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

Multivariate word properties in fluency tasks reveal markers of Alzheimer's dementia

INTRODUCTION

Verbal fluency tasks are common in Alzheimer's disease (AD) assessments. Yet, standard valid response counts fail to reveal disease-specific semantic memory patterns. Here, we leveraged automated word-property analysis to capture neurocognitive markers of AD vis-à-vis behavioral variant frontotemporal dementia (bvFTD).

METHODS

Patients and healthy controls completed two fluency tasks. We counted valid responses and computed each word's frequency, granularity, neighborhood, length, familiarity, and imageability. These features were used for group-level discrimination, patient-level identification, and correlations with executive and neural (magnetic resonanance imaging [MRI], functional MRI [fMRI], electroencephalography [EEG]) patterns.

RESULTS

Valid responses revealed deficits in both disorders. Conversely, frequency, granularity, and neighborhood yielded robust group- and subject-level discrimination only in AD, also predicting executive outcomes. Disease-specific cortical thickness patterns were predicted by frequency in both disorders. Default-mode and salience network hypoconnectivity, and EEG beta hypoconnectivity, were predicted by frequency and granularity only in AD.

DISCUSSION

Word-property analysis of fluency can boost AD characterization and diagnosis.

HIGHLIGHTS

We report novel word-property analyses of verbal fluency in AD and bvFTD. Standard valid response counts captured deficits and brain patterns in both groups. Specific word properties (e.g., frequency, granularity) were altered only in AD. Such properties predicted cognitive and neural (MRI, fMRI, EEG) patterns in AD. Word-property analysis of fluency can boost AD characterization and diagnosis.

Associations of category fluency clustering performance with in vivo brain pathology in autosomal dominant Alzheimer's disease

OBJECTIVES

Alzheimer's disease (AD) is known to impact semantic access, which is frequently evaluated using the Category Fluency (Animals) test. Recent studies have suggested that in addition to overall category fluency scores (total number of words produced over time), poor clustering could signal AD-related cognitive difficulties. In this study, we examined the association between category fluency clustering performance (i.e., stating words sequentially that are all contained within a subcategory, such as domestic animals) and brain pathology in individuals with autosomal dominant Alzheimer's disease (ADAD).

METHODS

A total of 29 non-demented carriers of the Presenilin1 E280A ADAD mutation and 32 noncarrier family members completed the category fluency test (Animals) and the Mini-Mental State Examination (MMSE). The participants also underwent positron emission tomography (PET) scans to evaluate in vivo amyloid-beta in the neocortex and tau in medial temporal lobe regions. Differences between carriers and noncarriers on cognitive tests were assessed with Mann-Whitney tests; associations between cognitive test performance and brain pathology were assessed with Spearman correlations.

RESULTS

Animal fluency scores did not differ between carriers and noncarriers. Carriers, however, showed a stronger association between animal fluency clustering and in vivo AD brain pathology (neocortical amyloid and entorhinal tau) relative to noncarriers.

CONCLUSION

This study indicates that using category fluency clustering, but not total score, is related to AD pathophysiology in the preclinical and early stages of the disease.

Meta-Analysis of Animal Fluency Performance in Amnestic Mild Cognitive Impairment and Cognitively Unimpaired Older Adults

Animal fluency is a commonly used neuropsychological measure that is used in the diagnosis of amnestic mild cognitive impairment (aMCI) and Alzheimer disease. Although most individuals with aMCI have clinically normal scores on this test, several studies have shown that aMCI individuals' performance is significantly lower than that of cognitively unimpaired (CU) individuals. The aim of this meta-analysis was to characterize the effect size of animal fluency performance differences between aMCI and CU individuals. Literature search with search terms used were: "animal fluency and mild cognitive impairment," "semantic fluency and mild cognitive impairment," "category fluency and mild cognitive impairment." Both the standardized mean difference and the raw mean difference were derived from random effects analyses. Demographically adjusted z-scores for animal fluency performance for the aMCI groups were obtained to determine normative performance. Nineteen studies were included in the analysis. The standardized mean difference for animal fluency performance between CU and aMCI was 0.89 (95% confidence interval: [0.73; 1.04], P <0.001), I2 =70.3% [52.7%; 81.4%], which reflects a large effect size with moderate heterogeneity. The raw mean difference was -4.08 [-4.75; -3.38], P <0.001. The mean animal fluency z-score for aMCI groups was in the Low Average range (z=-0.77). This study found a substantial difference in animal fluency performance between aMCI and CU individuals. The aMCI groups' normative performance did not fall into the impaired range, indicating that there are important subclinical differences in animal fluency performance that may inform the design of cognitive end points for Alzheimer's disease prevention trials.

Neuroanatomical correlates of macrostructural receptive abilities in narrative discourse in unilateral left hemisphere stroke: A behavioural and voxel-based morphometry study

BACKGROUND

Little is known about story retelling and comprehension abilities in groups with lower levels of education and socio-economic status (SES). A growing body of evidence suggests the role of an extended network supporting narrative comprehension, but few studies have been conducted in clinical populations, even less in developing countries.

AIMS

To extend our knowledge of the impact of a stroke on macrostructural aspects of discourse processes, namely main and complementary information, in individuals with middle-low to low SES and low levels of education. Relationships were tested between the performance in story retell and comprehension and reading and writing habits (RWH). Also, the associations between retelling and comprehension measures and their structural grey matter (GM) correlates were explored.

METHODS & PROCEDURES

A total of 17 adults with unilateral left hemisphere (LH) chronic ischaemic stroke without the presence of significant aphasia and 10 matched (age, education and SES) healthy controls (HC) participated in the study. Retell and comprehension tasks were performed after listening or reading narrative stories. Voxel-based morphometry (VBM) analysis was conducted on a subgroup of nine individuals with LH stroke and the 10 matched controls using structural magnetic resonance imaging (MRI).

OUTCOMES & RESULTS

Retelling and comprehension abilities were not significantly different between LH and HC, nonetheless quantitively lower in LH. Exploratory correlations showed that retelling and comprehension abilities in both written and auditory modalities were correlated with naming abilities. At the neural level, written comprehension positively correlated with GM density of the LH, including areas in the temporal pole, superior and middle temporal gyrus as well as the orbitofrontal cortex, precentral and postcentral gyri. Auditory narrative comprehension was associated with GM density of the lingual gyrus in the right hemisphere.

CONCLUSIONS & IMPLICATIONS

The present results suggest that retelling and comprehension of auditory and written narratives are relatively well-preserved in individuals with a LH stroke without significant aphasia, but poorer than in HC. The findings replicate previous studies conducted in groups with higher levels of education and SES both at the behavioural and neural levels. Considering that naming seems to be associated with narrative retell and comprehension in individuals with lower SES and education, this research provides evidence on the importance of pursuing further studies including larger samples with and without aphasia as well as with various SES and education levels.

WHAT THIS PAPER ADDS

What is already known on this subject Story retell and comprehension of auditory and written discourse have been shown to be affected after stroke, but most studies have been conducted on individuals with middle to high SES and high educational levels. What this paper adds to existing knowledge The study reports on narrative retell and comprehension in both auditory and written modalities in groups of HC and individuals with LH brain damage, with low-to-middle SES and lower levels of education. What are the potential or actual clinical implications of this work? This study highlights the importance of taking into consideration the sociodemographic and RWH of patients when assessing discourse retell and comprehension in both auditory and written modalities. It also underlines the importance of including patients without significant aphasia following LH stroke to look at the effect of both stroke and aphasia on narrative comprehension and story retelling.

Verbal fluency tests assess global cognitive status but have limited diagnostic differentiation: evidence from a large-scale examination of six neurodegenerative diseases

Verbal fluency is widely used as a clinical test, but its utility in differentiating between neurodegenerative dementias and progressive aphasias, and from healthy controls, remains unclear. We assessed whether various measures of fluency performance could differentiate between Alzheimer's disease, behavioural variant of frontotemporal dementia, non-fluent and semantic variants of primary progressive aphasia, progressive supranuclear palsy, corticobasal syndrome and healthy controls. Category and letter fluency tasks were administered to 33 controls and 139 patients at their baseline clinical visit. We assessed group differences for total number of words produced, psycholinguistic word properties and associations between production order and exemplar psycholinguistic properties. Receiver operating characteristic curves determined which measure could best discriminate patient groups and controls. The total word count distinguished controls from all patient groups, but neither this measure nor the word properties differentiated the patient groups. Receiver operating characteristic curves revealed that, when comparing controls to patients, the strongest discriminators were total word count followed by word frequency. Word frequency was the strongest discriminator for semantic variant of primary progressive aphasia versus other groups. Fluency word counts were associated with global severity as measured by Addenbrooke's Cognitive Examination Revised. Verbal fluency is an efficient test for assessing global brain-cognitive health but has limited utility in differentiating between cognitively and anatomically disparate patient groups. This outcome is consistent with the fact that verbal fluency requires many different aspects of higher cognition and language.

Phonological and Semantic Fluency in Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Semantic and Phonological fluency (SF and PF) are routinely evaluated in patients with Alzheimer's disease (AD). There are disagreements in the literature regarding which fluency task is more affected while developing AD. Most studies focus on SF assessment, given its connection with the temporoparietal amnesic system. PF is less reported, it is related to working memory, which is also impaired in probable and diagnosed AD. Differentiating between performance on these tasks might be informative in early AD diagnosis, providing an accurate linguistic profile.

OBJECTIVE

Compare SF and PF performance in healthy volunteers, volunteers with probable AD, and patients with AD diagnosis, considering the heterogeneity of age, gender, and educational level variables.

METHODS

A total of 8 studies were included for meta-analysis, reaching a sample size of 1,270 individuals (568 patients diagnosed with AD, 340 with probable AD diagnosis, and 362 healthy volunteers).

RESULTS

The three groups consistently performed better on SF than PF. When progressing to a diagnosis of AD, we observed a significant difference in SF and PF performance across our 3 groups of interest (p = 0.04). The age variable explained a proportion of this difference in task performance across the groups, and as age increases, both tasks equally worsen.

CONCLUSION

The performance of SF and PF might play a differential role in early AD diagnosis. These tasks rely on partially different neural bases of language processing. They are thus worth exploring independently in diagnosing normal aging and its transition to pathological stages, including probable and diagnosed AD.

Three verbal fluency tasks: Normative data and convergent validity in Argentines over 50 years

Abstract Verbal fluency tasks are frequently used in neuropsychological assessment, standing out for their easy application and good sensitivity to early cognitive impairment. However, in Argentina, the availability of updated norms is limited, especially for the action fluency variant. There is also little evidence of validity. Objectives: The aim of this study was to obtain Argentine norms for three verbal fluency tasks and to analyze their convergent validity. Methods: Using a nonprobability sampling method, 303 Argentines from a nonclinical population (age mean=66.8, 50–91 years) were recruited to participate in this study. Those with medical conditions that could compromise neuropsychological performance were excluded. Three verbal fluency tasks (i.e., phonological, semantic, and action), the Montreal Cognitive Assessment (MoCA) test, and the Digit Span-WAIS III test were administered. Correlations and multiple regressions were subsequently performed. Results: Education and age significantly explained 11.8% of the variance in phonological fluency, 15.8% of the variance in semantic fluency, and 20.2% of the variance in action fluency. Hence, the normative data varied according to educational level and age group, with normal performance limit values between 9 and 14 for phonological fluency, 11 and 18 for semantic fluency, and 8 and 17 for action fluency. Positive correlations were obtained between all verbal fluency tasks, as well as between the MoCA test and the Digit Span test. Conclusions: This study supports the applicability of three verbal fluency tasks in an Argentine context by providing age- and education-corrected norms and acceptable evidence of convergent validity.

Regression-Based Normative Data for Independent and Cognitively Active Spanish Older Adults: Verbal Fluency Tests and Boston Naming Test

An increased cognitive reserve is associated with changes in the pattern of cognitive decline during aging. Thus, normative data adapted to the characteristics of the target population are needed to reduce the possibility of false diagnoses. The aim of this work was to develop normative data for the Phonemic Verbal Fluency test, the Semantic Verbal Fluency test and the Boston Naming Test (BNT).

METHOD

Regression-based normative data were calculated from a sample of 118 non-depressed, cognitively active, independent community-dwelling adults aged 55 or older (64.4% women) from SABIEX (University for Seniors at the Universidad Miguel Hernández de Elche). Raw scores were regressed on age, sex, and education.

RESULTS

The effects of age and education varied across neuropsychological measures. No effect of sex was found in any of the tests assessed. Statistically significant differences were found in the proportion of low scores using SABIEX or population-based normative datasets. The level of agreement identifying individuals labeled as showing one or more low scores was only fair-to-good.

CONCLUSIONS

Normative data obtained from the general population might not be sensitive to identify low scores in cognitively active older adults, increasing the risk of misdiagnoses. A friendly calculator is available for neuropsychological assessment.

Reading and writing habits compensate for aging effects in speech connectedness

We investigate the association of short- and long-range recurrences (speech connectedness) with age, education, and reading and writing habits (RWH) in typical aging using an oral narrative production task. Oral narrative transcriptions were represented as word-graphs to measure short- and long-range recurrences. Speech connectedness was explained by the combination of age, education, and RWH, and the strength of RWH's coefficient reflects the aging effect.

Macrostructural Aspects in Oral Narratives in Brazilian Portuguese by Left and Right Hemisphere Stroke Patients With Low Education and Low Socioeconomic Status

OBJECTIVE

Individuals with a stroke in either the left hemisphere (LH) or the right hemisphere (RH) often present macrostructural impairments in narrative abilities. Understanding the potential influence of low education and low socioeconomic status (SES) is critical to a more effective assessment of poststroke language. The first aim was to investigate macrostructural processing in low-education and low-SES individuals with stroke in the LH or RH or without brain damage. The second aim was to verify the relationships between macrolinguistic, neuropsychological, and sociodemographic variables.

METHOD

Forty-seven adults with LH (n = 15) or RH (n = 16) chronic ischemic stroke and 16 matched (age, education, and SES) healthy controls produced three oral picture-sequence narratives. The macrostructural aspects analyzed were cohesion, coherence, narrativity, macropropositions, and index of lexical informativeness and were compared among the three groups. Then, exploratory correlations were performed to assess associations between sociodemographic (such as SES), neuropsychological, and macrostructural variables.

RESULTS

Both the LH and the RH presented impairments in the local macrostructural aspect (cohesion), whereas the RH also presented impairments in more global aspects (global coherence and macropropositions). All five macrostructural variables correlated with each other, with higher correlations with narrativity. Naming was correlated with all macrostructural variables, as well as prestroke reading and writing habits (RWH), showing that higher naming accuracy and higher RWH are associated with better macrostructural skills.

CONCLUSIONS

The present results corroborate the role of the LH in more local processing and that of the RH in more global aspects of discourse. Moreover, this study highlights the importance of investigating discourse processing in healthy and clinical populations of understudied languages such as Brazilian Portuguese, with various levels of education, SES, and RWH.

Lower Education and Reading and Writing Habits Are Associated With Poorer Oral Discourse Production in Typical Adults and Older Adults

During normal aging there is a decline in cognitive functions that includes deficits in oral discourse production. A higher level of education and more frequent reading and writing habits (RWH) might delay the onset of the cognitive decline during aging. This study aimed at investigating the effect of education and RWH on oral discourse production in older adults. Picture-based narratives were collected from 117 healthy adults, aged between 51 and 82 years (68.6 ± 6.38) with 0-20 years of formal education (10.1 ± 5.69). Measures of macro, microlinguistic and modalizations were computed and entered as dependent variables in hierarchical regression analyses that included age, education and RWH as regressors. Results revealed that higher education explained a better performance at the macrostructure and microstructure dimensions. Higher frequency of RWH explained the production of fewer modalizations. These results demonstrate the positive effect of education and RWH in oral discourse production in older adults. Therefore, higher attention should be given to these social factors.

The Lifetime of Experiences Questionnaire: Psychometric Properties and Relationships With Memory Function in an Iranian Elderly Sample

This study aimed to validate the Persian version of the Lifetime of Experiences Questionnaire (LEQ) and examine the relationship between life experience and memory function. To this end, two studies were conducted. Study one examined the factor structure, internal consistency, and convergent and discriminant validity of the Persian version of LEQ with 247 healthy elderly individuals (M age = 70.17, SD = 4.42; 55.9% women). The exploratory factor analysis yielded a five-factor solution, including Knowledge, Physical, Socialization, Artistic, and Leisure dimensions, which accounted for 42.42% of the explained variance. The internal consistency of the LEQ was in the acceptable range (α = 0.703). Also, the LEQ and its subscales (except the Artistic subscale) had a negative relationship with geriatric depression and a positive relationship with a healthy lifestyle, supporting the measure's convergent and discriminant validity. In the second study, we examined the relationship between LEQ (total and subscales score) and memory function using Pearson correlation and moderating analysis with 149 participants (M age = 70.37, SD = 4.29; 55.03% women). The results demonstrated that the LEQ total and subscales scores correlated positively with episodic memory. In the same vein, LEQ total score and Knowledge subscale showed a positive correlation with semantic memory. The results of moderation analysis showed that LEQ subscales have a different role in memory decline. The knowledge subscale as a content component moderates the effect of age on semantic memory (B = 0.005, t = 2.021, p = 0.045), while the mid-life non-specific activities, which are based on life stages, moderate the effect of age on episodic memory (B = 0.007, t = 3.348, p = 0.001). In conclusion, our results indicated that the Persian version of the LEQ is a valid and reliable instrument for measuring experiences and activities throughout life, which can be used in professional clinical and research settings in the aging context with Iranian elderly samples. Furthermore, our findings suggest that various life experiences can be considered cognitive reserves in old age.

Effects of White Matter Hyperintensities on Verbal Fluency in Healthy Older Adults and MCI/AD

BACKGROUND

White matter hyperintensities (WMHs) are markers for cerebrovascular pathology, which are frequently seen in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Verbal fluency is often impaired especially in AD, but little research has been conducted concerning the specific effects of WMH on verbal fluency in MCI and AD.

OBJECTIVE

Our aim was to examine the relationship between WMH and verbal fluency in healthy old age and pathological aging (MCI/AD) using quantified MRI data.

METHODS

Measures for semantic and phonemic fluency as well as quantified MRI imaging data from a sample of 42 cognitively healthy older adults and 44 patients with MCI/AD (total n = 86) were utilized. Analyses were performed both using the total sample that contained seven left-handed/ambidextrous participants, as well with a sample containing only right-handed participants (n = 79) in order to guard against possible confounding effects regarding language lateralization.

RESULTS

After controlling for age and education and adjusting for multiple correction, WMH in the bilateral frontal and parieto-occipital areas as well as the right temporal area were associated with semantic fluency in cognitively healthy and MCI/AD patients but only in the models containing solely right-handed participants.

CONCLUSION

The results indicate that white matter pathology in both frontal and parieto-occipital cerebral areas may have associations with impaired semantic fluency in right-handed older adults. However, elevated levels of WMH do not seem to be associated with cumulative effects on verbal fluency impairment in patients with MCI or AD. Further studies on the subject are needed.