Abstract
OBJECTIVE: : Autoimmune encephalitis (AE) remains an essential differential diagnosis in patients with first-episode psychosis (FEP). In this study, we aimed to assess to prevalence of AE in a cohort of FEP patients. METHODS: : We used a phenotype-driven algorithm to detect AE in patients with FEP. Initially, we screened patients for warning signs with a low or high pre-test probability for AE, defined as "yellow" and "red flags", respectively. In the next step, patients with red flags underwent cerebrospinal fluid analysis (including neural antibodies), while patients with yellow flags underwent tests for serum neural antibodies, electroencephalography, and brain magnetic resonance imaging. RESULTS: : We screened 78 patients with FEP and found that eight (10.3%) had at least one warning sign for AE: four (5.13%) patients had at least one red flag, while four (5.13%) had only yellow flags. Among these, two patients (2.56%) had anti-N-methyl-D-aspartate receptor encephalitis, while the remaining six (7.69%) received a primary psychiatric disorder diagnosis. CONCLUSION: : Our study highlights the importance of considering AE in the differential diagnosis of FEP.