Transdiagnostic approaches to mental health: linking adversity, cognition, candidate mechanisms, and novel digital interventions

Mental disorders are not natural kinds, and reductionist perspectives may obstruct progress in mental health research. This thesis took a transdiagnostic approach to mental health and found (1) that the jumping to conclusions reasoning bias (i.e., the tendency to make hasty decisions based on insufficient information) may play a role in the development and persistence of a transdiagnostic psychosis phenotype in the general population, (2) that individuals' stress sensitivity in daily life may form a transdiagnostic mechanism involved in linking adverse childhood experiences (i.e., childhood trauma, negative life events, bullying victimization) and various mental health problems in young service users, and (3) that social isolation may have been a significant factor impacting youth mental health during active lockdown in the COVID-19 pandemic. In addition, the dissertation synthesised the available evidence on digital interventions, such as smartphone-based mobile health (mHealth) interventions, internet-based (eHealth) interventions, and virtual-reality (VR) interventions, in diverse non-clinical and clinical settings. The findings indicate that eHealth, mHealth, and VR interventions developed and evaluated by research groups signal great promise in terms of their safety, acceptability, and effectiveness, especially when they are embedded in social and therapeutic contexts (e.g., peer-support, blended care).