Leptin levels among prepubertal children with Down syndrome compared with their siblings.

OBJECTIVES: To compare levels of leptin and other obesity-related hormones in prepubertal children with Down syndrome (DS), a population at high obesity risk, and those in unaffected siblings to better understand the pathophysiology of obesity in children with DS. STUDY DESIGN: This was a cross-sectional study of 35 children with DS and 33 control siblings, ages 4 to 10 years, with a fasting blood sample and anthropometric measurements to estimate body composition. Generalized estimating equations were used to account for the lack of independence between siblings. RESULTS: In addition to having higher body mass index and percent body fat, children with DS had higher leptin levels than unaffected siblings, even after adjustment for age, sex, race, and ethnicity (difference, 5.8 ng/mL; 95% CI, 2.4-9.3; P = .001) and further adjustment for percent body fat (difference, 2.7 ng/mL; 95% CI, 0.08-5.40, P = .04). Leptin and percent body fat were positively associated in both groups (P < .0001), but with a significantly greater positive association in the DS group, suggesting a significant effect modification (P < .0001). CONCLUSIONS: This group of children with DS had increased leptin levels for percent body fat than their unaffected siblings. This difference may contribute to the increased risk for obesity in children with DS.

Physical activity patterns in children with and without Down syndrome.

PURPOSE: To describe physical activity (PA) patterns in children with Down syndrome (DS) compared to their unaffected siblings. METHODS: Children with DS (n = 28) and their siblings (n = 30), between 3-10-years (mean +/- SD 7.1 +/- 2.1 years) participated in a nutrition and growth study. PA was measured over 7 days using accelerometers. RESULTS: Children with DS were younger (6.6 vs. 7.1 years) and heavier (BMI 18.4 vs. 16.7 kg m(-2)) than their siblings (p < 0.05). Overall, participants accumulated 2.5 hours per day in moderate- (MPA) and 59 min per day in vigorous-intensity activity (VPA), consistent with the current PA recommendations for children. Children with DS accumulated less VPA than their siblings (49.5 vs. 68.6 minutes per day; p = 0.04) and for shorter bouts (2.5 vs. 5.1 minutes per bout; p < 0.01), but spent similar time in MPA and low-intensity PA. Analyses adjusted for age, sex, race, ethnicity, income, maternal education and BMI showed similar results. CONCLUSIONS: Children with DS participated in less total and sustained VPA and had higher BMI levels compared with their siblings. Because children with DS have a tendency toward childhood obesity, increasing participation in VPA may be appropriate for prevention of obesity and promotion of lifelong health.

Child-feeding practices in children with down syndrome and their siblings.

OBJECTIVE: To compare parental feeding practices and evaluate their relationship to weight status among children with Down syndrome (DS) and their unaffected siblings. STUDY DESIGN: Cross-sectional study of sibling pairs, one child with DS (n = 36) and one child without DS (n = 36), between 3 and 10 years of age. Parents completed the Child Feeding Questionnaire (CFQ), which assesses six aspects of control in feeding, separately for each child. Children's height and weight were measured using standard research procedures for calculation of body mass index (BMI) and BMI Z scores (BMIZ). RESULTS: Mean BMIZ was higher among children with DS than their siblings (1.1 +/- 0.9 vs 0.1 +/- 1.1; P <.001), but there were no between-group differences in parents' perception of children's weight status. Parents reported greater use of restriction, greater feelings of responsibility for feeding and concern about child weight status, and lower pressure to eat for children with DS than for their siblings. After adjustment for BMIZ, differences remained significant only for concern (10.6 +/- 3.5 vs 6.4 +/- 3.4; P <.002). Perceived child overweight and concern were positively associated with BMIZ, whereas pressure was inversely associated with BMIZ. CONCLUSIONS: Differences in child-feeding practices may play a role in the development of obesity in DS.