Affective, Cognitive and Endocrinological Processes in the Daily Life of Individuals with Recurrent Major Depression and Their Course Over Time

In this dissertation, I explored the affective, cognitive, and physiological dynamics in the daily life of individuals with recurrent depressive episodes compared to healthy individuals. The dissertation is based on three studies, utilizing Ambulatory Assessment methodologies, including a measurement-burst design. These studies aimed to clarify mechanisms of micro-processes in daily life that could in-crease vulnerability to relapse and suggest potential therapeutic interventions. Study 1 (Chapter II) examined differences in daily affect and cognitions between individuals in remis-sion from recurrent depression and healthy controls, along with their reactivity to daily negative and positive events. Key findings indicated that higher levels of positive thoughts boosted mood in both groups, while rumination predicted decreases in positive affect specifically in remitted individuals. Re-mitted individuals showed greater increases in negative affect and rumination following negative events. Notably, positive events elicited a "mood brightening" effect, marked by stronger decreases in negative affect and rumination, along with greater increases in positive affect and positive thoughts. These results highlight the protective role of positive affect and cognitions, suggesting therapeutic approaches that sustain positive mood could support long-term remission. Study 2 (Chapter III) investigated associations between trait and state cognitions and salivary cortisol as a biological stress marker in daily life. Findings revealed that trait repetitive negative thinking, but not mindfulness, was linked to higher cortisol levels, particularly in individuals with recurrent depres-sion compared to healthy individuals. Additionally, momentary mind-wandering and mental shift prob-lems predicted increases in cortisol levels 20 minutes later. Within the recurrent depression group, higher average levels of mental shift problems were associated with elevated cortisol. Multilevel struc-tural equation models indicated that state cognitions did not mediate the effects of habitual repetitive negative thinking on cortisol release. These results underscore the independent roles of trait and state cognitions as internal stressors activating the hypothalamic-pituitary-adrenal axis, emphasizing the heightened physiological vulnerability of individuals with recurrent depression. Study 3 (Chapter IV) applied a measurement-burst design to explore intraindividual variability and change in affective, cognitive, and endocrinological responses to daily events over 4.4 years in initially remitted individuals with recurrent depression. Over bursts, negative affect more strongly increased following negative daily events, while positive affect and self-acceptance exhibited a more pro-nounced decrease. Rumination and cortisol reactivity remained stable in response to negative events. Conversely, positive daily events were linked to a more significant increase in positive affect over bursts. Depression levels served as a moderator of intraindividual variability, with higher depression levels being linked to blunted cortisol responses toward negative events. Additionally, a “cognition brightening” effect was observed, reflected by greater increases in self-acceptance and greater de-creases in negative affect toward positive daily events in those individuals with higher depression lev-els, though this effect seemed unsustainable over bursts. These findings highlight the intricate dynam-ics of affective, cognitive and endocrinological processes in recurrent depression, emphasizing the need for targeted interventions that account for the stability of these responses and the moderating role of depression levels. In conclusion, findings from these three studies underscore the importance of fostering positive affect and reducing maladaptive thought patterns in individuals with recurrent depression, providing valuable insights for relapse prevention. Integrating technology and advanced data methods into clinical prac-tice holds promise for tailoring interventions to individual needs and facilitating early detection of re-lapse risks, thereby promoting more effective and proactive care for those vulnerable to depressive relapses.