Leyton Cristian E, Hodges John R, Piguet Olivier, Ballard Kirrie J
Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, Australia; Neuroscience Research Australia, Randwick, NSW, Australia; ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Sydney, NSW, Australia.
Neuroscience Research Australia, Randwick, NSW, Australia; ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Sydney, NSW, Australia; School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia.
Cortex. 2017 Jan;86:45-54. doi: 10.1016/j.cortex.2016.10.019. Epub 2016 Nov 5.
The majority of logopenic variant primary progressive aphasia (lv-PPA) cases harbour Alzheimer pathology, suggesting that lv-PPA constitutes an atypical presentation of Alzheimer's disease (AD). However, even if caused by Alzheimer pathology, the clinical manifestations of lv-PPA differ from those observed in the typical or amnestic AD presentation: in lv-PPA, aphasia is the main feature while amnestic AD is characterised by impaired episodic memory. Anomia or impaired naming, however, is present in both AD presentations. Whether these presentations share anatomical and mechanistic processes of anomia has not been fully investigated. Accordingly, we studied naming performance and its relationship with regions of brain atrophy in 23 amnestic AD and 22 lv-PPA cases with presumed underlying Alzheimer pathology. Both AD groups displayed some degree of anomia and impaired word comprehension but these were particularly severe in lv-PPA and accompanied by a range of linguistic deficits, comprising phonological substitutions, superordinate semantic paraphasias and abnormal single-word repetition. Analysis of cortical thickness revealed that anomia was correlated with thinning in left superior temporal gyrus in both groups. In amnestic AD, however, anomia was also associated with thinning in right inferior temporal regions. Single-word comprehension (SWC), by contrast, was associated with cortical thinning involving bilateral fusiform gyri in both groups. These findings suggest that anomia in both amnestic AD and lv-PPA results from the involvement at multiple steps of word processing, in particular, semantic and lexical retrieval; in addition lv-PPA patients display a more marked involvement of phonological processing.
大多数logopenic变异型原发性进行性失语（lv-PPA）病例存在阿尔茨海默病病理改变，这表明lv-PPA构成了阿尔茨海默病（AD）的一种非典型表现。然而，即使由阿尔茨海默病病理改变引起，lv-PPA的临床表现也不同于典型或遗忘型AD表现中所观察到的情况：在lv-PPA中，失语是主要特征，而遗忘型AD的特征是情景记忆受损。然而，在这两种AD表现中均存在命名障碍或命名受损。这些表现是否共享命名障碍的解剖学和机制过程尚未得到充分研究。因此，我们研究了23例遗忘型AD患者和22例假定存在潜在阿尔茨海默病病理改变的lv-PPA患者的命名表现及其与脑萎缩区域的关系。两个AD组均表现出一定程度的命名障碍和词汇理解受损，但这些在lv-PPA中尤为严重，并伴有一系列语言缺陷，包括语音替换、上位语义性错语和异常的单词重复。皮质厚度分析显示，两组中命名障碍均与左侧颞上回变薄相关。然而，在遗忘型AD中，命名障碍还与右侧颞下区域变薄有关。相比之下，两组中单词理解（SWC）均与双侧梭状回皮质变薄有关。这些发现表明，遗忘型AD和lv-PPA中的命名障碍均源于单词处理多个步骤的受累，特别是语义和词汇检索；此外，lv-PPA患者在语音处理方面受累更为明显。
