Vanishing Boundaries: A Unifying Account of Multidimensional Emotion Dynamics and Alterations in Depression

Emotions are fundamentally integral to shaping the order and disorders in humanlives. Yet, a principled, quantitative framework explaining emotional dynamicsand their alteration in mental disorders has been elusive. This challenge arisesfrom the complex and multidimensional nature of emotions but also, at leastpartially, due to a shortage of large longitudinal measurements and the use ofgenerative mathematical models, leading to a spectrum of partially contrastingtheories. Our study seeks to overcome these challenges by employing dynamic systems theory, the mathematical study of complex systems. We apply this approach to a dataset containing over 400,000 texts from more than 1,600 individuals, with half reporting a diagnosis of Major Depressive Disorder (MDD), collected from X (previously Twitter). We examined the emotional experiences and significant life events described in these texts across one month, which we extracted using state-of-the-art natural language processing. The key result of our research is the discovery of emotion-specific dynamics – the unique ways in which different emotions maintain their influence over time. In individuals diagnosed with MDD, we observed a ’blunting’ of the inter-emotional dynamics; this is not merely a dulling of emotions, but rather a vanishing of the boundaries between them. Our findings thus challenge and unify traditional views in this area: if viewed in isolation, this blending of emotions could be misinterpreted as augmented negative, blunted positive emotions, and as Emotional Context Insensitivity (ECI). Our study therefore offers a principled mathematical understanding of emotion dynamics and their alterations within mental disorders, potentially leading to more effective therapeutic interventions.