Birth weight and catch up growth are associated with childhood impulsivity in two independent cohorts

Abstract

Individuals born after intrauterine growth restriction (IUGR) are more impulsive towards palatable foods, but it is not clear 1) if IUGR-related impulsivity is specific for foods and solely based on response inhibition and 2) if the development of impulsivity is due to being born IUGR per se or to growing up fast in the first few years of life (catch up growth). Children were classified in the IUGR group if the birth weight ratio was below 0.85. Delta z score for BMI was used as a measure of catch up growth. In MAVAN (N = 274), impulsivity was measured by the Information Sampling Task from the Cambridge Neuropsychological Test Automated Battery (IST - CANTAB), and in GUSTO using the Sticker Delay Task (N = 327). There is a significant effect of interaction between being born IUGR and the magnitude of catch up growth on the reflection impulsivity from IST-CANTAB at 60 months, in which greater catch up growth associates with greater impulsivity in the IST fixed condition in IUGR children. The finding was reproduced in children from the GUSTO cohort using the Sticker Delay Task. We confirmed that catch up growth interacts with IUGR, having a major role in the development of impulsivity in the first years of life and influencing inhibitory control and decision making processes.

Figure 1

Information Sampling Task. (a) Initial screen. The child is instructed to click on the gray boxes to open them, and she can open as many as she wants before deciding which color comprises the majority of the 25 boxes; (b) when the child decided that she had enough information to choose which color was more prevalent, she should click on the corresponding color at the bottom; (c) all boxes then automatically opened and a message about being correct or incorrect was displayed before the next trial.

Figure 2

Information Sampling Task (CANTAB at 60 months of age, MAVAN) - mean P correct score, win condition fixed. The lower the score depicted in the y axis, the more impulsive is the child. There is an interaction between being born IUGR (enclosed dots) and variation in BMI z-scores over the first 5 years of life on impulsivity scores, in which greater catch up growth is related to poorer scores (increased reflection impulsivity) in IUGR children.

Figure 3

Sticker Delay Task (41 months of age, GUSTO). The lower the score depicted in the y axis, the more impulsive is the child. There is an interaction between being born IUGR (enclosed dots) and variation in BMI z-scores over the first 4 years of life on impulsivity scores, in which greater catch up growth is related to poorer scores (increased impulsivity) in IUGR children.

Figure 4

Theoretical framework, life-course upwards spiral (follow the spiral from bottom to top). Please see details in the Discussion section. DA = dopamine.