activities conducted in different settings were highly similar.  This suggests that the benefits of green outdoor activities cannot be wholly attributed to differences in the activities themselves.

Because the "green" advantage was found among children living in diverse communities in different parts of the country, it seemed to hold despite what must have been wide variation in the specific "green outdoor", "built outdoor", and "indoor" settings available to different children.  In addition, because the "green" advantage was also found for children living in rural environments, where exposure to nature is plentiful, the apparent benefits of green spaces are unlikely to simply reflect the relative novelty of such spaces for children raised in urban environments.  According to the authors, the findings are thus consistent with the hypothesized restorative effect that exposure to natural settings can have on our ability to focus and attend.

The authors are cautious to note that their findings need to be supported with additional research and randomized controlled trials in which the impact of exposure to green settings can be more carefully evaluated.  For example, it would be important to document via methods other than parent report that exposure to natural settings is associated with a reduction in attention problems following the activity.  In particular, gathering information from teachers about whether outdoor time in natural settings improves children's attention in the classroom would be especially interesting data. Similarly, does exposure to green settings result in children being better able to work productively and accurately on school assignments?  This is a very important avenue to pursue, as it is the classroom where many children with ADHD experience their most profound struggles.

In regards to the need for additional controlled research, it is worth noting that the authors discuss an as yet unpublished study that appears to provide further support for the benefits that exposure to green settings may have on children with ADHD.  In this study, children with ADHD completed three guided walks that differed in the extent to which natural or urban elements predominated.  The 20-minute walks were counterbalanced for order, and controlled for time of day, day of week, walking guide, and walking pace.  Routes were chosen to involve roughly comparable amounts of noise and pedestrian density.  After each walk, an evaluator unaware of which walk the child had just completed administered several objective measures of attention.  Children's performance on these measures was said to significantly better after walking in the greenest setting than in the other settings.  The summary of this study sounds promising, although it will be necessary to carefully review the paper - once it is published - so that the meaning of the results can be better understood.

Should these provocative findings hold up in future research, particularly in studies that examine the impact of exposure to natural settings on classroom behavior, what might be the implications?  The authors suggest that "daily doses" of green time could potentially supplement medication and behavioral approaches to treating ADHD. These "doses" could take several forms, including doing class work or homework at a window with a relatively green view, or playing in a green yard or ball field at recess and after school.  Of course, even if this were shown to be helpful, there would be many children  - those living in densely populated urban settings - where exposure to natural environments during the day may just not be practical.  For these children, one wonders whether watching videos of natural landscapes could serve a similar function.

Although more work remains to be done, it is encouraging to see that rigorous scientific work on such a novel approach to assisting children with ADHD is being conducted.  In my view,  it is too early to know whether exposure to natural settings will provide clinically meaningful benefits to children with ADHD.  However, because this is certainly an inexpensive intervention that is unlikely to have any adverse effects, it would be reasonable for parents to see whether they notice any benefits for their child, and the authors have certainly opened up an exciting new line of research.


Information presented in Attention Research Update is for informational purposes only, and is not a substitute for professional medical advice.  Although newsletter sponsors offer products and services that I believe will be of interest to subscribers, sponsorship of Attention Research Update does not constitute a specific endorsement or guarantee of any company's product or services.