Nonliteral Language in Alzheimer Dementia: A Review

Abstract

The use of nonliteral language in clinical assessment, especially testing the patients' ability to interpret proverbs, has a long tradition in psychiatry. However, its diagnostic sensitivity and specificity in dementias is not yet clear. The aim of this review article is to examine the current evidence on nonliteral/figurative language (proverb, metaphor, metonymy, idiom, irony, sarcasm) comprehension in Alzheimer's disease and related disorders. A comprehensive literature search identified 25 studies (16 proverb, 3 metaphor, 0 metonymy, 5 idiom, 3 sarcasm) on nonliteral language comprehension in dementia. Studies predominantly indicate a deficit. Most studies investigated Alzheimer's dementia. Applied correctly, nonliteral language is a worthwhile diagnostic tool to evaluate language and abstract thinking in dementias. During assessment, familiarity testing (e.g., by asking "are you familiar with the proverb XY") is obligatory. Still, future research is needed in several areas: evidence on decline of nonliteral language over the course of the illness is limited. So far, almost no studies delineated proverb comprehension in high risk populations such as patients with mild cognitive impairment. Currently, there is a lack of studies addressing performance in direct comparison to relevant differential diagnosis like older-age depression, delirium, brain lesion, or other psychiatric conditions.

Where in the brain is nonliteral language? A coordinate-based meta-analysis of functional magnetic resonance imaging studies

“…It is well-documented that many patients with neurodevelopmental disorders such as autism and schizophrenia have difficulty in correctly understanding non-literal expressions (Rapp and Wild, 2011). These deficits are mainly attributed to right hemispheric rather than LH dysfunction (Mitchell and Crow, 2005), a conclusion that is no longer justified considering the contribution of the hemispheres.…”

“…Although it is highly speculative to state a reason for this, the lack of research on proverbs represents a clear difference in developmental studies (Nippold and Haq, 1996;Nippold et al, 1998), research in psychiatric patients (Rapp, 2009;Rapp and Schmierer, 2010;Rapp and Wild, 2011), and brain lesion research (Benton, 1968;Brundage and Brookshire, 1995;Chapman et al, 1997;Paul et al, 2003;Rapp, 2012;Ulatowska et al, 2001) where proverbs are very often used as stimuli.…”

“…The figurativeness of non-literal language inspired researchers to use metaphors (Aziz-Zadeh et al, 2006) and idioms (Boulenger et al, 2009) as stimuli to investigate motor semantics. The ability to comprehend non-literal language is impaired in a number of clinical populations (Gernsbacher and Pripas-Kapit, 2012;Thoma and Daum, 2006), including patients with schizophrenia (Rapp, 2009;Rapp and Schmierer, 2010), autistic subjects (Martin and McDonald, 2004), and patients with dementia (Rapp and Wild, 2011) or other neurodevelopmental disorders (Annaz et al, 2009).…”

What dementia reveals about proverb interpretation and its neuroanatomical correlates

“…In order to further understand brain regions critical for proverb interpretation, investigators have studied a variety of patient populations including those with Alzheimer's disease (Rapp & Wild, 2011); Parkinson's disease; schizophrenia (Gorham, 1956); aphasia; patients with frontal lobe damage (Benton, 1968;Van Lancker & Kemper, 1987;Winner & Garner, 1977); and agenesis of the corpus collosum (Paul, Van Lancker-Sidtis, Schieffer, Dietrich, & Brown, 2003). Even though studies have examined differences in social, emotional, and neurocognitive functioning between patients with Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD), there is paucity of studies that specifically examines differences in nonliteral language interpretation between these two groups, which are both disease processes targeting the frontal and temporal lobes to varying extents.…”

Cortical & Subcortical Dementias: A Psychoneurolinguistic Perspective

“…A decline of non-literal language including proverb comprehension is observed in patients with AD (Rapp& Wild, 2011). Many language tests have been designed to test the linguistic abilities of the patients with AD.…”