Daily patterns of anxiety in anorexia nervosa: associations with eating disorder behaviors in the natural environment.

The role of anxiety has been emphasized in etiological/maintenance models of anorexia nervosa. This study identified daily patterns of anxiety in anorexia nervosa and examined the likelihood of the occurrence of eating disorder behaviors in each trajectory, the daily temporal distribution of eating disorder behaviors in each trajectory, and the extent to which the tendency to exhibit particular anxiety trajectories was associated with baseline diagnostic and trait-level personality variables. Women with full or subthreshold anorexia nervosa (N = 118) completed a 2-week ecological momentary assessment (EMA) protocol during which they reported on a variety of behavioral and affective variables, including anxiety and eating disorder behaviors. Using latent growth mixture modeling to classify EMA days (N = 1,526) based on anxiety ratings, we identified 7 distinct daily anxiety trajectories. Overall differences between trajectories were found for rates of binge eating, self-induced vomiting, body checking, skipping meals, and dietary restriction. Furthermore, distinct daily temporal distributions of eating disorder behaviors were found across the trajectories, with peaks in the probability of behaviors frequently coinciding with high levels of anxiety. Finally, traits of personality pathology (affective lability, self-harm, social avoidance, and oppositionality) and the presence of a co-occurring mood disorder were found to be associated with the tendency to experience particular daily anxiety trajectories (e.g., stable high anxiety). Findings support the presence of within-person variability in daily anxiety patterns in anorexia nervosa and also provide evidence for an association between these anxiety patterns and eating disorder behaviors.