Prospective associations between depressed mood and anhedonia: reciprocal influences or stress influence?

Introduction: Depressed mood and anhedonia increase steadily through adolescence, and their associations become more tied at the transition to adulthood. However, it remains unclear whether the relationship is best explained by reciprocal influences or by a third variable. Method: This longitudinal study investigated the co-development and bidirectional relationships between the two symptoms over three waves among first-year university students (Mean age = 18.24 years, SD = 0.80, 41% male) using latent growth models, parallel latent growth modelling and random-intercept cross-lagged panel models. The moderating effects of childhood maltreatment on their links were explored as well. Results: In general, depressed mood and state/trait anhedonia decreased concomitantly over time after entering university. The majority of students (90%) decreased in depressed mood and anhedonia over time, while the remaining 10% progressively increased. At the between-person level, increases in depressed mood were accompanied by increases in state/trait anhedonia. However, these symptoms did not reciprocally predict each other at the within-person level. Multiple-group analyses found that depressed mood and state anhedonia reciprocally influenced among individuals with higher levels of childhood maltreatment. Conclusion: These findings emphasised that the core elements of major depressive disorder were not directly related to each other, but rather that moderating factors play a role.