Exploring the nature, development and effects of complex emotions in Sheffield and Plymouth, UK: a longitudinal mixed methods study protocol

Abstract: Complex emotions include difficulties with emotional regulation, impulsivity, identity, relationships and functioning. These experiences are often construed as borderline personality disorder, a highly stigmatised diagnosis. We will use a transdiagnostic approach to investigate the nature, course and lived experience of complex emotions, with lived experience involvement embedded throughout the programme. We aim to (1) model symptom and functional trajectories to identify subgroups with distinct needs; (2) elucidate mechanisms underlying outcomes, including interactions with social, cultural and environmental factors; (3) investigate associations between complex emotions and physiological and behavioural measures; and (4) integrate findings to inform interventions and service delivery.