Affect regulation and purging: An ecological momentary assessment study in purging disorder

Research suggests that affect may play an important role in the propensity to purge among women with purging disorder (PD). However, prior work has been constrained to cross-sectional or laboratory designs, which impact temporal interpretations and ecological validity. This study examined negative affect (NA) and positive affect (PA) in triggering and maintaining purging in PD using ecological momentary assessment. Women with PD (N = 24) made multiple daily ratings of affect and behavior for 2 weeks. Multilevel models examined associations between affect and purging at different levels of analysis, including a novel analytic approach to address the specificity of changes in affect relative to purging behavior by comparing trajectories of change on purge versus nonpurge days. For trajectories of affect over time, NA increased before purging and decreased following purging on purge days; however, only the decrease in NA following purging was significantly different from the trajectory of NA on nonpurge days. Conversely, PA failed to increase before purging on purge days compared with a matched time-point on nonpurge days. These findings suggest unique roles of PA in triggering and NA in maintaining purging in PD and support models in which purging functions to regulate affect. For comparisons of ratings before and after purging, NA increased and PA decreased after purging, highlighting how different analytic strategies produce different findings requiring integration into affect regulation models. These data provide insight into why women with PD purge after consuming normal amounts of food, a crucial first step for developing effective interventions.