The scope of using pragmatic language tests for early detection of dementia: A systematic review of investigations using figurative language

Abstract

INTRODUCTIONDementia cases are expected to rise to 81.1 million in 2040. Efforts are underway to develop diagnostic methods to facilitate early detection of the disease. Herein we review research findings focusing on pragmatic dysfunction in patients with dementia and evaluate the usefulness of assessing dementia and its progress with a battery of tests assessing figurative language skills.METHODSA total of 74,778 article titles were identified from EMBASE, PubMed, and Google Scholar databases. After systematic screening, 51 journal articles were selected for the final review.RESULTThe review suggests that impaired figurative language might be a marker for early cognitive decline. Different forms of figurative language may be impaired at different stages of the disease and in different types of dementia involving different neuropathologies.CONCLUSIONThe use of pragmatic tests in combination with the existing diagnostic protocols might increase the probability of early diagnosis.HIGHLIGHTS Pragmatic impairment could be a marker of early cognitive impairment. Figurative language—an important pragmatic aspect—is disrupted in mild cognitive impairment (MCI) and early Alzheimer's disease (AD). Figurative language impairment might precede literal language impairment. Pragmatic tests could be more sensitive than standard neuropsychological tests. Inclusion of pragmatic tests in diagnostic guidelines might bolster early detection.

Reply to Kljajevic's “Increasing sensitivity of clinical proverb tests for diagnosis of dementia”

“…10 As a result, we do not recommend using proverbs alone to assess dementia because the concept of using figurative language, particularly novel expressions, as a tool for early detection of dementia is based on the theory that interpreting these expressions requires the cooperation of several brain areas. 2 However, we agree with Kljajevic that investigating a wide range of figurative forms with varying semantic complexities is necessary to build sensitive instruments capable of discriminating preclinical Alzheimer's disease from normal cognitive aging. The clinical acceptance and application of these instruments would definitely be dependent on their sensitivity, but more importantly, on their availability, validity, and affordability in comparison to currently available biomarkers.…”

“…I would like to elaborate on the premise of semantic variations in proverbs and a few other points raised by Kljajevic 1 in their recent submission to Alzheimer's & Dementia in connection with our review article 2 that was published in the last issue of this journal. The clarification of the theoretical and practical issues at stake is a critical step in this emerging field of research and for the next generation of scientists seeking to develop sensitive language‐based tools for the early detection of dementia.…”

“… 10 As a result, we do not recommend using proverbs alone to assess dementia because the concept of using figurative language, particularly novel expressions, as a tool for early detection of dementia is based on the theory that interpreting these expressions requires the cooperation of several brain areas. 2 …”

Increasing sensitivity of clinical proverb tests for diagnosis of dementia

“…However, early diagnosis of dementia remains a challenge. Chakrabarty et al 2 propose that certain cognitive tests, such as those targeting pragmatic skills, may facilitate early detection of cognitive decline in dementia. The authors argue that disruption to pragmatic processing may precede a deficit in episodic memory, which is considered a hallmark of unfolding Alzheimer's disease (AD), 3 and that the hippocampus, which is a locus of early neurodegenerative changes in AD, 4 also supports pragmatic processing.The idea that comprehension of figurative language may provide a window into cognitive decline is not new.…”