Affective processes underlying restrictive eating in atypical anorexia nervosa: Comparisons to anorexia nervosa and bulimia nervosa using ecological momentary assessment.

OBJECTIVE: Certain symptom and risk/maintenance factor similarities between individuals with atypical anorexia nervosa (AN) and 'typical' AN have been documented, but few studies have investigated how atypical AN compares to bulimia nervosa (BN). Further, the role of affective mechanisms in maintaining restrictive eating in atypical AN has not been examined. The current study investigated whether atypical AN resembles AN and/or BN on affect-related processes using questionnaires and ecological momentary assessment (EMA).

METHOD: Women with atypical AN (n = 24), AN-restrictive subtype, (n = 27), AN-binge eating/purging subtype (n = 34), and BN (n = 58) completed questionnaires measuring depressive symptoms and emotion regulation difficulties. They also completed a 14-day EMA protocol during which they reported negative and positive affect and skipped meals five times/day (signal-contingent surveys) and restrictive eating after meals/snacks (event-contingent surveys).

RESULTS: Diagnostic groups generally did not differ on questionnaire measures nor affective patterns surrounding restrictive eating behaviors. Momentary changes in affect did not predict or follow restriction at meals/snacks, though higher momentary negative affect ratings predicted skipped meals, and higher positive affect was reported after skipped meals. Greater average negative affect and lower average positive affect predicted both restrictive eating behaviors.

DISCUSSION: Across diagnoses, reductions in food intake do not appear to be influenced by momentary changes in affect, though skipping meals may serve an emotion regulation function. Atypical AN seems to resemble AN and BN on affective processes underlying restrictive eating, raising further questions regarding the unique diagnosis of atypical AN.

PUBLIC SIGNIFICANCE: Though atypical anorexia appears to strongly resemble anorexia nervosa, it is less clear how this disorder relates to bulimia nervosa. It is further unknown whether affective-related processes underlie restrictive eating in atypical anorexia nervosa, and how these processes compare to those in anorexia nervosa and bulimia nervosa. Results suggest that atypical anorexia does not differ from anorexia nervosa or bulimia nervosa on emotion-related measures, nor in affective patterns surrounding restrictive eating behaviors.