Objective:
     
     This study aims to assess research trends in the association between schizophrenia and autoimmune diseases, systematically review their relationship, and evaluate the credibility of existing evidence.
   

Methods:
     
     Bibliometric analysis was conducted using the bibliometrix package in R, along with VOSviewer and CiteSpace. Relevant systematic reviews and meta-analyses were retrieved from six databases: PubMed, Web of Science, Embase, CINAHL, PsycINFO, and the Cochrane Library. Summary risk estimates were recalculated using the DerSimonian and Laird method under a random-effects model, and the credibility of the evidence was assessed.
   

Results:
     
     The bibliometric analysis found that "meta-analysis" has become a frequently used keyword and may be a focal point for future research. The umbrella review included 17 articles, containing 24 report data points from 12 quantitative reviews. Results indicated that 9 reports assessed the relationship between schizophrenia and autoimmune diseases. Schizophrenia was significantly associated with autoimmune neurological disorders (RR = 1.42; 95 % CI = 1.18-1.72), providing suggestive evidence. Seven reports evaluated the impact of schizophrenia on autoimmune diseases, showing highly suggestive evidence that schizophrenia patients had a pooled relative risk of 2.22 (95 % CI = 1.95-2.52) for psoriasis. Eight reports assessed the impact of autoimmune diseases on schizophrenia, with bullous pemphigoid patients showing significantly higher schizophrenia prevalence (OR = 2.63; 95 % CI = 2.03-3.39).
   

Conclusions:
     
     This study synthesizes evidence of varying levels, highlighting the association between schizophrenia and autoimmune diseases. It offers new insights for future exploration, fosters interdisciplinary collaboration, and provides valuable implications for public health policy development.