ARE THE BIOELECTRICAL IMPEDANCE RAW VARIABLES DIFFERENT IN INDIVIDUALS WITH DOWN SYNDROME?

INTRODUCTION: Individuals with Down syndrome (DS) experience changes in body composition and may develop obesity early increasing their risk for metabolic diseases. The raw variables of bioelectrical impedance analysis (BIA) that have been found associated with health risk in other populations may therefore differ between adults with and without DS. PURPOSE: To examine if BIA raw variables differ between adults with and without DS. METHODS: Forty adults, 20 with DS (24 ± 4 years; 8 men and 12 women) and 20 without DS (non-DS; 24 ± 3 years; 10 men and 10 women) were assessed with BIA (tetrapolar, hand to foot; single frequency at 50KHz). The assessments were conducted in the morning after an overnight fast, and participants were instructed to abstain from caffeine and alcohol for 24 hours prior. The BIA analyzed variables included: resistance (Ohms), reactance (Ohms), impedance (Ohms) and phase angle (°). In addition, we analyzed the anthropometric variables (weight, kg; height, cm; and waist circumference, cm). Differences between groups were analyzed with the independent t-tests and effect sizes (Cohen’s d). RESULTS: Adults with DS had lower body mass (DS: 61.1 ± 11.7 kg; non-DS: 69.5 ± 14.3 kg; p = 0.048; d = 0.6) and height (DS: 148.3 ± 9.75 cm; non-DS: 165.1 ± 8.6 cm; p < 0.001; d = 1.8), but no statistically significant differences were observed in BMI (DS: 27.8 ± 4.7 kg/m²; non-DS: 25.3 ± 3.9 kg/m²; p = 0.074; d = 0.6) and waist circumference (DS: 84.8 ± 10.2 cm; non-DS: 80.3 ± 10.6 cm; p = 0.179; d = 0.4). Individuals with DS had significantly lower values in BIA raw variables: resistance (DS: 463.8 ± 44.7 Ohms; non-DS: 527.5 ± 90.7 Ohms; p = 0.009; d = 0.9), reactance (DS: 50.9 ± 5.5 Ohms; non-DS 67.7 ± 10.8 Ohms; p < 0.001; d = 2.0), impedance (DS: 466.6 ± 44.8 Ohms; non-DS = 531.9 ± 91.0 Ohms; p = 0.008; d = 0.9) and phase angle (DS: 6.3 ± 0.6°; non-DS: 7.3 ± 0.9°; p < 0.001; d = 1.5). CONCLUSIONS: Despite having similar BMI and waist circumferences, adults with DS differ in BIA raw variables from adults without DS. These differences indicate that adults with DS may have reduced cellular integrity and muscle quality, greater adiposity, and lower muscle mass. This is consistent with research indicating reduced cellular integrity and health in individuals with DS. These results may inform the development of programs for physical activity and weight control for adults with DS.