Time reference, morphology and prototypicality: tense production in stroke aphasia and semantic dementia in Greek

A systematic review of the quantitative markers of speech and language of the frontotemporal degeneration spectrum and their potential for cross-linguistic implementation

Frontotemporal dementia (FTD) is a neurodegenerative disease spectrum with an urgent need for reliable biomarkers for early diagnosis and monitoring. Speech and language changes occur in the early stages of FTD and offer a potential non-invasive, early, and accessible diagnostic tool. The use of speech and language markers in this disease spectrum is limited by the fact that most studies investigate English-speaking patients. This systematic review examines the literature on psychoacoustic and linguistic features of speech that occur across the FTD spectrum across as many different languages as possible. 76 papers were identified that investigate psychoacoustic and linguistic markers in discursive speech. 75 % of these papers studied English-speaking patients. The most generalizable features found across different languages, are speech rate, articulation rate, pause frequency, total pause duration, noun-verb ratio, and total number of nouns. While there are clear interlinguistic differences across patient groups, the results show promise for implementation of cross-linguistic markers of speech and language across the FTD spectrum particularly for psychoacoustic features.

Time reference in aphasia: are there differences between tenses and aphasia fluency type? A systematic review and individual participant data meta-analysis

Time reference is used to build the temporal framework of discourse and is essential in ensuring efficient communication. Several studies have reported time reference deficits in fluent and non-fluent aphasia and have shown that tenses (past, present, future) are not all impaired to the same extent. However, there is little consensus on the dissociations between tenses, and the question of the influence of the type of aphasia (fluent vs. non-fluent) on time reference remains open. Therefore, a systematic review and an individual participant data meta-analysis (or mega-analysis) were conducted to determine (1) whether one tense is more impaired than another in fluent and non-fluent aphasia and, if so, (2) which task and speaker-related factors moderate tense effects. The systematic review resulted in 35 studies reporting the performance in time reference of 392 participants. The mega-analysis was then performed on 23 studies for a total of 232 participants and showed an alteration of past tense compared to present and future tenses in both types of aphasia. The analysis also showed a task and an age effect on time reference but no gender effect, independently of tenses. These results add to our knowledge of time reference in aphasia and have implications for future therapies.

Production of time reference in Turkish Broca's aphasia: The effect of morphological complexity

In PWA (people with aphasia) difficulties with sentences that refer to the past compared to non-past time reference have been shown for many languages, including Turkish. However, the impact of morphological complexity on past time reference ability in production has not yet been reported for Turkish-speaking PWA. Turkish, where verb forms have complex inflectional paradigms and exhibit overt and non-overt morphology, facilitates the examination of the effects of morphological complexity. The current study has two objectives: 1) to investigate whether the morphological complexity of the verb form affects time reference production of Turkish-speaking PWA and 2) to provide analysis for the error patterns discovered. Seventeen Turkish individuals with Broca's aphasia who were matched in age with a control group of 17 neurologically intact Turkish individuals were tested with a picture sentence completion task. Test conditions were present progressive, simple past, past perfect, past progressive, and future tense. The task required the participants to complete each sentence frame with a verb. Our findings show that Turkish-speaking PWA were more successful in producing verb forms referring to non-past than verb forms referring to the past time reference. The current study supports previous findings that past is more difficult than non-past time reference for Turkish-speaking PWA. In terms of morphological complexity, we find that PWA were more impaired when producing morphologically complex verb forms rather than morphologically simple forms. We argue that these impairments lie in the realization of overt morphology.

Light verb production in healthy ageing and dementia

BACKGROUND

Light verbs are highly frequent and semantically impoverished words. It is currently not known whether light verb production in discourse tasks differs by age or for people with dementia of the Alzheimer's type (DAT).

AIMS

The purpose of the current study was two-fold: (1) to determine whether there is a relationship between age and the proportion of light verbs produce during a narrative discourse task; and (2) to determine whether people with DAT produce a different proportion of light verbs compared with neurotypical adults.

METHODS & PROCEDURES

A total of 469 neurotypical adults and 12 participants with DAT produced narratives from a wordless picture book.

OUTCOME & RESULTS

The results indicated that light verb production increases as a function of age, even when controlling for education, and people with DAT produced a higher light verb-word ratio compared with neurotypical adults when matched for age and education.

CONCLUSION & IMPLICATION

Light verb use may increase as a function of age due to declines in retrieval ability. These declines are not only more pronounced in people with DAT, but also semantic knowledge deficits may contribute to a reliance on light verbs.

WHAT THIS PAPER ADDS

Light verbs are typically some of the first verbs learned due to their simple semantic construction and high frequency. However, two things are unknown: (1) how light verbs changed across the adult lifespan; and (2) whether cognitive impairment changes light verb production. The study found that light verb production increases as a function of age, and that people with DAT used a higher ratio of light verbs to words in a narrative task compared with neurotypical adults. However, despite the findings, more research is needed to determine their clinical utility. Future research may wish to investigate whether light verbs (1) facilitate comprehension in older adults or (2) may be used in cognitive-linguistic assessments for cognitive impairments.