Johns Hopkins University, Baltimore, MD, USA.
Cortex. 2011 Mar;47(3):342-52. doi: 10.1016/j.cortex.2009.12.001. Epub 2009 Dec 22.
The objective of this study is to determine which cognitive processes underlying spelling are most affected in the three variants of primary progressive aphasia (PPA): Logopenic variant primary progressive aphasia (lvPPA), Semantic variant primary progressive aphasia (svPPA), and Nonfluent variant primary progressive aphasia (nfvPPA).
23 PPA patients were administered The Johns Hopkins Dysgraphia Battery to assess spelling. Subtests evaluate for effects of word frequency, concreteness, word length, grammatical word class, lexicality (words vs pseudowords), and "regularity" by controlling for the other variables. Significant effects of each variable were identified with chi square tests. Responses on all spelling to dictation tests were scored by error type. 16 of the 23 subjects also had a high resolution MRI brain scan to identify areas of atrophy.
We identified 4 patterns of spelling that could be explained by damage to one or more cognitive processes underlying spelling. Nine patients (3 unclassifiable, 4 with lvPPA, 2 with svPPA) had dysgraphia explicable by impaired access to lexical representations, with reliance on sublexical phonology-to-orthography conversion (POC). Two patients (with nfvPPA) showed dysgraphia explicable by impaired access to lexical representations and complete disruption of sublexical POC. Seven patients (4 with lvPPA, 1 with svPPA, 2 unclassifiable) showed dysgraphia explicable by impaired access to lexical-semantic representations and/or lexical representations with partially spared sublexical POC mechanisms. Five patients (1 with nfvPPA, 2 with svPPA, 1 with lvPPA, and 1 unclassifiable) showed dysgraphia explicable by impairment of the graphemic buffer.
Any cognitive process underlying spelling can be affected in PPA. Predominance of phonologically plausible errors, more accurate spelling of regular words than irregular words, and more accurate spelling of pseudowords than words (indicating spared POC mechanisms) may indicate a low probability of progression to nfvPPA.
本研究旨在确定导致三种原发性进行性失语症（PPA）变体（语言流畅性变异型原发性进行性失语症[lvPPA]、语义变异型原发性进行性失语症[svPPA]和非流利型原发性进行性失语症[nfvPPA]）中拼写障碍的潜在认知过程。
对 23 名 PPA 患者进行约翰霍普金斯失写症检测，以评估拼写。子测验通过控制其他变量，评估词频、具体性、词长、语法词性、词汇性（单词与假词）和“规律性”对拼写的影响。通过卡方检验确定各变量的显著影响。所有听写测试的拼写错误类型由错误类型评分。23 名患者中的 16 名还进行了高分辨率 MRI 脑扫描，以确定萎缩区域。
我们发现了 4 种拼写模式，可以用影响拼写的一个或多个认知过程的损伤来解释。9 名患者（3 名无法分类，4 名 lvPPA，2 名 svPPA）存在因词汇知识获取障碍导致的失写症，依赖于亚词汇音位到拼写的转换（POC）。2 名患者（nfvPPA）存在因词汇知识获取障碍和亚词汇 POC 完全中断导致的失写症。7 名患者（4 名 lvPPA，1 名 svPPA，2 名无法分类）存在因词汇语义知识获取障碍和/或词汇知识获取障碍导致的失写症，亚词汇 POC 机制部分保留。5 名患者（1 名 nfvPPA，2 名 svPPA，1 名 lvPPA 和 1 名无法分类）存在因书写符号缓冲障碍导致的失写症。
任何拼写的潜在认知过程都可能受到 PPA 的影响。语音上合理错误的出现频率较高、规则词的拼写比不规则词更准确、假词的拼写比单词更准确（表明 POC 机制保留）可能提示进展为 nfvPPA 的概率较低。
