Influence of age and education on the processing of clustering and switching in verbal fluency tasks

Switching and its Impact on Perseveration in a Verbal Fluency Task: a Study in Persons With Alzheimer's Clinical Syndrome

OBJECTIVE

The relationship between perseveration and switching in semantic verbal fluency tasks and the possible role of self-generated interference one must overcome before switching back to a previously visited subcategory has not been explored.

PARTICIPANTS & METHOD

We studied the performance on semantic verbal fluency in 60 cognitively unimpaired subjects, 30 patients with amnestic mild cognitive impairment (aMCI) and 30 patients with Alzheimer's Clinical Syndrome-dementia (ACS-Dementia). Our primary analysis focused on the association of switching and switchback with the first perseverative error.

RESULTS

Perseveration was significantly associated with switchback in all three groups (χ2 = 24.88, p < .001). Within-cluster perseverations were few. The number of switchbacks was the only significant variable to predict perseverative responses (p < .01). Moving from cognitively unimpaired to aMCI to ACS-Dementia, progressively fewer switches and switchbacks were needed to trigger perseveration. In over half of the perseverations after a switchback in the cognitively unimpaired and aMCI groups and in over a third in the ACS-Dementia group, the subjects had already activated a new word in the switched back subcategory.

CONCLUSION

Switching between subcategories and subsequent switchback play an important role in triggering perseverations in semantic verbal fluency tasks in the cognitively unimpaired as well as in aMCI and ACS-Dementia. Self-generated interference caused by repeated switching may overwhelm the working memory capacity enough to reactivate a previously suppressed response when revisiting an earlier subcategory. Our findings may facilitate a deeper understanding of the cognitive mechanisms underlying perseveration in semantic fluency tests.

Phonological fluency norms for Spanish middle-aged and older adults provided by the SCAND initiative (P, M, & R)

OBJECTIVE

Verbal fluency tests are quick and easy to administer neuropsychological measures and are regularly used in neuropsychological assessment. Additionally, phonological fluency is a widely used paradigm that is sensitive to cognitive impairment. This paper offers normative data of phonological verbal fluency (letters P, M, R) for Spanish middle- and older-aged adults, considering sociodemographic factors, and different measures such as the total number of words, errors (perseveration and intrusions), and 15 sec-segmented scores.

METHOD

A total of 1165 cognitively unimpaired participants aged between 50 and 89 years old, participated in the study. Data for P were obtained for all participants. Letters M and R were also administered to a subsample of participants (852) aged 60 to 89 years. In addition, errors and words produced every 15 seconds were collected in the subsample. To verify the effect of sociodemographic variables, linear regression was used. Adjustments were calculated for variables that explained at least 5% of the variance (R2 ≥ .05).

RESULTS

Means and standard deviations by age, scaled scores, and percentiles for all tests across different measures are shown. No determination coefficients equal to or greater than .05 were found for sex or age. The need to establish adjustments for the educational level was only found in some of the measures.

CONCLUSIONS

The current norms provide clinically useful data to evaluate Spanish-speaking natives from Spain aged from 50 to 89 years. Specific patterns of cognitive impairment can be analyzed using these normative data and may be important in neuropsychological assessment.

A Systematic Review of Normative Data for Verbal Fluency Test in Different Languages

Verbal fluency tests are easy and quick to use in neuropsychological assessments, so they have been counted among the most classical tools in this context. To date, several normative data for verbal fluency tests have been provided in different languages and countries. A systematic review was carried out with studies that provide normative data for verbal fluency tests. Studies were collected from Scopus, PubMed and Web of Science. 183 studies were retrieved from the database search, of which 73 finally met the inclusion criteria. An analysis of the risk of bias regarding samples selection/characterization and procedure/results reports is conducted for each article. Finally, a full description of the normative data characteristics, considering country and language, verbal fluency task characteristics (type of task) and sample characteristics (number of subjects, gender, age, education) is included. The current systematic review provides an overview and analysis of internationally published normative data that might help clinicians in their search for valid and useful norms on verbal fluency tasks, as well as updated information about qualitative aspects of the different options currently available.

Systematic administration and analysis of verbal fluency tasks: Preliminary evidence for reliable exploration of processes underlying task performance

Verbal fluency (VF) tasks are typically scored by the number of acceptable words generated within an allotted time (i.e., total score). However, total scores do not provide insight into verbal and executive processes underlying VF task performance. Further analyses have been implemented to increase the analytical power of VF tasks, but systematic scoring guidelines are needed. We generated instructions for administration, scoring, and analyses of total scores, errors, temporal parameters, clustering, and switching with strong inter-rater reliability. To investigate the reliability of the proposed analysis, we modeled the performance of Finnish-speaking older adults (N = 50) in phonemic (/k/, /a/, and /p/) and semantic (animals) categories. Our results are in line with previous studies: We observed a higher performance on semantic than phonemic fluency (p ≤ 0.001, d = 0.91) and significant effects for education (p ≤ 0.001, d = 1.11) and gender (p ≤ 0.001, d = -1.11), but not for age (p = 0.10, d = 0.48). Most errors were repetitions. Performance declined over the allotted time frame as measured in 15-s segments (all ps < 0.001 with medium to large effect sizes). Task congruent clustering and switching were productive strategies (all ps < 0.001 with large effect sizes), and participants generated task discrepant clusters in both phonemic (p = 0.004, d = 0.69) and semantic tasks (p = 0.66, d = 0.18). The results substantiate the proposed method, providing evidence that these guidelines are a reliable starting point for VF task performance analyses in various clinical populations investigating VF task performance in depth.

Bear in mind: the role of personal background in semantic animal fluency - The SMART-MR study

Objectives

Semantic fluency is a prominent neuropsychological task, typically administered within the category 'animals'. With the increasing development of novel item-level metrics of semantic fluency, a concern around the validity of item-level analyses could be that personal background factors (e.g., hobbies like birdwatching or fishing) may disproportionally influence performance. We analyzed animal fluency performance at the item level and investigated the prevalence of individuals with abundant knowledge in specific classes of animals (e.g., birds, fish, insects) and the relationship of such knowledge with personal background factors and other cognitive tasks (episodic memory and executive functioning).

Method

Participants included 736 Dutch middle-aged to older adults from the SMART-MR cohort (mean age 58 ± 9.4 years, 18% women). Individuals were asked to name as many animals as possible for 2 min. Number of people with abundant animal class knowledge was calculated for the ability to recall a series of minimum ≥5 and up to ≥15 animals within a specific class with at most one interruption by an animal from another class. Subsequent analyses to investigate relationships of abundant class knowledge with sociodemographic characteristics (t-tests and chi-square tests) and cognitive performance (linear regressions) were performed for a cut-off of ≥10 animals within a specific class (90th percentile), with a sensitivity analysis for ≥7 animals (67th percentile).

Results

A total of 416 (56.2%) participants recalled a series of ≥5 animals from a specific class, 245 (33.3%) participants recalled ≥7, 78 (10.6%) participants recalled ≥10, and 8 (1.1%) participants recalled ≥15. Those who recalled a series of at least 10 animals within a class were older, more often men, and more often retired than those who did not. Moreover, they had a higher total score on animal fluency, letter fluency (i.e., executive functioning), and episodic memory tasks compared to those who did not.

Discussion

Our results suggest that the benefit of abundant animal class knowledge gained by personal background does not disproportionally influence animal fluency performance as individuals with such knowledge also performed better on other cognitive tasks unrelated to abundant knowledge of animal classes.

Normative Data for Single-Letter Controlled Oral Word Association Test in Older White Australians and Americans, African-Americans, and Hispanic/Latinos

Background

The Controlled Oral Word Association Test (COWAT) is a commonly used measure of verbal fluency. While a normal decline in verbal fluency occurs in late adulthood, significant impairments may indicate brain injury or diseases such as Alzheimer's disease. Normative data is essential to identify when test performance falls below expected levels based on age, gender, and education level.

Objective

This study aimed to establish normative performance data on single-letter COWAT for older community-dwelling adults.

Methods

Over 19,000 healthy men and women, without a diagnosis of dementia or a Modified Mini-Mental State Examination score below 77/100, were recruited for the ASPREE trial. Neuropsychological assessments, including the COWAT with letter F, were administered at study entry.

Results

Median participant age was 75 years (range 65-98), with 56.5% being women. The majority of participants had 9-11 years of education in Australia and over 12 years in the U.S. The COWAT performance varied across ethno-racial groups and normative data were thus presented separately for 16,335 white Australians, 1,084 white Americans, 896 African-Americans, and 316 Hispanic/Latinos. Women generally outperformed men in the COWAT, except for Hispanic/Latinos. Higher education levels consistently correlated with better COWAT performance across all groups, while the negative association with age was weaker.

Conclusions

This study provides comprehensive normative data for the COWAT stratified by ethno-racial groups in Australia and the U.S., considering age, gender, and education level. These norms can serve as reference standards for screening cognitive impairments in older adults in both clinical and research settings.

Supplementation with Flaxseed Oil Rich in Alpha-Linolenic Acid Improves Verbal Fluency in Healthy Older Adults

The effects of docosahexaenoic acid supplements on cognitive function have long been demonstrated, but the effects of alpha-linolenic acid, a precursor of docosahexaenoic acid, have not been fully tested. The search for functional foods that delay cognitive decline in the older adults is considered a very important area from a preventive perspective. The aim of this study was to conduct an exploratory evaluation of alpha-linolenic acid on various cognitive functions in healthy older subjects. Sixty healthy older adults aged 65 to 80 years, living in Miyagi prefecture, without cognitive impairment or depression, were included in the randomized, double-blinded, placebo-controlled clinical trial. Study subjects were randomly divided into two groups and received either 3.7 g/day of flaxseed oil containing 2.2 g of alpha-linolenic acid, or an isocaloric placebo (corn oil) containing 0.04 g of alpha-linolenic acid for 12 weeks. The primary endpoints were six cognitive functions closely related to everyday life: attention and concentration, executive function, perceptual reasoning, working memory, processing speed and memory function. After 12 weeks of intake, changes in verbal fluency scores on the frontal assessment battery at bedside, a neuropsychological test assessing executive function, in which participants are asked to answer as many words as possible in Japanese, were significantly greater in the intervention group (0.30 ± 0.53) than in the control group (0.03 ± 0.49, p < 0.05). All other cognitive test scores were not significantly different between the groups. In conclusion, daily consumption of flaxseed oil containing 2.2 g alpha-linolenic acid improved cognitive function, specifically verbal fluency, despite the age-related decline, in healthy individuals with no cognitive abnormalities. Further validation studies focusing on the effects of alpha-linolenic acid on verbal fluency and executive function in older adults are needed, as verbal fluency is a predictor of Alzheimer's disease development, important for cognitive health.

Executive functioning during verbal fluency tasks in bilinguals: A systematic review

BACKGROUND

Bilingualism is widespread and being bilingual is more common than being monolingual. The lifelong practice bilinguals receive from managing two languages seems to lead to a cognitive benefit. Conversely, bilingualism seems to affect language ability negatively due to less use of each known language.

AIMS

This systematic review aims to summarize the results of the studies on the effect of bilingualism on executive functioning assessed by verbal fluency tasks. The verbal fluency task is a neuropsychological measure of lexical retrieval efficiency and executive functioning.

METHODS

The review was conducted according to the PRISMA statement through searches in the scientific databases PsycINFO, PsycARTICLES, MEDLINE, PubMed, Web of Science and SCOPUS. Studies included in this review had at least one bilingual and monolingual group, participants over 18 years and one verbal fluency task. Studies that considered bimodal bilingual, second language learners, trilingual or multilingual people, and clinical populations were excluded. A total of 38 studies were included in the systematic review.

MAIN CONTRIBUTION

Quantitative analysis of performance did not show significant differences between monolinguals and bilinguals. Qualitative results are mixed, and no definitive conclusions can be drawn about a bilingual advantage or disadvantage in the verbal fluency tasks.

CONCLUSIONS

Normative data based on the monolingual population are not appropriate to test a bilingual population. It is necessary to take precautions in using this task, especially in clinical practice.

WHAT THIS PAPER ADDS

What is already known on the subject Bilingualism seems to lead to a cognitive benefit due to constantly monitoring the known languages to select the most suitable one for each interactional context and to affect language ability negatively due to less use of each known language but also to language ability negatively. What this paper adds to the existing knowledge This systematic review summarizes the results of the studies on the effect of bilingualism on executive functioning assessed by verbal fluency tasks, a neuropsychological measure of lexical retrieval efficiency and executive functioning. What are the potential or actual clinical implications of this work? Normative data based on the monolingual population are not appropriate to test a bilingual population. It is necessary to take precautions in using this task, especially in clinical practice.

Validity evidence for the Cognitive Screening Test in Stroke Patients

Abstract Cognitive deficits are common among post-stroke patients. Cognitive impairments of this sort are mediated by age and education. In Brazil, the only specific cognitive screening tool designed for post-stroke patients is the Cognitive Screening Test (Triagem Cognitiva - TRIACOG). The goal of this study was to investigate validity evidence related to external variables for the TRIACOG. Our sample included 153 adults and elderly people (M = 60.08, SD = 9.61) from Porto Alegre and metropolitan area, comprising 87 post-stroke patients and 66 healthy individuals. Three-way ANOVAs were used to assess main effects and interactions between the variables group (clinical/control), age and education. An influence of group and age on scores in the TRIACOG was found. We emphasize the relevance of these results to the selection of cut-off points for the tasks and cognitive functions assessed by the instrument, considering education and age, so as to allow more accurate identification of deficits in post-stroke patients.

An overactive mind: Investigating racing thoughts in ADHD, hypomania and comorbid ADHD and bipolar disorder via verbal fluency tasks

BACKGROUND

Adults with Attention Deficit Hyperactivity Disorder (ADHD) often report mental restlessness akin to racing thoughts found in hypomanic and mixed episodes of bipolar disorder (BD). Past research has suggested that racing thoughts in BD can be tackled via process-oriented verbal fluency measures. In ADHD, it is still unknown whether racing thoughts is due to comorbid BD, and its neuropsychological underpinnings remain to be investigated. To this aim, this study investigates process-oriented verbal fluency measures in adults with ADHD compared to adults with BD in a hypomanic episode, adults with ADHD + BD and healthy controls.

METHODS

Three verbal fluency tasks, i.e., the free, the letter and the semantic conditions, were administered to 37 adults with ADHD, 25 adults with BD in a hypomanic episode, 22 adults with comorbid ADHD + BD (euthymia) and 31 healthy subjects. Word production, clustering, and switching were analysed in verbal fluency tasks.

RESULTS

Adults with ADHD, ADHD + BD and hypomania showed increased switches in the free verbal fluency task, compared to healthy controls, despite equivalent number of words produced. Unlike the ADHD and ADHD + BD groups, phonological clustering measures in the semantic task were increased in the hypomanic group compared to healthy controls.

LIMITATIONS

BD groups were under medication.

CONCLUSIONS

Semantic overactivation, reflected by increased switches in the unconstrained verbal fluency task, appear to be a common mechanism involved in racing thoughts in both ADHD and BD. By contrast, unusual sounds-based associations are specific of hypomanic speech and might contribute to the distinction trait and state racing thoughts.

Functional Connectivity and Compensation of Phonemic Fluency in Aging

Neural compensatory mechanisms associated with broad cognitive abilities have been studied. However, those associated with specific cognitive subdomains (e.g., verbal fluency) remain to be investigated in healthy aging. Here, we delineate: (a) neural substrates of verbal (phonemic) fluency, and (b) compensatory mechanisms mediating the association between these neural substrates and phonemic fluency. We analyzed resting-state functional magnetic resonance imaging from 133 right-handed, cognitively normal individuals who underwent the Controlled Oral Word Association Test (COWAT) to record their phonemic fluency. We evaluated functional connectivity in an established and extended language network comprising Wernicke, Broca, thalamic and anti-correlated modules. (a) We conducted voxel-wise multiple linear regression to identify the brain areas associated with phonemic fluency. (b) We used mediation effects of cognitive reserve, measured by the Wechsler Adult Intelligence Scale—Information subtest, upon the association between functional connectivity and phonemic fluency tested to investigate compensation. We found that: (a) Greater functional connectivity between the Wernicke module and brain areas within the anti-correlated module was associated with better performance in phonemic fluency, (b) Cognitive reserve was an unlikely mediator in younger adults. In contrast, cognitive reserve was a partial mediator of the association between functional connectivity and phonemic fluency in older adults, likely representing compensation to counter the effect of aging. We conclude that in healthy aging, higher performance in phonemic fluency at older ages could be attributed to greater functional connectivity partially facilitated by higher cognitive reserve, presumably reflecting compensatory mechanisms to minimize the effect of aging.

Verbal fluency in Alzheimer's disease and mild cognitive impairment in individuals with low educational level and its relationship with reading and writing habits

Verbal fluency (VF) has contributed to building cognitive maps as well as differentiating healthy populations from those with dementia.

Objectives

To compare the performance of healthy controls and patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) in two semantic VF tasks (animals/clothes) and a phonemic VF task (letter P). Also, to analyze the relationship between the frequency of reading and writing habits (FRWH) and VF in individuals with low educational level.

Methods

Sixty-seven older adults aged 60-80 years and with 2-8 years of schooling were divided into three groups: controls (n=25), older adults with MCI (n=24), and older adults with AD (n=18). We analyzed the type, mean size, and number of clusters, switches, intersections, and returns. A post-hoc single-factor ANOVA analysis was conducted to verify differences between groups.

Results

Total words in the phonemic VF and the animal category discriminated the three groups. Regarding the animal category, AD patients performed worse than controls in the total number of words, taxonomic clusters, returns, and number of words remembered. We found a moderate correlation between FRWH and total number of words in the phonemic fluency.

Conclusions

Semantic (animate) and phonemic (total words) VF differentiated controls and clinical groups from each other - the phonemic component was more related to FRWH than the semantic one. The phonemic VF seems to be more related to cognitive reserve. VF tasks, considering total words and cluster analyses, are a valuable tool to test healthy and cognitively impaired older adults who have a low educational level.