Introduction:
Insatiable appetite, with uncontrolled hyperphagia, poses a challenging issue in Prader-Willi Syndrome (PWS). The causative factors of these abnormal eating behaviors remain unknown. It has been suggested that it may be caused by impaired hormone release which impacts the speed of gastric emptying (GE), and a change in hunger and fullness sensations.
Aims: To determine whether gut hormone levels have an impact on gastric emptying and/or appetite sensations in individuals with PWS, obese/overweight and lean controls.
Methods:
This is a observational cohort study where all subjects – PWS, obese/weight-matched and lean controls had a GE assessment by gastric scintigraphy. After eating a 99mTc-labelled breakfast (486kCal), images are acquired immediately after the meal and 1, 2 and 4 hours thereafter. Appetite sensations were assessed with a self-reported visual analog scale technique pre-meal and at specific time intervals post-meal with bloods drawn regularly to assess post prandial gut hormone release.
Results: 11 lean, 9 obese/weight-matched controls and 13 PWS subjects aged between 18 -51 were recruited. PWS had a similar average GE rate compared to lean and obese controls, however, 3 PWS subjects had delayed GE. There was no correlation observed between GE time and hunger and satiety scoring in all 3 groups. Similarly, we found no correlation between gastric emptying and appetite hormones in PWS and Obese subjects. In lean subjects, we observed a significant correlation between gastric emptying time and glucagon levels at 1 hour and 2 hours postprandially but not at 4 hours.
Conclusion: We identified 23% PWS subjects as having delayed GE, whereas GE was normal in all controls. Altered gut hormone levels doesn't seem to cause delayed GE. PWS subjects with delayed GE had similar appetite sensations as those with normal GE. This explains why delayed GE is usually undiagnosed in PWS.