A case of developmental deep dyslexia: What's left is right

Primary progressive aphasia (PPA) is a progressive neurodegenerative disorder characterized by the deterioration of language functions. The Han language bears some unique features from the Latin languages; however, the features of PPA in the Han language-speaking population are not well understood. In this study, we performed a 3-year follow-up on a Han language-speaking PPA patient with corresponding changes in magnetic resonance imaging (MRI). During the early stage, linguistic analysis revealed several symptoms including difficulty with auditory comprehension, right–left disorientation, reading disorders, and agraphia, specifically the execution of serial oral instructions. This Chinese PPA patient presented with a reading disorder, but his word comprehension ability remained intact. There are two different possible modalities of incorrect writing in this case. The patient also presented with noun–verb double dissociation. The early-stage MRI showed atrophy of the left frontal lobe, which was most severe in the inferior frontal gyrus. Three years later, the patient was found to have progressive atrophy in the parietal, frontal, and temporal lobes, among which the frontal lobe remained the most severely affected region. The brain imaging of the Chinese-speaking PPA patient showed changes similar to those of a Latin language-speaking PPA patient. The prominent change was asymmetrical atrophy in the frontal and temporal lobes. This is the first report of noun–verb double dissociation existing in a Chinese-language speaking PPA patient. The dissociation may be related to an impaired function of the inferior frontal gyrus, which is likely associated with verb-naming in Chinese-speaking people. Several unique features were observed in this case, including impairment in writing ability.