Trait-level and momentary correlates of bulimia nervosa with a history of anorexia nervosa.

Bulimia nervosa (BN) is characterized by recurrent binge eating and purging, and is associated with significant physical and psychosocial health impairments (1). Although BN is currently classified as a distinct psychiatric disorder (2), significant diagnostic crossover occurs within the eating disorders (3). Specifically, up to 65% of individuals with anorexia nervosa (AN) go on to develop BN over time (4–7), a trajectory that has been associated with a poorer prognosis and greater likelihood of relapse (8; 9). Compared to BN without a history of AN (BN−), BN with a history of AN (BN+) has been associated with lower current body mass index (BMI; kg/m2) and higher levels of dietary restraint, and some, but not all, studies report higher rates of lifetime anxiety disorders and greater shape- and weight-related concern in these individuals (10–13). Because evidence suggests that these two subgroups may have distinct clinical profiles, it has been proposed that consideration be given to formally subtyping BN by AN history in the upcoming DSM-5 (8). However, further replication is required. Moreover, it is unclear whether these subgroups differ with respect to functional aspects of their bulimic symptoms. Ecological momentary assessment (EMA) utilizes “real time” data to understand antecedents and consequences of behavior (14). Within the eating disorders field, EMA has been used to study the relation between negative affect and eating disorder behaviors (15). In adults with BN, momentary negative affect appears to increase prior to the occurrence of binge eating and purging and decrease thereafter, suggesting that bulimic symptoms in BN may reflect attempts to self-regulate emotions and/or be maintained by negative reinforcement (16–19). EMA data examining the role of negative affect as an antecedent and consequence of eating disorder behaviors are not yet available in AN, but cross-sectional data in adults with AN are suggestive of a relation between mood and behavior (7; 20; 21). To date, no studies have compared individuals with BN+ and BN− to ascertain potential differences in emotional antecedents and consequences to eating disorder behaviors. Such data could aid in our understanding of the onset and maintenance of these behaviors in BN, and could assist with the development of effective interventions. Although exercise has not been examined in EMA studies of BN or AN, this behavior is of particular interest as it is a common feature in both disorders (22), and several studies have suggested that exercise in individuals with eating disorders may function to modulate negative affect (22,23). Despite inconsistencies in the field in defining problematic exercise (23), a number of previous studies have found higher rates of excessive or compulsive exercise in AN than in BN (22; 24). However, it is unknown whether the function of exercise differs in BN+ versus BN−. The current study represents a replication and extension of the existing literature concerning individuals with BN with and without a history of AN. Our first aim was to compare BN+ and BN− with respect to BMI, dietary restraint, anxiety, shape and weight concerns, and psychiatric comorbidity, both at the trait and (when available) momentary level. We hypothesized that BN+ would have lower BMIs and report greater impairment in the aforementioned psychological domains on both trait and momentary measures. An exploratory aim was to examine between-group differences in negative affect as a precipitant and consequence of binge eating, purging, and exercise. Results could be used to inform the classification scheme for BN, including implications for DSM-5, and to assist with intervention development and treatment planning.