As we reported on Friday, a small, 17-person study published by researchers from the University of Illinois suggested they had the perfect treatment for kids with attention deficit disorder (ADHD) — a walk in the park.
We’re all for the most natural, simple treatments available. And this one really sounded good! What could be better than telling parents, “Hey, take your kid for a walk in the park and your child’s ADHD will be less severe.”
So why does this study make us hold our noses?
Besides the small sample size (which should raise warning bells for anyone who thinks this could apply to everyone), the other red warning flag to me was the use of the Digit Span Backwards test as the sole measure for the subjects. Why would the researchers choose this measure when there are perfectly good and well-accepted ADHD research measures available?
Good question, so let’s find out.
I first looked into the literature of the use of the Digit Span Backwards (DSB) test, because while I’m familiar with it, I never heard of it being used as the sole type of measure for severity of ADHD. It is most commonly used to assess neurological or cognitive deficits in people with neurological or cognitive problems (such as people with dyslexia, brain damage, alcohol drinking, dementia, and so forth). It’s also used to test memory performance under a wide range of conditions (such as testing, traumatic brain injury, long-term depression, etc.). In 90 citations I reviewed in PsycINFO, only 9 were found where this measure was used in connection with ADHD or with attention issues in children. Another 9 were found (some duplicates) when I also reviewed the citations the researchers referred to in their study.
In using Digit Span Backwards as a measure to test the performance of ADHD, one study found no deficit for the 26 children in the study (O’Donnell, 2005). This was after the recommendation cited (Hale, Hoeppner, & Fiorello, 2002) by the University of Illinois researchers was published, suggesting that the findings from the older study might not be robust enough to replicate for a small study (especially where sensitivity would be important). Other studies found a significant effect for only one type of ADHD — the combined type not the inattentive type. These differences and issues are largely glossed over by the current researchers.
Here’s the real kicker, however, left out of every media report published on the study:
Three other measures were administered after DSB: the Stroop Color-Word Test (Dodrill, 1978), Symbol
Digit Modalities (SDM) (Smith, 1968), and the Vigilance Task of the Gordon Diagnostic System Model 111-R (VT) (Gordon, McClure, & Aylward, 1996). Although all four measures have been widely used to test attention and impulse control in ADHD and other populations in between subjects designs, Stroop displayed practice effects (demonstrated in a repeated measures ANOVA comparing scores by session number) F(2,17) = 16.90, p < .0001, and Stroop, SDM, and VT displayed low power (power = .05, .28, and.07, respectively, in repeated measures ANOVAs comparing scores by condition). Thus, these measures are not further described here.
So the researchers had to throw out 3 of the 4 measures they were using to measure their results. This was after the study was completed because 8 of the original 25 subjects were dropped from the study (for reasons of non-compliance, errors in following directions or simply not completing the study — do any of these things sound familiar?). So you’re already starting off with a drop-out rate of 32%, meaning this technique will be useless in 1 out of 3 children it’s tried on. But then you add the insult of dropping 75% of the measures you were using and are left with a single remaining measure that has only 0.75 power and isn’t commonly used as a sole treatment measure for ADHD?
So How Helpful is a Walk in the Park on One Single Measure of Attention?
And what’s the difference between the two groups?
The effect of the park exposure on DSB performance was substantial. Expressed in terms of digit span, DSB performance was roughly six-tenths of a digit better after the park exposure than after the downtown exposure. [emphasis added]
That’s about one-half of one digit. This is “significant”? Maybe statistically, but I have serious doubts whether this translates into any actual clinical significance — e.g., made a difference in the child’s or parent’s life. We’d know if it did had the researchers included any parental rating measures in the study, but alas, they chose not to.
By the way, as an interesting aside, out of the 9 studies the researchers note in Table 1 that studied attention with the DBS, 2 of them (22%) found a negative difference in mean scores. Meaning that kids with ADHD actually scored better on the DBS than the non-ADHD control groups. Not exactly a sign of a stable and reliable measure, no? (For reference, I don’t know of any standard ADHD rating scale that has demonstrated a similar kind of effect.)
I guess what I’m saying is that if you’re going to claim a new treatment is better than some other treatment for ADHD, why not use industry-standard measures so we can truly compare apples to apples? We have at least a half-dozen standardized and normed research rating scales for ADHD, including the ADHD SRS, the Connors CPRS-R:S and the ADHD Rating Scale-IV, among others.
If a study has gone badly, the reasonable thing to do is to go back and redo it. I know that takes time, money and resources, but it’s the right thing to do. Or, at the very least, don’t make broad generalizations about your findings based upon such a tiny dataset and weak measures used:
Taken together, the findings from this study and the previous large-scale survey studies suggest that not only does exposure to nature enhance attention in children with ADHD, but also that this effect holds for a wide variety of children, settings, and activities.
Sorry, I don’t agree with that conclusion based upon this study. While it has provided a smidgen more data in this area, it’s not enough to draw any conclusions yet about these issues.
I can’t imagine a walk in the park harming any child, but at the same time, I don’t see that it’s likely to make much of a significant difference in the life of a child with attention deficit disorder.
Read the news article: Walk in the Park May Help Kids with ADHD
Read the Furious Seasons entry: Study: Nature Helps ADHD Kids Concentrate
Hale, J. B., Hoeppner, J. B., & Fiorello, C. A. (2002). Analyzing digit span components for assessment of attention processes. Journal of Psychoeducational Assessment, 20, 128-143.
O’Donnell, L. (2005). Cognitive and memory performance patterns associated with ADHD subtypes. Dissertation Abstracts International: Section B: The Sciences and Engineering, 65(9-B), 4843.
Talor, A.F. & Kuo, F.E. (2008). Children With Attention Deficits Concentrate Better After Walk in the Park. Journal of Attention Disorders 2008, doi:10.1177/1087054708323000.