Acute Effects of Aerobic Exercise on Executive Function and Attention in Adult Patients With ADHD

Abstract

Aerobic exercise can improve cognitive functions in healthy individuals and in various clinical groups, which might be particularly relevant for patients with ADHD. This study investigated the effects of a single bout of aerobic exercise on attention and executive functions in adult patients with ADHD, including functional MRI to examine the underlying neural mechanisms. On two different days, 23 adult patients with ADHD and 23 matched healthy controls performed in a flanker task, while functional MR images were collected, following 30 min of continuous stationary cycling with moderate intensity as well as after a control condition (watching a movie). Behavioral performance and brain activation were tested for differences between groups and conditions and for interactions to investigate whether exercise improves executive function to a greater extent in patients compared to healthy controls. Exercise significantly improved reaction times in congruent and incongruent trials of the flanker task in patients with ADHD but not in healthy controls. We found no changes in brain activation between the two conditions for either group. However, a subgroup analysis of ADHD patients with a higher degree of cardiorespiratory fitness revealed decreased activation in premotor areas during congruent trials and in premotor and medial frontal cortex during incongruent trials in the exercise compared to the control condition. Our results indicate exercise-induced improvements in attention and processing speed in patients with ADHD, demonstrating that adult patients with ADHD may benefit from an acute bout of exercise. These findings could be of high relevance for developing alternative treatment approaches for ADHD. In addition, results of the current study contribute to elucidate the neurophysiological mechanisms underlying the beneficial effects of exercise on cognition and to better understand the role of cardiorespiratory fitness on these effects.

The Contribution of Functional Magnetic Resonance Imaging to the Understanding of the Effects of Acute Physical Exercise on Cognition

“…In the domains of incomplete outcome data and selective reporting, all studies were judged as having a low risk of bias. Furthermore, with regard to the domain of "other bias", the majority of studies were judged as having an unclear bias because the study design did not meet recent recommendations [33] (e.g., it used only a posttest comparison [38,39,71,73,[99][100][101][102][103][104] and/or the prescription of exercise intensity was not optimal because it was not based on a graded exercise test [39,[71][72][73][103][104][105]).…”

“…In the reviewed studies, the acute effects of physical exercise were studied in healthy children [71,73], adolescents with and without bipolar disorder [105], younger adults with attention deficit hyperactivity disorder (ADHD) [100,102], healthy younger adults [38,39,72,99,101,102,106], and healthy older adults [103,104,107]. A detailed overview of the sample characteristics (e.g., age, gender, BMI, and cardiorespiratory fitness level) can be found in Table 1.…”

“…The sample size in the reviewed studies varied between 9 [71,73,99] and 34 participants [107]. In particular, the following sample sizes were used: < 10 participants [71,73,99], between 10 to 20 participants [38,39,72,99,102,106], and > 20 participants [100,101,[103][104][105]107].…”

“…Twelve of the studies were conducted in a within-subject design [38,39,[71][72][73][100][101][102][103][104]106,107] and six studies used a between-subjects design [99][100][101][102]105,106]. Furthermore, in four studies, a cognitive test using fMRI was performed prior to and after cycling [72,[105][106][107], whereas in 10 studies, testing was only performed after the cessation of the intervention conditions (e.g., cycling or seated rest/watching movie) [38,39,71,73,[100][101][102][103][104]106]. In these 10 studies, the order of the separate testing sessions was counterbalanced [38,39,71,73,[100][101][102][103][104]106].…”

“…Furthermore, in four studies, a cognitive test using fMRI was performed prior to and after cycling [72,[105][106][107], whereas in 10 studies, testing was only performed after the cessation of the intervention conditions (e.g., cycling or seated rest/watching movie) [38,39,71,73,[100][101][102][103][104]106]. In these 10 studies, the order of the separate testing sessions was counterbalanced [38,39,71,73,[100][101][102][103][104]106]. Furthermore, the testing sessions were separated by a time interval of at least two days [38,[100][101][102], seven days [39,71,73,106], or twelve days [103], and four studies reported that the testing sessions were performed at the same time of day [38,71,73,106].…”