An experimental study showed that overweight or obese children who underwent a 20-week exercise regimen consisting of at least three supervised exercise sessions per week showed substantial improvement in cognitive test performance compared to a control group. Minor improvements compared to control were also found in academic performance indicators, but no differences in brain structure were detected. The study was published in JAMA Network Open.
The prevalence of obesity and being overweight among children has more than quadrupled in the past 50 years. This increase is often associated with less active lifestyles of children. There is evidence that obesity might negatively affect brain health and development. On the other hand, increased activity is often associated with positive outcomes for organ development, including the brain.
Existing research has studied effects of different exercise regimens on various executive and cognitive functions, but the authors of the new research note that there are not many studies examining links between exercise on the one hand and the development of intelligence and brain structure on the other. One reason for this is that existing research identified intelligence as a highly heritable trait, determined primarily by genetics. But might it still be somewhat “malleable” during childhood, when it is still developing?
To answer this question, Francisko Ortega and his colleagues conducted a 20-week long experiment on a group of 109 obese and overweight children between 8 and 11 years of age. Of these children 45 were girls and their mean body mass index was 26.8 (healthy weight range is between 18.5 and 24.9). The children were randomly divided into two groups (experimental and control group). Experimental group was tasked with attending 90-minute supervised exercises at least 3 times per week during a 20-week period (experimental group). Both groups were given lifestyle recommendations.
Psychological assessments were conducted before and after the time when the first group underwent intervention, in 2016 and 2017. Neuroimaging procedures were done between 2017 and 2021. Researchers assessed crystalized and fluid intelligence (Spanish version of the Kaufman Brief Intelligence test), cognitive flexibility (Design Fluency Test and the Trail Making Test), inhibition (Stroop Color-Word Test), working memory (Delay Non-Match-to Sample computerized task, modified version) and academic achievement (Woodcock-Johnson III Test of Achievement).
They also conducted magnetic resonance imaging scans of children’s brains, used a gas analyzer to evaluate children’s cardiorespiratory fitness, and assessed their overall physical activity before and during intervention (week 10) using hip- and waist-worn accelerometers.
The strongest difference between the two groups after the 20-week exercise/intervention period was in the scores of crystallized intelligence and also on the overall intelligence score. The experimental group performed better on both of these assessments. After the intervention period, the experimental group also outperformed the control group on assessments of fluid intelligence, cognitive flexibility, executive function, academic skills, problem solving and mathematics, but these differences between groups were lower. No systematic differences between brain structures as obtained by neuroimaging were found.
The study highlights important possible links between physical activity and cognitive development of children. However, authors note that psychological assessments were not double blind allowing for the possibility that observed effects were due to differences in motivation at least to some extent. It remains to be explored in the future whether longer-lasting training regimens might induce structural changes to the brain and also to evaluate the extent to which these findings hold for populations that are not overweight or obese.
The paper, “Effects of an Exercise Program on Brain Health Outcomes for Children With Overweight or Obesity“, was authored by Francisco B. Ortega, Jose Mora-Gonzalez, Cristina Cadenas-Sanchez, Irene Esteban-Cornejo, Jairo H. Migueles, Patricio Solis-Urra, Juan Verdejo-Román, María Rodriguez-Ayllon, Pablo Molina-Garcia, Jonatan R. Ruiz, Vicente Martinez-Vizcaino, Charles H. Hillman, Kirk I. Erickson, Arthur F. Kramer, Idoia Labayen, and Andrés Catena.