Negative affect and binge eating: Reconciling differences between two analytic approaches in ecological momentary assessment research

Abstract

Objective: Ecological momentary assessment (EMA) research has produced contradictory findings regarding the trajectory of negative affect after binge-eating episodes. Given the clinical implications, the objective of the current study was to reconcile these inconsistencies by comparing the two most commonly employed statistical approaches used to analyze these data.

Method: Data from two EMA studies were analyzed separately. Study 1 included 118 adult females with full- or subthreshold DSM-IV anorexia nervosa. Study 2 included 131 adult females with full-threshold DSM-IV bulimia nervosa. For each dataset, the single most proximal negative affect ratings preceding and following a binge-eating episode were compared. The times at which these ratings were made, relative to binge-eating episodes, were also compared.

Results: The results indicate that the average proximal pre-binge ratings of negative affect were significantly higher than the average proximal post-binge ratings of negative affect. However, results also indicate that the average proximal post-binge ratings of negative affect were made significantly closer in time to the binge-eating episodes (∼20 min post-binge) than the average proximal pre-binge ratings of negative affect (∼2.5 hr pre-binge). A graphical representation of the results demonstrates that the average proximal pre-binge and post-binge ratings map closely onto the results of previous studies.

Discussion: These data provide one possible explanation for the inconsistent findings regarding the trajectory of negative affect after binge eating. Moreover, they suggest that the findings from previous studies are not necessarily contradictory, but may be complementary, and appear to bolster support for the affect regulation model of binge eating.

Keywords: affect regulation; binge eating; ecological momentary assessment; negative affect.

FIGURE 1

Visual comparison of results using the multilevel modeling approach and the single points approach. The solid curved line depicts results from the multilevel modeling approach. Specifically, it shows the momentary levels and trajectories of global negative affect relative to binge eating in Study 1-AN and Study 2-BN. In these analyses, the pre- and post-event trajectories of global negative affect were modeled separately using piecewise linear, quadratic, and cubic functions centered on the time at which each of the eating episodes occurred. Momentary observations (Level 1) were nested within subjects (Level 2). The black dots depict the average proximal pre-binge and average proximal post-binge ratings of negative affect. The location of these points represents the average time at which the ratings were taken relative to the binge-eating episode and the average intensity of negative affect reported during that rating. For Study 1-AN, the scaling of the y axis ranged from 8.0 to 40.0. For Study 2-BN, the scaling of the y axis ranged from 11.0 to 55.0