Nature walks versus medication: A pre-registered randomized-controlled trial in children with Attention Deficit/Hyperactivity Disorder

Abstract

Recent epidemiological studies have found that exposure to nature during childhood can substantially reduce the risk of developing ADHD. In 2009, Taylor and Kuo presented a highly influential study that found walking in a natural environment can improve cognitive performance in children with ADHD, through a process known as attention restoration. Their effect size was large and comparable to those of pharmacological treatments, although no studies to date have attempted to replicate the effect in comparison with medication under experimental conditions. We present a pre-registered (ACTRN12616000125426), double-blinded (medication), randomized-controlled trial that compared the effects of acute exposure to a natural (versus built) environment and medication (versus placebo) on Attention Network Task performance. Participants (n = 24; m = 10.5 years) experienced four treatment combinations (natural environment + medication; natural environment + placebo; built environment + medication; built environment + placebo) across four sessions in randomized order. Linear mixed models revealed improvements in accuracy, response speed, and response stability related to medication use. In contrast to Taylor and Kuo's (2009) findings, no improvements were found after exposure to nature. Explanations of divergent outcomes between the two studies may lie within adjustments made to the original protocol. Discussions of these changes and their implications for restorative environment research offer important insights for future studies exploring environmental effects on children with ADHD.