NMDA receptor antibody seropositivity in psychosis: A pilot study from the Bipolar-Schizophrenia Network for Intermediate Phenotypes (B-SNIP)

Antibodies against N-Methyl D-Aspartate Receptor in Psychotic Disorders: A Systematic Review

OBJECTIVE

The objective of this study was to provide comprehensive evidence synthesis including all available up-to-date data about the prevalence of N-methyl D-aspartate receptor (NMDAR) antibodies (ABs) in psychotic patients in order to evaluate the clinical relevance of ABs as well as to specify potential explanations of the heterogeneity of the findings and determine areas for further research.

METHODS

A literature search was conducted using the PubMed/Medline, Web of Knowledge, and Scopus databases.

RESULTS

Forty-seven studies and 4 systematic reviews (including 2 meta-analyses) were included in the present review. Studies that used cell-based assays (CBAs) provided heterogeneous results on AB prevalence, obviously depending on the type of detection assay and sample characteristics. Improvement of AB detection methods is necessary to determine the real prevalence of ABs across different groups of patients and healthy people. Live CBAs seem to have better sensitivity but probably poorer specificity than fixed CBAs. Moreover, some links between AB-positive status and acute symptoms are possible. A small amount of data on immunotherapy in AB-positive patients raises the possibility of its effectiveness but obviously require further research.

CONCLUSIONS

NMDAR ABs are definitely present in a subset of psychotic patients. NMDAR ABs might shape psychosis and underlie some symptoms, and immunotherapy might be regarded as a treatment option for patients failing to respond to other therapies.

Screening for pathogenic neuronal autoantibodies in serum and CSF of patients with first-episode psychosis

Patients with autoimmune encephalitides, especially those with antibodies to the N-methyl-D-aspartate receptor (NMDAR), often present with prominent psychosis and respond well to immunotherapies. Although most patients progress to develop various neurological symptoms, it has been hypothesised that a subgroup of patients with first-episode psychosis (FEP) suffer from a forme fruste of autoimmune encephalitis. Without accurate identification, this immunotherapy-responsive subgroup may be denied disease-modifying treatments. Thirty studies addressing aspects of this hypothesis were identified in a systematic review. Amongst other shortcomings, 15/30 reported no control group and only 6/30 determined cerebrospinal fluid (CSF) autoantibodies. To ourselves address these-and other-limitations, we investigated a prospectively ascertained clinically well-characterised cohort of 71 FEP patients without traditional neurological features, and 48 healthy controls. Serum and CSF were tested for autoantibodies against seven neuronal surface autoantigens using live cell-based assays. These identified 3/71 (4%) patient sera with weak binding to either contactin-associated protein-like 2, the NMDAR or glycine receptor versus no binding from 48 control samples (p = 0.28, Fisher's test). The three seropositive individuals showed no CSF autoantibodies and no differences from the autoantibody-negative patients in their clinical phenotypes, or across multiple parameters of peripheral and central inflammation. All individuals were negative for CSF NMDAR antibodies. In conclusion, formes frustes of autoimmune encephalitis are not prevalent among FEP patients admitted to psychiatric care. Our findings do not support screening for neuronal surface autoantibodies in unselected psychotic patients.