LETTERS TO THE EDITORS
Letter 3: PANDAS and the immunologic hypothesis in the obsessive-compulsive disorder
PANDAS y la hipótesis inmunológica en el trastorno obsesivo-compulsivo
Dear Editor,
The subject of PANDAS is indeed a controversial one in the literature, which, happily, gives us the opportunity to discuss new alternative interpretations of psychiatric conditions with the scientific community. The return of psychiatry to medical models has, without doubt, gained force with the introduction of categorical classifications (such as the DSMs and ICDs) and with the introduction of psychopharmaceuticals as important treatment tools. These arrivals have had enormous repercussions on the technological advance of complementary diagnostic approaches (neuroimaging, molecular genetic testing, etc.) and on therapy, which aspects still deserve bigger and better investigations. The study of the etiology of psychiatric diseases, despite everything, still progresses at a crawl. We have little evidence on the causal aspects of psychiatric disorders, with the exception of isolated case histories or postulations based on theory. We are, however, on the right path.
When Galileo, in 1632, defended heliocentrism in Dialogo dei massimi sistemi (Dialogue on the Two Great World Systems), he was put under house arrest by the Inquisition and banned from publishing for defending a hypothesis considered, at the time, absurd and heretical. According to legend, at the point of sentencing Galileu said, "Eppur si muove" (Yet, still it moves). The intention is not to equate the concept of PANDAS with such genius, but, in citing Galileo, to refer to the fact that, at first, new hypotheses will be seen as improbable or impossible.
The scientific method thus makes it possible for both positive and negative findings to occur in relation to the same event, for which reason man resorts to statistics, allowing certain inferences to be true, on the basis of a model of hypothesis formation. These hypotheses often spring from unprepossessing and occasional observations. Unfortunately human observation is subject to bias, such as, for example, the fact that we value the positive factors in a study and devalue negative findings, or the fact that we ignore the totality of variables possibly involved in the hypothesis. Nevertheless we accept that negative results are indispensable to finding out the truth.
The truth is that the relationship between OCD and infectious processes is not so recent as all that. When Esquirol, in 1838 (in Berrios1), classified obsessive phenomena as a form of monomania, he defined it as "a chronic infirmity of the brain, without fever, characterized by partial damage to the intellect, emotions or will." Thus, "&$91;...&$93; the subject finds himself linked with acts that do not originate from his reason or emotions and which are rejected by his conscience and which his will is unable to stop."
Even current evidence that OCD symptoms improve with medication that inhibits seratonin reuptake2,3 could be questioned since the benefits derived from increased serotonin neurotransmission do not necessarily prove that abnormalities in this system are the only cause of OCD symptoms since serotonergic neurons also modulate the functions of several other systems (dopaminergic, noradrenergic, etc.). Therefore, the hypothesis is that each OCD patient, depending upon the neurotransmission system and neuronal pathways that they utilize or that are dysfunctional, (whether because of immunologic or other, unknown, causes), may exhibited a diverse range of symptoms and may respond more or less to any given pharmaceutical or combination of pharmaceuticals or therapeutic strategies. This is evidence of the heterogeneous nature of the disease that we nowadays refer to as OCD. This title, however, could in fact represent a number of different diseases or a single disease with a number of different subtypes. In the same manner, Tourette syndrome could be included in this model.
More research is still needed on the subject of PANDAS, with adequate methodology and sufficient sample sizes, so that we may better understand the complex hypothesis of immunologic etiopathogenesis for psychiatric disorders.
In this spirit, we feel privileged to be given the opportunity for our review article to be read and constructively analyzed, since the stimulus for those entering the art of research has certainly been enriched.
REFERENCES
1. Berrios GE. Historia de los trastornos obsesivos. In: Ruiloba JV, Berrios GE, eds. Estados obsesivos. 2ª ed. Barcelona: Masson; 1995. pp. 1-14.
2. Piccinelli M, Pini S, Bellantuono C. Efficacy of drug treatment in obsessive-compulsive disorders: a meta-analytic review. Br J Psychiatry 1995;166:424-43.
3. Stein DJ, Spadaccini E, Hollander E. Meta-analysis of pharmacoterapy trials for obsessive-compulsive disorder. Int Clin Psychopharmacol 1995;10:11-8.
Ygor Arzeno Ferrão
Graduate Program, School of Medicine, Universidade de São Paulo (USP); Physician, Hospital Psiquiátrico São Pedro, Brazil.
Ramiro Ronchetti
Medical student, Fundação Faculdade Federal de Ciências Médicas de Porto Alegre, Brazil.
Publication Dates
-
Publication in this collection
13 Sept 2005 -
Date of issue
Aug 2004
