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Abstract

In this thesis, I adopted a transdiagnostic perspective on early mental health problems and pursued three overarching goals. First, I aimed to investigate digital markers in the prediction of clinical outcomes. Second, I aimed to examine how early adversity may combine and interact with putative candidate mechanisms in the development of psychopathology. Third, I aimed at the development of a hybrid transdiagnostic intervention for enhancing resilience in youth with early mental health problems. I aimed to explore its reach, putative mechanisms of change involved, and personalised intervention trajectories including context factors (i.e., what works for whom under which circumstances?). In line with the first goal, Chapter II presented the first study, which examined the predictive value of momentary manifestations of negative symptoms as digital markers for clinical outcomes in individuals at ultra-high risk for psychosis using an experience sampling design. I found evidence for momentary manifestations of negative symptoms, especially social anhedonia, to predict clinical outcomes. Higher levels of momentary manifestations of negative symptoms were associated with higher levels of illness severity and poorer functioning at 1- and 2-year follow-up. This approach offers important insights into service users’ symptoms in the context of their daily life, which are relevant for research and practice. Moreover, subjective experiences of negative symptoms, especially social anhedonia, in daily life may be a promising target for future intervention approaches in the early stages of psychosis. Addressing the second aim, Chapters III and IV presented investigations of stress reactivity and threat anticipation as putative mechanisms linking early adversity with psychopathology. In Chapter III, I examined stress reactivity as a putative mechanism linking childhood trauma with clinical outcomes in individuals at ultra-high risk for psychosis. Replicating previous findings, childhood trauma modified the effect of daily stressors on negative affect and psychotic experiences. Individuals exposed to higher levels of childhood trauma showed more intense psychotic experiences and stronger increases in negative affect in response to minor daily stressors. In addition, there was some evidence suggestive of the predictive value of stress reactivity for clinical outcomes at follow-up. Some evidence for partial mediation of the association of childhood trauma and clinical outcomes via stress reactivity emerged. Taken together, these findings added evidence to the mediated synergy model and highlighted stress reactivity as a promising target mechanism for ecological momentary interventions. In Chapter IV, I investigated the role of threat anticipation in the development of psychopathology. I found evidence that threat anticipation and experiences of early adversity were associated with psychopathology. In addition, 184 I observed mediation effects for the association between early adversity and psychopathology via pathways through threat anticipation. This suggests the relevance of threat anticipation as a putative transdiagnostic mechanism linking early adversity with psychopathology that may be targeted by prevention and intervention approaches. In line with the third goal, Chapter V presented an intervention manual for a hybrid compassion-focused intervention targeting putative transdiagnostic candidate mechanisms such as stress reactivity and threat anticipation in youth with early mental health problems (i.e., EMIcompass) and provided promising initial evidence on the intervention’s reach. In Chapter VI, I explored putative therapeutic mechanisms of change in the EMIcompass intervention. I did not detect initial signals of a mediation of the effect of experimental condition on clinical outcomes at follow-up via putative therapeutic mechanisms. However, results show that, if targeted successfully, change in self-compassion and emotion regulation may be promising targets for intervention and prevention approaches. To explore personalised intervention trajectories including context factors, Chapter VII presented a realist evaluation of the implementation of EMIcompass. Qualitative results indicated that the EMIcompass intervention worked by strengthening participants’ soothing system and improved their well-being. In addition, there was evidence indicating that the intervention may even improve the functioning of participants’ drive system. The digital delivery format was perceived as facilitating the translation into daily life and lowering the burden of, and barriers to, treatment. The findings may inform the development and implementation of future digital mental health interventions in general and future versions of EMIcompass in particular.