Investigation of cognition in schizophrenia: psychometric properties of instruments for assessing working memory updating

Abstract

Objective: This study describes the development of two updating measures of working memory (WM): Letter Updating Test (LUT) and Word Updating Test (WUT). Methods: In stage 1, items were created and the instruments were assessed by experts and laymen. In stage 2, tests were given to 15 patients with schizophrenia and 15 paired controls. All were able to understand and respond to the instruments. In stage 3, 141 patients with schizophrenia and 119 healthy controls aged 18 to 60 took part; they were assessed on WM, processing speed (PS) and functional outcome. Results: The results showed adequate rates of internal consistency for both measures developed, for both the total sample and each group separately, as well as evidence of convergent validity, discriminant validity and sensitivity to differentiate performance among the groups. Principal component analysis yielded two components, one for updating tests and other for PS measures, indicating factorial validity. Positive and significant, yet low, correlations were found with functionality measures. Conclusion: These results provide adequate psychometric parameters for the measures developed, applicable to cognitive research settings in schizophrenia. RESUMOObjetivo: O estudo descreve o desenvolvimento de duas medidas de atualização da memó-ria de trabalho (MT): Teste de Atualização de Letras (TAL) e Teste de Atualização de Palavras (TAP). Métodos: Na etapa 1 foram criados itens e os instrumentos foram analisados por experts e leigos. Na etapa 2, os testes foram aplicados em 15 pacientes com esquizofrenia e 15 controles pareados. Todos foram capazes de compreender e responder aos instrumentos. Na etapa 3, participaram 141 pacientes com esquizofrenia e 119 controles saudáveis com idades entre 18 e 60 anos, avaliados em MT, velocidade de processamento (VP) e funcionalidade. Resultados: Os resultados revelaram bons índices de consistência interna para ambas as medidas desenvolvidas, tanto para a amostra total como para cada grupo separadamente,

Component mechanisms of executive function in schizophrenia and their contribution to functional outcomes

“…Neuroimaging data from healthy individuals support the unity/diversity model in that the updating mechanism appears to mainly recruit areas in the lateral prefrontal cortex,12 that switching between mental sets is thought to depend on the medial prefrontal cortex,13 and that inhibition tasks mainly activate the orbitofrontal cortex 14. In schizophrenia, some of these skills present consistent evidence of impairment,15 -17 association with diagnostic gene candidates,18,19 association with peripheral levels of chemokines, brain-derived neurotrophic factor (BDNF) and oxidative markers,20 and potentially available homologous animal models 21…”

Neuropsychological correlates of remission in chronic schizophrenia subjects: The role of general and task-specific executive processes

“…The Keep Track Task was used to measure updating ( Berberian et al, 2015 ). In this task, adapted from Yntema (1963) , first several target categories were shown in the computer screen (animals, colors, countries, distances, metals, and relatives).…”

“…Letter Memory Task was the second updating measure ( Berberian et al, 2015 ). In this task, adapted from Morris and Jones (1990) , several letters from a list were sequentially presented for 2000 ms per letter.…”