title: Prevalence of anti-N-methyl-D-aspartate (NMDA) receptor [corrected] antibodies in patients with schizophrenia and related psychoses: a systematic review and meta-analysis.
abstract: BACKGROUND
  Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an autoimmune condition caused by immunoglobulin (Ig)G antibodies directed against the NR1 subunit of the NMDA glutamate receptor. Approximately 65% of cases present with psychiatric symptoms, particularly psychosis. It remains to be established whether anti-NMDA receptor antibodies can cause a 'purely' psychotic illness without overt neurological symptoms.
  
  
  METHODS
  We conducted a systematic literature search to establish what proportion of patients with schizophrenia and related psychoses have antibodies directed against the NMDA receptor. Studies were included if (a) subjects had a diagnosis of schizophrenia, schizophrenia spectrum disorder or first-episode psychosis (FEP) using standard criteria, (b) serum was analysed for the presence of anti-NMDA receptor antibodies; and (c) the purpose of the study was to look for the presence of anti-NMDA receptor antibodies in patients with a primary psychiatric diagnosis without clinical signs of encephalitis.
  
  
  RESULTS
  Seven studies were included, comprising 1441 patients, of whom 115 [7.98%, 95% confidence interval (CI) 6.69-9.50] were anti-NMDA receptor antibody positive. Of these, 21 (1.46%, 95% CI 0.94-2.23) patients were positive for antibodies of the IgG subclass. Prevalence rates were greater in cases than controls only for IgG antibodies; other subclasses are of less certain aetiological relevance. There was significant heterogeneity in terms of patient characteristics and the antibody assay used.
  
  
  CONCLUSIONS
  A minority of patients with psychosis are anti-NMDA receptor antibody positive. It remains to be established whether this subset of patients differs from antibody-negative patients in terms of underlying pathology and response to antipsychotic treatment, and whether immunomodulatory treatments are effective in alleviating psychotic symptoms in this group.
authors: National Institute for Health Research (NIHR) Biomedical Research Centre, South London and Maudsley NHS FoundationTrust and Institute of Psychiatry, King's College London,UK.
authors: T A
authors: TA
authors: Pollak
authors: National Institute for Health Research (NIHR) Biomedical Research Centre, South London and Maudsley NHS FoundationTrust and Institute of Psychiatry, King's College London,UK.
authors: R
authors: R
authors: McCormack
authors: Department of Immunobiology,King's College London,UK.
authors: M
authors: M
authors: Peakman
authors: Section of Cognitive Neuropsychiatry, Department of Psychosis Studies,Institute of Psychiatry, King's College London,UK.
authors: T R
authors: TR
authors: Nicholson
authors: Section of Cognitive Neuropsychiatry, Department of Psychosis Studies,Institute of Psychiatry, King's College London,UK.
authors: A S
authors: AS
authors: David
mesh_terms: D001323:Autoantibodies / Q000276:immunology*; D006801:Humans; D011618:Psychotic Disorders / Q000276:immunology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000276:immunology*; D012559:Schizophrenia / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D016194:Receptors, N-Methyl-D-Aspartate