Differential effects of aging on two verbal fluency tasks

Letter and Category Fluency: Normative Data for Lebanese Older Adults

Background: Verbal fluency tasks are frequently used for neuropsychological assessment in clinical practice and research. It consists of two tasks namely category and letter fluency tests. Objective: To determine normative values in category (animals, vegetables, fruits) and letter fluency [Mim () “M”, Alif () “A”, Baa () “B”] tasks in Arabic language in 60 s. Methods: This study was a cross-sectional national survey and included 859 community-dwelling, cognitively intact Lebanese residents aged ≥55 years. Norms were presented according to age (55–64 years, 65–74 years, ≥75 years), sex and level of education (illiterate, no diploma, primary certificate, baccalaureate or higher). Results: Level of education had the most significant positive effect on verbal fluency tasks performance amongst Lebanese older adults. The negative effect of older age was more prominent in the category fluency task compared to the letter fluency task. Women outperformed men in vegetables and fruits categories. Conclusion: This study provides clinicians with normative scores of category and letter fluency tests, which can be used for neuropsychological assessment of older Lebanese patients being evaluated for cognitive disorders.

Factors associated with verbal fluency in older adults living with HIV in West Africa: A longitudinal study

OBJECTIVE

Verbal fluency decline, observed both in aging and HIV infection, has been related to lower quality of life. This study aimed to evaluate the factors associated with categorical fluency in people living with HIV (PLHIV) aged ≥60 years living in West Africa.

METHODS

In this longitudinal study, PLHIV aged ≥60 years, on antiretroviral therapy (ART) for ≥6 months were included in three clinics (two in Côte d'Ivoire, one in Senegal) participating in the West Africa International epidemiological Databases to Evaluate AIDS (IeDEA) collaboration. Categorical fluency was evaluated with the Isaacs Set Test at 60 s at baseline and 2 years later. Factors associated with verbal fluency baseline performance and annual rates of changes were evaluated using multivariate linear regression models.

RESULTS

Ninety-seven PLHIV were included with 41 of them (42%) having a 2-year follow-up visit. The median age was 64 (62-67), 45.4% were female, and 89.7% had an undetectable viral load. The median annual change in categorical fluency scores was -0.9 (IQR: -2.7 to 1.8). Low baseline categorical fluency performance and its decline were associated with older age and being a female. Low educational level was associated with low baseline categorical fluency performance but not with its decline. Categorical fluency decline was also associated with marital status and hypertension.

CONCLUSIONS

Among older West African PLHIV, usual socio-demographic variables and hypertension were the main factors associated with low categorical fluency performance and/or its decline. Interventions that focus on supporting cardiometabolic health are highly recommended to prevent cognitive disorders in PLHIV.

Age-Related Differences in the Neural Processing of Idioms: A Positive Perspective

We examined whether older adults benefit from a larger mental-lexicon size and world knowledge to process idioms, one of few abilities that do not stop developing until later adulthood. Participants viewed four-character sequences presented one at a time that combined to form (1) frequent idioms, (2) infrequent idioms, (3) random sequences, or (4) perceptual controls, and judged whether the four-character sequence was an idiom. Compared to their younger counterparts, older adults had higher accuracy for frequent idioms and equivalent accuracy for infrequent idioms. Compared to random sequences, when processing frequent and infrequent idioms, older adults showed higher activations in brain regions related to sematic representation than younger adults, suggesting that older adults devoted more cognitive resources to processing idioms. Also, higher activations in the articulation-related brain regions indicate that older adults adopted the thinking-aloud strategy in the idiom judgment task. These results suggest re-organized neural computational involvement in older adults' language representations due to life-long experiences. The current study provides evidence for the alternative view that aging may not necessarily be solely accompanied by decline.

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.

Epigenetic Age Acceleration and Cognitive Function in African American Adults in Midlife: The Atherosclerosis Risk in Communities Study

Methylation levels measured at defined sites across the genome have recently been shown to be correlated with an individual's chronological age. Age acceleration, or the difference between age estimated from DNA methylation status and chronological age, has been proposed as a novel biomarker of aging. In this study, the cross-sectional association between two different measures of age acceleration and cognitive function was investigated using whole blood samples from 2,157 African American participants 47-70 years of age in the population-based Atherosclerosis Risk in Communities (ARIC) Study. Cognition was evaluated using three domain-specific tests. A significant inverse association between a 1-year increase in age acceleration calculated using a blood-based age predictor and scores on the Word Fluency Test was found using a general linear model adjusted for chronological age, gender, and years of education (β = -0.140 words; p = .001) and after adding other potential confounding variables (β = -0.104 words, p = .023). The results were replicated in 1,670 European participants in the Generation Scotland: Scottish Family Health Study (fully adjusted model: β = -0.199 words; p = .034). A significant association was also identified in a trans-ethnic meta-analysis across cohorts that included an additional 708 European American ARIC study participants (fully adjusted model: β = -0.110 words, p = .003). There were no associations found using an estimate of age acceleration derived from multiple tissues. These findings provide evidence that age acceleration is a correlate of performance on a test of verbal fluency in middle-aged adults.

Response initiation and inhibition and the relationship with fluid intelligence across the adult lifespan

Background

Cognitive processes associated with frontal lobe functioning are often termed “executive functions.” Two such processes are initiation and inhibition or the starting and stopping of responses. It has recently been claimed dysfunction of executive abilities can be explained by a single measure of fluid intelligence. Here, we test this claim, specifically for the executive abilities of response initiation and inhibition, across the healthy lifespan.

Method

In a cohort of 336 healthy adults (18–89 years), initiation and inhibition were assessed with the Hayling test, Stroop test, and phonemic and semantic verbal fluency. All participants also completed a measure of fluid intelligence. The relationship between fluid intelligence and executive measures was explored across the lifespan using a continuous approach. Mediation models were computed to assess whether age-related decline across the four initiation/inhibition tasks could be fully explained by a single measure of fluid intelligence.

Results

Age was negatively correlated with response initiation/inhibition and fluid intelligence. The mediation analyses identified only partial mediation of fluid intelligence for age and Hayling performance. By contrast, fluid intelligence did not mediate performance on the Stroop test or phonemic and semantic verbal fluency.

Conclusions

Response initiation/inhibition are not able to be explained by fluid intelligence. The results support a multifactorial theory of executive functions and provide evidence for the inclusion of multiple specific executive measures in a thorough neuropsychological assessment of age-related cognitive decline.

Age and pain differences in non-verbal fluency performance: Associations with cortical thickness and subcortical volumes

Musculoskeletal pain is a cause of disability in older individuals and is commonly associated with executive function deficits. In particular, verbal fluency deficits have been previously reported in older individuals with and without musculoskeletal pain, however, no studies have examined non-verbal fluency. The present study investigated non-verbal fluency performance in younger and older individuals and associations with clinical and experimental pain. The NEPAL study included older (n = 63) and younger (n = 28) individuals who completed demographic, and clinical pain assessments followed by a multi-modal QST battery. A subset of participants (older n = 39/63, younger n = 11/28) underwent a structural 3T MRI to extract cortical thickness and subcortical gray matter volumes. The Ruff Figural Fluency Test was administered to assess fluid/divergent thinking, ability to shift cognitive set, and planning strategies. Total Unique Designs drawn and Error Ratio assessed participants' ability to minimize repetition while maximizing unique productions. Adjusting for race and education, older participants with chronic pain had significantly lower Total Unique Designs (67.1 ± 20.3) compared to older adults without chronic pain (78.8 ± 15.9) and younger controls (93.8 ± 20.3, p < 0.001). Within the older sample, those with chronic pain had a significantly greater Error Ratio (0.22 ± 0.3) compared to those without chronic pain (0.09 ± 0.06) and younger controls (0.05 ± 0.05, p = 0.002). In older participants, greater Total Unique Design scores were significantly associated only with lower pressure pain sensitivity (r = 0.300, p = 0.031) while greater Error Ratio scores were significantly associated with greater thermal pain sensitivity (r = 0.304, p = 0.027). However, after accounting for sleep quality, clinical and experimental pain associations were eliminated. Across all participants, non-verbal fluency performance was associated with cortical thickness in frontal, parietal and temporal regions as well as several subcortical gray matter structures even after adjusting for multiple comparisons (p's < 0.001). Our findings suggest a pain-related deficit in non-verbal fluency beyond the established age-related decrements that may be dependent on sleep quality and was associated with specific patterns of gray matter structure.

Linguistic factors associated with phonemic fluency performance in a sample of bilingual Hispanic undergraduate students

Research has demonstrated that bilingualism impacts neuropsychological performance, but the findings on its effects on verbal fluency have been mixed. This study compared the verbal fluency performance of non-Hispanic White monolingual speakers with a Hispanic bilingual population. Ninety-nine Spanish-English bilingual Hispanic and thirty English-speaking monolingual non-Hispanic White undergraduates completed the Controlled Oral Word Association Test (COWAT). Students also completed a general cognitive and English reading measure. Bilingual students completed an in-depth language questionnaire to gauge language dominance, age of acquisition of second language (AoA), and first language learned. Results revealed that both language dominance and AoA influence phonemic fluency performance in bilingual Hispanics. English-dominant and balanced bilingual students performed similarly to monolingual students. Spanish-dominant bilingual students scored lower than monolinguals or the other bilingual groups. Bilingual students with early AoA (<7 years) performed on par with monolingual students. Late AoA bilinguals performed significantly lower than early AoA bilinguals. Results illustrate the clinical importance of obtaining a full linguistic history of bilingual clients in order to accurately interpret verbal fluency performance, as this is essential for proper diagnoses and treatments.

Photobiomodulation improves the frontal cognitive function of older adults

OBJECTIVES

The frontal lobe hypothesis of age-related cognitive decline suggests that the deterioration of the prefrontal cortical regions that occurs with aging leads to executive function deficits. Photobiomodulation (PBM) is a newly developed, noninvasive technique for enhancing brain function, which has shown promising effects on cognitive function in both animals and humans. This randomized, sham-controlled study sought to examine the effects of PBM on the frontal brain function of older adults.

METHODS/DESIGNS

Thirty older adults without a neuropsychiatric history performed cognitive tests of frontal function (ie, the Eriksen flanker and category fluency tests) before and after a single 7.5-minute session of real or sham PBM. The PBM device consisted of three separate light-emitting diode cluster heads (633 and 870 nm), which were applied to both sides of the forehead and posterior midline, and delivered a total energy of 1349 J.

RESULTS

Significant group (experimental, control) × time (pre-PBM, post-PBM) interactions were found for the flanker and category fluency test scores. Specifically, only the older adults who received real PBM exhibited significant improvements in their action selection, inhibition ability, and mental flexibility after vs before PBM.

CONCLUSIONS

Our findings support that PBM may enhance the frontal brain functions of older adults in a safe and cost-effective manner.

Aging Modulates the Hemispheric Specialization during Word Production

Although older adults exhibit normal accuracy in performing word retrieval and generation (lexical production; e.g., object naming), they are generally slower in responding than younger adults. To maintain accuracy, older adults recruit compensatory mechanisms and strategies. We focused on two such possible compensatory mechanisms, one semantic and one executive. These mechanisms are reflected at inter- and intra-hemispheric levels by various patterns of reorganization of lexical production cerebral networks. Hemispheric reorganization (HR) changes were also evaluated in relation to increase naming latencies. Using functional magnetic resonance imaging (fMRI), we examined 27 healthy participants (from 30 years to 85 years) during an object naming task, exploring and identifying task-related patterns of cerebral reorganization. We report two main results. First, we observed a left intra-hemispheric pattern of reorganization, the left anterior-posterior aging (LAPA) effect, consisting of supplementary activation of left posterior (temporo-parietal) regions in older adults and asymmetric activation along the left fronto-temporal axis. This pattern suggests that older adults recruit posterior semantic regions to perform object naming. The second finding consisted of bilateral recruitment of frontal regions to maintain appropriate response times, especially in older adults who were faster performers. This pattern is discussed in terms of compensatory mechanism. We suggest that aging is associated with multiple, co-existing compensation and reorganization mechanisms and patterns associated with lexical production.

Effects of age, education, and gender on verbal fluency in healthy adult Arabic-speakers in Egypt

The objective of this study is to establish the effects of age, gender, and education and to provide preliminary normative data for letter and category fluency tasks in the Egyptian Arabic-speaking population. We evaluated 139 cognitively healthy volunteers aged 20-93 by adapting the letter and category verbal fluency tasks for the Egyptian population. On the letter fluency task, mean number of words generated in one-minute beginning with the Arabic letter "Sheen" (pronounced "sh") was 8.14 words per minute (SD = 3.25). Letter fluency was significantly influenced by education. On category fluency tasks, mean number of animal names generated in one minute was 14.63 words (SD = 5.28). Category fluency was significantly influenced by age and education. We were able identify that age significantly affects category fluency while education significantly affected both letter and category fluency. We were also able to provide preliminary normative data for both tasks in the Egyptian population.

Association Between Accelerated Multimorbidity and Age-Related Cognitive Decline in Older Baltimore Longitudinal Study of Aging Participants without Dementia

OBJECTIVES

To explore the association between rate of physical health deterioration, operationalized as rising multimorbidity overtime, and longitudinal decline in cognitive function in older adults without dementia.

DESIGN

Longitudinal (Baltimore Longitudinal Study of Aging (BLSA)).

SETTING

Community.

PARTICIPANTS

BLSA participants aged 65 and older followed for an average of 3 years and free of dementia or mild cognitive impairment (MCI) at baseline and follow-up (N = 756).

MEASUREMENTS

Standardized neurocognitive tests evaluating mental status, memory, executive function, processing speed, and verbal fluency were administered. Multimorbidity was assessed at each visit as number of diagnosed chronic diseases from a predefined list. Faster accumulation of chronic diseases was defined as upper quartile of rate of change in number of diseases over time (≥0.25 diseases/year).

RESULTS

Faster accumulation of chronic diseases was significantly associated with greater rate of decline on the Category (P = .01) and Letter (P = .01) Fluency Tests. Similar trends were also found for the Trail-Making Test Parts A (P = .08) and B (P = .07); no association was found with rate of change in visual and verbal memory.

CONCLUSION

Although further investigations are required to validate the results and fully understand the underlying mechanisms, these findings suggest that accelerated deterioration of physical health is associated with accelerated decline with aging in specific cognitive domains in older adults without dementia.

Does Bilingual Language Control Decline in Older Age?

We investigated age-related decline of bilingual language control. Thirteen older and 13 younger bilinguals performed a verbal fluency task (completing the same letter and semantic categories in each language and switching languages after every category), and a non-linguistic flanker task. In letter fluency, bilinguals produced fewer correct responses after switching languages, suggesting inhibition of the previously-used language. However, this testing-order effect did not differ between groups and older bilinguals produced few wrong-language intrusions, implying intact ability to apply inhibition in older age. In contrast, age-related deficits in the flanker task were robust, implying dissociations between language control and domain-general executive control. In semantic fluency, there were no testing-order effects but older bilinguals produced more intrusions than younger bilinguals, and more intrusions than in letter fluency. Thus, bilinguals may flexibly modulate the degree of inhibition when they can benefit from semantic priming between languages, but less efficiently so in older age.

Interacting effects of age and time of day on verbal fluency performance and intraindividual variability

We explored the effects of age and time of day (TOD) on verbal fluency ability with respect to performance level and intraindividual variability (IIV). Verbal fluency, which involves complex cognitive operations, was examined in 20 older (mean age = 72.8 years) and 20 younger (mean age = 24.2 years) adults with test start time alternating between morning and evening across four days. Older adults generated more words in the morning and younger adults more in the evening, corresponding with self-report peak TOD. Age by TOD interactions were also observed across fluency tasks on the number of switches among subcategory exemplars during word generation and on the IIV observed in switching behavior. Older adults exhibited greater variability in switching in the evening than in the morning, whereas younger adults showed the opposite pattern. These findings demonstrate that processes involving energization (initiating and sustaining) and attentional control may be particularly sensitive to age differences in TOD influences on cognition.

Semantic retrieval over time in the aging brain: Structural evidence of hippocampal contribution

This study investigates relationship between regional cerebral volumes and performances over time of a categorical fluency task, in a sample of older adults (n = 316). Using voxel-wise technique, the relationship between local grey matter volume and Isaacs Set Test (IST) scores at its early (first 15 sec) and late (last 15 sec) phase production was analyzed with a linear regression model adjusting for age, sex, educational level, ApoEɛ4 allele, handedness and Grey Matter atrophy. Lower early IST scores were associated with smaller volumes in bilateral inferior frontal gyri and in right thalamus, whereas lower late IST scores were associated to smaller left inferior parietal gyrus and left anterior hippocampus. An analysis based on automatic segmentation of hippocampus confirmed the latest relationship which cannot be attributed to the correlation of each variable with global cognitive impairment because it remained when MMSE was accounted for. We observed a switch from frontal to temporo-parietal regions as words retrieval become more difficult over time. Automatic speech production of the early phase of the category fluency task is dependent on executive networks integrity whereas controlled speech production of the late phase is dependent on memory networks integrity, including left hippocampus. These results are concordant with recent imaging studies expanding the implication of hippocampus to semantic memory performances and they underlie the need to consider verbal fluency task over time.

Component analysis of verbal fluency performance in younger participants with moderate-to-severe traumatic brain injury

PRIMARY OBJECTIVE

To investigate phonemic and semantic verbal fluency performance in a group of young adult participants with and without traumatic brain injury.

RESEARCH DESIGN

Group comparison.

METHODS AND PROCEDURES

Twenty-five participants with moderate-to-severe TBI and 25 participants with no brain damage (NBD) were given phonemic and semantic verbal fluency tasks. Responses were analysed quantitatively and qualitatively.

MAIN OUTCOMES AND RESULTS

Young participants with moderate-to-severe TBI generated significantly fewer total correct words and sub-categories for both fluency conditions when compared to controls. The total number of correct words generated on the phonemic condition and for the semantic category of animals was positively correlated with the number of category switches produced during the task.

CONCLUSIONS

While young participants with moderate-to-severe TBI produced fewer total correct words on both verbal fluency conditions in comparison to controls, these differences were greater on the phonemic condition. Participants with moderate-to-severe TBI switched less frequently on both fluency tasks and produced smaller cluster sizes only on the phonemic task in comparison to controls. These results are in contrast with previous investigations that have observed greater age-related declines on semantic tasks when compared to phonemic tasks.

Mechanisms of age-related decline in memory search across the adult life span

Three alternative mechanisms for age-related decline in memory search have been proposed, which result from either reduced processing speed (global slowing hypothesis), overpersistence on categories (cluster-switching hypothesis), or the inability to maintain focus on local cues related to a decline in working memory (cue-maintenance hypothesis). We investigated these 3 hypotheses by formally modeling the semantic recall patterns of 185 adults between 27 to 99 years of age in the animal fluency task (Thurstone, 1938). The results indicate that people switch between global frequency-based retrieval cues and local item-based retrieval cues to navigate their semantic memory. Contrary to the global slowing hypothesis that predicts no qualitative differences in dynamic search processes and the cluster-switching hypothesis that predicts reduced switching between retrieval cues, the results indicate that as people age, they tend to switch more often between local and global cues per item recalled, supporting the cue-maintenance hypothesis. Additional support for the cue-maintenance hypothesis is provided by a negative correlation between switching and digit span scores and between switching and total items recalled, which suggests that cognitive control may be involved in cue maintenance and the effective search of memory. Overall, the results are consistent with age-related decline in memory search being a consequence of reduced cognitive control, consistent with models suggesting that working memory is related to goal perseveration and the ability to inhibit distracting information.

Plasticity of verbal fluency in older adults: a 90-minute telephone-based intervention

BACKGROUND

There is evidence for specific age-related deficits in tasks of verbal fluency.

OBJECTIVE

The aim of the present study was to evaluate training and transfer effects after 3 weeks of telephone-based verbal fluency training in old age.

METHODS

Participants were assigned to one of three training groups, an active control group, or a no-contact control group. Training consisted of 15 sessions of 6 min each over a period of 3 weeks. For the training tasks, different versions of the verbal fluency task were used, each targeting a specific underlying cognitive process (i.e., processing speed, shifting, or inhibition). To measure transfer effects, a neuropsychological test battery including digit symbol substitution, trail making, go/no-go, digit span, n-back, and a verbal learning and memory test was administered before and after training.

RESULTS

Our findings revealed training gains for initial letter fluency training and phonemic switching training, but not for excluded letter fluency training. Moreover, after initial letter fluency training and phonemic switching training, transfer to other verbal fluency tasks was found. In addition, phonemic switching training led to improvement in an untrained short-term memory task.

CONCLUSION

The findings demonstrate that a telephone-based cognitive intervention of overall 90 min significantly improved cognitive performance in healthy older adults above and beyond the improvements in the active control group. The findings provide the basis for cognitive interventions that could easily be integrated into everyday lifestyles and are still targeting specific cognitive functions.

Sleep onset/maintenance difficulties and cognitive function in nondemented older adults: the role of cognitive reserve

This study examined the relationship between cognitive function and sleep onset/maintenance difficulties (SO/MD) in nondemented older adults. We hypothesized that SO/MD negatively impacts cognition and that older adults with lower education would be especially vulnerable to its effects. The sample comprised 549 older adults from the Einstein Aging Study (EAS), a community-based cohort. Participants completed neuropsychological assessment and a sleep questionnaire. Univariate ANCOVAs were performed with cognitive performance as a dependent variable, SO/MD (present or absent) and education (lower: ≤ 12 years; higher: >12 years) as between-subjects factors, and age, ethnicity, gender, depression, and cardiovascular comorbidies as covariates. Participants were an average age of 79.7 ± 5.0 years (range = 71-97 years). Fifty-seven percent (n = 314) of the sample met criteria for SO/MD. Among participants with SO/MD, those with lower education performed more poorly on a test of category fluency than participants with higher education (means: 35.2 vs. 41.0; p < .001); among older adults without SO/MD, educational attainment had no measurable effect on cognition (SO/MD × education interaction (F(1,536) = 14.5; p = .00)). Consistent with the cognitive reserve hypothesis, older adults with lower education appear selectively vulnerable to the negative effects of sleep onset/maintenance difficulties on tests of verbal fluency.

Neural processing of overt word generation in healthy individuals: the effect of age and word knowledge

Verbal fluency is a classical and widely used neuropsychological instrument to assess cognitive abilities. Results of previous studies indicate an influence on verbal fluency performance of both, age and word knowledge. So far, no imaging study has investigated the neural mechanisms underlying an age and word knowledge related decline on the quantitative verbal output in a highly demanding overt and continuous semantic fluency task. Fifty healthy volunteers (age 22-56 years, verbal IQ 95-143) overtly and continuously articulated words in response to ten visually presented semantic categories while BOLD signal was measured with fMRI. Verbal responses were recorded with an MRI compatible microphone and transcribed after the scanning session. The number of produced words as well as age, word knowledge and level of education was implemented in the design matrix enabling a separate analysis of these factors on both, neural responses and behavioral differences. There was a significant correlation of level of education and number of generated words, but no significant correlations of generated words and age or word knowledge were observed. On the neural level, a widespread network was found for the word production task as contrasted with the resting condition, encompassing the bilateral superior temporal gyri, the cerebellum and the SMA. An age related positive correlation was found in the bilateral inferior and middle frontal gyri, the anterior cingulate gyrus, the left precentral gyrus and the right insula. A lower word knowledge resulted in enhanced BOLD responses in the right superior temporal gyrus and the left superior frontal gyrus. Results are interpreted in terms of compensation mechanisms countervailing potential age and word knowledge related effects.

Age and verbal fluency: the mediating effect of speed of processing

Background and Purpose

Cognitive decline is a function of normal aging; however, the effect of age on various domains is differential. This study examined the effect of age on verbal fluency and showed how speed of processing modifies fluency performance in healthy older adults compared to younger individuals.

Methods

Three age groups, 62 young (17–40 years), 30 middle-aged (41–59 years), and 38 older adults (60–78 years), were studied using the Controlled Oral Word Association Test, National Adult Reading Test, and speed-of-processing composite score. The study examined the effect of age on fluency before and after controlling for processing speed and intelligence quotient.

Results

The young group performed better than the older group on category fluency as measured by animal category (p < .001) and on processing speed composite score (p < .001). However, the older group performed better than the young group on the National Adult Reading Test (p < .05) and on letter fluency after controlling for the decline in processing speed (p < .05). Processing speed had a significant effect on both category and letter fluency (p < .01) in older adults.

Conclusions

This study suggests that aging adversely affects some but not all cognitive domains and that age-related decline in processing speed contributes to age-related changes in fluency.

Preliminary Arabic normative data of neuropsychological tests: the verbal and design fluency

OBJECTIVES

The objective of the present study was to provide preliminary norms for three fluency tests in Arabic language: the verbal fluency (phonemic and semantic) and design fluency tests.

METHODS

Three Arabic letters have been chosen for the phonemic fluency task, in accordance with the letter selection procedure described in the development of the standard test. Animal fluency was chosen for the semantic fluency, and the Five-Point test for the design fluency test.

PARTICIPANTS

An Arabic speaking sample of 215 healthy participants (125 male, 90 female), with age ranging from 18-59 years and with different educational levels, were selected for this study.

RESULTS

Age and education significantly influenced performance in the verbal phonemic and semantic tasks, but not in the design fluency test. No gender effect was found in any of the three tasks. The education effects were linear, while age effects appeared to be curvilinear.

CONCLUSION

This pattern is congruent with that reported in the western literature. The implications of these results in relation to the development of Arabic norms were discussed. It was concluded that these tests could be used in an Arabic-speaking population with due considerations to the effects of age and education.

The effect of age and sex on clustering and switching during speeded verbal fluency tasks

Past research has been inconsistent with regard to the effects of normal aging and sex on strategy use during verbal fluency performance. In the present study, both Troyer et al.'s (1997) and Abwender et al.'s (2001) scoring methods were used to measure switching and clustering strategies in 60 young and 72 older adults, equated on verbal ability. Young adults produced more words overall and switched more often during both phonemic and semantic fluency tasks, but performed similarly to older adults on measures of clustering. Although there were no sex differences in total words produced on either fluency task, males produced larger clusters on both tasks, and females switched more frequently than males on the semantic but not on the phonemic fluency task. Although clustering strategies appear to be relatively age-insensitive, age-related changes in switching strategies resulted in fewer overall words produced by older adults. This study provides evidence of age and sex differences in strategy use during verbal fluency tests, and illustrates the utility of combining Troyer's and Abwender's scoring procedures with in-depth categorization of clustering to understand interactions between age and sex during semantic fluency tasks.

FAS and CFL forms of verbal fluency differ in difficulty: a meta-analytic study

The Controlled Oral Word Association (COWA) Test is a brief and sensitive measure of executive cognitive dysfunction. There are two commonly used forms of the test, one using the letters F, A, and S, and the other using C, F, and L. This study examines the relative difficulty of the two forms using a meta-analytic approach that includes multiple samples of normal individuals. The effects of age, education, gender composition, exclusion criteria, and age of study are also examined. Results indicate that the CFL form of the test is more difficult and that age, education, and the use of strict exclusion criteria influence performance. Performance is more variable for the FAS form, and age and age of study influence performance variability.

The impact of dementia, age and sex on category fluency: greater deficits in women with Alzheimer's disease

A category specific effect in naming tasks has been reported in patients with Alzheimer's dementia. Nonetheless, naming tasks are frequently affected by methodological problems, e.g., ceiling effects for controls and "nuisance variables" that may confound results. Semantic fluency tasks could help to address some of these methodological difficulties, because they are not prone to producing ceiling effects and are less influenced by nuisance variables. One hundred and thirty-three participants (61 patients with probable AD; and 72 controls: 36 young and 36 elderly) were evaluated with semantic fluency tasks in 14 semantic categories. Category fluency was affected both by dementia and by age: while in nonliving-thing categories there were differences among the three groups, in living thing categories larger lexical categories produced bigger differences among groups. Sex differences in fluency emerged, but these were moderated both by age and by pathology. In particular, fluency was smaller in female than male Alzheimer patients for almost every subcategory.

Verbal fluency in bilingual Spanish/English Alzheimer's disease patients

Studies have demonstrated that in verbal fluency tests, monolinguals with Alzheimer's disease (AD) show greater difficulties retrieving words based on semantic rather than phonemic rules. The present study aimed to determine whether this difficulty was reproduced in both languages of Spanish/English bilinguals with mild to moderate AD whose primary language was Spanish. Performance on semantic and phonemic verbal fluency of 11 bilingual AD patients was compared to the performance of 11 cognitively normal, elderly bilingual individuals matched for gender, age, level of education, and degree of bilingualism. Cognitively normal subjects retrieved significantly more items under the semantic condition compared to the phonemic, whereas the performance of AD patients was similar under both conditions, suggesting greater decline in semantic verbal fluency tests. This pattern was produced in both languages, implying a related semantic decline in both languages. Results from this study should be considered preliminary because of the small sample size.

Covariates of Production and Perseveration on Tests of Phonemic, Semantic and Alternating Fluency in Normal Aging

Standard measures of phonemic and semantic fluency, as well as fluency measures that impose additional demands upon set-switching were administered to younger and older adults. No age effect was found for total output on semantic fluency, while older participants generated significantly more responses relative to their younger counterparts on the phonemic measure. However, older adults made significantly more perseverative errors on both these measures. For tests of alternating fluency, only where participants were required to switch between two semantic dimensions, was an age deficit observed. Although the correlation between phonemic repetitions and age remained significant when performance on the Digit Symbol Test or a measure of fluid intelligence was partialled out, age effects for semantic repetitions and semantic alternating fluency were substantially reduced. The age benefit for number of correct responses upon phonemic fluency was significantly attenuated when a measure of crystallized intelligence was entered as a control variable. The theoretical and practical implications of these results are discussed.

Effects of the dopamine agonist piribedil on prefrontal temporal cortical network function in normal aging as assessed by verbal fluency

Normal aging has been associated with impaired performance in verbal fluency suggesting a prefrontal temporal cortical network (PFTCN) deficiency. In this study, we investigated the effects of a 2-month treatment period with a dopaminergic agonist (DA) on PFTCN function. Forty healthy, elderly volunteers were assessed on semantic and phonemic verbal fluency after two months of a placebo or a DA treatment (i.e. piribedil 50 mg/day) in a double-blind crossover design. Protocols were scored considering clustering, (i.e. production of words within semantic or phonemic categories, depending on the integrity of temporal lobe), and switching (i.e. the ability to shift between clusters, depending on frontal lobe functioning). Results revealed no significant main effect of the DA treatment on either verbal fluency variables but showed a significant interaction with working memory capacities, with high-capacity span subjects improving phonemic switching on DA whereas low-capacity span subjects performed more poorly on the drug than off. These data are consistent with the literature and confirm the crucial link between working memory capacities and dopamine agonist effects. The present study also provides evidence that pharmacological remediation of age-related cognitive decline has to be taken into consideration.

Age-related differences in performance of phonemic verbal fluency measured by Controlled Oral Word Association Task (COWAT): a meta-analytic study

Meta-analytical procedures were used to examine the research findings on age-related changes in phonemic verbal fluency measured by the Controlled Oral Word Association Task (COWAT). Data from 26 studies comparing adults from different age ranges were analyzed. An effect of aging was found in almost all age comparisons especially after 40 years of age. Results revealed a decline of this verbal ability after 60 years, which accelerates through the late 80s. Gender may influence COWAT performance after the sixth decade, favoring women over men. These results may be important in clinical situations where COWAT is used to assert pathological changes.

Differentiating Alzheimer's disease from subcortical vascular dementia with the FAB test

BACKGROUND

The frontal assessment battery (FAB) test is a composite tool for assessing executive functions related to the frontal lobe. Neuropsychological and blood-flow studies indicate distinct patterns of deterioration of anterior and posterior cortical function in Alzheimer's disease (AD) and subcortical vascular dementia (VD) patients. We predict that the FAB score may be useful for discriminating VD from AD.

OBJECTIVE

To evaluate the clinical usefulness of the FAB test for differential diagnosis of AD and VD.

METHODS

We compared FAB scores in 25 patients with AD, 27 patients with VD, and 80 age-matched normal control subjects. The AD group was matched for age, education and MMSE score with the VD group. The subtest scores in FAB were also compared among the three groups.

RESULTS

The FAB scores were significantly decreased in both the AD and VD groups compared to the control group, and the reduction were greater in the VD group. Among the FAB subtests, mental flexibility (phonological verbal fluency) was the only subtest that significantly discriminated VD from the other two groups.

CONCLUSIONS

The FAB test can provide useful information for differentiating AD and VD at the bedside.

A longitudinal study of quantitative and qualitative features of category verbal fluency in incident Alzheimer's disease subjects: results from the PAQUID study

Category fluency tests were administered at baseline and after 3 and 5 years on two subgroups of subjects from a population-based cohort of elderly subjects: 52 cases of incident possible and probable Alzheimer's disease (AD) and 104 age- and education-matched subjects who remained nondemented. Quantitative and qualitative features of category fluency were assessed to determine how changes occur within 5 years of the diagnosis of AD. Consistent with previous results, we found that the number of words produced on this task was already significantly lower 5 years before the diagnosis in subjects with incident AD as compared with subjects who did not become demented. However, the rate of repetitions only significantly increased in AD subjects at the time of diagnosis, and the rate of intrusions remained low and not significantly different between the two groups. Thus, it is concluded that dysfunction in cognitive processes underlying repetitions and intrusions in verbal fluency tasks, such as inhibitory processes and working memory, may not be the main cause of the very early deficit in verbal fluency occurring in AD.

Age-related psychomotor slowing as an important component of verbal fluency

Generalized psychomotor slowing is a characteristic of normal aging, and there is evidence suggesting that this feature is also central in dementia. The present article aims to evaluate the importance of psychomotor slowing as a factor underlying changes in the performance of verbal fluency tasks in normal and pathological aging. In study 1 reading and handwriting speed were used to predict performance on written and oral verbal fluency tasks (VFTs) in healthy elderly subjects (n = 20) and in patients of the Alzheimer type disease (n = 20). In study 2, spectrographic techniques were used to obtain reaction times, average of voice intensity and duration of single word production in young individuals (n = 20), healthy elderly subjects (n = 20), and in patients of the Alzheimer type disease (n = 7). Additionally, duration of single word production were also obtained. The results suggest that age-related psychomotor decline in word production speed is an important determinant of VFT.

Cerebral oxygenation changes in the prefrontal cortex: Effects of age and gender

Multi-channel near-infrared spectroscopy (NIRS) is an optical method, which allows non-invasive in vivo measurements of changes in the concentration of oxygenated (O(2)Hb) and deoxygenated (HHb) hemoglobin in living brain tissue, simultaneously from multiple measurement points. In the present study, 44 young and 42 elderly subjects were investigated by means of multi-channel NIRS (optical topography) during performance of the verbal fluency task (VFT). The aim of the study was to analyze the effects of the subjects' age and gender on functional brain activation during this cognitive task. In summary, the results clearly show that the VFT activated the left and right dorsolateral prefrontal cortex (increases in O(2)Hb and more localized decreases in HHb), with an obvious left-hemispheric dominance. The elderly subjects generally exhibited less activation and no left hemispheric lateralization effect. In contrast to a previous study, we did not find a clear influence of the subjects' gender on the brain activation pattern.

Normative data for the Animal, Profession and Letter M Naming verbal fluency tests for Dutch speaking participants and the effects of age, education, and sex

Previous research has indicated that performance on verbal fluency tests (VFTs) is influenced by language and/or culture. Consequently, normative VFT data for English-speaking people cannot be used for people for whom English is not their first language. The aim of the present study was to provide normative data for the Animal Naming, Profession Naming, and Letter M Naming (four-letter words beginning with the letter M) VFTs for Dutch-speaking populations, based on a large sample (N = 1856) of healthy men and women aged 24-81 years of different educational levels. The results showed that age affected the performance of all VFTs profoundly, but the age effect was not uniform: in the Profession and Letter M Naming VFTs, performance was stable in young adulthood but declined strongly after age 50. In contrast, in the Animal Naming VFT, performance appeared to decline linearly, starting early in life. Furthermore, males had higher scores than females on the Profession Naming VFT, and higher educated participants outperformed their lower educated counterparts on all three VFTs. Regression-based normative data were prepared for the 3 VFTs, and the advantages of using a regression-based normative approach instead of a traditional normative approach are discussed.

Category and letter verbal fluency across the adult lifespan: relationship to EEG theta power

The purpose of this study was to examine the impact of age, sex, and education on category and letter verbal fluency task performance. A secondary goal was to examine whether resting EEG theta power in bilateral frontal and temporal lobes impacts age-associated decline in verbal fluency task performance. A large sample (N = 471) of healthy, normal participants, age 21-82, was assessed for letter fluency (i.e., FAS), and for category fluency (i.e., Animal Naming), and with a 32-channel EEG system for 'eyes-open' resting theta power. The effects of age, sex, and education were examined using analyses of variance. Correlation analyses were used to test the impact of theta power on age and fluency performance by controlling for the effects of theta when examining the relationship between the other two variables. The results indicated that performance on both fluency tests declined linearly with age, but that the rate of decline was greater for category fluency. These age changes were not associated with education level, and there were no sex differences. While theta power was negatively associated with age and positively associated with Animal Naming performance, it did not moderate the relationship between the two. The differential age-associated decline between category and letter fluency suggests separate neurobiological substrates underlying the two domains of performance, which is not related to theta activity.

Compromised arterial oxygen saturation in elderly asthma sufferers results in selective cognitive impairment

Forty elderly patients with asthma or chronic obstructive pulmonary disorder (COPD) were compared to a comparison group of forty age-matched healthy volunteers on a range of measures of cognitive performance, and levels of arterial haemoglobin oxygen saturation recorded. Members of the patient group were found to have significantly lower oxygen saturation compared to the comparison group, and performed significantly poorer on tests of delayed word recall and serial subtractions, but not on other tasks. Correlational analysis between participants' oxygen saturation levels and test scores across the whole sample indicated significant positive relationships existed for the digit symbol substitution and serial subtractions tasks. The results are discussed in terms of cerebral oxygen delivery, glucose metabolism, age related cognitive decline, and relative task demands.

Attenuating Demographic Influences on Verbal Fluency and Animal Naming in a Psychiatric Sample

Measures of verbal fluency are common additions to neuropsychological evaluations. Due to the literature demonstrating the impact of demographic variables on these measures, corrective norms have recently been published. However, these norms have yet to be cross-validated. This study sought to cross-validate these norms in a racially diverse psychiatric sample. In addition, this study sought to evaluate the utility of Wide Range Achievement Test, 3rd Edition (WRAT3) Reading Recognition and Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) Vocabulary in attenuating the effect of demographic variables on these measures of verbal fluency. Results supported the utility of Gladsjo et al.'s (1999) norms. Further analysis revealed that both WRAT3 Reading Recognition and WAIS-III Vocabulary scores also attenuated the impact of demographic variables on these measures and accounted for more of the variance. Together, these results suggest that, although the demographically corrected norms adequately attenuate the impact of these variables, norms corrected for WRAT3 Reading Recognition or WAIS-III Vocabulary may account for more of the variance and therefore might be more appropriate and universally applicable.

Semantic and phonological processing in illiteracy

Researchers of cognitive processing in illiteracy have proposed that the acquisition of literacy modifies the functional organization of the brain. They have suggested that, while illiterate individuals have access only to innate semantic processing skills, those who have learned the correspondence between graphemes and phonemes have several mechanisms available to them through which to process oral language. We conducted 2 experiments to verify that suggestion with respect to language processing, and to elucidate further the differences between literate and illiterate individuals in the cognitive strategies used to process oral language, as well as hemispheric specialization for these processes. Our findings suggest that semantic processing strategies are qualitatively the same in literates and illiterates, despite the fact that overall performance is augmented by increased education. In contrast, explicit processing of oral information based on phonological characteristics appears to be qualitatively different between literates and illiterates: effective strategies in the processing of phonological information depend upon having had a formal education, regardless of the level of education. We also confirmed the differential abilities needed for the processing of semantic and phonological information and related them to hemisphere-specific processing.

The verbal fluency task in the Greek population: normative data, and clustering and switching strategies

We assessed 300 healthy adults in Greece on measures of semantic and phonemic verbal fluency in order to develop norms for the Greek population. We also evaluated the strategies that the participants used spontaneously in order to maximize word production, namely clustering and switching techniques. Our tasks comprised three semantic and three phonemic categories. Consistent with previous investigations of English-speaking samples, we found a contribution of demographic variables to word fluency. Specifically, level of education contributed to total word production, number of switches, and number of repetitive responses on both semantic and phonemic tasks, and the average cluster size only on the phonemic task. Age contributed to total word production and cluster size on the semantic task, and to number of switches on both semantic and phonemic tasks. Sex contributed only to total word production on the semantic task. In our sample, clustering and switching strategies were related to total word production on both tasks, suggesting that these strategies were used effectively. We present tables of normative data stratified by age and level of education. We have also included detailed guidelines for scoring clusters relevant to the Greek population.