Background: Although discourse-level assessments contribute to predicting real-world performance in persons with aphasia (PWA), the use of discourse measures is uncommon in clinical settings due to resource-heavy procedures. Moreover, assessing function word use in discourse requires the arduous procedure of defining grammatical categories for each word in language transcripts. Aims: The purpose of this exploratory study was twofold: (1) to develop core function word lists as a clinicianfriendly means of evaluating function word use in discourse; and (2) to examine the ability of the core function word measure to differentiate PWA from cognitively healthy adults and persons with fluent aphasia from nonfluent aphasia. Methods & Procedures: The 25 most commonly used function words (core function words) were extracted from narrative language samples from 470 cognitively healthy adults, which were divided into seven age groups (20s, 30s, 40s, 50s, 60s, 70s and 80s). The percent agreement of core function words for 11 PWA (fluent aphasia = 5; non-fluent aphasia = 6) and 11 age-and education-matched controls were then calculated. Percent agreement for the core function words produced was compared between the controls and the PWA group, and between participants with fluent aphasia and non-fluent aphasia. Outcomes & Results: The results indicated that PWA produced fewer core function words from the lists than the control group, and that core function word use was strongly correlated with aphasia severity. Persons with non-fluent aphasia produced fewer core function words than those with fluent aphasia, although this could be a confound of aphasia classification from the use of the Western Aphasia Battery (WAB)-Revised. Conclusions & Implications: Core function word lists consisting of a limited number of items for quantifying function word use in discourse remain in a nascent stage of development. However, the findings are consistent with previous studies analysing the total production of function words in language samples produced by PWA. Therefore, core function words may potentially serve as a clinician-friendly manner of quantifying function words produced in discourse.

<b><i>Purpose:</i></b> We aimed to investigate: (1) the clinical, diagnostic value of a written discourse task, and (2) the relationship between executive functions and written discourse within the spectrum of individuals with mild cognitive impairment (MCI). <b><i>Method:</i></b> To determine whether written discourse performance predicts clinical course among individuals with MCI, we retrospectively classified individuals with MCI as converters (<i>N</i> = 26) who were later diagnosed with dementia or as a stable MCI group (<i>N</i> = 45). We quantified core word measures from written discourse samples obtained from the Cookie Theft picture description task. <b><i>Result:</i></b> Written discourse measures differentiated converters from the stable MCI group. Converters produced a fewer number of core words than the stable MCI group. A measure of executive function significantly predicted performance on the production of core words in written discourse for the converters. In a multivariable regression, production of core words remained the only explanatory variable closely associated with the progression to dementia in MCI. <b><i>Conclusion:</i></b> Written discourse tasks can predict the likelihood of MCI progressing to dementia, independently of recall and an executive function measure. Correlational results suggest that written discourse performance was associated with executive function as measured by the Trail Making Test. Our findings emphasize the usefulness of including written discourse tasks in language assessment batteries targeting preclinical dementia populations.

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