Exploring the bidirectional causal relationship between Autism Spectrum Disorder and Schizophrenia using Mendelian randomization.

This study looked at whether autism and schizophrenia are genetically linked by analyzing DNA data from large studies. The researchers found that having autism increases the risk of developing schizophrenia, and having schizophrenia increases the risk of developing autism. This suggests these conditions share some common genetic factors and may influence each other's development.

This Mendelian randomization study examined the bidirectional causal relationship between Autism Spectrum Disorder (ASD) and Schizophrenia (SCZ) using genetic data from large-scale genome-wide association studies. The researchers analyzed summary data from the IEU GWAS database for ASD and the Psychiatric Genomics Consortium for SCZ in European populations. The study found evidence of bidirectional causality, with ASD increasing risk for SCZ (OR: 1.19, 95% CI: 1.12-1.26, P < .001) and SCZ increasing risk for ASD (OR: 1.12-1.14 across different datasets, P = .002-.003). This suggests each condition may contribute to the development of the other, providing new insights into shared genetic mechanisms and potential common pathways in their etiology.

Results suggest clinicians should monitor for psychotic symptoms in autistic individuals and assess for autism features in people with schizophrenia. May inform development of shared therapeutic targets and integrated assessment protocols for both conditions.

Study limited to European populations, reducing generalizability. Sample sizes not reported for individual analyses. Mendelian randomization assumptions may not hold completely. Cannot establish specific mechanisms underlying the bidirectional relationship or timing of onset.

Autism Spectrum Disorder (ASD), characterized mainly by stereotyped behaviors and social impairments, affects about one in 100 children worldwide. Schizophrenia (SCZ), a chronic mental illness, affects 1% of the global population. The pathogenesis and specific treatment strategies for ASD and SCZ remain unclear. Previous research has suggested similarities in SCZ and ASD etiology and symptoms.

However, no definitive correlation has been confirmed. Therefore, we conducted a Mendelian randomization study to assess the relationship between SCZ and ASD, providing new insights into their etiology and treatment. We used the two-sample Mendelian randomization (TSMR) approach to investigate the bidirectional causal association between SCZ and ASD, employing summary-level genome-wide association studies (GWAS) data. ASD summary data from the IEU GWAS database and SCZ summary data from the Psychiatric Genomics Consortium (PGC) were used as exposure and outcome variables, respectively.

Statistical analysis was performed using the TwoSampleMR package in R version 4.3.2, with sensitivity analysis conducted to verify the result's reliability. Based on the results of the MR analysis, we retrieved and analyzed the relevant genetic information from the GWAS Catalog. TSMR analysis revealed higher ASD risk in SCZ (IVW: OR: 1.19, 95% CI: 1.12-1.26, P < .001). Bidirectional MR analysis confirmed a causal relationship between ASD and SCZ (IVW: scz2018clozuk (Clozapine UK), OR: 1.12, 95% CI: 1.04-1.21, P = .003; scz2019asi, OR: 1.14, 95% CI: 1.05-1.23, P = .002).

Our study demonstrated a bidirectional relationship between SCZ and ASD in the European population, suggesting that each may induce the onset of the other.