Differentiation between anti-CASPR2 encephalitis with initial psychiatric symptoms and primary psychiatric disorders, and a diagnostic prediction model: a prospective descriptive study.

BACKGROUND

Anti-contactin-associated protein-like 2 (anti-CASPR2) encephalitis is highly susceptible to misdiagnosis as a primary psychiatric disorder when isolated psychiatric symptoms occur in its early stage.

METHODS

Data on patients with acute or subacute psychiatric symptoms from January 2023 to March 2024 were collected and divided into an anti-CASPR2 encephalitis group (case group) and a primary psychiatric disorder group (control group). The differences between the two groups were evaluated, and logistic regression analysis was conducted to identify significant predictors of anti-CASPR2 encephalitis. Receiver operating characteristic (ROC) curve and decision curve analysis were used to evaluate the predictive performance and clinical utility of the anti-CASPR2 encephalitis model.

RESULTS

The study included 18 patients with anti-CASPR2 encephalitis and 14 with primary psychiatric disorders. Patients in the case group were older on average and had a shorter onset time compared to the control group (P < 0.05). The case group reported fewer social life events and had a higher prevalence of positive cranial magnetic resonance imaging (MRI) findings and serum CASPR2 antibodies (P < 0.05). Binary logistic regression identified older age, shorter onset time and abnormal cranial MRI findings as independent risk factors for anti-CASPR2 encephalitis. The predictive model demonstrated high concordance with clinical observations and strong clinical utility.

CONCLUSION

Anti-CASPR2 encephalitis is more likely to occur in elderly patients with an acute onset, fewer social stressors, and abnormal cranial MRI findings. This diagnostic prediction model provides a reliable tool for the early differentiation between anti-CASPR2 encephalitis and primary psychiatric disorders.