Bechter, K. (2013). "Updating the mild encephalitis hypothesis of schizophrenia." Prog Neuropsychopharmacol Biol Psychiatry 42: 71-91.

Bechter, K. (2013). "Virus infection as a cause of inflammation in psychiatric disorders." Mod Trends Pharmacopsychiatri 28: 49-60.

Endres, D., et al. (2019). "Psychiatric Presentation of Anti-NMDA Receptor Encephalitis." Front Neurol 10: 1086.

Foucher, J. R. and V. Bennouna Greene (2010). "La CIM et le DSM ou l’impossible validation : pourquoi le ver est dans le fruit." Annales médico-psychologiques.

Stöber, G., et al. (1992). "The role of maternal infectious diseases during pregnancy in the etiology of schizophrenia in offspring."

Wright, P., et al. (1995). "Maternal influenza, obstetric complications, and schizophrenia." Am J Psychiatry 152(12): 1714-1720.

Report

Viral infections, neurodegenerative & psychiatric diseases: an arduous search for clues …

Viruses & schizophrenia

“Schizophrenia” is a name that defines an etiologically heterogeneous disorder with probable multiple and complex pathophysiological mechanisms which remain however poorly defined. As such, the classification of psychosis remains highly matter of debate[1]. Nevertheless, despite different methodological and clinical approaches, several epidemiological studies have described a tight link between maternal infections and risk of schizophrenia in the offspring in a subtype of schizophrenic patients (Stöber, Franzek et al. 1992, Wright, Takei et al. 1995). Several pathogens are suspected to exert potential deleterious effects following an infection during pregnancy. These include bacteria, the single-cell protozan parasite Toxoplasma gondii as well as several viruses, among which the herpes simplex and the influenza virus. A study in a sample of 80 patients and 80 matched control subjects revealed that “the monthly distribution of gestational infections in the mothers of schizophrenic patients … was significantly different from the comparison group” (Stöber, Franzek et al. 1992). The rate of infection in both the mothers of control subjects and the mothers of schizophrenic patients was similar. However, the mothers of schizophrenic patients reported more infections during the second trimester, especially during the fifth month of gestation. Influenza and respiratory infections were the most frequent, accounting for up to 70% of the second-trimester infections (Stöber, Franzek et al. 1992, Wright, Takei et al. 1995). Other studies on the 1957 type A2 influenza epidemic have reported some association between exposure to the epidemics during the second trimester of fetal life and schizophrenia. The low level neuroinflammation found in a subpopulation of schizophrenic patients has led to the “Mild Encephalitis” hypothesis which states that such inflammation might indeed constitute the core mechanism underlying the pathophysiology of a subgroup of severe psychiatric disorders, potentially after viral infection (Bechter 2013, Bechter 2013). Recently, the case of a young woman who developed an acute polymorphic psychotic episode following a a booster vaccination against tetanus, diphtheria, pertussis, and polio (Tdap-IPV) has been reported (Endres, Rauer et al. 2019). The authors (Department of Psychiatry & Psychotherapy, University of Freiburg) diagnosed an Anti-N-methyl D-aspartate (NMDA) receptor autoimmune encephalitis probably responsible for the neuropsychiatric syndrome. Viral infections have been shown to trigger autoimmune reactions. In addition, it is suspected that virus-induced neuroinflammation can trigger antibody formation as well. While herpes simplex is the main suspect in this context, other viruses (varicella zoster, for example) may also potentially trigger the encephalitic autoimmune response. Vaccinations may also play a role as unspecific triggers, as illustrated by the study of (Endres, Rauer et al. 2019). Last, but not least, let’s remind the cases of first episode of psychosis with psychopathology relating to COVID 19 reported last May (2020) for 2 women who presented to an academic psychiatric centre in Bangalore, India (Chandra, Shiva et al. 2020). (see § What about the neurological and psychiatric effects of SRAS Cov2?)

[1] [For further details on this issue, refer to the comments by Prof Ludger Tebartz van Elst (Department of Psychiatry & Psychotherapy, University of Freiburg) and by Dr Jack Foucher (University Hospital Strasbourg & Circle of Excellence on Psychosis) in Neurex newsletter 31 and to Foucher, J. R. and V. Bennouna Greene (2010).

Conclusion : SARS Cov2, a time bomb for neurological and psychiatric disease?

Even though the long term effects of SARS Cov2 infection are highly speculative at the moment, several hints constitute a significant warning for the clinical and scientific community to assess 1. the middle term and late effects of Covid 19 (Serrano-Castro, Estivill-Torrús et al. 2020) and 2. The links between viruses and nervous system function in general.