IntroductionMany gaps exist in our understanding of the developmental pathways to severe mental illness (SMI), including borderline personality disorder (BPD) and psychosis. However, those who have experienced adverse childhood experiences (ACEs) are at an increased risk and there is evidence to suggest that one of the earliest markers is emotional dysregulation. An area which has received relatively less research attention is the role neurodevelopmental disorders (NDDs) play. The aim of this feasibility study was therefore to explore the clinical profiles of young people early in the course of SMI, including their profiles of ACEs, emotional regulation difficulties, borderline personality traits and NDDs.MethodsA cross-sectional study of young people (aged 15–25) at risk of SMI, currently being seen within NHS mental health services, was conducted. This included those with early symptoms of psychosis and/or BPD as assessed by diagnostic interview. Eligible participants self-completed a battery of sociodemographic, clinical, and psychological measures in the company of a researcher. This included assessments of: symptoms of NDDs; borderline pathology traits; ACEs; and difficulties in emotional regulation. Statistical analyses included Mann–Whitney U tests and multiple regression.ResultsOf the 118 potentially eligible participants who were referred, 48 were ultimately included in the study. Young people early in the course of SMI reported a high prevalence of ACEs and deficits in emotional regulation. In total, 79% met criteria for attention deficit hyperactivity disorder (ADHD) and/or autism spectrum disorder (ASD). Emotional dysregulation was found to significantly mediate the association between both ACEs and the frequency of NDDs and borderline personality traits, however given the small sample size these results are preliminary in nature.ConclusionYoung people early in the course of SMI are at an increased risk of experiencing multiple childhood adversities and our results indicate a high prevalence of NDDs amongst them. Emotional dysregulation emerged as a potentially significant early marker of future clinical severity. We suggest that the clinical implications of our findings include routine screening for NDDs and ACEs and an increased recognition of the significance of emotional dysregulation. However, larger scale longitudinal studies are needed to investigate these preliminary findings further.