Re-evaluating the predictive value of reinforcement motivation on outcome in anorexia nervosa: The role of affective symptoms.

BACKGROUND

Reinforcement motivation, particularly heightened punishment sensitivity and its imbalance relative to reward sensitivity ("motivational bias"), can predict outcomes in anorexia nervosa (AN). However, previous studies did not account for affective symptoms, which are intertwined with reinforcement processes and illness trajectory. This study examined whether affective symptoms explain outcomes beyond reinforcement motivation.

METHODS

Adolescent girls and young women with AN (n = 192; Mage = 16.33 years, SD = 2.61) completed self-report measures of punishment/reward sensitivity, depressive symptoms, and trait anxiety at treatment admission and at 1-year follow-up. Outcomes included ED symptoms, body mass index, and multidimensional recovery (Morgan-Russell outcome assessment schedule). Cross-sectional comparisons included long-term recovered individuals (n = 154) and healthy controls (n = 440); longitudinal associations were tested using nested linear regression.

RESULTS

Patients with AN and recovered individuals showed elevated punishment sensitivity (η2ₚ = 0.19) and stronger motivational bias (punishment>reward; η2ₚ = 0.17). At baseline, reinforcement motivation and affective symptoms showed limited predictive utility. Longitudinally, shifts in motivational bias were associated with ED symptoms and multidimensional outcomes (|β| > 0.248, pFDR < .002), whereas changes in affective symptoms were the most robust and consistently associated predictors (|β| > 0.173, pFDR < .017).

CONCLUSIONS

Depressive symptom improvement emerged as the key predictor of outcome, showing stronger associations with follow-up ED symptoms and psychosocial functioning than reinforcement motivation. While changes in reinforcement motivation accompanied ED outcomes, affective symptom change was more predictive across outcomes. These findings emphasize the importance of prioritizing affective processes within developmentally tailored AN treatment frameworks.