‘Hungry Eyes’: visual processing of food images in adults with Prader-Willi syndrome.

BACKGROUND: Prader-Willi syndrome (PWS) is a genetic disorder associated with intellectual disabilities, compulsivity, hyperphagia and increased risks of life-threatening obesity. Food preferences in people with PWS are well documented, but research has yet to focus on other properties of food in PWS, including composition and suitability for consumption. It is also unclear how food perceptions differ across the two major genetic subtypes of PWS.

METHODS: This study examined neural responses to food stimuli in 17 adults with PWS, nine with paternal deletions and eight with maternal uniparental disomy (UPD), and in nine age-matched typical controls. Visual event-related potentials (ERPs) were recorded in response to food images varying in food composition and suitability for consumption during a passive viewing paradigm.

RESULTS: Group differences were observed for the N1 and P3 responses reflecting perceptual categorisation and motivational relevance respectively. The deletion group categorised food stimuli in terms of composition while the UPD group performed more similar to the controls, and focused on the suitability of food for consumption. Individual differences in N1 amplitude correlated with body mass index and scores on the Hyperphagia Questionnaire.

CONCLUSION: Differences are seen in how people with PWS because of deletion or UPD perceive visual food stimuli even within the first milliseconds of stimuli exposure. Implications are discussed for in vivo food behaviours and for future ERP or neuroimaging studies on hunger, satiety and food perception in PWS.