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Topic: Neurovascular and neuroinflammation mechanisms

associated with bipolar disorder

Psychotic and nonpsychotic mood disorders in

autoimmune encephalitis: diagnostic issues and

research implications

2
1
3
Giuseppe Quaranta , Nunzio Bucci , Cristina Toni , Giulio Perugi 1,3
1 Department of Experimental and Clinic Medicine, Section of Psychiatry, University of Pisa, 56100 Pisa, Italy.
2 Department of Mental Health, Health District, 74100 Taranto, Italy.
3 Institute of Behavioural Science, G.De Lisio, 56100 Pisa, Italy.

ABSTRA CT

Recent research on autoimmune disorders suggests additional links between systemic and central nervous system (CNS) pathophysiology,
among which the identification of antibody‑induced limbic encephalitis provided the strongest evidence for the potential involvement of
autoimmunity in the pathogenesis of severe mood and psychotic symptoms. In these illnesses, psychiatric symptoms predominate in the
initial phase of the disorder in up to 70% of the cases, and they often lead patients to early psychiatric evaluation. For this reason, it is very
important to increase the limited knowledge among psychiatrists about these autoimmune neuropsychiatric diseases, which can mimic
psychiatric syndromes, in particular, those typically presented in severe mood disorders and schizophrenia. On the other hand, similarities
in clinical presentation suggest that neuroinflammation and systemic immune dysregulation may play a role in the pathophysiology of
severe mood and psychotic disorders. A complex interaction between periphery and immune cells of the CNS may result in cellular
damage through mechanisms involving excitotoxicity, oxidative stress, and mitochondrial dysfunction. These pathways are possibly
shared between comorbid medical disorders and severe mood and psychotic disorders and may reflect common underlying vulnerability.
Key words: Autoimmune encephalitis, mood disorders, psychosis

INTRODUCTION In recent times, the discovery of a range of
autoantibodies acting on specific synaptic sites in
The connection between autoimmunity and the brain has been an important development for
neuropsychiatric symptoms has long been acknowledged, the identification of different forms autoimmune
and William Osler provided a description of psychosis in encephalitis, often characterized by the initial
systemic lupus erythematosus in 1895. The myasthenic psychiatric presentation. The predominance of a
syndromes are good examples of how autoantibodies can psychopathological expression often leads patients
cause neurological symptoms. As another example, to early psychiatric evaluation and treatment.
[1]
[3]
some paraneoplastic syndromes such as cerebellar As a result, in many cases, the correct diagnosis
degeneration or limbic encephalitis (LE) are associated may be delayed because of the limited knowledge
with highly specific antibodies against intracellular among psychiatrists about these autoimmune
neuronal proteins and aggressive cytotoxic T‑cell neuropsychiatric diseases mimicking psychiatric
responses that usually lead to irreversible deficits. [2] syndromes, in particular, severe mood disorders and
schizophrenia. [4‑6] Moreover, the fact that a variety of
Corresponding Author: Dr. Giulio Perugi, Department neuropsychiatric disorders may initially present with
of Experimental and Clinic Medicine, Section of Psychiatry,
University of Pisa, Via Roma 67, 56100 Pisa, Italy. This is an open access article distributed under the terms of the Creative
E‑mail: giulio.perugi@med.unipi.it Commons Attribution‑NonCommercial‑ShareAlike 3.0 License, which allows
others to remix, tweak, and build upon the work non‑commercially, as long as the
Access this article online author is credited and the new creations are licensed under the identical terms.
Quick Response Code: For reprints contact: nn_editor001@nnjournal.net
Website:
www.nnjournal.net
Cite this article as: Quaranta G, Bucci N, Toni C, Perugi G. Psychotic and
nonpsychotic mood disorders in autoimmune encephalitis: diagnostic issues
DOI: and research implications. Neuroimmunol Neuroinflammation 2015;2:228-36.
10.4103/2347-8659.160986
Received: 12-03-2015; Accepted: 13-04-2015

228 © 2015 Neuroimmunology and Neuroinflammation | Published by Hongkong Partner Publishing Co. Limited