Beatty William W, Testa Julie A, English Shelley, Winn Peter
a Department of Psychiatry and Behavioral Sciences.
b Department Family Medicine , University of Oklahoma Health Sciences Center , Oklahoma City.
Neuropsychol Dev Cogn B Aging Neuropsychol Cogn. 1997 Dec;4(4):273-279. doi: 10.1080/13825589708256652.
Several lines of evidence suggest that in Alzheimer's disease (AD) there is a progressive degradation of the hierarchical organization of semantic memory. to evaluate this hypothesis, clustering and switching on phonemic and semantic fluency tasks were studied. For elderly controls, both clustering and switching were correlated with the numbers of correct words generated on both fluency tests, but the contribution of clustering was greater on the semantic task. Patients with AD generated fewer correct words and made fewer switches than controls on both fluency tests. the average size of their semantic clusters was smaller and the contribution of clustering to word generation was less than for controls. Severity of dementia was correlated with the numbers of correct words and switches, but not with cluster size. These results are consistent with various hypotheses which maintain that the structure of semantic memory in AD is degraded but provide no evidence that this process is progressive. Instead, progressive worsening of verbal fluency in AD seems to be more strongly associated with the deterioration of mechanisms that govern initiation of search for appropriate subcategories.
多项证据表明，在阿尔茨海默病（AD）中，语义记忆的层次组织存在渐进性退化。为了评估这一假设，研究了音素流畅性和语义流畅性任务中的聚类和转换情况。对于老年对照组，聚类和转换都与两种流畅性测试中生成的正确单词数量相关，但聚类在语义任务中的贡献更大。在两种流畅性测试中，AD患者生成的正确单词比对照组少，转换也比对照组少。他们语义聚类的平均规模较小，聚类对单词生成的贡献也小于对照组。痴呆严重程度与正确单词数量和转换相关，但与聚类规模无关。这些结果与各种假设一致，这些假设认为AD中语义记忆的结构退化，但没有证据表明这一过程是渐进性的。相反，AD中言语流畅性的逐渐恶化似乎与控制搜索合适子类别的启动机制的恶化更密切相关。
