Verbal working memory in individuals with schizophrenia and their first degree relatives: relationship with negative and disorganized symptoms.

OBJECTIVE: To determine whether there are differences in verbal working memory amongst subjects with schizophrenia, their first degree relatives and controls, and to evaluate the influence of symptoms on these differences, as an initial step to assess whether this cognitive function is an endophenotype. METHODS: We examined 197 cases with schizophrenia, 197 first degree relatives and 200 controls through psychiatric interviews and the Letters and Numbers Sequencing test (LNS). Performance was compared among the three groups adjusting for age, sex and education level. Adjustment for "negative symptoms" and "disorganization" was performed afterwards. RESULTS: Subjects with schizophrenia showed lower performance in the LNS than their first degree relatives and the healthy controls; the effect sizes were 0.75 and 1.18 respectively. There was a small difference between relatives and controls (effect size =0.38). These differences were significant after adjustment for negative and disorganized symptoms, but the effect sizes became smaller: 0.26 for relatives vs. subjects with schizophrenia, 0.56 for controls vs. subjects with schizophrenia and 0.33 for relatives vs. controls. Among individuals with schizophrenia, performance in the LNS was not associated with disorder duration, disease onset age, antipsychotics, history of depressive episodes or substance use disorders. CONCLUSION: Results suggest verbal working memory may be considered as an endophenotype in schizophrenia.

Memoria de trabajo verbal en individuos con esquizofrenia y sus familiares de primer grado: Relación con los sintomas negativos y desorganizados / Verbal working memory in individuals with schizophrenia and their first degree relatives: relationship with negative and disorganized symptoms

Objetivo: Determinar si hay diferencias en la memoria de trabajo verbal entre sujetos con esquizofrenia, familiares de primer grado y controles, y evaluar la influencia que pueden tener en estas diferencias los síntomas del trastorno, como un paso para establecer si esta función cognitiva es un endofenotipo. Métodos: A 197 sujetos con esquizofrenia, 197 familiares de primer grado y 200 controles comunitarios, se les hizo evaluación psiquiátrica y se les aplicó la prueba sucesión de letras y números (SLN). Se comparó el desempeño de los tres grupos ajustando por edad, sexo y escolaridad, y luego se ajustó también por síntomas negativos y desorganizados. Resultados: Los sujetos con esquizofrenia mostraron un menor desempeño en la SLN con respecto a sus familiares de primer grado no-afectados y los controles, con tamaños de efecto de 0,75 y 1,18 respectivamente. Hubo una diferencia pequeña pero significativa entre familiares y controles (tamaño de efecto =0,38). Estas diferencias siguieron siendo significativas después de ajustar por síntomas negativos y desorganizados, pero los tamaños de efecto disminuyeron a: 0,26 para familiares vs sujetos con esquizofrenia, 0,56para controles vs sujetos con esquizofrenia y 0,33 para familiares vs controles. Entre los sujetos con esquizofrenia, el desempeño en la SLN no se asoció significativamente con duración del trastorno, edad de inicio, uso de antipsicóticos, ni historia de episodios depresivos o trastornos por uso de sustancias. Conclusión: Los resultados sugieren que la memoria de trabajo verbal puede ser considerada un endofenotipo de la esquizofrenia (AU)

Objective: To determine whether there are differences in verbal working memory amongst subjects with schizophrenia, their first degree relatives and controls, and to evaluate the influence of symptoms on these differences, as an initial step to assess whether this cognitive function is an endophenotype. Methods: We examined 197 cases with schizophrenia, 197 first degree relatives and 200 controls through psychiatric interviews and the Letters and Numbers Sequencing test (LNS). Performance was compared among the three groups adjusting for age, sex and education level. Adjustment for “negative symptoms” and “disorganization” was performed afterwards. Results: Subjects with schizophrenia showed lower performance in the LNS than their first degree relatives and the healthy controls; the effect sizes were 0.75 and 1.18 respectively. There was a small difference between relatives and controls (effect size =0.38). These differences were significant after adjustment for negative and disorganized symptoms, but the effect sizes became smaller: 0.26 for relatives vs. subjects with schizophrenia, 0.56 for controls vs. subjects with schizophrenia and 0.33 for relatives vs. controls. Among individuals with schizophrenia, performance in the LNS was not associated with disorder duration, disease onset age, antipsychotics, history of depressive episodes or substance use disorders. Conclusion: Results suggest verbal working memory may be considered as an endophenotype in schizophrenia (AU)