Profiling text comprehension impairments in aphasia

Abstract

Background: Research in aphasia has focused on acquired dyslexias at the single word level, with a paucity of assessment techniques and rehabilitation approaches for individuals with difficulty at the text level. A rich literature from research with paediatric populations and healthy non-brain damaged, skilled adult readers allows the component processes that are important for text reading to be defined and more appropriate assessments to be devised.

Aims: To assess the component processes of text reading in a small group of individuals with aphasia who report difficulties in reading at the text level. Do assessments of component processes in reading comprehension reveal distinct profiles of text comprehension? To what extent are text comprehension difficulties caused by underlying linguistic and/or cognitive deficits?

Methods & Procedures: Four individuals with mild aphasia who reported difficulties in reading at the text level took part in a case-series study. Published assessments were used to confirm the presence of text comprehension impairment. Participants completed a range of assessments to provide a profile of their linguistic and cognitive skills, focusing on processes known to be important for text comprehension. We identified the following areas for assessment: reading speed, language skills (single word and sentence), inferencing, working memory and metacognitive skills (monitoring and strategy use).

Outcomes & Results: Performance was compared against age-matched adult control data. One participant presented with a trend for impaired abilities in inferencing, with all other assessed skills being within normal limits. The other three had identified linguistic and working memory difficulties. One presented with a residual deficit in accessing single word meaning that affected text comprehension. The other two showed no clear link between sentence processing difficulties and text comprehension impairments. Across these three, data suggested a link between verbal working memory (VWM) capacity and specific inferencing skills.

Conclusions: Successful text reading relies on a number of component processes. In this paper we have made a start in defining those component processes and devising tasks suitable to assess them. From our results, assessment of VWM and inferencing appears to be critical for understanding text comprehension impairments in aphasia. It is possible that rehabilitation input can capitalise on key meta-cognitive skills (monitoring, strategy use) to support functional reading in the face of existing linguistic, text comprehension and memory impairments.

Keywords:

• acquired dyslexia
• aphasia
• reading
• text comprehension
• written comprehension
• reading strategies

Acknowledgements

We would like to thank Alice Albery, Sarah Green, Sophie Clarke and Laurie Clarke for help with data collection and initial analyses. Thanks to Alison Cox for recommending the assessment of working memory and to the reviewers for very useful comments on the first draft. Our sincere thanks go to the individuals with aphasia who gave their valuable time and feedback during the development and testing of the assessment tasks.