Predictors of treatment effects allow individual tailoring of treatment characteristics, thereby saving resources and optimizing outcomes. Electrical stimulation coupled with language intervention has shown promising results in improving language performance in individuals with Primary Progressive Aphasia (PPA). The current study aimed to identify language and cognitive variables associated with response to therapy consisting of language intervention combined with transcranial direct current stimulation (tDCS). Forty individuals with PPA received written naming/spelling intervention combined with anodal tDCS or Sham, using a between-subjects, randomized design, with intervention delivered over a period of 3 weeks. Participants were assessed using a battery of neuropsychological tests before and after each phase. We measured letter accuracy during spelling of trained and untrained words, before, immediately after, 2 weeks, and 2 months after therapy. We used step-wise regression methods to identify variables amongst the neuropsychological measures and experimental factors that were significantly associated with therapy outcomes at each time-point. For trained words, improvement was related to pre-therapy scores, in RAVLT (5 trials sum), pseudoword spelling, object naming, digit span backward, spatial span backward and years post symptom onset. Regarding generalization to untrained words, improvement in spelling was associated with pseudoword spelling, RAVLT proactive interference, RAVLT immediate recall. Generalization effects were larger under tDCS compared to Sham at the 2-month post training measurement. We conclude that, for trained words, patients who improve the most are those who retain for longer language skills such as sublexical spelling processes (phoneme-to-grapheme correspondences) and word retrieval, and other cognitive functions such as executive functions and working memory, and those who have a better learning capacity. Generalization to untrained words occurs through improvement in knowledge of phoneme-to-grapheme correspondences. Furthermore, tDCS enhances the generalizability and duration of therapy effects.

中文翻译：

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认知和语言表现可预测拼写干预和tDCS在原发性失语症中的作用。

治疗效果的预测变量允许对治疗特征进行个性化定制，从而节省资源并优化结果。电刺激与语言干预相结合已显示出在改善患有原发性失语症（PPA）的人的语言表现方面取得了可喜的结果。当前的研究旨在确定与语言反应结合经颅直流电刺激（tDCS）组成的治疗反应相关的语言和认知变量。40名PPA个体接受受试者之间的随机设计，并接受书面的命名/拼写干预，以及阳极tDCS或Sham的书面干预，干预期为3周。在每个阶段之前和之后，使用一系列神经心理学测试对参与者进行评估。我们在治疗之前，之后，2周和2个月的拼写训练有素和未经训练的单词期间测量了字母的准确性。我们使用逐步回归方法在每个时间点识别与治疗结果显着相关的神经心理学指标和实验因素中的变量。对于训练有素的单词，其改善与治疗前分数，RAVLT（5个试验总和），伪单词拼写，对象命名，数字向后跨距，空间跨距向后以及症状发作的年限有关。关于对未经训练的单词的泛化，拼写的改进与伪单词的拼写，RAVLT的主动干扰，RAVLT立即回想有关。在训练后的2个月中，tDCS下的泛化效果比Sham大。我们得出结论，对于训练有素的单词，进步最大的患者是那些保留较长语言技能的患者，例如亚词法拼写过程（音素到音素的对应关系）和单词检索，以及其他认知功能，例如执行功能和工作记忆，以及具有较好学习能力的患者。通过提高音素到音素对应关系的知识，可以将未受训练的单词泛化。此外，tDCS增强了治疗效果的普遍性和持续时间。通过提高音素到音素对应关系的知识，可以将未受训练的单词泛化。此外，tDCS增强了治疗效果的普遍性和持续时间。通过提高音素到音素对应关系的知识，可以将未受训练的单词泛化。此外，tDCS增强了治疗效果的普遍性和持续时间。