Gender differences on the WAIS-IV in patients with schizophrenia / Diferencias de género en la WAIS-IV en pacientes con esquizofrenia

Abstract Introduction Results from studies that have investigated gender differences in neuropsychological functioning in schizophrenia have been inconsistent. Differences in the illness stage, in the demographic and clinical characteristics of the samples, and the instruments used to measure cognition may have contributed to the heterogeneity in the results. Objective Investigate the heterogeneity in the results comparing cognitive functioning in chronically ill male and female patients with schizophrenia. Method Twenty-five women and twenty-five men chronically ill patients with schizophrenia matched on age, age at illness onset, and years of education were evaluated in cognitive functioning using the WAIS-IV. Results Men showed higher scores than women on the two global measures, on the perceptual reasoning and working memory indices, and on the information, visual puzzles, digit span, and arithmetic subtests of the WAIS-IV. Cohen's d effect sizes were high for the two global measures and the two indices (d > .68). Discussion and conclusion Overall, in chronically stable patients with diagnosis of schizophrenia, women's performance on cognitive functioning was below men's when assessed with the WAIS-IV, except in the case of processing speed. This pattern of gender differences is similar to the pattern observed in healthy populations. Our results can help to clarify the heterogeneity in the results from studies on gender differences in cognitive functioning in schizophrenia and may be valuable in designing cognitive-targeted interventions for schizophrenia.

Resumen Introducción Los resultados de los estudios que han investigado diferencias de género en funcionamiento neuropsicológico en la esquizofrenia han sido inconsistentes. Diferencias en la fase de la enfermedad, en las características demográficas y clínicas de las muestras y en los instrumentos utilizados podrían explicar esa heterogeneidad. Objetivo Investigar la heterogeneidad en los resultados comparando el funcionamiento cognitivo de pacientes con diagnostico de esquizofrenia. Método Veinticinco mujeres y veinticinco hombres pacientes con diagnóstico de esquizofrenia equiparados en edad, edad al inicio de la enfermedad y nivel educativo se evaluaron en funcionamiento cognitivo utilizando la WAIS-IV. Resultados Los hombres mostraron puntuaciones más altas que las mujeres en las dos medidas globales, en los índices de razonamiento perceptivo y de memoria de trabajo y en las subtests de la WAIS-IV de información, puzles visuales, amplitud de dígitos y aritmética. Los tamaños de efecto d de Cohen fueron altos en las dos medidas globales y en los dos índices (d > .68). Discusión y conclusión En conjunto, la ejecución de las mujeres en funcionamiento cognitivo está por debajo de la de los hombres cuando se mide con la WAIS-IV, excepto en el caso de la velocidad de procesamiento. Este patrón de diferencias de género es similar al patrón observado en población sana. Nuestros resultados pueden ayudar a clarificar la heterogeneidad de resultados en los estudios sobre diferencias de género en el funcionamiento cognitivo en la esquizofrenia y podrían ser útiles en el diseño de intervenciones centradas en la cognición.

Relationship of Working Memory, Processing Speed, and Fluid Reasoning in Psychiatric Patients

OBJECTIVE: The present study aimed to investigate relationship among cognitive factors (working memory and processing speed) and fluid reasoning (Gf) in psychiatric patients using a standardized clinical tool. METHODS: We included the responses of 115 heterogeneous patients who were diagnosed with the MINI-Plus 5.0 and WAIS-IV/WMS-IV was administered. For our analysis, structured equation modeling (SEM) was conducted to evaluate which cognitive variables are closely related to the Gf. RESULTS: The results showed that the visual working memory was the strongest predictor of the Gf compared to other cognitive factors. CONCLUSION: Processing speed was capable of predicting the Gf, when visual working memory was controlled. The inter-relationship among the Gf and other cognitive factors and its clinical implications were further discussed.

Modality-Specific Working Memory Systems Verified by Clinical Working Memory Tests

OBJECTIVE: This study was to identify whether working memory (WM) can be clearly subdivided according to auditory and visual modality. To do this, we administered the most recent and universal clinical WM measures in a mixed psychiatric sample. METHODS: A total of 115 patients were diagnosed on the basis of DSM-IV diagnostic criteria and with MINI-Plus 5.0, a structured diagnostic interview. WM subtests of Korean version of Wechsler Adult Intelligence Scale-IV and Korean version of Wechsler Memory Scale-IV were administered to assess WM. Confirmatory factor analysis (CFA) was used to observe whether WM measures fit better to a one-factor or two-factor model. RESULTS: CFA results demonstrated that a two factor model fits the data better than one-factor model as expected. CONCLUSION: Our study supports a modality model of WM, or the existence of modality-specific WM systems, and thus poses a clinical significance of assessing both auditory and visual WM tests.

A Case Study of a Machine-Learning Approach in Differential Diagnosis of Schizophrenia: The Predictive Capacity of WAIS-IV / 신경정신의학

OBJECTIVES: Machine learning (ML) encompasses a body of statistical approaches that can detect complex interaction patterns from multi-dimensional data. ML is gradually being adopted in medical science, for example, in treatment response prediction and diagnostic classification. Cognitive impairment is a prominent feature of schizophrenia, but is not routinely used in differential diagnosis. In this study, we investigated the predictive capacity of the Wechsler Adult Intelligence Scale IV (WAIS-IV) in differentiating schizophrenia from non-psychotic illnesses using the ML methodology. The purpose of this study was to illustrate the possibility of using ML as an aid in differential diagnosis. METHODS: The WAIS-IV test data for 434 psychiatric patients were curated from archived medical records. Using the final diagnoses based on DSM-IV as the target and the WAIS-IV scores as predictor variables, predictive diagnostic models were built using 1) linear 2) non-linear/non-parametric ML algorithms. The accuracy obtained was compared to that of the baseline model built without the WAIS-IV information. RESULTS: The performances of the various ML models were compared. The accuracy of the baseline model was 71.5%, but the best non-linear model showed an accuracy of 84.6%, which was significantly higher than that of non-informative random guessing (p=0.002). Overall, the models using the non-linear algorithms showed better accuracy than the linear ones. CONCLUSION: The high performance of the developed models demonstrated the predictive capacity of the WAIS-IV and justified the application of ML in psychiatric diagnosis. However, the practical application of ML models may need refinement and larger-scale data collection.