Language impairments caused by stroke (post-stroke aphasia, PSA) and neurodegeneration (primary progressive aphasia, PPA) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, PPA and PSA have rarely been directly compared in detail. Rather, previous studies have compared certain subtypes (e.g. semantic variants) or have focused on a specific cognitive/linguistic task (e.g. reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intra- and intergroup variations on all four extracted components. Classification analysis was used to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia formed a true diagnostic category (i.e. within group homogeneity and distinct between-group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (i) a multidimensional rather than categorical classification system may be a better conceptualization of aphasia from both causes; and (ii) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.

中文翻译：

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原发进行性失语和中风后失语的分级多维多维组内和组间变异。

由中风（中风后失语，PSA）和神经退行性疾病（原发性进行性失语，PPA）引起的语言障碍具有重叠的症状，术语，通常分为分类亚型。令人惊讶的是，很少直接比较过PPA和PSA。相反，先前的研究已经比较了某些亚型（例如，语义变体）或专注于特定的认知/语言任务（例如，阅读）。这项研究评估了PSA和PPA整个范围内的各种语言和认知任务。我们应用了方差极大值旋转的主成分分析来探索评估得分中方差的潜在结构。对于PSA和PPA，发现了类似的语音，语义和流利性相关组件。通过对两种病因的组合主成分分析，发现了所有四个提取成分的分级组内和组间变异。使用分类分析来正式测试PPA或PSA的任何亚型是否存在任何分类界限。语义性痴呆形成了真正的诊断类别（即组内同质性和组间差异性明显），而PPA和PSA的其他亚型之间或之间存在相当大的重叠和分级变化。这些结果表明：（i）多维分类系统而非分类分类系统可能是两种原因都可以更好地将失语症概念化；（ii）尽管病理类型非常不同，但这些广泛的失语症类别具有相当大的共同特征。