An exploration of the semantic network in Alzheimer's disease: Influence of emotion and concreteness of concepts

Abstract

Semantic deficits are often reported in even the very early stages of Alzheimer's disease (AD), but investigations usually focus on concrete and non-emotional entities, ignoring the broad range of concepts that feature in everyday conversations. Emotional concepts (e.g., snake) have been found to be processed more accurately than neutral ones (e.g., chair) in AD. Our aim here was therefore to explore the dimensions of both concreteness and emotion within the semantic framework, and in particular to determine whether abstract emotional words (e.g., grief) are processed as accurately as concrete emotional ones (e.g., snake) in AD. We administered a semantic priming (SP) task (lexical decision), yielding an implicit measurement of semantic memory, to 15 patients with AD and 31 normal controls. Concrete and abstract word pairs either shared a semantic relationship (e.g., table-chair, motive-reason), a semantic and emotional relationship (e.g., snake-viper; grief-sadness), or no relationship at all (e.g., pencil-horse). On the basis of response time differences between these conditions, we obtained four SP scores: concrete neutral SP, abstract neutral SP, concrete emotional SP, and abstract emotional SP. In the AD group, the SP score for abstract neutral concepts was not significant, and significantly below the other three SP scores, that seems to reflect a major deterioration in these concepts. An abnormal hyperpriming effect was observed in the concrete neutral SP condition (SP score significantly higher than that of controls), reflecting a partial deterioration in these concepts. These results suggest that, without an emotional relationship, abstract words deteriorate more quickly than concrete words. No such dissociation linked to the concreteness effect was observed with emotional words. Therefore, in AD, emotional concepts would be affected later, be they concrete or abstract.

Comprehension of concrete and abstract words in semantic variant primary progressive aphasia and Alzheimer’s disease: A behavioral and neuroimaging study

“…Studies in normal healthy participants have found that emotional valence was accessed earlier than semantic aspects such as concreteness of verbs (Palazova, Sommer, & Schacht, 2013). Furthermore, one study showed that in AD, abstract words deteriorated more quickly than concrete words when there was no emotional valence to the words, but this difference between abstract and concrete words was not observed when emotional words were used (Giffard, Laisney, Desgranges, & Eustache, 2015). This suggests that words may be less prone to deterioration in some neurodegenerative diseases when they are emotionally anchored.…”

Self-reference effect on memory in healthy aging, mild cognitive impairment and Alzheimer's disease: Influence of identity valence

“…This attention bias for positive information is believed to improve memory (the so-called positivity effect), as the more information is attended, the more likely it is to be remembered later on (Carstensen, 2006). Regarding aMCI and AD,research on the impact of emotion and/or valence on memoryhas provided mixed results, reporting either an effect of emotion (Giffard, Laisney, Desgranges, & Eustache, 2015; ), no effect of emotion(Abrisqueta-Gomez, Bueno, Oliveira, & Bertolucci, 2002;Kensinger, Brierley, Medford, Growdon, & Corkin, 2002), an effect of positive valence (Kalenzaga, Piolino, & Clarys, 2014;Maki, Yoshida, Yamaguchi, & Yamaguchi, 2013;Werheid, McDonald, Simmons-Stern, Ally, & Budson, 2011;Werheid et al, 2010) or an effect of negative valence Döhnel et al, 2008;Boller et al, 2002). The question of whether the effect of emotionally-laden material on memory is maintained through self-reference across the spectrum of ADpathology still requires much more investigation.…”

The Deterioration of Semantic Networks in Alzheimer’s Disease

“…In AD, as well as in other neurodegenerative diseases, this effect has been noted to suffer a reversal. Giffard et al (64) conducted a study in which they compared the processing of different concrete and abstract words that could either have a positive, neutral or negative emotional valence. Their result supports the concreteness effect for neutral concepts, while there is no effect for emotional concepts.…”