Findings published online ahead of the print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine show that researchers at the University of Chicago discovered important new associations between obesity, sleep-disordered breathing (SDB) and cognitive processing among elementary school children.

Study author Karen Spruyt, PhD, assistant professor in the Department of Pediatrics at the Pritzer School of Medicine comments:

“The intricate interdependencies between BMI, SDB and cognition shown in our study are of particular importance in children, as their brains are still rapidly developing. Rising rates of obesity in children may amplify these relationships. Public health campaigns targeting obesity should emphasize not only the health benefits but the potential educational benefits of losing weight.”

She explains:

“SDB amplified the risk of adverse cognitive and weight outcomes, while weight amplified the risk of SDB and adverse cognitive outcomes. Impaired cognitive functioning was associated with an increased risk of adverse weight outcomes and SDB, good cognitive abilities may be protective against increased body weight and SDB.”

For the study, researchers enrolled 351 schoolchildren of the average age of 7.9 years in Louisville, Kentucky. They conducted neurocognitive testing with the Differential Abilities Scale in all children, followed by an overnight polysomnogram or sleep study, in which they measured the children’s’ SDB by using the obstructive apnea/hypopnea index (AHI) that was defined as the number of apnea and hypopneas per hour of total sleep time. The children’s’ body mass index (BMI) was included in the anthropometric measurements. Researchers then evaluated the data by using a structural equation model, which is a statistical technique for testing and estimating causal relations between the variables of interest.

The “sleep-disordered breathing” analysis showed that the role of SDB had a significant mediator role on the association of BMI with cognitive performance; with SDB increasing both adverse cognitive and adverse weight outcomes. The “weight” analysis revealed that BMI increased the risks of adverse SDB and cognitive outcomes. The last analysis of “cognition” as the mediator showed that the poor ability to perform complex mental processing functions increased the risk of adverse weight and SDB outcomes.

Dr. Spruyt stated:

“The mediator roles of weight and SDB were comparable, both adversely affecting cognitive functioning. Poorer integrative mental processing may also increase the risk of adverse health outcomes.”

According to the researchers the study had some limitations, for example, it included only normally developing children and therefore limited generalization of the results to more impaired populations. They also point out that including children with more severe SDB might have changed the magnitude of the mediation effects.

Dr. Spruyt concluded:

“Along with campaigns targeting childhood obesity screening for SDB in overweight children and children with learning difficulties may be justified based on our results.”

Written by Petra Rattue