Executive Function as a Moderator of Obesity in Infancy

Childhood overweight and obesity have experienced epidemic growth in recent years. Excessive adiposity presents challenges to orthopedic, neurological, pulmonary, gastroenterological, endocrinal, and social development. Thus, the time course of weight development in early childhood is of special public health concern. A major goal of childhood obesity research is to identify mechanisms contributing to excess weight gain. In infancy, executive function has been identified as one possible contributor. Unfortunately, no studies have yet examined infant obesity risk with respect to executive function development. In this study, we present the first evidence that executive function may be linked to obesity risk in infancy. Thirty middle-class, primarily White infants visited the lab of the ETSU Program for the Study of Infancy at 18 and 21 months of age. Measures of infant weight and recumbent length were taken at both ages. Weightfor-length BMI z-scores were derived from international growth curves published by the World Health Organization. Executive function was measured at the 21-month visit, using the Multilocation Search Task. In this task, infants are shown the location of a cracker in one of five drawers. Once infants select the correct drawer on three successive trials, the cracker is moved to a new drawer in plain view of the child, and the child is asked to find the cracker again. The location of the cracker is changed on two more trials. Children’s perseverating responses to the old cracker location is viewed as an inverse measure of executive function. Results showed that from 18 to 21 months of age, BMI z-scores decreased significantly [t(30) = 2.63, p = .013]. This finding suggests that on average, infant BMI scores decreased across the three-month period. To explore whether executive function performance varied as a function of infant BMI, we divided our sample into two BMI groups via median split. A mixed-design ANOVA revealed that infants with the greatest decreases in BMI from 18 to 21 months (i.e., the “Hi Decrease” group), showed the greatest gains in performance across the three trials of the executive function task [F(2, 25) = 5.29, p = .012]. Specifically, by Trial 3 of the multilocation search task, Hi Decreasers were making an average of 0.57 perseverative errors, whereas the Lo Decreasers were making an average of 2.231 perseverative errors. These results are consistent with expectations. To the extent that executive function capacity helps regulate weight gain, it stands to reason that infants with greater executive function capacity would be advantaged in regulating their eating behaviors. Although we recognize that there are likely multiple contributors to infant and child obesity, findings from the present study supports the possibility that one of these contributors may be executive function. To our knowledge, this is the first study documenting a link between executive function and infant BMI