Refining the psychiatric syndrome of anti‐N‐methyl‐d‐aspartate receptor encephalitis

Objective To review the psychiatric symptoms of anti‐N‐methyl‐d‐aspartate (NMDA) receptor encephalitis, in an attempt to differentiate the presentation from a primary psychiatric disorder. Method A systematic literature review of PubMed and EMBASE of all published cases of anti‐NMDA receptor encephalitis was performed from inception to January 2018. Results There were 706 cases of anti‐NMDA receptor encephalitis identified. Cases were typically young (mean age 22.6 years, SD 14.8), female (F : M ratio 3.5 : 1) and presented with significant behavioural disturbance. Reported behaviour was most commonly severe agitation and aggression, abnormal speech, and catatonia. Psychosis occurred in 45.8% of cases. Investigation results were inconsistent (MRI abnormal in 35.6%, EEG abnormal in 83.0%) and non‐specific. Psychiatric treatment often required multiple psychotropics, and there may be increased risk of significant side‐effects such as neuroleptic malignant syndrome. Prognosis was usually good; however, cognitive and behavioral symptoms remained prominent during recovery, and psychiatrist involvement was required in this period. Conclusion The presentation of anti‐NMDA receptor encephalitis is variable. However, there are often psychiatric features which are atypical to a primary psychiatric illness, such as severe agitation, speech abnormalities, and catatonia, which may help early identification.