Evaluating a Maintenance-Based Treatment Approach to Preventing Lexical Dropout in Progressive Anomia

Purpose Primary progressive aphasia (PPA) and the amnestic variant of Alzheimer's disease (AD) are neurodegenerative conditions characterized by a profound loss of functional communication abilities. Communicative impairment in AD and PPA is especially apparent in the domain of naming common objects and familiar faces. We evaluated the effectiveness of a language intervention targeting maintenance of an individualized core vocabulary in a longitudinal cohort of older adults experiencing either PPA or AD. Method PPA ( n = 9) and AD ( n = 1) patients were administered a semantically based language treatment for up to 2 years. Patients repeatedly named and generated semantic features for a personalized lexicon consisting of 100 words. We evaluated naming accuracy and off-line neuropsychological measures at four successive timepoints. Naming accuracy was assessed in patients ( n = 7) who completed at least three recurrent evaluations. Off-line neuropsychological performance was assessed across timepoints in all patients. Results Patients demonstrated relative preservation of naming trained words relative to a steep decline for untrained (control) words. The greatest decrements were observed for naming people relative to objects. Conclusion These results suggest that consistent training of a finite set of words can protect a core lexicon composed of crucial target concepts (e.g., a spouse's name). We discuss potential benefits and clinical implications of maintenance-based approaches to promoting language functioning in the context of neurodegeneration.

Concurrent Validity and Reliability of the Core Lexicon Measure as a Measure of Word Retrieval Ability in Aphasia Narratives

Purpose General agreement exists in the literature that clinicians struggle with quantifying discourse-level performance in clinical settings. Core lexicon analysis has gained recent attention as an alternative tool that may address difficulties that clinicians face. Although previous studies have demonstrated that core lexicon measures are an efficient means of assessing discourse in persons with aphasia (PWAs), the psychometric properties of core lexicon measures have yet to be investigated. The purpose of this study was (a) to examine the concurrent validity by using microlinguistic and macrolinguistic measures and (b) to demonstrate interrater reliability without transcription by raters with minimal training. Method Eleven language samples collected from PWAs were used in this study. Concurrent validity was assessed by correlating performance on the core lexicon measure with microlinguistic and macrolinguistic measures. For interrater reliability, 4 raters used the core lexicon checklists to score audio-recorded discourse samples from 10 PWAs. Results The core lexicon measures significantly correlated with microlinguistic and macrolinguistic measures. Acceptable interrater reliability was obtained among the 4 raters. Conclusions Core lexicon analysis is potentially useful for measuring word retrieval impairments at the discourse level. It may also be a feasible solution because it reduces the amount of preparatory work for discourse assessment.

Using AphasiaBank for Discourse Assessment

AphasiaBank is a shared, multimedia database for the study of communication in aphasia. This article describes a variety of discourse measurement tools and teaching resources available at the AphasiaBank website. The discourse measurement tools include main concept analysis, core lexicon checklists, correct information unit computation techniques, and other automated analyses using the CLAN program. These tools can be used to measure a variety of aspects of language production for assessment as well as treatment evaluation and clinical research purposes. Importantly, they are intended to help make the discourse analysis process more efficient and reliable. Teaching resources include an online tutorial on aphasia, videos of typical behaviors seen in aphasia, group treatment videos, classroom activities, tutorial screencasts, and conference posters. These resources can be used for a variety of clinical and educational purposes. The AphasiaBank website is part of the larger TalkBank project which provides many other shared databases and resources that are relevant to professionals interested in communication and communication disorders.

Moving Toward Non-transcription based Discourse Analysis in Stable and Progressive Aphasia

Measurement of communication ability at the discourse level holds promise for predicting how well persons with stable (e.g., stroke-induced), or progressive aphasia navigate everyday communicative interactions. However, barriers to the clinical utilization of discourse measures have persisted. Recent advancements in the standardization of elicitation protocols and the existence of large databases for development of normative references have begun to address some of these barriers. Still, time remains a consistently reported barrier by clinicians. Non-transcription based discourse measurement would reduce the time required for discourse analysis, making clinical utilization a reality. The purpose of this article is to present evidence regarding discourse measures (main concept analysis, core lexicon, and derived efficiency scores) that are well suited to non-transcription based analysis. Combined with previous research, our results suggest that these measures are sensitive to changes following stroke or neurodegenerative disease. Given the evidence, further research specifically assessing the reliability of these measures in clinical implementation is warranted.

A Tutorial on Core Lexicon: Development, Use, and Application

Evidence suggests that discourse-level assessment in aphasia should be implemented within clinical settings. However, existing discourse measures that are time and labor intensive in process prevent speech-language pathologists from applying such measures to their clinical practices. This article provides an overview of a lexicon-based analysis (core lexicon measure) that recently was developed and investigated for clinical usability. A new approach to core lexicon measures provides a simple scoring method with short instructions, which may be practical and time efficient for assessment and management of persons with aphasia. The article concludes with suggestions for clinical application and implementation.

A Compendium of Core Lexicon Checklists

Core Lexicon (CoreLex) is a relatively new approach assessing lexical use in discourse. CoreLex examines the specific lexical items used to tell a story, or how typical lexical items are compared with a normative sample. This method has great potential for clinical utilization because CoreLex measures are fast, easy to administer, and correlate with microlinguistic and macrolinguistic discourse measures. The purpose of this article is to provide clinicians with a centralized resource for currently available CoreLex checklists, including information regarding development, norms, and guidelines for use.

Dominant words rise to the top by positive frequency-dependent selection

A puzzle of language is how speakers come to use the same words for particular meanings, given that there are often many competing alternatives (e.g., “sofa,” “couch,” “settee”), and there is seldom a necessary connection between a word and its meaning. The well-known process of random drift—roughly corresponding in this context to “say what you hear”—can cause the frequencies of alternative words to fluctuate over time, and it is even possible for one of the words to replace all others, without any form of selection being involved. However, is drift alone an adequate explanation of a shared vocabulary? Darwin thought not. Here, we apply models of neutral drift, directional selection, and positive frequency-dependent selection to explain over 417,000 word-use choices for 418 meanings in two natural populations of speakers. We find that neutral drift does not in general explain word use. Instead, some form of selection governs word choice in over 91% of the meanings we studied. In cases where one word dominates all others for a particular meaning—such as is typical of the words in the core lexicon of a language—word choice is guided by positive frequency-dependent selection—a bias that makes speakers disproportionately likely to use the words that most others use. This bias grants an increasing advantage to the common form as it becomes more popular and provides a mechanism to explain how a shared vocabulary can spontaneously self-organize and then be maintained for centuries or even millennia, despite new words continually entering the lexicon.