The prevalence of autoimmune encephalitis in patients presenting with first-episode psychosis

Abstract

Background: Psychosis, a broad heterogeneous syndrome characterised by delusions and hallucinations, has a life-time prevalence of 3%. Usually, no organic cause is identified and the clinical outcome is highly variable. Recently, autoimmune anti-neuronal encephalitis has been identified as a cause of psychosis although the prevalence is undetermined. Objectives: To assess the prevalence of autoimmune encephalitis in patients admitted to hospital for management of their first episode of psychosis. Methods: Between 28 July 2013 and 13 May 2015, all patients aged between 12 and 50 years of age admitted to the Royal Brisbane and Women's Hospital or the Queensland Children's Hospital mental health services for their first presentation of psychosis were tested for anti-neuronal antibodies. Where patients were positive for plasma antibodies, neurological and immunological consultation and investigations determined the significance of the antibodies in these patients. Findings: During the study, 151 patients were admitted and 116 consented to participate. Five patients were found to have anti-neuronal antibodies from plasma samples. Subsequent neurology review determined that four of these patients had an autoimmune encephalitis (N-methyl-d-aspartate-receptor [NMDAr] encephalitis, n = 3; and voltage-gated potassium channel [VGKC] antibody encephalitis; n = 1) and their care subsequently involved immunemodulatory therapy and tumour resection (n = 2) rather than psychiatric care. Conclusions: Between 3% and 4% of patients admitted for a first episode of psychosis had a neuronal autoimmune disorder. Early identification of these patients and referral for appropriate treatment is critical to optimise recovery.L6116370642016-08-16 <br />