Introduction: Early cardiovascular (CV) disease caused by obesity begins in childhood and leads to increased morbidity and mortality in adulthood. Adolescents with intellectual and developmental disabilities (IDD) have twice the frequency of obesity as the typically developed population. Hypothesis: We hypothesize that early cardiac dysfunction will be present in this obese population before undergoing a 6 month diet/exercise weight loss program and that the dysfunction will improve with weight loss. Methods: Overweight (4) and obese (11) subjects with mild-moderate IDD (IQ 40-74) enrolling in a weight loss program were consented for this study. Subjects with congenital heart disease were excluded. An echo with LVEF and 2D longitudinal LV global peak strain (3 apical views; GLVS) and RV strain (1 apical view; GRVS) was performed blinded to other results. Analysis included T-test and simple linear regression, p≤0.05 significant. Results: Participants had Down syndrome (6) or were on the autism spectrum (9), with nearly equal genders (47% female). Baseline GLVS was in the low-normal to mildly diminished range in 14 (93%) subjects with preserved LVEF (all>55%) and normal LV volume. Increased baseline body weight predicted diminished GLVS (P=0.034). Body weight, BMI, and GLVS improved at 6 months. Improvements in GLVS and BMI over the 6 months were associated (p=0.049). There were no significant differences in GLVS (baseline or 6 month change) between autism and Down syndrome groups (p=0.81). Conclusions: Baseline abnormalities in biventricular strain (preserved LVEF/TAPSE) are present in this small IDD population. This dysfunction appears reversible with 6 months of weight loss. These data provide compelling justification for larger studies to better define associated variables and preventive strategies. [ABSTRACT FROM AUTHOR]