Abstract:

The core feature of major depressive disorder, as defined in the DSM-5, is persistent mood disturbances characterized by excessive sadness and significantly reduced pleasant emotional experiences. Previous studies explored the emotion dysregulation of major depressive disorder by examining the static and trait-related aspects of overall emotional intensity, based on the trait model of personality. However, in real-life contexts, an individual's emotional experiences are not static but dynamically fluctuate in response to intricate social situations. Emotion is a dynamic process influenced by social interaction, individual evaluation processes and the external environment. Emotion dynamics consider the temporal dimension and volatility as the intrinsic features of emotions, to investigate how micro-level emotional fluctuation patterns impact psychological well-being at the macro-level. Researches on emotion dynamics have emphasized that the emotion dysregulation in major depressive disorder goes beyond increased negative emotional intensity and decreased positive emotional intensity. It also manifests as abnormal emotional dynamic patterns, specifically characterized by deviations in indicators of emotion dynamic such as emotion variability, instability, inertia, and others. Therefore, the objective of this systematic review is to summarize the dynamic features of emotion dysregulation in major depression from the perspective of emotion dynamics.

This systematic review conducted a comprehensive search of the Web of Science, PubMed, Scopus, and PsycInfo databases from January 1, 2013 to January 1, 2023. A total of 18 studies were included in this review, which utilized ecological momentary assessment to explore the differences in indicators of emotion dynamics between clinical populations with depression and the control group. Consistent with findings from traditional cross-sectional retrospective studies and laboratory research, studies based on ecological momentary assessment indicated that patients with depression experience higher average intensity of negative emotions and lower average intensity of positive emotions in their daily lives. Significantly, this review offered a more nuanced understanding of emotion dysregulation in major depressive disorder beyond average emotional intensity. The key findings were as follows: (1) Patients with depression had greater negative emotion fluctuations compared with the healthy control group. These fluctuations manifested as greater negative emotion variability and instability. Compared to the healthy control group, individuals with depression exhibited a greater overall fluctuation in negative emotional experiences in their daily lives, with more pronounced fluctuations between two consecutive time points. (2) Depressed patients exhibited a rigid and inflexible emotional system, characterized by greater negative emotion inertia and denser emotion networks. Compared to the healthy control group, individuals with depression exhibited a greater tendency for negative emotions experienced in the past to persist into the next moment. Depressed patients had a greater number of connections and stronger linkages between nodes in their emotional networks. (3) Depressed patients exhibited abnormalities in emotional reactivity. This was reflected as the mood brightening effect after positive events and greater negative emotion reactivity after negative events. Compared to the healthy control group, individuals with depression exhibited greater emotional improvement following positive events and greater increase in negative emotions following negative events. (4) Patients with depression experienced decreased complexity in their emotional system. This manifested as a lower level of emotion differentiation. Compared to the control group, individuals with depression tended to perceive and report emotions in a relatively simplistic and generalized manner, lacking the ability to differentiate subtle distinctions between discrete emotions. Furthermore, patients with remitted depression also exhibited some degree of emotion dysregulation, providing empirical support for the complications or scar model and the set-point theory.

This review was the first to comprehensively elucidate the primary features of emotion dysregulation in major depressive disorder viewed from emotion dynamics. The findings of this review provided further theoretical support for recent dynamic models of mental disorders, including complex dynamical system theory and network theory. Research in clinical psychology might benefit from accurately modeling the dynamic feature of psychopathology and approaching psychopathology as a system. As for clinical practice, the results contributed to the identification of potential intervention targets with high ecological validity for individualized treatment and relapse prevention of depression. In accordance with the principles of personalized medicine, psychiatrists could target specific features of a patient's emotion dysregulation as focal points for tailored and precise interventions, thereby enhancing the effective remission rates of depression. Furthermore, the insights from an emotion dynamics perspective inspired clinical practitioners to utilize more digitized and intelligent tools, such as smartphones and wearable devices, for advancing clinical assessments and treatments in the realm of mental disorders. This ongoing progress contributed to innovation and development in remote mental health services within the digital age.

Key words: major depressive disorder, emotion dynamics, emotion dysregulation, ecological momentary assessment