Progressive supranuclear palsy (PSP) can be difficult to distinguish from Parkinson's disease (PD), but has a much graver prognosis. PSP is characterised severely reduced output on measures of phonemic fluency, suggesting that it may be a specific marker of PSP. However, reduced phonemic fluency has also been noted in PD, and very few studies have actually compared phonemic fluency in PSP and PD. Although anecdotal reports suggest that phonemic fluency output in PSP may have specific characteristics, with more low-frequency words and perseverative errors, no study to date has formally explored this. Further investigation into phonemic fluency output and its cognitive and neuroanatomical correlates is now critical for improving our understanding of the verbal fluency in PSP. In this study, we compared phonemic fluency characteristics (including quantity, frequency and error rates) in patients with PSP, PD and focal frontal or subcortical lesions, and age- and education-matched healthy controls. We then compared these characteristics with performance on extensive neuropsychological testing. We found that PSP patients generated significantly fewer words than patients with PD and patients with right frontal focal lesions, and healthy controls. Phonemic fluency was also significantly reduced in patients with left frontal and subcortical focal lesions. However, there were no significant group differences in word frequency or error rates. Phonemic fluency was best predicted by performance on the Vocabulary and Hayling neuropsychological tests. We argue that these findings provide important evidence that reduced phonemic fluency is a hallmark of PSP and argue that the specificity of this impairment betrays an underlying impairment in energization, reflecting dysfunction of left frontal and subcortical networks.

进行性核上性麻痹（PSP）可能很难与帕金森氏病（PD）区别开来，但预后较差。PSP在音素流畅度方面的输出严重降低，这表明它可能是PSP的特定标记。但是，PD中的音素流利性也有所降低，很少有研究实际比较PSP和PD中的音素流利性。尽管有传闻表明，PSP中的语音流利度输出可能具有特定的特征，包括更多的低频词和持续性错误，但迄今为止，尚无正式的研究。现在，进一步研究音素流利度输出及其认知和神经解剖学相关性对于提高我们对PSP口语流利度的理解至关重要。在这个研究中，我们比较了PSP，PD和局灶性额叶或皮层下病变以及年龄和教育程度相匹配的健康对照患者的语音流畅性特征（包括数量，频率和错误率）。然后，我们将这些特征与广泛的神经心理学测试的性能进行了比较。我们发现，PSP患者产生的单词明显少于PD患者，右侧额叶病变患者和健康对照者。左额额叶和皮层下局灶性病变患者的音素流畅度也显着降低。但是，单词频率或错误率没有显着的组差异。语音流利程度最好通过词汇和海灵神经心理学测试的表现来预测。