Effects of semantic relations, repetition of words, and list length in word list recall of Alzheimer's patients

Arq Neuropsiquiatr 2008;66(2-B):312-317 Effects of semantic relations, repetition of words, and list length in word list recall of Alzheimer’s patients Orlando F.A. Bueno1, Paulo H.F. Bertolucci2, Maria Gabriela M. Oliveira1, Jacqueline Abrisqueta-Gomez3 Abstract – Introduction: Semantic relations among words and repetition enhance free recall, but it is unknown if these facilitating factors are effective in dementia.   Method: Alzheimer’s patients (MILD-Alz, MOD-Alz) were compared to healthy elderly. Fifteen-word lists were read out to the subjects. In four sets of lists the words in intermediary input positions were semantically related or not, or the midlist words were repeated, or they were repeated and semantically related.   Results: The usual third peak of recall of semantically related words was not observed in MOD-Alz, repetition of words did not increase recall of the patients, and the combination of relatedness and repetition benefited only MID-Alz. In a second experiment, with related or unrelated midlist words, and list length shortened from 15 to 9 words, semantic facilitation was observed in mild and moderate Alzheimer´s patients, although diminished compared to controls.   Conclusion: Progression of dementia turns facilitating factors of recall less effective. Key words: memory, word list recall, Alzheimer’s disease, semantic relations, repetition. Efeitos da relação semântica, repetição de palavras e extensão das listas na recordação de pacientes com doença de Alzheimer Resumo – Introdução: Relacionamento semântico e repetição facilitam a recordação livre mas não se sabe se esses fatores continuam efetivos na demência.   Método: O desempenho de pacientes com doença de Alzheimer (MILD-Alz e MOD-Alz) foi comparado com o de idosos sadios na recordação livre de listas de 15 palavras, utilizando quatro diferentes conjuntos de listas que continham ou não palavras relacionadas nas posições intermediárias, palavras repetidas, ou ainda palavras repetidas e semanticamente relacionadas.   Resultados: O terceiro pico usual na recordação das palavras semanticamente relacionadas não foi observado em MODAlz; a repetição não aumentou a recordação dos pacientes; a combinação de relacionamento e repetição beneficiou apenas MILD-Alz. Em outro experimento, com palavras intermediárias relacionadas ou não, e em que a extensão das listas foi reduzida para 9 palavras, observou-se facilitação semântica em MILD-Alz e MODAlz.   Conclusão: A progressão da demência diminui a eficácia de fatores facilitadores da recordação. Palavras-chave: memória, recordação livre de palavras, doença de Alzheimer, relação semântica, repetição. One of the first and most prominent manifestations of Alzheimer’s disease (AD) is memory impairment, being episodic memory severely and consistently affected (for review see1). It is also known that operations that require controlled processing, as in attention demanding tasks, decay very soon in AD patients2. Moreover, many studies have shown the loss of the ability to access and use semantic knowledge, as has been demonstrated in several kinds of tasks3,4. Impairment in the capacity to use semantic knowledge may be due to a degradation of semantic memory5,6, but this interpretation is not consensual7,8 as the possibility of a disruption of the information accessing process was not ruled out. The word free recall test is largely used to study memory dysfunctions. The subject is presented with lists of words that are read out one by one. At the end of each list, s/he is asked to remem- 1 Professor Adjunto do Departamento de Psicobiologia; 2Professor Adjunto do Departamento de Neurologia e Neurocirurgia; 3Doutora em Ciências, Universidade Federal de São Paulo - UNIFESP, São Paulo SP, Brazil. Financial support: Associação Fundo de Incentivo à Psicofarmacologia (AFIP) and Conselho Nacional de Pesquisa e Tecnologia (CNPq). Received 14 May 2007, received in final form 7 March 2008. Accepted 24 March 2008. Dr. Orlando F.A. Bueno – Department of Psychobiology / Universidade Federal de São Paulo / Escola Paulista de Medicina - Rua Napoleão de Barros 925 - 04024-002 São Paulo SP - Brasil. E-mail: 312 Alzheimer’s disease: word list recall Bueno et al. Arq Neuropsiquiatr 2008;66(2-B) ber as many words as s/he can, in any order. By studying the input positions of the remembered words, a U-shaped curve is obtained, reflecting a better recollection of the words placed in the beginning of the list (primacy effect), as well as the words in the last positions (recency effect). The primacy effect reflects an aspect of long-term memory, possibly resulting from a prolonged processing of the first words in the list when compared to those in the middle9, the recency effect, on the other hand, can be supported by short-term memory10. The introduction of semantically related words alters the pattern of the serial position curve, producing peaks of high recollection of these words11,12. Repetition of words in the middle of the lists also causes another peak of recollection of these repeated words11. The performance of AD patients in verbal free recall is impaired (e.g.12-14), with a decrease in the total number of remembered words and alterations in the serial position curve due to the absence or considerable deficit of the primacy effect and a decrease (usually modest and sometimes none at all) of the recency effect15-17. To our knowledge no work has been done to investigate the beneficial effects of spaced repetition of items and only one18 the relatedness of words in free recall in AD patients. If the capacity to use semantic knowledge is lost because semantic memory is degraded, the result would be the lack of benefit produced by semantically related words. In the present study we manipulated the three midlist words, introducing semantically related words or repeating words throughout the lists, in order to verify if Alzheimer’s patients in mild or moderate stage would still profit from these mnemonic enhancers. METHOD Experiment 1 Subjects – Fifteen patients with probable AD and 9 healthy subjects (CON) with similar age and academic background were examined. The patients, referred by the Department of Neurology of Hospital São Paulo, had a history of cognitive decline and memory problems, but normal consciousness. The diagnosis of probable Alzheimer’s disease was given according to the criteria of the National Institute of Neurological Disorders and Communicative Disorders and Stroke-Alzheimer’s Disease and Related Disorders Association - NINCDS-ADRDA 1 and the Diagnostic and Statistical Manual of Mental Disorders, third edition (DSM-III)19. Patients were tested using clinical-neurological examinations comprising laboratory, imaging (computerized tomography and magnetic resonance) as well as neuropsychological testing (including the score obtained in the Mini-Examination of the Mental State (MMSE), adapted for the Brazilian population20. Severity of clinical state was (...truncated)