On the Possible Relationship Between Anti-Streptolysin-O Titer and Neuropsychiatric Disorders Other than PANS.

Abstract

[Author Affiliation]Marco Pozzi. 1 Istituto Di Ricovero e Cura a Carattere Scientifico ( IRCCS) Eugenio Medea, Lecco, Italy.Simone Pisano. 2 Department of Medicine and Public Health, Second University of Naples, Naples, Italy.Silvana Bertella. 1 Istituto Di Ricovero e Cura a Carattere Scientifico ( IRCCS) Eugenio Medea, Lecco, Italy.Paola Lombardi. 2 Department of Medicine and Public Health, Second University of Naples, Naples, Italy.Paolo Pellegrino. 3 Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences L. Sacco, Luigi Sacco University Hospital, Universita di Milano, Milan, Italy.Massimo Molteni. 1 Istituto Di Ricovero e Cura a Carattere Scientifico ( IRCCS) Eugenio Medea, Lecco, Italy.Emilio Clementi. 1 Istituto Di Ricovero e Cura a Carattere Scientifico ( IRCCS) Eugenio Medea, Lecco, Italy. 4 Unit of Clinical Pharmacology, National Research Council ( CNR) Institute of Neuroscience, Department of Biomedical and Clinical Sciences L. Sacco, Luigi Sacco University Hospital, Universita di Milano, Milan, Italy.Carmela Bravaccio. 5 Department of Translational Medical Sciences, University Federico II of Naples, Naples, Italy.Sonia Radice. 3 Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences L. Sacco, Luigi Sacco University Hospital, Universita di Milano, Milan, Italy.* The first two authors contributed equally.Funding: This work was supported by Agenzia Italiana del Farmaco (AIFA) and by the Italian Ministry of Health (Ricerca Corrente 2015, to E.C.). The funding public institutions had no role in any part of the work.Address correspondence to: Emilio Clementi, PhD, Department of Biomedical and Clinical Sciences, University of Milano, Via GB Grassi 74, 20157 Milano, Italy, E-mail: emilio.clementi@unimi.itTo The Editor:Renewed interest in the relationship between autoimmune diseases and psychiatric disorders has been raised by a recent consensus paper describing pediatric acute-onset neuropsychiatric syndrome (PANS) (Chang et al. 2014), which also includes the previously known pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) (Swedo et al. 1998). Although the diagnostic process is still debated and differential diagnosis may be challenging, several features of both disorders have been described. PANDAS is characterized by an infection-mediated (by group A-β hemolytic Streptococcus) abrupt, dramatic onset of neuropsychiatric symptoms mainly including, but not limited to, tics and obsessive-compulsive behaviors, whereas PANS may be caused by several triggers, not only postinfectious ones, and may present, together with obsessive-compulsive behaviors, with the predominant feature of acute-onset food refusal, rather than tics (Murphy et al. 2014). Anti-streptolysin O (ASO) titration is supportive of the diagnosis of PANDAS or PANS, and should be performed when they are suspected (Kiessling et al. 1993; Murphy et al. 2015; Pozzi et al. 2014). In the case of isolated measurements, the diagnostic threshold has been set at 400 U/mL, whereas the normality threshold is generally 200 U/mL, although it may be adjusted by age (Chang et al. 2014). It is also known that elevated ASO titers may be linked with a plurality of conditions that are not always pathological; however, scant data are available on the possible association of group A Streptococcus and ASO titers with the occurrence of neuropsychiatric manifestations other than Sydenham's chorea and PANDAS or PANS (Pozzi et al. 2014).Autoimmunity-based etiological hypotheses are increasingly being probed for neuropsychiatric diseases, such as autism spectrum disorders (ASD) (Keil et al. 2010). We have explored the distribution of ASO titers in a wide pediatric neuropsychiatric population, aiming to check for differences among groups of patients with different psychiatric diagnoses. …