Estandarización de la Figura de Taylor en población mexicana / Taylor's Figure Standardization on Mexican population

ABSTRACT

In order to perform a neuropsychologycal evaluation, the clinician may use several instruments; nevertheless, most of them have been designed for use on populations with very different social and cultural backgrounds from that of Mexico. This makes the research on the standardization of methods of evaluation for Mexican population a very important task for both clinical and research settings. Normative data obtained from Mexican population is necessary because it provides the clinician that works with Mexican patients with a reference framework that allows him or her to correctly classify a particular behavior of an individual as normal or abnormal and thus make specific evaluations and cooperate in diagnostic. Researchers interested on cognitive functioning also require qualitative and quantitative equivalent instruments that may allow them to objectively evaluate the efficacy of short-time interventions as in a pre- and post-treatment experimental designs; and it is precisely for this reason that Taylor's figure was developed. Taylor's figure (TF) was originally designed as an alternative to Rey-Osterrieth's complex figure (ROCF), in order to use it in test-retest situations. Similar to ROCF, Taylor's figure has two modalities copy and memory. The former evaluates constructional praxia, while the latter measures immediate recalling. Parallel tests, that is, different tests that evaluate the same variables, are useful because they reduce the measurement error involved in applying the task twice to the same person (i.e. learning), thus increasing the validity of follow up evaluations of cognitive functioning. <ability for organizing and articulating several parts that lead to a whole. It's a voluntary movement directed towards the end of building upon different elements, through the use of instruments or tools. Constructional praxia is the bond that brings together motor organization and viso-spatial perception in order to accomplish behavior. Evaluation of both of these functions is important because they are commonly affected in psychiatric and neurological disorders; examples of this are the reported failures in using adequate organization strategies in patients with anorexia nervosa. These patients also remember significantly less information in immediate recalling. Another example of failures in processes evaluated by TF are patients with obsessive-compulsive disorder whom also present deficits in the implementation of organizing strategies and recall information very poorly. The goal of this work was to obtain normative data on TF for the Mexican population. In order to accomplish this, we applied the test to a sample of 2100 healthy participants between 9 and 15 years old. Each age group consisted of 150 males and 150 females selected at random from different schools in Mexico City and the surrounding State of Mexico. In order to screen out individuals that may present psychiatric or neurological disorders that may influence the test results, subject's parents had to complete a brief questionary designed by the authors for this puorpose. Each application was realized individually by a trained professional and a three minute interval was left in every case between the copy and the memory modalities. Another goal of this study was to enable the use of TF as a parallel test of evaluation to ROCF, which could be useful on clinical and research settings. Because of this, criteria for sample size and sample selection were the same designed and used for the 1996 standardization of the ROCF by Galindo et al. It is important to note that, since Galindo et al. considered the application and scoring methods designed by Osterrieth for ROCF incomplete, they redesigned them to include an operational definition of the measured variables and a systematic analysis of the possible attributes of each of the 18 perceptual units. Galindo et al. designed a new application protocol and both a qualitative and a quantitative procedure for scoring the ROCF that reported high inter-evaluator reliability. For this study, the Galindo et al. methodology was adapted to TF. Average and standard deviation of total scores for both copy and memory were calculated for each age group. The discriminative power of each component of the figure was tested by comparing, through an independent sample t test, the score obtained on it by the group with the 27% lower scores of the sample with the group with the 27% highest. The 18 perceptual units showed a high discriminative power in both modalities copy (t = 84.64; p<0.001) and memory (t = 82.79; p<0.001). The reliability of the test was calculated using Cronbach's alpha (.76 for the copy and .75 for the memory). Finally, frequency distribution of total scores, for both modalities, showed a normal distribution. The relation of age and test execution was different for each modality. While the total score of the copy modality evidently increases with age, this happens in the memory modality only to a point. Visual examination of the distribution of total memory score and age shows that older groups present a slight decrement compared to their younger counterparts. However this decrement has also been described by other authors. A further line of research on the qualitative and quantitative similarities of both Taylor's and Rey-Osterrieth's Complex Figures is suggested; so both tests can be used on test-retest research on evaluation of cognitive functioning.

RESUMEN

Dentro del ámbito neuropsicológico existe una serie de instrumentos de evaluación que en su mayoría han sido diseñados en un contexto sociocultural diferente al nuestro, por lo que es importante contar con pruebas neuropsicológicas estandarizadas en sujetos mexicanos. Desde esta perspectiva, los datos de una población normativa nos permiten tener un marco de referencia para comparar y establecer diagnósticos diferenciales dentro de la práctica clínica. Asimismo, dentro del ámbito de la investigación se requieren instrumentos que en teoría sean equivalentes en cuanto a la función que evalúan para llevar un seguimiento sobre el funcionamiento cognoscitivo de una población en particular a lo largo del tiempo. La Figura de Taylor se diseñó como una alternativa a la Figura Compleja de Rey-Osterrieth para aplicarla en situaciones de test-retest. Consta de dos modalidades una de copia que evalúa la praxia de construcción y otra de memoria inmediata. El término <movimiento voluntario dirigido que tiene el fin de armar o construir diferentes elementos a través del uso de instrumentos o herramientas. La praxia constructiva vincula un componente de organización motora con la percepción visoespacial y como resultado de este vínculo se ejecuta el movimiento. Con el objetivo de estandarizar la Figura de Taylor, se aplicó la prueba a una muestra compuesta por 2100 sujetos mexicanos dentro de un rango de edad de nueve a 15 años. Los parámetros para la selección y tamaño de la muestra, así como los criterios que se siguieron para la aplicación y calificación de la prueba, fueron los mismos que diseñaron y utilizaron Galindo et al., para la estandarización de la Figura Compleja de Rey-Osterrieth. Por cada grupo de edad se calcularon, tanto para la copia como para la memoria, las medias y desviaciones estándar. El análisis de la discriminación de reactivos se realizó comparando las medias de cada reactivo de 27% de los sujetos con las calificaciones más altas y las de 27% de aquellos que obtuvieron las calificaciones más bajas. Las 18 unidades preceptuales mostraron un alto poder discriminativo, en la modalidad de copia t (84.64) p<.001 y en la memoria t (82.79) p<.001. La distribución de los puntajes obtenidos en la muestra pone de manifiesto que existe un patrón de normalidad en ambas modalidades de la figura.