title: Prevalence of elevated serum anti-N-methyl-D-aspartate receptor antibody titers in patients presenting exclusively with psychiatric symptoms: a comparative follow-up study.
abstract: Increasing numbers of patients with elevated anti-N-methyl-D-aspartate (NMDA) receptor antibody titers presenting exclusively with psychiatric symptoms have been reported. The aim of the present study was to clarify the prevalence of elevated serum anti-NMDA receptor antibody titers in patients with new-onset or acute exacerbations of psychiatric symptoms. In addition, the present study aimed to investigate the association between elevated anti-NMDA receptor titers and psychiatric symptoms.
  
  
  
  The present collaborative study included 59 inpatients (23 male, 36 female) presenting with new-onset or exacerbations of schizophrenia-like symptoms at involved institutions from June 2012 to March 2014. Patient information was collected using questionnaires. Anti-NMDA receptor antibody titers were measured using NMDAR NR1 and NR2B co-transfected human embryonic kidney (HEK) 293 cells as an antigen (cell-based assay). Statistical analyses were performed for each questionnaire item.
  
  
  
  The mean age of participants was 42.0 ± 13.7 years. Six cases had elevated serum anti-NMDA antibody titers (10.2 %), four cases were first onset, and two cases with disease duration >10 years presented with third and fifth recurrences. No statistically significant difference in vital signs or major symptoms was observed between antibody-positive and antibody-negative groups. However, a trend toward an increased frequency of schizophrenia-like symptoms was observed in the antibody-positive group.
  
  
  
  Serum anti-NMDA receptor antibody titers may be associated with psychiatric conditions. However, an association with specific psychiatric symptoms was not observed in the present study. Further studies are required to validate the utility of serum anti-NMDA receptor antibody titer measurements at the time of symptom onset.
authors.affiliation: Department of Neurology, Haga Red Cross Hospital, 2461 Daimachi, Moka, Tochigi, 321-4306, Japan. yacht-po@jichi.ac.jp.|Division of Neurology, Department of Internal Medicine, Jichi Medical university, Shimotsuke, Tochigi, Japan. yacht-po@jichi.ac.jp.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Ando
authors.affiliation: Division of Neurology, Department of Internal Medicine, Jichi Medical university, Shimotsuke, Tochigi, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Shimazaki
authors.affiliation: Department of Psychiatry, Jichi Medical University, Shimotsuke, Tochigi, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Shiota
authors.affiliation: Department of Neurology, International University of Health and Welfare Hospital, Nasushiobara, Tochigi, Japan.
authors.forename: Syuichi
authors.initials: S
authors.lastname: Tetsuka
authors.affiliation: Department of Neurology, Junwakai Memorial Hospital, Miyazaki, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakao
authors.affiliation: Department of Psychiatry, Tochigi Prefectural Okamotodai Hospital, Utsunomiya, Tochigi, Japan.
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Shimada
authors.affiliation: Department of Psychiatry, Jichi Medical University, Shimotsuke, Tochigi, Japan.|Department of Psychiatry, Tochigi Prefectural Okamotodai Hospital, Utsunomiya, Tochigi, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kurata
authors.affiliation: Department of Psychiatry, Tochigi Prefectural Okamotodai Hospital, Utsunomiya, Tochigi, Japan.
authors.forename: Jinichi
authors.initials: J
authors.lastname: Kuroda
authors.affiliation: Department of Psychiatry, Sato Hospital, Yaita, Tochigi, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yamashita
authors.affiliation: Department of Psychiatry, Sato Hospital, Yaita, Tochigi, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Sato
authors.affiliation: Department of Psychiatry, Jichi Medical University, Shimotsuke, Tochigi, Japan.|Department of Psychiatry, Kamitsuga General Hospital, Kanuma, Tochigi, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Psychiatry, Kamitsuga General Hospital, Kanuma, Tochigi, Japan.
authors.forename: Shinkichi
authors.initials: S
authors.lastname: Eto
authors.affiliation: Department of Psychiatry, Oyama Fujimidai Hospital, Shimotsuke, Tochigi, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Onishi
authors.affiliation: Department of Life Science, Medical Research Institute and Department of Neurology, Kanazawa Medical University, Uchinada, Ishikawa, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Department of Psychiatry, Jichi Medical University, Shimotsuke, Tochigi, Japan.|Department of Psychiatry, Oyama Fujimidai Hospital, Shimotsuke, Tochigi, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kato
mesh_terms: D000328:Adult; D060426:Anti-N-Methyl-D-Aspartate Receptor Encephalitis / Q000097:blood / Q000150:complications* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016194:Receptors, N-Methyl-D-Aspartate / Q000276:immunology*; D012559:Schizophrenia / Q000097:blood / Q000209:etiology* / Q000276:immunology; D016036:Seroepidemiologic Studies
chemical_list: D001323:Autoantibodies; D016194:Receptors, N-Methyl-D-Aspartate
keywords: Anti-N-methyl-D-aspartate receptor antibody; Human embryonic kidney 293 cell; Prospective study; Psychiatric symptom; Schizophrenia