Frontal Behavioral Symptoms in Prader-Willi Syndrome

Abstract

Prader-Willi syndrome (PWS) is a genetically determined neurodevelopmental disorder characterized by marked obesity and peculiar behavioral features, which are the major causes of morbidity and mortality in PWS. The most remarkable behavioral feature in PWS is hyperphagia and it has been the major focus of much of the research to date. Persons with PWS also show behavioral symptoms that are not related to food. These include temper tantrums, uncontrollable impulse, aggressive behavior, lability of mood, and compulsive behavior. These behavioral features in PWS are strikingly similar to behavioral symptoms of patients with frontal pathologies affecting the orbitofrontal cortex (OFC). In addition, previous neuroimaging studies have reported that individuals with PWS had changes in regional activity in some brain regions including the OFC. To investigate how frequently individuals with PWS manifest frontal behavioral symptoms, we surveyed the prevalence of eating behavioral features as well as noneating ones (stereotypy and collecting behavior) in PWS by using assessment tools developed originally for patients with frontal pathologies. These behavioral features were highly prevalent in individuals with PWS, and the severity of each domain of eating behavior was significantly correlated with that of stereotypy and collecting behavior. Our findings along with those of some previous studies suggest that behavioral features in PWS are likely to be associated with the dysfunction of the OFC and its related areas. The elucidation of the pathophysiological basis of the behavioral symptoms of PWS would provide a clue to the treatment of these symptoms, as well as throw light on the mechanisms underlying the similar abnormal behavior involved in pathological overeating and obesity.