Dysgraphia in primary progressive aphasia: Characterisation of impairments and therapy options

This is an Accepted Manuscript of an article published by Taylor & Francis in Aphasiology on January 3, 2014, available online: http://www.tandfonline.com/10.1080/02687038.2013.869308.Background: Spelling impairment is common in primary progressive aphasia (PPA). Although behavioural interventions tend to focus on spoken language, remediation of written language may be desirable, either because an individual’s regular use of writing makes it a priority or because writing is needed for communication in cases where it is better preserved than spoken language. Aims: This paper has three aims: (1) to provide an up-to-date survey of spelling and handwriting impairments in each variant of PPA, (2) to provide guidance on characterisation of dysgraphia and identification of loci of impairment, and (3) to outline possible interventions. Because the number of studies which have specifically evaluated therapy for dysgraphia in PPA is small, this paper also reviews relevant studies of therapy in non-progressive dysgraphia. Main Contribution: Review of the literature indicated that the most common pattern of spelling impairment in the semantic variant of PPA is surface dysgraphia (impairment in lexical spelling). The profile is more variable in the non-fluent and logopenic variants of PPA, but most commonly there is impairment in lexical spelling and in phoneme-to-grapheme conversion. Review of the literature on therapy for dysgraphia indicated that four main types of therapy have been evaluated and shown to improve spelling performance: (1) training of spelling of specific target words (used to ameliorate lexical and graphemic buffer impairments), (2) training of sound-to-spelling correspondence rules (used to treat impairment in assembled spelling), (3) training in segmentation of stimulus words into smaller chunks (to make them manageable for a damaged graphemic buffer, or as a first stage in applying sound-to-spelling correspondence rules), and (4) learning to identify and self-correct errors (used in treatment of graphemic buffer disorder). Conclusions: It is likely that spelling impairment in PPA would be responsive to treatment, although this has only been demonstrated in the logopenic variant. Reported improvements following therapy for anomia demonstrate that relearning is possible in PPA, despite the progressive nature of the condition. This gives reason for optimism regarding a positive response to therapy for dysgraphia in all variants of PPA