Risk factors at the low end of the psychosis continuum: Much the same as at the upper end?

We investigated risk factors for subclinical symptoms of psychosis, and focused on two psychosis dimensions previously identified in the Zurich Study, namely “schizophrenia nuclear symptoms” and “schizotypal signs”. We examined the data from 9814 Swiss conscripts from 2003. The psychosis symptom dimensions were derived from the Symptom-Checklist-90-R (SCL-90-R), and were regressed on a broad range of known risk factors for psychosis. Risk factors typically assigned to schizophrenia and other psychotic disorders – cannabis use, childhood adversity, reading and writing difficulties, attention deficit hyperactivity disorder (ADHD), psychiatric disorders and addiction in parents and the extended family – are relevant also at subclinical levels. Our analyses suggested that specific risk factors may be assigned to distinct psychosis dimensions, as previously determined in an analysis from the Zurich Study. If there are different pathways to psychosis characterized by specific symptom dimensions and risk factors, they mostly co-exist and interact at different symptom load levels.