Insulin sensitivity and brain reward activation in overweight Hispanic girls: a pilot study.

BACKGROUND: Insulin resistance is a link between obesity and the associated disease risk. In addition to its role as an energy regulatory signal to the hypothalamus, insulin also modulates food reward. OBJECTIVE: To examine the relationship of insulin sensitivity (SI) and fasting insulin with cerebral activation in response to food and non-food cues in children. METHODS: Twelve overweight Hispanic girls (age: 8-11) participated in two study visits, a frequently sampled intravenous glucose tolerance test and a functional neuroimaging session (GE HDxt 3.0Tesla) with visual stimulation tasks. Blocks of images (high calorie [HC], low calorie [LC] and non-food [NF]) were presented in randomized order. RESULTS: Comparing HC with NF, SI was inversely associated with activation in the anterior cingulate (r2 = 0.65; P < 0.05), the insula (r2 = 0.69; P < 0.05), the orbitofrontal cortex (r2 = 0.74; P < 0.05), and the frontal and rolandic operculum (r2 = 0.76; P < 0.001). Associations remained significant after adjustment for body mass index. Association of fasting insulin and cerebral activation disappeared after adjustment for waist circumference. CONCLUSION: In addition to weight loss, insulin sensitivity may pose an important target to regulate neural responses to food cues in the prevention of excessive weight gain.