Schizophrenia is a severe mental illness characterised by positive symptoms, negative symptoms, and cognitive symptoms. In recent years, an increasing number of doctors and scholars have focused on cognitive symptoms; however, the mechanisms underlying cognitive impairment remain unclear. Recently, exosome research methods have provided new avenues for investigation. This study applies exosome research methods to first-episode, drug-naive schizophrenia patients to explore gene expression changes associated with cognitive impairment and gain a deeper understanding of the mechanisms underlying cognitive impairment. By integrating basic research with clinical findings, we aim to further investigate the molecular mechanisms underlying cognitive impairment in schizophrenia patients, identify potential intervention targets, and provide insights for future drug development.

This single-center, prospective cohort study will enroll 200 drug-naive schizophrenia patients and 100 demographically matched healthy volunteers to identify biological signatures of cognitive impairment and to develop predictive models for subsequent change. At baseline we will administer the MATRICS Consensus Cognitive Battery (MCCB), clinical rating scales, multimodal magnetic resonance imaging (MRI), and collect fasting blood and first-morning urine for multi-omics assays. Participants are re-evaluated at 4, 8 and 12 weeks during naturalistic antipsychotic treatment, repeating cognitive testing, clinical scales, and blood/urine sampling. Primary analyses will link baseline omics to the MCCB overall composite score; secondary analyses will model the longitudinal trajectories of both cognition and biomarkers to derive parsimonious predictors of cognitive gain versus persistent impairment. The resulting biomarker panels are expected to inform future stratified clinical trials and mechanism-based cognitive remediation strategies.

Inclusion Criteria:

• Healthy volunteers matched to the patient group on sex, age, and education level;
• No family history of psychiatric disorders among first- or second-degree relatives (two generations);
• Ethnic Han Chinese;
• Able and willing to provide written informed consent.

Exclusion Criteria:

• Any serious physical illness, including but not limited to uncontrolled hypertension, severe cardiovascular, cerebrovascular, pulmonary, thyroid, or metabolic disease, diabetes, epilepsy, or metabolic syndrome;
• Current or past diagnosis of substance-induced psychotic disorder, delusional disorder, brief psychotic disorder, or mood disorder with psychotic features;
• Pregnancy or breastfeeding;
• Any condition that would interfere with the ability to give informed consent or complete study procedures.

This study will recruit two groups from the outpatient and inpatient services of Tianjin Anding Hospital and surrounding communities in Tianjin, China. The patient cohort will consist of 200 Han Chinese adults aged 18-65 years who are in their first episode of schizophrenia or schizophreniform disorder and have never received antipsychotics or received them for ≤4 weeks lifetime and ≤2 weeks immediately before enrollment. The healthy control cohort will include 100 Han Chinese adults matched to the patient group on sex, age, and education; they must have no personal or family history of major psychiatric disorders and show no cognitive impairment on formal testing.