The multisensory mind: a systematic review of multisensory integration processing in Anorexia and Bulimia Nervosa

Individuals with Anorexia Nervosa and Bulimia Nervosa present alterations in the way they experience their bodies. Body experience results from a multisensory integration process in which information from different sensory domains and spatial reference frames is combined into a coherent percept. Given the critical role of the body in the onset and maintenance of both Anorexia Nervosa and Bulimia Nervosa, we conducted a systematic review to examine multisensory integration abilities of individuals affected by these two conditions and investigate whether they exhibit impairments in crossmodal integration. We searched for studies evaluating crossmodal integration in individuals with a current diagnosis of Anorexia Nervosa and Bulimia Nervosa as compared to healthy individuals from both behavioral and neurobiological perspectives. A search of PubMed, PsycINFO, and Web of Sciences databases was performed to extract relevant articles. Of the 2348 studies retrieved, 911 were unique articles. After the screening, 13 articles were included. Studies revealed multisensory integration abnormalities in patients affected by Anorexia Nervosa; only one included individuals with Bulimia Nervosa and observed less severe impairments compared to healthy controls. Overall, results seemed to support the presence of multisensory deficits in Anorexia Nervosa, especially when integrating interoceptive and exteroceptive information. We proposed the Predictive Coding framework for understanding our findings and suggested future lines of investigation.Diagnoses of Anorexia Nervosa and Bulimia Nervosa have increased dramatically in recent years, taking on the characteristics of a mental health emergency. More research is therefore needed to better understand these conditions, especially given their complex and multifaceted nature. Patients affected by these conditions report significant alterations in body-self experience. Body experience results from a cross-modal integration process in which information from different sensory modalities and spatial frames is combined. Therefore, we systematically reviewed studies that focused on multisensory integration in patients affected by Anorexia Nervosa and Bulimia Nervosa, as it may play a key role in the onset and maintenance of these pathologies. Studies in this review found multisensory integration difficulties in patients with Anorexia Nervosa, but not enough studies were retrieved to draw conclusions regarding Bulimia Nervosa. We discussed findings trying to link behavioral, neuropsychological, and neuroscientific evidence in light of the predictive coding framework to provide a different perspective on patients' distorted body experiences. This may lead to new insights to refine our understanding of these complex and poorly understood disorders.