Transsyndromic Trajectories From Pre-Onset Self-Harm and Subthreshold Psychosis to the First Episode of Psychosis: A Longitudinal Study

Across subthreshold psychotic and nonpsychotic syndromes, symptoms experienced before the onset of a first episode of psychosis (FEP) may index distinct illness trajectories. We aimed to examine the associations between three types of pre-onset symptoms (self-harm, suicide attempts, and subthreshold psychotic) and outcome trajectories during FEP. Participants with FEP were recruited from PEPP-Montreal, a catchment-based early intervention service. Pre-onset symptoms were systematically assessed through interviews with participants (and their relatives) and reviews of health and social records. Over 2 years of follow-up at PEPP-Montreal, 3-8 repeated measures were collected for positive, negative, depressive, and anxiety symptoms, as well as functioning. We applied linear mixed models to examine associations between pre-onset symptoms and outcome trajectories. We found that on average over follow-up, participants with pre-onset self-harm had more severe positive, depressive, and anxiety symptoms compared with other participants (standardized mean differences: 0.32-0.76), while differences in negative symptoms and functioning were not significant. Associations did not differ by gender and remained similar after adjusting for the duration of untreated psychosis, substance use disorder, or baseline diagnosis of affective psychosis. Over time, depressive and anxiety symptoms improved among individuals with pre-onset self-harm, such that they converged with other individuals by the end of the follow-up. Similarly, pre-onset suicide attempts were associated with elevated depressive symptoms that improved over time. Pre-onset subthreshold psychotic symptoms were not associated with outcomes, except for a slightly different trajectory of functioning. Individuals with pre-onset self-harm or suicide attempts may benefit from early interventions that target their transsyndromic trajectories.