The Danish Region Midt Schizophrenia Cohort - Representative, long-term follow-up of first-episode schizophrenia spectrum disorder.

Abstract

Introduction: Schizophrenia spectrum disorders (SSD) are complex illnesses influenced by genetic, biological and psycho-social factors, necessitating large clinical deep-phenotyped cohorts. Here, we describe the Region Midt Schizophrenia (RMS) Cohort, which aims to establish such a large, representative cohort with long-term follow-up, enabling large-scale studies on SSD etiology and prognosis.

Methods: The RMS cohort includes patients aged ≥15 years diagnosed with a first-episode SSD recruiting at 6 Danish psychiatric hospitals. Baseline and follow-up assessments at 1, 2, 3, and 12 months and 2, 3, 5, and 10 years cover sociodemographic measures, psychotic and negative symptoms, adverse childhood experiences (ACEs), level of functioning, sleep, actigraphy, cognition, side effects, and medication adherence. Blood is collected at baseline and months 3 and 12 and at years 2, 3, 5 and 10 enabling comprehensive molecular analyses, e.g. genetics and omics. Age- and sex-matched healthy controls will complete a baseline assessment including blood draw. Participants give informed consent for linkage with Danish nationwide register-based data.

Status and perspectives: By February 23rd, 2026, a total of 131 participants with SSD have been recruited (109 with schizophrenia, median age 25 years (IQR 8), 54% females). Retention rates at 1, 2, 3 and 12 months are 86%, 80%, 78%, and 75%, respectively. Our vision is continuous recruitment of 100 participants/year, establishing a large, deep-phenotyped, and representative clinical cohort with long-term follow-up. The RMS cohort will serve as the basis for several studies on etiological and prognostic factors and is designed to match with similar international cohorts enabling further collaborations.

Ethics and dissemination: The protocol has been approved by the ethics committee of the Central Denmark Region (reference: 1-10-72-147-23). Study findings will be published in peer-reviewed journals independent of whether they are positive, negative, or inconclusive, and will be presented at national and international conferences.