What Drives Task Performance in Fluency Tasks in People With HIV?

Abstract

Introduction: Fluency tasks require language (i.e., semantics, phonological output lexicon, and phonological assembly) and executive functions (i.e., inhibition; mental set shifting; updating, and monitoring). Little is known about whether people with human immunodeficiency virus (HIV) are more impaired on a specific type of fluency task and what aspects of language and executive functions drive such performance.Aims: To understand (1) whether people with HIV are more impaired in animal, letter, or unconstrained fluency relative to a normative sample; (2) whether there exist differences between tasks relative to the total number of words; and (3) which aspects of executive function and language are involved in their performance.Methods: Data from animal, letter, and unconstrained fluency of 50 Spanish-speaking people with HIV were analyzed. The number of switches and mean cluster size for each task and 10 word properties (e.g., frequency, age of acquisition, length in graphemes) for each of the correct words were measured. A chi-square test was used to address Aim 1, linear mixed effects models for Aim 2, and random forests and conditional inference trees for Aim 3. The results were cross-validated with a normative sample.Results: People with HIV were not more impaired in animal, letter, or unconstrained fluency relative to a normative sample. People with HIV produced fewer words in letter fluency compared to animal and unconstrained fluency. In addition, they produced fewer words in animal fluency compared to unconstrained fluency. Number of switches emerged as the most important variable to predict the total number of correct words when considering the three tasks together and for each task separately. Word frequency was relevant to predict animal fluency, age of acquisition to predict letter fluency, and cluster size to predict unconstrained fluency. These results were cross-validated with the exception cluster size.Conclusion: People with HIV rely on language (phonological output lexicon, not necessarily semantics) and executive functioning (updating and monitoring) to produce words in fluency tasks. These results concur with the current literature. Future work may correlate fluency scores with other tests measuring language and executive functions or study other types of fluency tasks (e.g., action, cities, supermarket, and professions).

What Drives Task Performance in Animal Fluency in Individuals Without Dementia? The SMART-MR Study

“…This approach is relevant because, for example, frequency has been shown to correlate with the age of acquisition (e.g., Ellis & Morrison, 1998) and frequency with length (e.g., Hauk & Pulvermüller, 2004), and this in turn makes it difficult to provide clear results regarding the linguistic processes affected or relevant to perform different tasks. In our results, we showed that, among several item-level metrics, number of switches was the most strongly related variable to the total number of words in people with Alzheimer's disease and in people with HIV (Rofes et al, 2020(Rofes et al, , 2021. In addition, age of acquisition in people with Alzheimer's disease and word frequency in people with HIV determined the total number of words produced on animal fluency.…”

“…Specific to executive functions, we expected number of switches to be a strong determinant of the total number (Abwender et al, 2001;Rofes et al, 2020Rofes et al, , 2021. Specific to language function, we expected frequency and age of acquisition to be related to total number of words (Forbes-Mckay et al, 2005;Rofes et al, 2020Rofes et al, , 2021Vonk, Jonkers, et al, 2019). Regarding the interconnection of metrics that determine the total number of words, we expected number of switches and age of acquisition to be the strongest determinants of total number of words (Rofes et al, 2020).…”

“…We hypothesized that sequence information and item-level metrics related to both language and executive functions would determine the total number of words. Specific to executive functions, we expected number of switches to be a strong determinant of the total number (Abwender et al, 2001;Rofes et al, 2020Rofes et al, , 2021. Specific to language function, we expected frequency and age of acquisition to be related to total number of words (Forbes-Mckay et al, 2005;Rofes et al, 2020Rofes et al, , 2021Vonk, Jonkers, et al, 2019).…”

“…As such, animal fluency may require more semantic input than letter fluency (Henry & Crawford, 2004). However, this reasoning does not imply that animal fluency does not require selecting entries in the phonological output lexicon (Rofes et al, 2020(Rofes et al, , 2021.…”