El funcionamiento cognitivo como endofenotipo de la anorexia nerviosa. Estudio en familiares no afectados por la enfermedad

Abstract

El perfil cognitivo de los pacientes con anorexia nerviosa se caracteriza por dificultades en la flexibilidad mental y en la coherencia central. El objetivo de este trabajo fue analizar si los familiares de primer grado no afectados de los pacientes presentan estas dificultades cognitivas, que podrían representar rasgos endofenotípicos de la enfermedad. Fueron estudiadas 34 mujeres: 17 familiares de primer grado (madres y hermanas) de pacientes con anorexia nerviosa y 17 controles sanos agrupados por edad y escolaridad. Se consideraron el índice de masa corporal, la ansiedad, la depresión, los síntomas obsesivo-compulsivos y los relacionados con los trastornos alimentarios. Se evaluó la coherencia central, mediante la copia de la Figura Compleja de Rey, y la flexibilidad mental, mediante el test de Stroop, el test de los trazos B y el test de fluencia fonológica. Los familiares de pacientes con anorexia nerviosa presentaron un menor rendimiento en las medidas de coherencia central (p < .05) y en fluencia fonológica (p < .05) que los controles sanos. Se observó una correlación entre el test de Stroop y los síntomas de depresión y trastornos alimentarios (p < .05). Los familiares de primer grado no afectados de pacientes con anorexia nerviosa presentaron dificultades en la coherencia central y, en menor grado, en la flexibilidad mental. Los resultados en los familiares indican que este perfil podría ser mediado genéticamente, constituyendo un rasgo característico de la anorexia nerviosa y, por ende, un posible candidato a endofenotipo neuropsicológico de esta enfermedad. Palabras clave: anorexia nerviosa, neuropsicología, coherencia central, flexibilidad mental, endofenotipo.

The cognitive profile of patients with anorexia nervosa is characterized by difficulties in central coherence and mental flexibility. Central coherence is defined by the ability to integrate incoming information in its own context, and weakness in central coherence is characterized by poor overall processing and superior detail processing. Mental flexibility is defined by the ability to change the course of a thought or action according to the demands of the environment. Alterations in this cognitive domain generate rigid and inflexible behavior. An open question in the literature is whether these cognitive characteristics are a transient state derived from the disease or whether they are stable traits associated with anorexia nervosa and endophenotypical features of this disease. The concept of endophenotype refers to the internal phenotype that is not clinically appreciable but can be observed indirectly through deficits that arise in the performance of certain neuropsychological tests. In recent years the search for endophenotypes has been renewed in the field of psychiatry as they would constitute an important route for the understanding of the biological and genetic bases of mental illnesses, constituting markers that allow a diagnosis before the onset of clinical symptomatology. For a cognitive marker to be considered an endophenotype it must meet a series of characteristics such as being measurable, inherited, found in patients with and without active disease and in first-degree relatives not affected by the disease. The aim of the present study was to assess whether difficulties in central coherence and mental flexibility are shared by unaffected first-degree relatives of patients with anorexia nervosa and thus constitute an endophenotypical feature of this disease. This is a cross-sectional, descriptive-comparative study in which 34 women participated: 17 unaffected first-degree relatives of patients with anorexia nervosa (mothers and sisters) and 17 healthy controls matched by age and education. For the study of central coherence the copy of Rey’s Complex Figure was used and to assess set-shifting the Stroop test, the Trail Making Test B and the Phonological Fluency test were used. Demographic and clinical aspects such as age, educational level, body mass index, anxiety, depression, obsessive-compulsive and eating disorder related symptoms were also evaluated. First-degree relatives of patients with anorexia nervosa showed lower performance on measures of central coherence (p < .05) and phonological fluency (p < .05) than healthy controls. A correlation was observed between the Stroop test and depression and eating disorders symptoms (p < .05). The results of this study show that unaffected first-degree relatives of patients with anorexia nervosa presented alterations in central coherence and, to a lesser degree, in mental flexibility. These results, in addition to previous research in which difficulties persisted even after recovery, indicate that these alterations could be genetically mediated, constituting a characteristic trait of anorexia nervosa and therefore a possible candidate for neuropsychological endophenotype of this disease. Regarding practical implications of the study, the findings reinforce the importance of cognitive remediation treatments not only for patients with anorexia nervosa but also emphasize that they could be useful for unaffected family members. Taking into account that family intervention is a widely used tool in the psychological treatment of anorexia, improving the perception of the patient and his relatives about cognitive biases, could contribute to raising awareness of the disease, something that patients with anorexia nervosa do not usually have, and generate a positive impact on the response to treatment as a whole.