Light verb production in healthy ageing and dementia.

Abstract

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