Attention Research Update

February 2009

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

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


                          Support for Attention Research Update is provided by Cogmed

Cogmed has developed a computerized training program to improve working memory, which is a frequent problem for children and adults with ADHD.  Research has shown that Cogmed's program can enhance working memory, and that improvements in working memory are associated with reductions in attention and learning problems.  You can learn more at Cogmed.com. 

Clinicians interested in learning about the benefits of incorporating working memory training into their practice are invited to request an information package for professionals.

Can a walk in the park help children with ADHD?

Can contact with nature enhance attentional functioning in children with ADHD?

The notion that exposure to nature might improve attention problems in children is based on Attention Restoration Theory - ART.  According to this theory, humans have two types of attention: voluntary attention (also known as directed attention); and involuntary attention.  Voluntary attention is the form of attention employed when we engage in tasks that require are not inherently easy to attend to. After prolonged and intense use, voluntary attention becomes fatigued.

Involuntary attention, in contrast, does not require conscious effort -- think of settings or activities in which remaining focused and attentive seems to happen naturally and without any deliberate effort.  According to ART, exposure to natural environments can help the voluntary attention system recover when it has become fatigued, in part it draws on involuntary attention thus allowing the mechanism underlying directed attention to rest and rejuvenate. 

These ideas led to several studies testing whether children's attention deficit symptoms would be more manageable after exposure to natural settings. The first was an interview study conducted with parents of 96 children diagnosed with ADHD. Parents were presented with a list of different activities that occurred in indoor activities, in man-made outdoor settings, and in natural outdoor settings.  Parents rated each activity in terms of how well their child seemed able to attend after participating in the activity.. Results indicated that children's ability to attend was rated as significantly improved after activities that occurred in green spaces.  You can read a full review of this study at www.helpforadd.com/2002/july.htm

The second study was a larger survey conducted with 452 parents of children diagnosed with ADHD. Similar to the initial study, parents rated 49 common after-school and weekend activities in terms of whether it made their child's inattentive 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. 

Activities were described as occurring in 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, a neighborhood space that doesn't have much greenery), or indoor settings. Once again, children's ADHD symptoms were rated as significantly improved after participating in green outdoor activities compared to activities.  You can read the full review of this study at www.helpforadd.com/2004/september.htm

While these studies yielded interesting and provocative findings, the absence of a true experimental design - including an appropriate control group - prevented strong conclusions about the impact of nature on children's ADHD symptoms from being made.  The goal in the study reported below [Taylor and Kuo (2008). Children with attention deficits concentrate better after walk in the park. Journal of Attention Disorders] was thus to test the impact of exposure to nature on children with ADHD in a controlled experimental investigation.

Participants were 12 children 7 to 12 years old with a confirmed diagnosis of ADHD (15 boys and 2 girls).  The basic design was to expose children to 3 different types of environments - an urban park, a downtown area, and a residential area - and to test their attention/concentration following this exposure.  The prediction was that children would show enhanced attention/concentration following exposure to nature.

Each child was taken on a roughly 20-minute walk through each of the 3 settings.  These walks occurred on separate days and the order was counterbalanced so that the walk in each type of occurred in the first, second, and third position an equal number of times.  Children receiving medication treatment did not receive medicine on these days until after the walk and attentional testing was completed. 

Children completed puzzles before each walk in order to ensure some degree of attentional fatigue.  The child and his/her guide were then driven to their assigned setting and walked a routed designed to be completed at a relaxed pace in about 20 minutes.

After the walk, children were returned to a quiet, indoor facility where the child was tested.  The primary test was Digit Span Backwards, a widely used measure of concentration that is sensitive to deficits in attention and working memory.  The test involves listening to a span of digits and then repeating them back in reverse order.  Following a correct response the next sequence increases by one digit; the child continues until two consecutive trials are failed.  The longest span of digits successfully reversed is the child's score.

Because children were tested after walking in all 3 settings, each child served as his/her own control.  This type of study design, referred to as a 'within subjects design', provides an excellent method for comparing the impact of different 'treatments' on subsequent performance.  In this case, the researchers examined whether the number of digits children recalled after the nature walk was higher than the number recalled after walking in the other two settings.

- Results -

As predicted, children recalled a significantly greater number of digits on the Digit Span Backwards Test after walking in the natural setting.  On average, they recalled roughly two-thirds of digit more than after walking in the downtown or residential area.  While this may not seem like a lot, the authors note that the magnitude is similar to that reported in two studies testing the impact of stimulant medication on Digit Span Backwards in children with ADHD.  They also note that the difference is similar to what is typically found between children with and without ADHD.  In addition to performing better afterwards, children reported enjoying the walk in nature significantly more than the other two settings.

- Summary and Implications -

In this carefully controlled experimental study, a 20-minute walk in nature produced significant gains in children's performance on a standardized test of attention/concentration.  In fact, the gains were comparable to those associated with stimulant medication treatment. These findings thus reinforce and extend results from previous interview studies by providing experimental support for these earlier results.  Collectively, these findings make a compelling case that exposure to nature can yield at least temporary benefits for children with ADHD.

Is exposure to nature a potential treatment for ADHD?  The authors are appropriately careful when discussing this issue.  They note that they have not yet examined whether benefits also occur for hyperactive-impulsive symptoms, the other common feature of ADHD.  They also note that they have not yet tested whether exposure to nature is associated with gains in children's academic performance.

Finally, and this is especially important, they emphasize that they examined the effects on attention only immediately after exposure to natural environments.  Thus, they emphasize that their study provides "...no objective performance data showing that the effects of nature doses last long enough to be of practical use in managing ADHD symptoms."

While recognizing this important limitation, the authors also argue that testing whether "doses" of nature can help treat ADHD deserves prompt attention.  Unlike other existing treatments, "...spending time in relatively natural outdoor areas does not entail any unusual risks or negative side effects, nor is there any social stigma associated with spending time outdoors."  One can imagine that schools could be designed to help children benefit from exposure to nature were those benefits to be conclusively documented in studies that build on the current work.  Also, given that exposure to natural settings is suggested to enhance attention by allowing the directed attention system to 'rest and rejuvenate', it seems that there should be other ways to accomplish this that could be more easily incorporated into the school day.

In conclusion, while it is premature to conclude that exposure to nature can be a useful treatment for ADHD, the work of these researchers has raised an intriguing area to pursue.  Let's hope that a follow-up study addressing some of the limitations associated with the current work will be available for review in the not too distance future.

Thanks again to Cogmed for supporting this issue of Attention Research Update

(c) 2009 David Rabiner, Ph.D.

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.