Background: Animal fluency is a widely used task to assess people with Alzheimer’s disease (AD) and other neurological disorders. The mechanisms that drive performance in this task are argued to rely on language and executive functions. However, there is little information regarding what specific aspects of these cognitive processes drive performance on this task. Objective: To understand which aspects of language (i.e., semantics, phonological output lexicon, phonological assembly) and executive function (i.e., mental set shifting; information updating and monitoring; inhibition of possible responses) are involved in the performance of animal fluency in people with AD. Methods: Animal fluency data from 58 people with probable AD from the DementiaBank Pittsburgh Corpus were analyzed. Number of clusters and switches were measured and nine word properties (e.g., frequency, familiarity) for each of the correct words (i.e., each word counting toward the total score, disregarding non-animals and repetitions) were determined. Random forests were used to understand which variables predicted the total number of correct words, and conditional inference trees were used to search for interactions between the variables. Finally, Wilcoxon tests were implemented to cross-validate the results, by comparing the performance of participants with scores below the norm in animal fluency against participants with scores within the norm based on a large normative sample. Results: Switches and age of acquisition emerged as the most important variables to predict total number of correct words in animal fluency in people with AD. Cross-validating the results, people with AD whose animal fluency scores fell below the norm produced fewer switches and words with lower age of acquisition than people with AD with scores in the normal range. Conclusion: The results indicate that people with AD rely on executive functioning (information updating and monitoring) and language (phonological output lexicon, not necessarily semantics) to produce words on animal fluency.

Objectives: The purpose of the current study was to investigate the effects of syntactic structure as a function of the canonicity of word-order on sentence comprehension ability and to explore the relationship between working memory capacity and sentence comprehension ability for Korean-speaking normal elderly adults. Methods: A total of 51 normal elderly individuals participated in the study. The sentence comprehension task (SCT) consisted of three syntactic structures (active sentences with 2-place verbs, active sentences with 3-place verbs, and passive sentences) with the canonicity of word order being manipulated for each syntactic structure. A total of 36 sentences were administered to participants using a sentence-picture paradigm. Digit and word span tasks were used as working memory measures. Results: A two-way repeated ANOVA revealed significant effects for sentence type and the canonicity. A two-way interaction was significant, indicating that performance was differentially affected by sentence type as a function of canonicity. Participants showed the worst performance on passive sentences under the canonical word order; when sentences followed the non-canonical word order, they exhibited worse performance on active sentences with 3-place verbs. The SCT was highly correlated with working memory measures. Conclusion: Even though Korean is considered a free word-order language, these results suggest that the canonicity of word order affects sentence comprehension ability for normal elderly adults. More studies need to be conducted to further examine the critical factors that are associated with age-related changes in sentence comprehension ability.

This study investigated the best predictor to capture age-related changes in passive-sentence production using a constrained sentence-production paradigm and explored the role of working-memory capacity in relation to the task demands of the sentence-production tasks. A total of 60 participants participated in the study ranging in age from 21 to 86. All were administered a syntactic-priming and a sentence-completion task under either canonical or noncanonical word-order conditions. Age was significantly and negatively correlated with sentence-production tasks, and the most demanding condition with a noncanonical word order under the syntactic priming paradigm was the best predictor of aging. Working-memory capacity was significantly and positively correlated with all conditions, but the significant correlation remained only for the most demanding condition (the priming task with a noncanonical word order) after controlling for age. Sentence-production abilities were vulnerable to aging, and these effects manifested most clearly when the task demands were high enough to tax individuals’ cognitive capacity. Working-memory capacity partially accounted for age-related changes in sentence-production abilities.

Background: The purpose of the current study was to investigate the effects of working-memory (WM) capacity on age-related changes in abilities to comprehend passive sentences when the word order was systematically manipulated. Methods: A total of 134 individuals participated in the study. The sentence-comprehension task consisted of the canonical and non-canonical word-order conditions. A composite measure of WM scores was used as an index of WM capacity. Results: Participants exhibited worse performance on sentences with non-canonical word order than canonical word order. The two-way interaction between age and WM was significant, suggesting that WM effects were greater than age effects on the task. Conclusions: WM capacity effects on passive-sentence comprehension increased dramatically as people aged, suggesting that those who have larger WM capacity are less vulnerable to age-related changes in sentence-comprehension abilities. WM capacity may serve as a cognitive reserve associated with sentence-comprehension abilities for elderly adults.

Oh SJ, et al. Dement Neurocogn Disord. 2019 Jun;18(2):47-61. https://doi.org/10.12779/dnd.2019.18.2.47

Purpose: The purpose of the study was to examine cross-linguistic differences in a picture-description task between Korean- and English-speaking individuals with Broca's and anomic aphasia to determine whether a variation exists in the use of verbs and nouns across the language and aphasia groups. Method: Forty-eight individuals (male = 29; female = 19) participated in the study ( n = 28 for aphasic group and n = 20 healthy controls). Data for English speakers were obtained from the Aphasia Bank Project. We used the picture-description task to obtain connected speech samples and analyzed noun- and verb-related linguistic variables. Results: Korean speakers with aphasia produced more verbs per utterance and a lower noun-to-verb ratio than English speakers with aphasia, whereas English speakers produced more nouns than Korean speakers. The Korean anomic group produced more verbs than Korean speakers with Broca's aphasia, whereas no effects were significant for English speakers with aphasia depending on the type of aphasia. Conclusions: Aphasia symptoms vary as a function of linguistic features of languages that individuals with aphasia used premorbidly. Furthermore, the linguistic characteristics of the individual's language influenced aphasia symptoms more strongly than the type of aphasia. It is theoretically and clinically important that this cross-linguistic study provides different perspectives, and that noun–verb deficits may vary depending on linguistic features.