Diseño a doble ciego y el uso de placebos psicológicos en investigación de resultados en psicoterapia: Es posible? Un estudio piloto de viabilidad

• Published in: Interdisciplinaria Vol. 31; no. 1; pp. 73 - 91
• Main Author: Cazabat, Eduardo H.
• Format: Journal Article
• Language: English; Spanish
• Published: CIIPCA-CONICET 2014; CONICET, Centro Interamericano de Investigaciones Psicológicas y Ciencias Afines
• ISSN: 0325-8203; 1668-7027
• DOI: 10.16888/interd.2014.31.1.5

El uso de placebos y diseños a doble ciego ha cumplido un papel crucial en la investigación clínica en Medicina. Su aplicación a la investigación de resultados en psicoterapia ha sido controversial. Muchos autores niegan la posibilidad de su aplicación debido a que el terapeuta debería conocer la condición del procedimiento aplicado. Se presenta detalladamente un estudio en el que se utilizó un procedimiento placebo correspondiente a EMDR (Eye Movement Desensitization and Reprocessing --Desensibilización y Reprocesamiento por Movimientos Oculares) con un Diseño Experimental de Caso Único. Los objetivos fueron los siguientes: poner a prueba la viabilidad de la implementación de un placebo de tipo psicológico en EMDR y la aplicación de un diseño a doble ciego en el estudio de resultados en EMDR. Se seleccionaron tres pacientes que sufrían de Trastorno por Estrés Postraumático. Se estableció una línea de base de la sintomatología presentada. Luego, los sujetos fueron asignados aleatoriamente a tres condiciones experimentales durante tres sesiones: (a) aplicación del protocolo EMDR sin ningún tipo de estimulación con auriculares en silencio (placebo 1), (b) aplicación del protocolo EMDR con estimulación bilateral auditiva simultánea (no alternada) (placebo 2) y (c) aplicación del protocolo estándar de EMDR con estimulación auditiva bilateral alternada (tratamiento activo). Tales procedimientos resultaron igualmente creíbles para el paciente y para el terapeuta. Esto permitió el desarrollo de un diseño de investigación a doble ciego para la investigación de resultados en EMDR. Finalmente, se discuten algunas posibles aplicaciones e implicancias de la introducción del uso de placebos psicológicos y diseño a doble ciego en la investigación en psicoterapia. Palabras clave: Investigación de resultados en psicoterapia; Doble ciego; Placebo psicológico; EMDR; Diseño experimental de caso único. Double blind design and placebos have been of crucial importance in medical clinical research. Their use in outcomes research in the field of psychotherapy has been controversial, though. Their feasibility in such case has been denied by many authors based on the assumption that the psychotherapist would need to know the nature of the applied procedure. In view of this, the author has conducted a pilot feasibility study on three subjects within the context of his doctoral dissertation. Said dissertation aims at establishing the role of alternating bilateral auditory stimulation in the processing of traumatic memories as used in the EMDR (Eye Movement Desensitization and Reprocessing) technique. To such end, the EMDR basic principles and procedures are introduced--with particular attention to alternating bilateral auditory stimulation--and a pilot study using placebos during EMDR administration is presented in detail. The goals of this study are testing the feasibility of: (a) using a psychological placebo in EMDR therapy, and (b) applying a double blind design study in EMDR outcomes research. A single case experimental design was performed on three different patients suffering from PTSD (Posttraumatic Stress Disorder). A symptomatology baseline was established throughout three weekly sessions using the DTS (Davidson Trauma Scale) and the OQ-45.2 (Outcomes Questionnaire 45.2). First, three CDs were recorded--one with no sound at all (CD-1, silence condition); another one with auditory stimulation consisting of a tic-tac sound recorded in monaural condition, and reproduced simultaneously over both earphones at a rate of one beat per second (CD-2, monaural condition) and a third one with alternating bilateral auditory stimulation consisting of the exact same sound recorded in stereophonic condition, and reproduced alternatively over the left and right earphones (CD-3, stereo condition)--. At a second stage, these three experimental conditions were assigned randomly to the three subjects, who were administered: (a) EMDR protocol without any type of stimulation, with no sound coming out of the earphones using CD-1 (placebo 1), (b) EMDR protocol with simultaneous bilateral auditory stimulation using CD-2 (placebo 2), and (c) EMDR protocol with alternating bilateral auditory stimulation using CD-3 (active treatment). In all cases, the experimental conditions were implemented during three full sessions in which the CDs were reproduced for the subjects through earphones, instead of speakers, to ensure that the psychotherapist was unaware of the actual conditions. Subsequently, the standard EMDR protocol (i.e., with alternating bilateral auditory stimulation) was administered to each subject until the end of the treatment, determined either by the symptoms being resolved or the maximum of ten sessions being completed. As a result of this pilot study, the author concludes that the feasibility of using double blind studies and placebos in EMDR psychotherapy has indeed been established. Since no apparent difficulties in the administration of the placebos were detected during the study, the use of psychological placebos seems viable. Such procedure is equally credible for the patient as well as for the psychotherapist, which renders possible the development of a double blind design in EMDR outcomes research. It should be noted, though, that the credibility of the placebo was not formally assessed, but rather was perceived through the author's informal observation. Developing assessment criteria and formal tools to evaluate the credibility of placebo procedures is advisable if future investigations on the subject are to be carried. Even though this study was conducted under a Single Case Experimental Design, the placebo procedure employed could be easily adapted for its use in between group's designs. Finally, some of the possible applications and consequences regarding the introduction of placebos and double blind design in psychotherapy research are discussed. Key words: Outcomes research in psychotherapy; Double blind; Psychological placebo; Single case experimental design; EMDR.