The Relevance of Autoimmune Encephalitis and Autoimmune Psychosis in Psychiatry

Autoimmune encephalitis (AE) remains an essential differential diagnosis in Psychiatry. While this condition is rare, psychiatrists must be aware of its relevant fundamental, clinical, and therapeutic aspects. Among the various AE subtypes, research focused on anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis given its strong association with psychiatric features. During the early stage, most of the patients with anti-NMDAR encephalitis have isolated or predominant psychiatric features. While only a minority of the cases remain purely psychiatric, numerous researchers consider the need to establish a new diagnostic category of autoimmune psychosis (AP). This novel concept led to a plethora of studies searching for neural antibodies in psychiatric patients. However, the lack of clear conclusions perpetuates the ongoing debate and highlights the increasing relevance of AE to Psychiatry. This also raises new and old questions. The consensus definition of AP closely follows previous AE criteria but emphasizes pure psychiatric syndromes with mild neurological signs. The high prevalence of neurological soft signs in both schizophrenic and affective spectrum disorders complicates the use of mild neurological signs as diagnostic criteria in psychiatric samples. The field of AE has recently faced an unexpected increase in diagnosed patients. Initially, the diagnosis was limited to primary neurological cases, but it has since expanded to include an increasing number of primary psychiatric cases. As a result, there is now a broad overlap between AE and AP, which has led to discussions about the diagnostic criteria for patients with pure or predominant psychiatric syndromes. It is interesting to note that the current diagnostic criteria for both AE and AP do not necessarily require any previously established neuroinflammation criteria. Instead, the diagnosis can be made based on the prevalence of specific central nervous system antibodies, primarily found in cerebrospinal fluid, in the context of a clinical and paraclinical evaluation.

While a broader approach can be assumed, this Research Topic aims to tackle the most relevant aspects of AE for psychiatrists:
● the link between the pathogenesis of anti-NMDAR encephalitis and the glutamate hypothesis of schizophrenia, which could provide essential insights into the pathogenesis, neurobiology, and treatment of psychosis;
● the psychiatric features of AE during the early stages of the disease, with a focus on the existing screening approaches, the validity of existing criteria for AE and AP, and potential specific psychiatric phenotypes;
● symptomatic treatment and behavioral management of patients with AE;
● to evaluate similarities and differences between AE and AP, including in timeline perspective of clinical symptoms, epidemiological aspects, and by the validity of used diagnostic parameters; this includes a timeline scenario of change from early to advanced stages of the disease and in relation to prevalence of neurological soft signs in so-called primary psychiatric disorders;
● diagnostic methods in AE and AP.

By addressing these fundamental, clinical, and therapeutic aspects, this Research Topic aims to improve psychiatrists' understanding of AE and AP. We welcome all types of papers emphasizing the relevant aspects of AE and AP in Psychiatry, mainly Original Research, Review, and Systematic Review papers. In addition, we welcome Opinion, Perspective, and Case Report papers if they provide valuable insights into the discussion.

Keywords: autoimmune encephalitis, anti-nmda receptor encephalitis, autoimmune psychosis, neural antibodies, first-episode psychosis

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