Non-verbal social communication in individuals with eating disorders: an ethological analysis in experimental setting

Purpose Evidence that social difficulties promote the development and the maintenance of eating disorders (EDs) derive from self-reported data and only partially from experimental tasks. This study objectively assessed non-verbal behaviors of individuals with EDs in a psycho-social stress scenario. Methods Thirty-one women suffering from EDs (13 with anorexia nervosa and 18 with bulimia nervosa) and 15 healthy women underwent the Trier Social Stress Test (TSST), the paradigm of psycho-social stress, and were videotaped. Throughout the procedure, anxiety feelings were measured by the State-Trait Anxiety Inventory state subscale and saliva samples were collected to evaluate cortisol levels. Non-verbal behaviors were analyzed through the Ethological Coding System for Interviews and were compared between study samples through multivariate analysis of variance. Multivariate regression analyses were performed to assess the association between anxiety, cortisol and behavioral responses to TSST. Results Women with EDs showed reduced submissiveness, flight (cutoff from social stimuli) and gesture compared to healthy peers during TSST. Submissiveness and flight behaviors were negatively associated with stress-induced anxiety, while TSST-induced anxiety and cortisol increases were positively associated with looking at the other's face behavior in participants with EDs. In this population, cortisol reactivity was also positively associated with submissiveness and negatively with gesture. Conclusion Women with EDs showed a hostile and freezing response to acute psycho-social stress: reduced submissiveness and flight may represent strategies to manage social anxiety. These findings confirm that the non-verbal behavior assessment provides complementary information to those derived from traditional measurements and suggests research and clinical implications.