Proficiency and Control in Verbal Fluency Performance across the Lifespan for Monolinguals and Bilinguals

Age-Related Differences in Speech and Gray Matter Volume: The Modulating Role of Multilingualism

Speech involves complex processes such as language formulation, motor coordination, and cognitive functions. As people age, their speech abilities often decline, showing reduced fluency and complexity. Older adults also show decreased gray matter volume. However, the relationship between age-related differences in speech and gray matter volume remain unclear. Multilinguals may exhibit unique age-related speech patterns depending on their language profiles. This study investigates the relationships between age-related differences in brain structure and multilingual speech across different languages, considering the effects of multilingual experience. An integrated measure of speech was calculated and used to reflect the overall speech quality, which was lower in older than younger adults. Native language speech (i.e., Cantonese) was better than non-native language speech (i.e., Mandarin), especially in older adults. More extensive use of multiple languages was associated with enhanced speech quality in both native and non-native languages. Age significantly impacts whole brain gray matter volume, which was lower in older than younger adults. The right middle temporal gyrus emerged as a critical region for speech in both languages in older adults. Bilateral putamen shows sensitivity to the effect of multilingual experience on speech performance in older adults. These findings underscore the complex interplay between age, multilingualism, and brain structure, providing valuable insights into the neural mechanisms underlying multilingual speech performance.

Language experience influences performance on the NIH Toolbox Cognition Battery: A cluster analysis

Studies investigating the effects of bilingualism on cognitive function have often yielded conflicting results, which may stem in part from the use of arbitrary criteria to categorize participants into groups based on language experience. The present study addresses this limitation by using a machine learning algorithm, known as cluster analysis, to identify naturally occurring subgroups of participants with similar language profiles. In a sample of 169 participants with varying degrees of first- and second-language proficiencies and ages of acquisition, the cluster analysis yielded four bilingual subgroups: late-unbalanced, early-unbalanced, late-balanced, and early-balanced. All participants completed the NIH Toolbox Cognition Battery. Results revealed that early-balanced and early-unbalanced bilinguals scored higher than late-unbalanced bilinguals on the cognitive flexibility and inhibitory control subtests of the NIH Toolbox Cognition Battery, whereas late-unbalanced bilinguals scored higher than early-balanced bilinguals on the verbal working memory subtest of the NIH Toolbox Cognition Battery. Bilingual language experience did not impact performance on measures of processing speed, episodic memory, and English vocabulary. These findings demonstrate the utility of data-driven approaches to capture the variability in language experience that exists in the real world. We conclude that different bilingual experiences can shape a wide range of cognitive abilities, from working memory to inhibitory control.

Investigating the cognitive architecture of verbal fluency: evidence from an interference design on 487 controls

Introduction

Numerous studies have explored the linguistic and executive processes underlying verbal fluency using association designs, which provide limited evidence. To assess the validity of our model, we aimed to refine the cognitive architecture of verbal fluency using an interference design.

Methods

A total of 487 healthy participants performed letter and semantic fluency tests under the single condition and dual conditions while concurrently performing a secondary task that interferes with speed, semantics, phonology, or flexibility. We examined the effect of such interference on fluency indices including correct responses, clustering, switching, and time course.

Results

(1) All secondary tasks decreased fluency (p < 0.0001, all), (2) including a simple concurrent task that solely engages the attentional activation system (i.e., speed interference) and (3) a complex concurrent task that affects the ability to alternate (i.e., flexibility interference). (4) Linguistic secondary tasks (which engage phonological and semantic processes, in addition to attention) led to a greater decrease in fluency than speed interference (p < 0.0001), (5) with a more pronounced decrease in semantic fluency induced by semantic interference (p < 0.0001), and (6) the highest decrease in all types of fluency induced by phonological interference (p < 0.0001). In terms of derived indices, (7) speed interference decreased switching without affecting clustering (p < 0.0001) and (8) phonological interference mainly affected the first time interval, whereas speed and flexibility interference primarily affected the last time interval (p < 0.0001, all).

Discussion

These results, based on an interference design, indicate that letter and semantic fluency involve output lexico-phonological and semantic processes with which the strategic search process interacts, as well as an attentional component necessary to accelerate overall processing. These results also highlight interactions with other executive processes, such as those involved in stimulus dimension alternation, which require further analysis. They support our model and provide information concerning derived indices. The commonly claimed associations of executive function with switching and of semantic ability with clustering are only partially supported by our results. Finally, word production appears to be modulated by different cognitive processes over time, with a prominence of the phonological output lexicon in early production and more demanding processing (i.e., executive functioning) in late production.

Using semantic verbal fluency to estimate the relative and absolute vocabulary size of bilinguals: An exploratory study of children and adolescents

INTRODUCTION

The full assessment of bilingual children often involves at least one language for which formal vocabulary tests are lacking and which the examiner does not speak. We examined, in a sample of children with typical development (TD), whether a semantic verbal fluency task, typically used in research as a measure of executive function, could be used in the place of a formal vocabulary test to estimate vocabulary knowledge when formal tests are not available.

METHOD

113 TD monolingual French speakers and TD bilinguals and with varying degrees of exposure to French, age 6 to 17 years, completed tests of vocabulary knowledge and semantic verbal fluency. A subset of 64 participants spoke French and English and were tested in both languages. Verbal fluency measures calculated using a traditional method which uses specific rules for superordinate categories and for animals of different sex and age and a simplified scoring method which simply counts all words produced, included the total number of words produced in each language, Total Vocabulary and Conceptual Vocabulary measures combining both languages, as well as analyses of lexical composition and word frequency within the study sample.

RESULTS

Linear regressions revealed that the number of words produced predicted vocabulary size in a language-specific way, with slightly stronger predictions made by the simplified scoring method. As expected, bilinguals produced more words and more unique words in their language of greater exposure, while different exposure groups were equivalent in measures combining both languages, including their Total vocabulary and Conceptual vocabulary. Producing unusual words (infrequently produced in the study sample) indicated higher vocabulary scores.

CONCLUSIONS

This study supports the use of the verbal fluency task as a quick and simple tool to obtain a rough estimate of vocabulary size in TD monolinguals and bilinguals. This tool shows promise as well in clinical work with other populations, subject to further verification.

Enhancement of phonemic verbal fluency in multilingual young adults by transcranial random noise stimulation

Several studies have analyzed the effects of transcranial direct current stimulation on verbal fluency tasks in non-clinical populations. Nevertheless, the reported effects on verbal fluency are inconsistent. In addition, the effect of other techniques such as transcranial random noise stimulation (tRNS) on verbal fluency enhancement has yet to be studied in healthy multilingual populations. This study aims to explore the effects of tRNS on verbal fluency in healthy multilingual individuals. Fifty healthy multilingual (Spanish, English and Basque) adults were randomly assigned to a tRNS or sham group. Electrodes were placed on the left dorsolateral prefrontal cortex and left inferior frontal gyrus. All participants performed phonemic and semantic verbal fluency tasks before, during (online assessment) and immediately after (offline assessment) stimulation in three different languages. The results showed significantly better performance by participants who received tRNS in the phonemic verbal fluency tasks in Spanish (in the online and offline assessment) and English (in the offline assessment). No differences between conditions were found in Basque nor semantic verbal fluency. These findings suggests that tRNS on the left prefrontal cortex could help improve phonemic, yet not semantic, fluency in healthy multilingual adults.

Semantic fluency in 3-6 years old preschoolers: which executive functions?

Semantic Fluency (SF) increases with age, along with the lexicon and the strategies to access it. Among the cognitive processes involved in controlling lexical access, Executive Functions (EF) play an essential role. Nevertheless, which EF, namely inhibition, working memory, and cognitive flexibility, are specifically tapped by SF during preschool years, when these basic EF components are developing and differentiating, is still unknown. The study had a two-fold aim: 1. to analyze in preschoolers the role of EF basic components on SF; 2. to investigate if EF mediated the effect of age on SF. A total of 296 typically developing preschoolers (M age = 57.86; SD = 9.91; month range = 33-74) were assessed with an SF task and EF tasks measuring the main EF basic components. Results showed that during preschool, response inhibition, working memory, and cognitive flexibility were significant predictors of SF, explaining 27% of its variance. Moreover, the effect of age on the SF task performance correlated with the improvement of these EF components. This study supports the importance of considering cognitive control processes in 3-6 year-old preschoolers as they underline important competencies for the child's development, such as the ability to quickly access vocabulary.

Microstructural analysis of verbal fluency performance in relapsing-remitting multiple sclerosis based on the impact of disability level

Verbal fluency (VF) evaluates language and cognitive abilities. This study compared VF in Relapsing-Remitting Multiple Sclerosis (RRMS) and healthy controls (HC), examining variables including correct responses (CR), mean cluster size (MCS), switches (S), and fluency difference score (FDS). RRMS participants were subgrouped by Expanded Disability Status Scale (EDSS), to explore the relationship between MS severity and VF. Twenty-four RRMS participants and matched HCs underwent Mini-Mental State Exam and VF Test. Statistical analysis compared VF between RRMS subgroups based on severity levels, and in HC. RRMS significantly impacted the CR, and S (CRSF p = 0.01, SSF p = 0.002; CRPF=0.002, SPF p = 0.002), while there was no significant difference in FDS between RRMS groups (p = 0.9). No significant relationship was found between EDSS scores, and VF subtests (CRSF p = 0.061, MCSSF p = 0.46, SSF p = 0.051, CRPF p = 0.521, MCSPF p = 0.966, SPF p = 0.599). In RRMS, our results demonstrate impairments in all VF parameters except the MCSSF+PF, and FDS. This study suggests that intact MCSSF+PF may reflect preserved verbal memory and word recall, while significant switching differences may indicate impaired cognitive flexibility. Similar FDS to those of HC suggest that no performance discrepancy in subtests in RRMS. Intact MCS might be a distinctive pattern in the early clinical stage of MS.

Normative data for verbal fluency and naming tests in Spanish-speaking adults in the United States

BACKGROUND

Linguistic deficits are common across neurological and neurodegenerative disorders. Currently there are limited neuropsychological norms available for Spanish-speaking adults residing in the U.S.

OBJECTIVE

To generate norms for two verbal fluency tests and the Boston Naming Test (BNT) in a Spanish-speaking population in the U.S., with adjustments for demographic and cultural variables.

METHODS

The sample consisted of 245 adults from the U.S. Participants completed phonological and semantic verbal fluency tests and the BNT. A standardized four-step statistical procedure was used.

RESULTS

For the phoneme F, interactions between Spanish proficiency, age, and education arose. Better performance on phonemes A, S, and M was related to education. Spanish proficiency, acculturation, and time in the U.S. were associated with the phonemes S, A, P, M, and R. An age by education interaction was found for phonemes M and R. The FAS and PMR triads were related to age, sex, time in U.S., and Spanish proficiency. For the semantic verbal fluency tests, an interaction between education and Spanish proficiency arose. For the BNT, test scores were related to education, and significant interactions were also found based on education's interaction with Spanish proficiency and acculturation.

CONCLUSION

This study highlights the importance of accounting for sociodemographic and acculturative factors when developing normative data for verbal fluency tests and the BNT for dominant Spanish-speaking adults in the U.S. These sociodemographically-adjusted norms will help improve accuracy of diagnosis and interpretation of linguistic test performance in Spanish speakers living in the U.S.

Multilingualism is associated with small task-specific advantages in cognitive performance of older adults

The protective effects of multiple language knowledge on the maintenance of cognitive functions in older adults have been discussed controversially, among others, because of methodological inconsistencies between studies. In a sample of N = 528 German monolinguals and multilinguals (speaking two or more languages) older than 60 years, this study examined (1) whether speaking multiple languages is positively related to performance on tasks of interference suppression, working memory, concept shifting, and phonemic and semantic fluency, and (2) whether language proficiency and age of second language acquisition (AoA) are associated with cognitive performance of multilinguals. Controlling for education and daily activity, we found small cognitive benefits of speaking multiple languages on interference suppression, working memory, and phonemic fluency, but not on concept shifting and semantic fluency. Furthermore, no substantive correlations were found between language proficiency or AoA and cognitive performance. In conclusion, multilingualism appears to have small incremental effects on cognitive performance beyond education and daily activity in older age that are task-specific and widely independent of proficiency and AoA.

Phonological and semantic verbal fluency test: Scoring criteria and normative data for clustering and switching strategies for Colombian children and adolescents

BACKGROUND

Verbal fluency tests (VFT) are highly sensitive to cognitive deficits. Usually, the score on VFT is based on the number of correct words produced, yet it alone gives little information regarding underlying test performance. The implementation of different strategies (cluster and switching) to perform efficiently during the tasks provide more valuable information. However, normative data for clustering and switching strategies are scarce. Moreover, scoring criteria adapted to Colombian Spanish are missing.

AIMS

(1) To describe the Colombian adaptation of the scoring system guidelines for clustering and switching strategies in VFT; (2) to determine its reliability; and (3) to provide normative data for Colombian children and adolescents aged 6-17 years.

METHODS & PROCEDURES

A total of 691 children and adolescents from Colombia completed phonological (/f/, /a/, /s/, /m/, /r/ and /p/) and semantic (animals and fruits) VFT, and five scores were calculated: total score (TS), number of clusters (NC), cluster size (CS), mean cluster size (MCS) and number of switches (NS). The intraclass correlation coefficient was used for interrater reliability. Hierarchical multiple regressions were conducted to investigate which strategies were associated with VFT TS. Multiple regressions were conducted for each strategy, including as predictors age, age2 , sex, mean parents' education (MPE), MPE2 and type of school, to generate normative data.

OUTCOMES & RESULTS

Reliability indexes were excellent. Age was associated with VFT TS, but weakly compared with strategies. For both VFT TS, NS was the strongest variable, followed by CS and NC. Regarding norms, age was the strongest predictor for all measures, while age2 was relevant for NC (/f/ phoneme) and NS (/m/ phoneme). Participants with higher MPE obtained more NC, and NS, and larger CS in several phonemes and categories. Children and adolescents from private school generated more NC, NS and larger CS in /s/ phoneme.

CONCLUSIONS & IMPLICATIONS

This study provides new scoring guidelines and normative data for clustering and switching strategies for Colombian children and adolescents between 6 and 17 years old. Clinical neuropsychologists should include these measures as part of their everyday practice.

WHAT THIS PAPER ADDS

What is already known on the subject VFT are widely used within the paediatric population due to its sensitivity to brain injury. Its score is based on the number of correct words produced; however, TS alone gives little information regarding underlying test performance. Several normative data for VFT TS in the paediatric population exist, but normative data for clustering and switching strategies are scarce. What this paper adds to existing knowledge The present study is the first to describe the Colombian adaptation of the scoring guidelines for clustering and switching strategies, and provided normative data for these strategies for children and adolescents between 6 and 17 years old. What are the potential or actual clinical implications of this work? Knowing VFT's performance, including strategy development and use in healthy children and adolescents, may be useful for clinical settings. We encourage clinicians to include not only TS, but also a careful analysis of strategies that may be more informative of the underlying cognitive processes failure than TS.

Relationship between lexical, reading and spelling skills in bilingual language minority children and their monolingual peers

This study was conducted on a population of primary school children including bilingual language minority (BLM) children with L2-Italian and a variety of languages as L1 (e.g., Chinese, Albanian, Latin), and Italian-speaking monolingual children. The variety of languages ecologically reflects the nowadays composition of classes in the Italian school system. The aims were to investigate in both linguistic groups: (1) the developmental patterns of lexical, reading and spelling skills; (2) the pattern of predictive relations between lexical, reading and spelling skills. 159 primary school children from Grade 2 to Grade 5 participated in the study: BLM (n = 80) and monolingual (n = 79) children aged between 7 and 11 years. Each participant completed a vocabulary task (lexical skills), a text reading task (reading accuracy and reading speed) and a text dictation task (orthographic errors). ANOVA statistics showed the comparison of patterns between monolingual and BLM children in lexical, reading, and writing skills. Results show lower performances in lexical, reading and spelling skills in BLM children learning Italian as a second language compared to monolingual peers. Second, partial correlations performed separately for monolinguals and BLM with lexical ability as a control variable, illustrated that all variables correlated with each other in both groups. This result provides the option of performing hierarchical regressions. Finally, hierarchical regression analyses showed that the pattern of predictive relations between lexical, reading and spelling skills is the same across language groups, with the key role of orthographic accuracy as the pivotal process around which reading and lexical skills are built.

Even young children make multiple predictions in the complex visual world

Children can anticipate upcoming input in sentences with semantically constraining verbs. In the visual world, the sentence context is used to anticipatorily fixate the only object matching potential sentence continuations. Adults can process even multiple visual objects in parallel when predicting language. This study examined whether young children can also maintain multiple prediction options in parallel during language processing. In addition, we aimed at replicating the finding that children's receptive vocabulary size modulates their prediction. German children (5-6 years, n = 26) and adults (19-40 years, n = 37) listened to 32 subject-verb-object sentences with semantically constraining verbs (e.g., "The father eats the waffle") while looking at visual scenes of four objects. The number of objects being consistent with the verb constraints (e.g., being edible) varied among 0, 1, 3, and 4. A linear mixed effects model on the proportion of target fixations with the effect coded factors condition (i.e., the number of consistent objects), time window, and age group revealed that upon hearing the verb, children and adults anticipatorily fixated the single visual object, or even multiple visual objects, being consistent with the verb constraints, whereas inconsistent objects were fixated less. This provides first evidence that, comparable to adults, young children maintain multiple prediction options in parallel. Moreover, children with larger receptive vocabulary sizes (Peabody Picture Vocabulary Test) anticipatorily fixated potential targets more often than those with smaller ones, showing that verbal abilities affect children's prediction in the complex visual world.

Cognitive impairment in multiple sclerosis: "classic" knowledge and recent acquisitions

Multiple sclerosis (MS) is a central nervous system (CNS) disease characterized by inflammation, axonal demyelination, and neurodegeneration, which can have a strong impact on all aspects of the life of the patient. Multiple sclerosis causes motor, sensory, cerebellar, and autonomic dysfunctions, as well as cognitive and psychoemotional impairment. The most frequently compromised cognitive domains are complex attention/information processing, memory, executive and visuospatial functions. Recently, alterations have also been evidenced in complex cognitive functions, such as social cognition, moral judgment, and decision-making. Cognitive impairment is characterized by high variability and can affect work skills, social interactions, coping strategies and more generally the quality of life of patients and their families. With the use of sensitive and easy-to-administer test batteries, an increasingly accurate and early diagnosis is feasible: this allows to determine the effectiveness of possible preventive measures, to predict the future progression of the disease and to improve the quality of life of patients. There is currently limited evidence regarding the efficacy, on cognitive impairment, of disease-modifying therapies. The most promising approach, which has received strong empirical support, is cognitive rehabilitation.

Does bilingualism come with linguistic costs? A meta-analytic review of the bilingual lexical deficit

A series of recent studies have shown that the once-assumed cognitive advantage of bilingualism finds little support in the evidence available to date. Surprisingly, however, the view that bilingualism incurs linguistic costs (the so-called lexical deficit) has not yet been subjected to the same degree of scrutiny, despite its centrality for our understanding of the human capacity for language. The current study implemented a comprehensive meta-analysis to address this gap. By analyzing 478 effect sizes from 130 studies on expressive vocabulary, we found that observed lexical deficits could not be attributed to bilingualism: Simultaneous bilinguals (who acquired both languages from birth) did not exhibit any lexical deficit, nor did sequential bilinguals (who acquired one language from birth and a second language after that) when tested in their mother tongue. Instead, systematic evidence for a lexical deficit was found among sequential bilinguals when tested in their second language, and more so for late than for early second language learners. This result suggests that a lexical deficit may be a phenomenon of second language acquisition rather than bilingualism per se.

The Spanish-English bilingual experience and cognitive change in Hispanics/Latinos from the Hispanic Community Health Study/Study of Latinos-Investigation of Neurocognitive Aging

INTRODUCTION

Studies suggest bilingualism may delay behavioral manifestations of adverse cognitive aging including Alzheimer's dementia.

METHODS

Three thousand nine hundred sixty-three participants (unweighted mean population age ≈56 years) at Hispanic Community Health Study/Study of Latinos baseline (2008-2011) self-reported their and their parents' birth outside the United States, Spanish as their first language, and used Spanish for baseline and comparable cognitive testing 7 years later (2015-2018). Spanish/English language proficiency and patterns of use were self-rated from 1 = only Spanish to 4 = English > Spanish. Cognitive testing included test-specific and global composite score(s) of verbal learning, memory, word fluency, and Digit Symbol Substitution (DSS). Survey linear regression models examined associations between baseline bilingualism scores and cognition.

RESULTS

Higher second-language (English) proficiency and use were associated with higher global cognition, fluency, and DSS at follow-up and better than predicted change in fluency.

DISCUSSION

The bilingual experience was more consistently related to 7-year level versus change in cognition for Hispanics/Latinos.

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.

WPPSI-IV and NEPSY-II performance in mono- and bilingual 5-6-year-old children: Findings from The FinSwed Study

Children's language background relates to their neurocognitive development. Knowledge of this relationship is important as bilingualism is common. However, research regarding language background in relation to performance on cognitive tests such as the WPPSI-IV and NEPSY-II is scarce. The present study compared WPPSI-IV and NEPSY-II performances between 5- and 6-year-old Swedish-speaking monolingual (n = 45) and Swedish-Finnish-speaking simultaneous bilingual (n = 34) children in Finland. The participants were gathered by stratified sampling and were assessed with the Swedish versions of the tests. In profile analyses, a significant monolingual advantage was found in some WPPSI-IV subtests and indexes requiring expressive vocabulary (Vocabulary, Similarities, Picture Naming, and Vocabulary Acquisition Index) and visuospatial skills (Object Assembly and Visual Spatial Index). No group differences were found between mono- and bilingual children in receptive language, visual memory, or fluid intelligence. Additionally, no differences were found on the Full Scale IQ. The performance on the WPPSI-IV Similarities subtest improved in a subgroup of bilinguals when answers in both Swedish and Finnish were accounted for, instead of accepting only answers in Swedish. No significant differences were found between mono- and bilinguals on the language and memory tasks of NEPSY-II. These findings highlight the importance of considering the child's language background when assessing expressive language in young children, as well as the benefits of assessing bilinguals in both of their languages.

Verbal production dynamics and plasticity: functional contributions of language and executive control systems

Bilingual language production requires both language knowledge and language control in order to communicate in a target language. Learning or improving a language in adulthood is an increasingly common undertaking, and this has complex effects on the cognitive and neural processes underlying language production. The current functional magnetic resonance imaging (fMRI) experiment investigated the functional plasticity of verbal production in adult language learners, and examined the dynamics of word retrieval in order to dissociate the contributions of language knowledge and executive control. Thirty four adults who were either intermediate or advanced language learners, underwent MRI scanning while performing verbal fluency tasks in their native and new languages. A multipronged analytical approach revealed (i) time-varying contributions of language knowledge and executive control to verbal fluency performance, (ii) learning-related changes in the functional correlates of verbal fluency in both the native and new languages, (iii) no effect of learning on lateralization, and (iv) greater functional coupling between language and language control regions with greater second language experience. Collectively, our results point to significant functional plasticity in adult language learners that impacts the neural correlates of production in both the native and new languages, and provide new insight into the widely used verbal fluency task.

Using big data to understand bilingual performance in semantic fluency: Findings from the Canadian Longitudinal Study on Aging

OBJECTIVES

This study aimed to characterize verbal fluency performance in monolinguals and bilinguals using data from the Canadian Longitudinal Study on Aging (CLSA).

METHODS

A large sample of adults aged 45-85 (n = 12,875) completed a one-minute animal fluency task in English. Participants were English-speaking monolinguals (n = 9,759), bilinguals who spoke English as their first language (L1 bilinguals, n = 1,836), and bilinguals who spoke English as their second language (L2 bilinguals, n = 1,280). Using a distributional modeling approach to quantify the semantic similarity of words, we examined the impact of word frequency and pairwise semantic similarity on performance on this task.

RESULTS

Overall, L1 bilinguals outperformed monolinguals on the verbal fluency task: they produced more items, and these items were of lower average frequency and semantic similarity. Monolinguals in turn outperformed L2 bilinguals on these measures. The results held across different age groups, educational, and income levels.

DISCUSSION

These results demonstrate an advantage for bilinguals compared to monolinguals on a category fluency task, when performed in the first language, indicating that, at least in the CLSA sample, bilinguals have superior semantic search capabilities in their first language compared to monolingual speakers of that language.

Assessing language background and experiences among heritage bilinguals

The language backgrounds and experiences of bilinguals have been primarily characterized using self-report questionnaires and laboratory tasks, although each of these assessments have their strengths and weaknesses. The Electronically Activated Recorder (EAR), an audio recording device, has recently become more prominent as a method of assessing real-world language use. We investigated the relationships among these three assessment tools, to understand the shared variance in how these measures evaluated various aspects of the bilingual experience. Participants were 60 Southern California heritage bilingual college students who spoke a variety of heritage languages and began to learn English between the ages of 0-to 12-years. Participants completed both self-report and laboratory-based measures of language proficiency and use, and they wore the EAR for 4  days to capture representative samples of their day-to-day heritage language (HL) use. The results indicated that self-reported HL use and English age of acquisition were significant predictors of real-world language use as measured by the EAR. In addition, self-reported HL proficiency and laboratory-based HL proficiency, as measured by verbal fluency, were mutually predictive. While some variability was shared across different assessments, ultimately, none of the measures correlated strongly and each measure captured unique information about the heritage bilingual language experience, highlighting the dissociation between language experience measured at a single point in time and an accumulated life history with a heritage language. These findings may provide guidance for bilingualism researchers about which assessment tool, or combination of tools, may be best for their specific research questions.

Graph Theory Analysis of Semantic Fluency in Russian-English Bilinguals

BACKGROUND

Semantic category fluency is a widely used task involving language, memory, and executive function. Previous studies of bilingual semantic fluency have shown only small differences between languages. Graph theory analyzes complex relationships in networks, including node and edge number, clustering coefficient, average path length, average number of direct neighbors, and scale-free and small-world properties.

OBJECTIVE

To shed light on whether the underlying neural processes involved in semantic category fluency testing yield substantially different networks in different languages.

METHOD

We compared languages and methods using both network analysis and conventional analysis of word production. We administered the animal naming task to 51 Russian-English bilinguals in each language. We constructed network graphs using three methods: (a) simple association of unique co-occurring neighbors, (b) corrected associations between consecutive words occurring beyond chance, and (c) a network community approach using planar maximally filtered graphs. We compared the resultant network analytics as well as their scale-free and small-world properties.

RESULTS

Participants produced more words in Russian than in English. Small-worldness metrics were variable between Russian and English but were consistent across the three graph theory analytical methods.

CONCLUSION

The networks had similar graph theory properties in both languages. The optimal methodology for creating networks from semantic category fluency remains to be determined.

Multifactorial approaches to study bilingualism in the aging population: Past, present, future

A better understanding and more reliable classification of bilinguals has been progressively achieved through the fine-tuning methodology and simultaneously optimizing the measurement tools. However, the current understanding is far from generalization to a larger population varying in different measures of bilingualism-L2 Age of acquisition (L2 AOA), L2 usage and exposure, and L2 proficiency. More recent studies have highlighted the importance of modeling bilingualism as a continuous variable. An in-depth look at the role of bilingualism, comparing groups, may be considered a reductionist approach, i.e., grouping based on one measure of bilingualism (e.g., L2 AOA) may not account for variability in other measures of bilingualism (L2 exposure, L2 use or L2 proficiency, amongst others) within and between groups. Similarly, a multifactorial dimension is associated with cognitive performance, where not all domains of cognition and subcomponents are equally influenced by bilingualism. In addition, socio-cultural and demographical factors may add another dimension to the impact of bilingualism on cognitive performance, especially in older adults. Nevertheless, not many studies have controlled or used the multiple socio-cultural and demographical factors as a covariate to understand the role of different aspects of bilingualism that may influence cognitive performance differently. Such an approach would fail to generalize the research findings to a larger group of bilinguals. In the present review paper, we illustrate that considering a multifactorial approach to different dimensions of bilingual study may lead to a better understanding of the role of bilingualism on cognitive performance. With the evolution of various fine-tuned methodological approaches, there is a greater need to study variability in bilingual profiles that can help generalize the result universally.

Verbal fluency difficulties in aphasia: A combination of lexical and executive control deficits

BACKGROUND

Verbal fluency tasks are routinely used in clinical assessment and research studies of aphasia. People with aphasia produce fewer items in verbal fluency tasks. It remains unclear if their output is limited solely by their lexical difficulties and/or has a basis in their executive control abilities. Recent research has illustrated that detailed characterization of verbal fluency performance using temporal characteristics of words retrieved, clustering and switching, and pause durations, along with separate measures of executive control stands to inform our understanding of the lexical and cognitive underpinnings of verbal fluency in aphasia.

AIMS

To determine the locus of the verbal fluency difficulties in aphasia, we compared semantic and letter fluency trials between people with aphasia and healthy control participants using a wide range of variables to capture the performance between the two groups. The groups were also tested on separate measures of executive control to determine the relationship amongst these tasks and fluency performance.

METHODS & PROCEDURES

Semantic (animal) and letter (F, A, S) fluency data for 60s trials were collected from 14 people with aphasia (PWA) and 24 healthy adult controls (HC). Variables, such as number of correct responses, clustering and switching analyses, were performed along with temporal measures of the retrieved words (response latencies) and pause durations. Participants performed executive control tasks to measure inhibitory control, mental-set shifting and memory span.

OUTCOMES & RESULTS

Compared with HC, PWA produced fewer correct responses, showed greater difficulty with the letter fluency condition, were slower in getting started with the trials, showed slower retrieval times as noted in within- and between-cluster pause durations, and switched less often. Despite these retrieval difficulties, PWA showed a similar decline in the rate of recall to HC, and had similar cluster size. Executive control measures correlated primarily with the letter fluency variables: mostly for PWA and in one instance for HC.

CONCLUSIONS & IMPLICATIONS

Poorer performance for PWA is a combination of difficulties in both the lexical and executive components of the verbal fluency task. Our findings highlight the importance of detailed characterization of fluency performance in deciphering the underlying mechanism of retrieval difficulties in aphasia, and illustrate the importance of using letter fluency trials to tap into executive control processes.

WHAT THIS PAPER ADDS

What is already known on the subject PWA typically show impaired performance in verbal fluency tasks. It is debated whether this impaired performance is a result of their lexical difficulties or executive control difficulties, or a combination of both. This debate continues because previous studies have mostly used semantic fluency condition without including letter fluency condition; used a limited range of variables (e.g., number of correct responses); and not included separate executive control measures to explain the performance pattern in aphasia. This research addresses these outstanding issues to determine the specific contribution of lexical and executive control processes in verbal fluency in aphasia by including: both semantic and letter fluency conditions; a wide range of variables to identify the relative contribution of lexical and executive control mechanisms; and independent measures of executive control. What this paper adds to existing knowledge Using the multidimensional analysis approach for verbal fluency performance from both semantic and letter fluency conditions, this is the first study to systematically demonstrate that PWA had difficulties in both lexical and executive control components of the task. At the individual level, PWA had greater difficulty on the letter fluency condition compared with semantic fluency. We observed significant correlations between the executive control measures and verbal fluency measures primarily for the letter fluency condition. This research makes a significant contribution to our understanding of lexical and executive control aspects in word production in aphasia. What are the potential or actual clinical implications of this work? From a clinical perspective, this research highlights the importance of using a full range of verbal fluency and executive control measures to tap into the lexical as well as executive control abilities of PWA, and also the utility of using letter fluency to tap into the executive control processes in PWA.

Clustering and Switching in Verbal Fluency Across Varying Degrees of Cognitive Control Demands: Evidence From Healthy Bilinguals and Bilingual Patients With Aphasia

Different linguistic contexts place varying amounts of cognitive control on lexical retrieval in bilingual speakers, an issue that is complicated in bilingual patients with aphasia (BPWA) due to subsequent language and cognitive deficits. Verbal fluency tasks may offer insight into the interaction between executive and language control in healthy bilinguals and BPWA, by examining conditions with varying cognitive control demands. The present study examined switching and clustering in verbal fluency tasks in BPWA and healthy bilinguals across single- and dual-language conditions. We also examined the influence of language processing and language proficiency on switching and clustering performance across the dual-language conditions. Thirty-five Spanish-English BPWA and twenty-two Spanish-English healthy bilinguals completed a language use questionnaire, tests of language processing, and two verbal fluency tasks. The semantic category generation task included four conditions: two single-language conditions (No-Switch L1 and No-Switch L2) that required word production in each language separately; one dual-language condition that allowed switching between languages as desired (Self-Switch); and one dual-language condition that required switching between languages after each response (Forced-Switch). The letter fluency task required word production in single-language contexts. Overall, healthy bilinguals outperformed BPWA across all measures. Results indicate that switching is more sensitive to increased control demands than clustering, with this effect being more pronounced in BPWA, underscoring the interaction between semantic executive processes and language control in this group. Additionally, for BPWA switching performance relies on a combination of language abilities and language experience metrics.

Bilingualism and Its Implications for Neuropsychological Evaluation

OBJECTIVE

In the background of a large population of bilinguals globally, the study aimed to develop standards of neuropsychological testing in the context of bilingualism. Because bilingualism is known to affect cognitive processes, bilinguals and monolinguals were compared on their performance on cognitive tests, to investigate the possibility of the need for separate normative data for the two groups.

METHOD

A comprehensive neuropsychological test battery, standardized across five Indian languages: the Indian Council of Medical Research-Neuro Cognitive Tool Box (ICMR-NCTB) was administered to 530 participants (267 monolingual and 263 bilinguals matched for age and education). A systematic method of testing cognition in bilinguals was developed; to identify the appropriate language for testing, ensure language proficiency of examiner, and to interpret the bilingual responses. Additionally, the performance of bilinguals on the ICMR-NCTB was compared with monolinguals.

RESULTS

Cognitive testing in the bilingual context was performed in the most proficient language of the participants, by examiners well versed with the language. Results from the language-based tests suggested that the frequent occurrence of borrowed- and language-mixed words required consideration while scoring. The reported bilingual effect on cognitive processes did not reflect as differences in the performance between bilinguals and monolinguals.

CONCLUSIONS

Observations from the study provide robust recommendations for neuropsychological testing in the context of bilingualism. Results indicate that separate normative data may not be required for bilinguals and monolinguals. The study will be relevant and provide a reference framework to address similar issues in the large population of bilinguals in other societies.

The Bilingual Native Speaker Competence: Evidence From Explicit and Implicit Language Knowledge Using Elicited Production, Sentence-Picture Matching, and Pupillometry

The present pilot study investigated potential effects of early and late child bilingualism in highly proficient adult bilinguals. It has been shown that some early second language (eL2) speakers stagnate when it comes to complex linguistic phenomena and that they display subtle difficulties in adulthood. Therefore, we have chosen the complex structure of double object constructions. We investigate the long-term achievement in a combined-method approach using elicited production, explicit comprehension by sentence-picture matching and a measure of implicit linguistic knowledge, namely pupillometry. This eye tracking method is suitable for measuring implicit reactions of the pupils to unexpected or ungrammatical stimuli. For production, ditransitive structures were elicited by means of a game. For comprehension, a sentence-picture matching task was conducted. Two pictures were shown on a monitor that were equal with respect to the involved objects, but the thematic roles of direct and indirect objects were interchanged. Items were controlled for length, gender, animacy, semantic likelihood and word order. Reaction times and accuracy scores were analyzed. To this end, N = 18 bilingual adult speakers of German (+ another language, mean age: 26.5) with different ages of onset participated in this study and were compared to N = 26 monolingual German adult speakers (mean age 23.9). All participants had a proficiency of German above 89% correct in placement and cloze tests. Results show fully comparable productive and comprehensive competencies in monolinguals and bilinguals including the reaction times in the sentence-picture matching task and a word order effect on the reaction times in both groups. In the pupillometry task, we found monolinguals and bilinguals to be sensitive to differing conditions with respect to grammatical and ungrammatical utterances. However, we find between group differences in pupil dilations in that bilinguals react differently to strong grammatical violations than monolinguals. These results are discussed with respect to the term of native speaker competence and the variation within both groups.

Hand preference in referential gestures: Relationships to accessing words for speaking in monolingual and bilingual children

INTRODUCTION

Infants' right-hand preference for pointing is associated with higher vocabulary. It is not clear whether the link between right-hand preference for gesturing and language persists into the preschool years. The primary purpose of the present study was to test whether preschool children's hand preference for referential gestures was associated with their language abilities. Secondarily, we predicted that the children's right-hand preference would be negatively associated with their visuospatial abilities. We also predicted that monolingual children would show a strong right-hand preference while bilinguals might show a reduced right-hand preference.

METHODS

Monolingual and bilingual children between the ages of four and six years did a storytelling task. Their referential gestures were coded for hand use (right, left, both). We measured language skills (receptive vocabulary, semantic fluency).

RESULTS

We found no difference between bilinguals and monolinguals on hand preference. Semantic fluency was a positive predictor and vocabulary a negative predictor of right-hand preference. Children's visuospatial abilities were not a predictor of right-hand preference.

CONCLUSION

These results suggest that right-hand preference may help children select semantically appropriate words out of their existing vocabulary. In other words, this preference may be related to children's construction of the message that they would like to produce. The association between hand preference and language skills persists into the preschool years.

Aging affects steaks more than knives: Evidence that the processing of words related to motor skills is relatively spared in aging

Lexical-processing declines are a hallmark of aging. However, the extent of these declines may vary as a function of different factors. Motivated by findings from neurodegenerative diseases and healthy aging, we tested whether 'motor-relatedness' (the degree to which words are associated with particular human body movements) might moderate such declines. We investigated this question by examining data from three experiments. The experiments were carried out in different languages (Dutch, German, English) using different tasks (lexical decision, picture naming), and probed verbs and nouns, in all cases controlling for potentially confounding variables (e.g., frequency, age-of-acquisition, imageability). Whereas 'non-motor words' (e.g., steak) showed age-related performance decreases in all three experiments, 'motor words' (e.g., knife) yielded either smaller decreases (in one experiment) or no decreases (in two experiments). The findings suggest that motor-relatedness can attenuate or even prevent age-related lexical declines, perhaps due to the relative sparing of neural circuitry underlying such words.

Intervención en el control inhibitorio en niños con y sin trastorno de lenguaje dentro del aula

El objetivo de este trabajo fue evaluar el impacto de una intervención escolar en control inhibitorio llevada a cabo dentro de diversas aulas de segundo ciclo de primaria (9-11 años) que tenían alumnos con Trastorno del Desarrollo del Lenguaje (n = 5) o dislexia (n = 4) y sus compañeros de aula sin dificultades (n = 6). El diseño siguió un modelo pre-post intervención con las variables dependientes fluidez verbal, memoria fonológica y control inhibitorio. La intervención consistió en ocho sesiones de 10 minutos a todo el grupo clase, dos por semana durante cuatro semanas, más una sesión larga de 1 hora en grupo pequeño en medio de las sesiones, en las que se realizaba actividades basadas en diferentes tareas de control inhibitorio (“Stroop”, “Go-no go”, “Plots”, “Simon”,…). Los niños con TDL y dislexia mostraron una puntuación más baja en memoria fonológica antes de la intervención. La intervención sólo tuvo efecto en una leve mejora en todos los grupos en la memoria fonológica. Sin embargo, las comparaciones entre los grupos post-intervención mostraron puntuaciones significativamente más bajas en el grupo TDL respecto a los otros dos en fluencia verbal y control inhibitorio, que pueden indicar una posible mejoría de los grupos de dislexia y sin dificultades en estas variables. En conclusión, la intervención tuvo un escaso efecto, especialmente en el grupo con TDL. Se requieren más trabajos con un mayor número de participantes y de sesiones de intervención para poder corroborar la falta de efecto específico sobre el control inhibitorio y la fluencia verbal en los grupos intervenidos.

The role of language ability in verbal fluency of individuals with multiple sclerosis

BACKGROUND

While cognitive deficits in memory and processing speed have been well-documented in individuals with multiple sclerosis (MS), language is largely considered to be intact. Verbal fluency deficits observed in MS are often attributed to impaired processing speed and executive functions rather than language ability. The current study evaluates the contribution of various cognitive factors to verbal fluency including language ability, oral-motor speed, processing speed, and executive functions.

METHODS

We analyzed pre-existing data from seventy-four (74) individuals with MS who completed a battery of neuropsychological tests designed to assess individual ability for various cognitive factors. We conducted linear multiple regression analyses with letter and category verbal fluency as outcome variables and performance on other cognitive domains (e.g., processing speed, executive functioning) as predictors.

RESULTS

Both vocabulary and processing speed predicted letter fluency while only vocabulary predicted category fluency. These findings suggest that the observed verbal fluency deficits in MS may reflect both impaired language ability and processing speed.

CONCLUSION

We propose that further research on language ability in MS is needed to determine if comprehensive neuropsychological test batteries for persons with MS should include tests of language ability to fully understand the cognitive profile of any given patient. Given the importance of language ability, it may be necessary to conduct a more thorough assessment of language in individuals with MS who experience a deficit in this domain.

Validation Study of a German Cognitive Battery for Huntington's Disease: Relationship Between Cognitive Performance, Functional Decline, and Disease Burden

Objective

Cognitive decline is a key characteristic of Huntington’s disease (HD). This study aimed to investigate the diagnostic accuracy of a cognitive battery with six tests used by most HD research centers to assess cognitive impairment in HD.

Method

In total, 106 HD patients in different disease stages with more (HD-CD, N = 30) and less cognitive impairments (HD-NC, N = 70) and 100 healthy controls (NC) were matched by age, sex, and education and were examined using a standardized protocol including cognitive, motor, and functional assessments.

Results

One-way between-groups analysis of variance showed that controls performed significantly better than HD patients and that HD-NC significantly outperformed HD-CD patients in all cognitive tests (NC > HD-NC > HD-CD), with all Games-Howell post-hoc tests p < .001. Analyses using area under the receiver-operating characteristic curve (AUC) disclosed the diagnostic accuracy of all tests included in the battery to discriminate between NC and HD patients with AUC ranging from 0.809 to 0.862 (all p < .001) and between HD-CD and HD-NC patients with AUC ranging from 0.833 to 0.899 (all p < .001). In both analysis, Stroop Color Naming Test showed the highest discriminative potential. Additional analyses showed that cognitive deficits in all domains progressed with disease duration. Moreover, cognitive performance correlated with the severity of motor and functional impairment (all p < .001) and with the Disease Burden Score regardless of disease duration and age.

Conclusion

Our results indicate that the cognitive battery is a suitable tool for assessing cognitive impairment in HD.

Predictors of verbal fluency performance in monolingual and bilingual children: The interactive role of English receptive vocabulary and fluid intelligence

INTRODUCTION

Previous research has found that when bilingual and monolingual children are equated on English receptive vocabulary, bilingual children outperform monolingual children on verbal fluency tasks (e.g., Pino Escobar et al., 2018; Zeng et al., 2019). However, the locus of these differences in performance is poorly understood. The current study investigated the linguistic and cognitive components that underlie verbal fluency performance in bilingual and English-speaking monolingual children.

METHODS

Students in fourth and sixth grade (63 bilinguals and 31 monolinguals) performed both category and letter fluency tasks in English where they named members of provided categories in one-minute trials (e.g., animals, words that start with "F", respectively). Participants also completed a battery of English language measures (e.g., English receptive vocabulary, English word reading fluency) and cognitive measures (e.g., fluid intelligence, working memory).

RESULTS

Although monolinguals outperformed bilinguals on English receptive vocabulary, no group differences emerged on verbal fluency measures. When English receptive vocabulary served as a covariate, bilinguals generated significantly more items than monolinguals in the verbal fluency tasks. For monolinguals, only English receptive vocabulary accounted for unique variance in verbal fluency performance. However, for bilinguals, receptive vocabulary and fluid intelligence were significant predictors in both fluency tasks. Additionally, for bilinguals, fluid intelligence impacted the strength of the relationship between English receptive vocabulary and letter fluency performance; they were not significantly correlated for individuals with low cognitive ability and were strongly correlated for individuals with high cognitive ability.

CONCLUSIONS

Results suggest that unlike monolingual children, bilingual children recruit additional cognitive resources to meet the demands imposed by the verbal fluency task.

The Independent and Interactive Associations of Bilingualism and Sex on Cognitive Performance in Hispanics/Latinos of the Hispanic Community Health Study/Study of Latinos

Sixty percent of Hispanics/Latinos are bilingual which research suggests may confer certain cognitive advantages. Female sex confers cognitive advantages in verbal learning and memory compared to male sex, regardless of race or ethnicity. Understanding the independent and interactive associations of bilingualism and sex with cognition may aid in predicting cognitive aging in Hispanics/Latinos. We examined baseline (2008-2011) data from the Hispanic Community Health Study/Study of Latinos, a multicenter, prospective community-based study. Our analyses included 6,110 males and females ≥45 years old who self-reported birth and parents' origin outside of the continental US, Spanish as their first language, and were evaluated in Spanish. Bilingualism was assessed along a Likert scale (1 = only Spanish to 4 = English>Spanish) for language proficiency (reading/spoken) and patterns of use (thinking/socializing). Cognitive testing included verbal learning, memory, fluency, and Digit Symbol Substitution (DSS). Linear regression models adjusted for relevant confounders, the complex survey design, and sampling weights. Participants' self-reported language proficiency was Spanish better than English, while patterns of use suggested more Spanish than English. Higher language proficiency was associated with higher performance on all cognitive indices while higher patterns of use associated with higher fluency and DSS scores (p-values < 0.01). Female sex was associated with higher performance on all cognitive indices (p-values < 0.05). There were no significant interactions with bilingualism (regardless of metric) by sex on cognition. For Hispanics/Latinos residing in the continental US and reporting birth and parents' origin elsewhere, bilingualism and female sex have independent cognitive benefits that are important to consider when evaluating cognitive performance.

Lexical and Cognitive Underpinnings of Verbal Fluency: Evidence from Bengali-English Bilingual Aphasia

Research in bilingual healthy controls (BHC) has illustrated that detailed characterization of verbal fluency along with separate measures of executive control stand to inform our understanding of the lexical and cognitive underpinnings of the task. Such data are currently lacking in bilinguals with aphasia (BWA). We aimed to compare the characteristics of verbal fluency performance (semantic, letter) in Bengali-English BWA and BHC, in terms of cross-linguistic differences, variation on the parameters of bilingualism, and cognitive underpinnings. BWA showed significant differences on verbal fluency variables where executive control demands were higher (fluency difference score, number of switches, between-cluster pauses); whilst performed similarly on variables where executive control demands were lower (cluster size, within-cluster pauses). Despite clear cross-linguistic advantage in Bengali for BHC, no cross-linguistic differences were noted in BWA. BWA who were most affected in the independent executive control measures also showed greater impairment in letter fluency condition. Correlation analyses revealed a significant relationship for BWA between inhibitory control and number of correct responses, initial retrieval time, and number of switches. This research contributes to the debate of underlying mechanisms of word retrieval deficits in aphasia, and adds to the nascent literature of BWA in South Asian languages.

The Impact of Bilingualism on Executive Functions in Children and Adolescents: A Systematic Review Based on the PRISMA Method

Approximately half of the world's population is bilingual or multilingual. The bilingual advantage theory claims that the constant need to control both known languages, that are always active in the brain, to use the one suitable for each specific context improves cognitive functions and specifically executive functions. However, some authors do not agree on the bilingual effect, given the controversial results of studies on this topic. This systematic review aims to summarize the results of studies on the relationship between bilingualism and executive functions. The review was conducted according to PRISMA-statement through searches in the scientific database PsychINFO, PsycARTICLES, MEDLINE, and PUBMED. Studies included in this review had at least one bilingual and monolingual group, participants aged between 5 and 17 years, and at least one executive function measure. Studies on second language learners, multilingual people, and the clinical population were excluded. Fifty-three studies were included in the systematic review. Evidence supporting the bilingual effect seems to appear when assessing inhibition and cognitive flexibility, but to disappear when working memory is considered. The inconsistent results of the studies do not allow drawing definite conclusions on the bilingual effect. Further studies are needed; they should consider the role of some modulators (e.g., language history and context, methodological differences) on the observed results.

Assessing within-task verbal fluency performance: the utility of individual time intervals in predicting incident mild cognitive impairment

The current study aimed to determine whether word generation performance on individual within-task 20-second time intervals predicted conversion to Mild Cognitive Impairment (MCI) status. Longitudinal data (Mean follow-up=2.95±1.64 years) was collected from cognitively-healthy community-dwelling older adults (N=344; %female=56.1). Performance on letter and semantic fluency tasks was divided into three consecutive within-task 20-second intervals. Incident MCI status (n=50) was determined via established diagnostic case conference. Fully adjusted Cox proportional-hazards regression models revealed that greater word production on semantic fluency across all time intervals significantly predicted a reduced risk of incident MCI [0-20 seconds (HR=0.906, p=0.002), 21-40 seconds (HR=0.904, p=0.02), and 41-60 seconds (HR=0.892, p=0.017)]. Conversely, on letter fluency, greater word production within the 41-60 second time interval only was significantly associated with reduced risk of incident MCI (HR=0.886, p=0.002). Overall, the clinical use of within-interval performance is supported given evidence of predictive sensitivity and ease of administration.

Exploring Language Learning as a Potential Tool against Cognitive Impairment in Late-Life Depression: Two Meta-Analyses and Suggestions for Future Research

Late-life depression (LLD) affects about an eighth of community-dwelling seniors. LLD impacts well-being, with loneliness and small social networks being typical. It has also been linked to cognitive dysfunction and an increased risk of developing dementia. Safety and efficacy of pharmacological treatments for LLD have been debated, and cognitive dysfunction often persists even after remission. Various cognitive interventions have been proposed for LLD. Among these, one has received special attention: foreign language learning could serve as a social intervention that simultaneously targets brain structures affected in LLD. Lifelong bilingualism may significantly delay the onset of cognitive impairment symptoms by boosting cognitive reserve. Even late-life foreign language learning without lifelong bilingualism can train cognitive flexibility. It is then counterintuitive that the effects of language learning on LLD have never been examined. In order to create a theoretical basis for further interdisciplinary research, this paper presents a status quo of current work through two meta-analyses investigating cognitive functioning in LLD on the one hand and in senior bilinguals or seniors following a language course on the other hand. While LLD was consistently associated with cognitive dysfunction, inconsistent results were found for bilingualism and language learners. Possible reasons for this and suggestions for future research are subsequently discussed.

Does bilingualism influence neuropsychological test performance in older adults? A systematic review

OBJECTIVE

Using standardized tests which have been normed on monolinguals for the assessment of bilinguals presents challenges to the accurate characterization of cognitive profile as the literature provides compelling evidence for the influence of bilingualism on cognitive abilities. However, little is known about the generalizability of these findings to clinical neuropsychology. The aim of this review was to address this gap by summarizing current evidence on the performance of bilingual older adults on standardized tests routinely used in clinical practice.

METHOD

A systematic search of Web of Science, PsycINFO and PubMed was conducted. 27 cross-sectional and longitudinal studies which use at least one standardized neuropsychological test for cognitive impairment were included in the review. Potential demographic (cultural/linguistic background of the participants, immigrant status), clinical (diagnostic status), and methodological confounders (language of test administration, components of bilingualism) were also examined. The review protocol was registered at the PROSPERO International Prospective Register of Systematic Review with registration number CRD42018114658.

RESULTS

The results of this review revealed some bilingual advantage on measures of inhibitory control and bilingual disadvantage on measures of verbal fluency in cross-sectional studies. Bilingualism status was not associated with test performance in longitudinal studies. However, findings lack consistency due to demographic variables and methodological differences across studies.

CONCLUSION

Neuropsychological tests assessing language domains and, to some extent executive function act as clinically relevant features of bilingualism for neuropsychological evaluation. However, immigration status, acculturation level and language of test administration needs to be taken into account when assessing bilingual older adults.

Dissociation in Age-Related Developmental Trajectories Between Phonetic Fluency and Semantic Fluency Tests: Analysis of Longitudinal Data From the Yakumo Study

Possible age-related differences in Phonemic Fluency Test (PFT) and Semantic Fluency Test (SFT) performance were examined by using longitudinal data of healthy older adults. The performance trajectories of 81 older adults in the 2 tests were analyzed for 11 years, from 65 to 75 years of age, via individually calculated linear regression coefficients. The results indicated that the PFT and SFT performance showed an age-related decline. However, the declining slope of the SFT was steeper than that of the PFT performance. These findings correspond with those of previous cross-sectional studies and suggest a future need to examine neurobiological substrates underlying the two domains of verbal fluency abilities.

Regression-Based Normative Data for Children From Latin America: Phonological Verbal Fluency Letters M, R, and P

This study is part of a larger project to generate norms for letter verbal fluency test (VFT) in 3,284 children from nine Latin American countries. The letter VFT (letters M, R, and P) was administered and multiple linear regressions, including age, age², MPE (mean parental education), MPE², sex, and interactions were used as predictors. Results showed significant differences across countries for all scores. Age affected scores linearly except for Ecuador (P-letter), in which a quadratic effect was found. Scores increased linearly as a function of MPE, with the exception of Mexico (R-letter), in which a quadratic effect was found. Age by MPE (M- and P-letters), and age by MPE² (R-letter) interactions were found in Mexico. Sex had an impact on letter R in Cuba, and letter P in Ecuador and Paraguay. Age² by sex interaction was found in Ecuador (P-letter). These norms will be useful for clinical neuropsychologists in these countries to evaluate their patients' verbal fluency.

Selective Difficulties in Lexical Retrieval and Nonverbal Executive Functioning in Children With HbSS Sickle Cell Disease

Language deficits in multilingual children with sickle cell disease (SCD) are poorly understood. We tested the hypothesis that selective language deficits in this population could relate to an impaired frontal lobe functioning often associated with high-risk homozygous HbS disease (HbSS). In all, 32 children from immigrant communities with HbSS SCD aged 6 to 12 years (mean age = 9.03, n = 9 with silent infarcts) and 35 demographically matched healthy controls (mean age = 9.14) were tested on their naming skills, phonological and semantic fluency, attention, and selected executive functions (response inhibition and planning skills). Analyses of variance showed significant differences between patients and controls in inhibition and planning (p = .001 and .001), and phonological fluency (p = .004). The poorer performance in phonological fluency of the children with SCD was not associated with any visible brain damage to language areas. Hierarchical regression analyses showed that, whereas the control children's vocabulary knowledge explained their performance in the phonological fluency tasks, only inhibition skills accounted for variance in the performance of the children with SCD. These results suggest a selective impairment of verbal and nonverbal executive functioning (i.e., planning, inhibition, and phonological fluency) in children with SCD, with deficits possibly owing to frontal area hypoxia.

May Subjective Language Complaints Predict Future Language Decline in Community-Dwelling Subjects?

Subjective cognitive complaints are rather prevalent in the elderly population and are associated with an increased risk of cognitive impairment and dementia. However, the predictive role of specific types of cognitive complaints has been less systematically assessed. The aim of the present study is to examine the predictive value of language complaints for cognitive and language decline in a cohort of community-dwelling healthy older adults, followed longitudinally over a 5-year period. A total of 402 subjects were enrolled in a prospective longitudinal study on aging and cognition. Participants answered a cognitive complaints questionnaire including two questions directed to language and were classified at baseline as having “Language Complaints” (LC) or “No Language Complaints” (NLC). They also performed a neuropsychological assessment tackling attention/processing speed, memory, executive functioning, and language at baseline. From these, 275 (68.4%) participated in a follow-up evaluation 4.9 (±0.6) years later. At re-evaluation, subjects had a mean age of 70.4 (±8.3) years, 7.5 (±4.4) years of education, and 63.3% were female. Multivariate linear regression analysis was used to investigate whether language complaints at baseline predicted poorer language performance at follow-up or increased the risk of cognitive decline, with correction for sex, depressive symptoms, living status, baseline performance, and composite memory and executive performance. Results indicated that LC subjects had significantly worse performances than NLC subjects on semantic fluency 5 years later, but with a similar rate of decline overtime that was not associated with a follow-up outcome of cognitive decline/dementia. Language difficulties may represent a specific type of age-related cognitive complaints. Longer follow-ups are necessary to understand if they are associated with an increased risk of language or cognitive decline.

Association Between White Matter Microstructure and Verbal Fluency in Patients With Multiple Sclerosis

Verbal fluency refers to the ability to generate words quickly and efficiently according to predefined phonological or semantic criteria. Deficits in verbal fluency limit patients' ability to communicate effectively and to function well in social setups. Multiple sclerosis (MS) patients suffer from various cognitive impairments, and some of them experience language deficits as well. The goal of this study is to examine the contribution of the dorsal and ventral language pathways to verbal fluency in MS patients. All patients (N = 33) underwent diffusion MRI (dMRI) and fluency measurements. Diffusion parameters were calculated along dorsal and ventral language-related pathways and their right-hemispheric homologs, identified individually in each patient. Significant correlations were found between fluency measures and mean fractional anisotropy (FA) in several pathways, including the left fronto-temporal arcuate fasciculus (AFft), bilateral inferior fronto-occipital fasciculus (IFOF), and bilateral frontal aslant tract. Along-tract correlations revealed a more selective pattern of associations: letter-based fluency was associated with FA in a segment of the left AFft (dorsal pathway), while category-based fluency was associated with FA in a segment of the right IFOF (ventral pathway). The observed pattern of associations, mapping letter-based fluency to the dorsal stream and category-based fluency to the ventral stream, fits well within the dual stream framework of language processing. Further studies will be necessary to assess whether these associations generalize to the typical adult population or whether they are tied to the clinical state.

Executive Processes Underpin the Bilingual Advantage on Phonemic Fluency: Evidence From Analyses of Switching and Clustering

Bilinguals often show a disadvantage in lexical access on verbal fluency tasks wherein the criteria require the production of words from semantic categories. However, the pattern is more heterogeneous for letter (phonemic) fluency wherein the task is to produce words beginning with a given letter. Here, bilinguals often outperform monolinguals. One explanation for this is that phonemic fluency, as compared with semantic fluency, is more greatly underpinned by executive processes and that bilinguals exhibit better performance on phonemic fluency due to better executive functions. In this study, we re-analyzed phonemic fluency data from the Betula study, scoring outputs according to two measures that purportedly reflect executive processes: clustering and switching. Consistent with the notion that bilinguals have superior executive processes and that these can be used to offset a bilingual disadvantage in verbal fluency, bilinguals (35-65 years at baseline) demonstrated greater switching and clustering throughout the 15-year study period.

Comparing Semantic Fluency in American Sign Language and English

This study investigated the impact of language modality and age of acquisition on semantic fluency in American Sign Language (ASL) and English. Experiment 1 compared semantic fluency performance (e.g., name as many animals as possible in 1 min) for deaf native and early ASL signers and hearing monolingual English speakers. The results showed similar fluency scores in both modalities when fingerspelled responses were included for ASL. Experiment 2 compared ASL and English fluency scores in hearing native and late ASL-English bilinguals. Semantic fluency scores were higher in English (the dominant language) than ASL (the non-dominant language), regardless of age of ASL acquisition. Fingerspelling was relatively common in all groups of signers and was used primarily for low-frequency items. We conclude that semantic fluency is sensitive to language dominance and that performance can be compared across the spoken and signed modality, but fingerspelled responses should be included in ASL fluency scores.

Language Dominance, Verbal Fluency, and Language Control in two Groups of Russian–English Bilinguals

This study explored language dominance, verbal fluency, and language control abilities of two groups of younger and older Russian–English bilinguals who had spent similar amounts of time as immigrants in the U.S. Verbal fluency tasks (based on letter and semantic cues, including a new method to elicit parallel letter-fluency data for Russian and English) were used to measure the bilinguals’ current lexical retrieval skills in addition to self-assessments of language proficiencies at time of study and time of arrival. Stroop tasks (naming colors with incongruent cues) were used to measure younger and older bilinguals’ ability to control interference during color-naming. Findings demonstrate that the older immigrants were less fluent in L2 naming tasks and that they remained dominant (more proficient) in their L1 whereas the younger immigrants had become relatively balanced bilinguals in terms of proficiency, fluent in both the L1 and L2. Younger and older bilinguals were equally capable of controlling interference across and within the two languages. We propose that it is not balance in bilingual proficiency that positively affects language control abilities, but balance as stability of language systems. Stability of language systems can be achieved if bilingual usage patterns remain relatively constant over several years and if no radical changes in language learning and maintenance efforts are required.