Anti-NMDAR antibodies in new-onset psychosis. Positive results in an HIV-infected patient.

The role of neuronal surface autoantibodies (NSAs) in non-encephalitic psychosis is of recent and controversial interest. Most of the studies relating NSAs with psychosis are retrospective and only focused on the N-methyl-d-aspartate glutamate receptor (NMDAR). Our goal was to evaluate the prevalence of IgG antibodies against the NMDAR NR1 subunit (NMDAR-Abs) along with five additional NSAs in 61 first psychotic episode patients and 47 matched controls. We found two patients positive for NMDAR-Abs (3.3%). One of them was eventually considered to have been misdiagnosed and reclassified as encephalitis. The other met the criteria for bipolar I disorder, presented no neurological symptoms and had a comorbid HIV infection of vertical transmission. This is the first reported case of an HIV-infected patient with psychosis associated with NSAs. This study shows that patients presenting with clinically incomplete forms of anti-NMDAR encephalitis, with predominant or isolated psychiatric symptoms, can remain undetected if no ancillary tests are performed. To improve patient diagnosis and treatment of individuals with a first psychotic episode, more detailed neurological examinations might be needed. Further studies are required to better clarify the role of NSAs in the neuropsychiatric effects of HIV infection.