NMDA Receptor Encephalitis May Present As a Pure Psychiatric Episode

NEJM Journal Watch:

NMDA Receptor Encephalitis May Present As a Pure Psychiatric Episode

Clinicians need to be aware of this unusual presentation.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, which can present as a schizophrenic or depressive disorder, is rare and is diagnosed by the presence of immunoglobulin G antibodies to the NR1 subunit of the NMDAR. These researchers examined the occurrence of pure psychiatric syndromes at disease onset or relapse in 571 patients diagnosed with NMDAR encephalitis.

In this group, 23 (4%; median age, 20) presented with isolated psychiatric syndromes €” 5 at the first episode of NMDAR encephalitis, and 18 during a relapse. Twenty-one patients were women, 10 of whom had an underlying ovarian teratoma. Magnetic resonance imaging of the brain was abnormal in 10 patients, and 17 had elevated lymphocytic pleocytosis in cerebrospinal fluid. The predominant clinical picture was psychosis with a mood disorder: 17 patients were delusional, 10 had hallucinations, 13 were aggressive, and 11 were manic. Of the 23 patients, 19 had full or substantial recovery after treatment with immunotherapy and, where appropriate, removal of the teratoma. Psychiatric medications were utilized as necessary to control symptoms.


New-onset psychosis can be a presenting symptom of NMDAR encephalitis. Young women are at greater risk than men, with illness often due to a previously undiagnosed ovarian teratoma. Subtle neurological signs (tics, isolated movement disorders) or abnormalities on electroencephalography or imaging should increase suspicion. Diagnosis is made with serum NR1 IgG antibodies, but in 15% of cases, this test has negative results, requiring testing of cerebrospinal fluid (Lancet Neurol 2013; 12:157) [PubMed ® abstract]. General screening is not indicated, but awareness is warranted.

Jonathan Silver, MD reviewing Kayser MS et al. JAMA Neurol 2013 Jul 22.


Kayser MS et al. Frequency and characteristics of isolated psychiatric episodes in anti €“N-methyl-D-aspartate receptor encephalitis. JAMA Neurol 2013 Jul 22; [e-pub ahead of print]. [PubMed ® abstract]

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