Main Concept Production in Persons with Aphasia: A Comparison of Subtypes

Abstract

Narrative abilities are negatively impacted in persons with aphasia (PWAs), with even the mildest PWAs producing narratives that, though well-structured, are characterized by reduced lexical diversity, complexity, content, length, coherence, and more (e.g., Andreetta, Cantagallo, & Marini, 2012; Capilouto, Wright, and Wagovich, 2006; Fergadiotis & Wright, 2011; Nicholas & Brookshire, 1995; Ulatowska, North, & Macaluso-Haynes, 1981). Even those categorized as “not aphasic by WAB” (NABW) produce significantly different story retell narratives compared to typical and aphasic peers (Author2, Dillow, & Author1, 2013). Diminished narrative abilities, and associated reduced functional communication, have a marked negative impact on quality of life (QoL) in PWAs, more so than physical limitations that accompany stroke (Hilari, 2011; Northcott & Hilari, 2011). Indeed, narrative ability may be a better predictor of life participation and QoL than traditionally administered outcome measures (Ross & Wertz, 1999), making imperative the advancement of narrative assessment and treatment. Three primary barriers to narrative assessment impede widespread use - standardization, norm-reference, and time constraints. AphasiaBank developers (http://talkbank.org/AphasiaBank/) addressed the first barrier by making available a standard discourse protocol. Regarding the second barrier, norm-referenced Main Concept (MC) lists based on 150+ control transcripts for three different types of discourse were recently developed using AphasiaBank (Author2, Campbell, Williams, Dillow, & Author1, 2013). The MC lists included concepts spoken by 50% of the control population. The authors elected to develop MC lists primarily because 1) MC analysis is a reliable and valid method of assessing narrative adequacy in PWAs (Nicholas & Brookshire, 1995), and 2) generation of standardized, norm-referenced, non-transcription-based MC lists would reduce the amount of time required for narrative assessment (third barrier). Previous MC research has revealed differences between controls and PWAs, and between fluent and non-fluent PWAs (Kong, 2009, 2011; Nicholas & Brookshire, 1995). Previous MC studies have also combined certain codes (see Discussion), which may lead to inaccurate representation of communicative abilities and/or masking of differences between subtypes. We extracted lengthy narrative samples of a large group of PWAs and analyzed the samples with a multi-level MC coding system using norm-referenced MCs in order to determine 1) if there were significant differences in MC production between different aphasia subtypes, and 2) if so, which subtypes were significantly different from each othe