Verbal fluency in Huntington's disease: a longitudinal analysis of phonemic and semantic clustering and switching

Effects of workbook training using editorials and newspaper articles in adults with preclinical stage of dementia

Early detection and intervention in individuals in the pre-clinical stage of dementia are crucial. This study aimed to examine whether there are significant differences in (1) word retrieval, (2) subjective communication ability, (3) intervention satisfaction through the 'Fill-in-the-blanks in editorial and newspaper articles' training in patients with subjective cognitive decline and mild cognitive impairment corresponding to the pre-clinical stage of dementia. Ninety-nine patients (50 in the intervention group and 49 in the control group) aged 50-84 years were administered pre- and post-test after 6 weeks of intervention (30 sessions). Regarding word retrieval, there were significant intervention effects on confrontation naming, semantic fluency, and phonemic fluency. The majority of participants in the intervention group were highly satisfied with the training. In terms of intervention satisfaction, the majority of the participants in the intervention group showed high satisfaction with all the questions. This result confirmed the improvement of word retrieval ability through mass communication content-based 'Fill-in-the-blanks' training, and ultimately helps to provide a clinical basis for applying this intervention to prevent dementia.

Longitudinal changes in qualitative aspects of semantic fluency in presymptomatic and prodromal genetic frontotemporal dementia

BACKGROUND

The semantic fluency test is one of the most widely used neuropsychological tests in dementia diagnosis. Research utilizing the qualitative, psycholinguistic information embedded in its output is currently underexplored in presymptomatic and prodromal genetic FTD.

METHODS

Presymptomatic MAPT (n = 20) and GRN (n = 43) mutation carriers, and controls (n = 55) underwent up to 6 years of neuropsychological assessment, including the semantic fluency test. Ten mutation carriers became symptomatic (phenoconverters). Total score and five qualitative fluency measures (lexical frequency, age of acquisition, number of clusters, cluster size, number of switches) were calculated. We used multilevel linear regression modeling to investigate longitudinal decline. We assessed the co-correlation of the qualitative measures at each time point with principal component analysis. We explored associations with cognitive decline and grey matter atrophy using partial correlations, and investigated classification abilities using binary logistic regression.

RESULTS

The interrater reliability of the qualitative measures was good (ICC = 0.75-0.90). There was strong co-correlation between lexical frequency and age of acquisition, and between clustering and switching. At least 4 years pre-phenoconversion, GRN phenoconverters had fewer but larger clusters (p < 0.001), and fewer switches (p = 0.004), correlating with lower executive function (r = 0.87-0.98). Fewer switches was predictive of phenoconversion, correctly classifying 90.3%. Starting at least 4 years pre-phenoconversion, MAPT phenoconverters demonstrated an increase in lexical frequency (p = 0.009) and a decline in age of acquisition (p = 0.034), correlating with lower semantic processing (r = 0.90). Smaller cluster size was predictive of phenoconversion, correctly classifying 89.3%. Increase in lexical frequency and decline in age of acquisition were associated with grey matter volume loss of predominantly temporal areas, while decline in the number of clusters, cluster size, and switches correlated with grey matter volume loss of predominantly frontal areas.

CONCLUSIONS

Qualitative aspects of semantic fluency could give insight into the underlying mechanisms as to why the "traditional" total score declines in the different FTD mutations. However, the qualitative measures currently demonstrate more fluctuation than the total score, the measure that seems to most reliably deteriorate with time. Replication in a larger sample of FTD phenoconverters is warranted to identify if qualitative measures could be sensitive cognitive biomarkers to identify and track mutation carriers converting to the symptomatic stage of FTD.

Pearls & Oy-sters: Huntington Disease Presenting as Primary Progressive Aphasia: A Case of Semantics

We present a case of semantic variant primary progressive aphasia as the presenting feature in a patient with Huntington disease (HD). The patient initially developed progressive language impairment including impaired naming and object knowledge and single-word comprehension and then developed chorea and behavioral changes. An MRI of the brain showed left anterior temporal lobe and hippocampal atrophy. A neurologic FDG PET/CT showed reduced metabolism in the head of the left caudate nucleus. Huntingtin gene testing revealed an expansion of 39 CAG repeats in 1 allele. This case outlines the substantial overlap between the clinical presentation of HD and frontotemporal lobar degeneration syndromes and provides commentary on the investigation of these neurodegenerative diseases.

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.

Excessive response to provocation rather than disinhibition mediates irritable behaviour in Huntington's disease

Background

Irritable and impulsive behaviour are common in Huntington's disease (HD: an autosomal dominant disorder causing degeneration in cortico-striatal networks). However, the cognitive mechanisms underlying these symptoms remain unclear, and previous research has not determined if common mechanisms underpin both symptoms. Here we used established and novel tasks to probe different aspects of irritable and impulsive behaviour to determine the neural mechanisms involved.

Methods

We recruited a cohort of 53 gene positive HD participants and 26 controls from non-affected family members and local volunteers. We used established questionnaire measures of irritability in HD (Snaith Irritability Scale, Problem Behaviours Assessment) and impulsivity [Urgency, Premeditation Perseverance, Sensation-seeking, Positive urgency scale (UPPSP), Barratt Impulsivity Scale], in addition to cognitive tasks of provocation, motor inhibition, delay discounting and decision making under uncertainty. We used generalised linear models to determine differences between cases and controls, and associations with irritability in the HD group.

Results

We found differences between cases and controls on the negative urgency subscale of the UPPSP, which was associated with irritability in HD. The frustrative non-reward provocation task also showed differences between cases and controls, in addition to predicting irritability in HD. The stop signal reaction time task showed case-control differences but was not associated with irritability in HD. None of the other measures showed group differences or predicted irritability in HD after correcting for confounding variables.

Discussion

Irritability in HD is mediated by excessive response to provocation, rather than a failure of motor inhibition.

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.

A comparison of techniques for deriving clustering and switching scores from verbal fluency word lists

Objective

To compare techniques for computing clustering and switching scores in terms of agreement, correlation, and empirical value as predictors of incident cognitive impairment (ICI).

Methods

We transcribed animal and letter F fluency recordings on 640 cases of ICI and matched controls from a national epidemiological study, amending each transcription with word timings. We then calculated clustering and switching scores, as well as scores indexing speed of responses, using techniques described in the literature. We evaluated agreement among the techniques with Cohen’s κ and calculated correlations among the scores. After fitting a base model with raw scores, repetitions, and intrusions, we fit a series of Bayesian logistic regression models adding either clustering and switching scores or speed scores, comparing the models in terms of several metrics. We partitioned the ICI cases into acute and progressive cases and repeated the regression analysis for each group.

Results

For animal fluency, we found that models with speed scores derived using the slope difference algorithm achieved the best values of the Watanabe–Akaike Information Criterion (WAIC), but with good net reclassification improvement (NRI) only for the progressive group (8.2%). For letter fluency, different models excelled for prediction of acute and progressive cases. For acute cases, NRI was best for speed scores derived from a network model (3.4%), while for progressive cases, the best model used clustering and switching scores derived from the same network model (5.1%). Combining variables from the best animal and letter F models led to marginal improvements in model fit and NRI only for the all-cases and acute-cases analyses.

Conclusion

Speed scores improve a base model for predicting progressive cognitive impairment from animal fluency. Letter fluency scores may provide complementary information.

Visualizing and Quantifying Longitudinal Changes in Verbal Fluency Using Recurrence Plots

The verbal fluency task, where participants name as many instances of a specific semantic or phonemic category as possible in a certain time limit, is widely used to probe language and memory retrieval functions in research and clinical settings. More recently, interests in using longitudinal observations in verbal fluency to examine changes over the lifespan have grown, in part due to the increasing availability of such datasets, yet quantitative methods for comparing repeated measures of verbal fluency responses remain scarce. As a result, existing studies tend to focus only on the number of unique words produced and how this metric changes over time, overlooking changes in other important features in the data, such as the identity of the words and the order in which they are produced. Here, we provide an example of how the literature of recurrence analysis, which aims to visualize and analyze non-linear time series, may present useful visualization and analytical approaches for this problem. Drawing on this literature, we introduce a novel metric (the "distance from diagonal," or DfD) to quantify semantic fluency data that incorporates analysis of the sequence order and changes between two lists. As a demonstration, we apply these methods to a longitudinal dataset of semantic fluency in people with Alzheimer's disease and age-matched controls. We show that DfD differs significantly between healthy controls and Alzheimer's disease patients, and that it complements common existing metrics in diagnostic prediction. Our visualization method also allows incorporation of other less common metrics-including the order that words are recalled, repetitions of words within a list, and out-of-category intrusions. Additionally, we show that these plots can be used to visualize and compare aggregate recall data at the group level. These methods can improve understanding of verbal fluency deficits observed in various neuropsychiatric and neurological disorders.

Differential linguistic features of verbal fluency in behavioral variant frontotemporal dementia and primary progressive aphasia

Frontotemporal dementia (FTD) is an early-onset neurodegenerative disorder with a heterogeneous clinical presentation. Verbal fluency is regularly used as a sensitive measure of language ability, semantic memory, and executive functioning, but qualitative changes in verbal fluency in FTD are currently overlooked. This retrospective study examined qualitative, linguistic features of verbal fluency in 137 patients with behavioral variant (bv)FTD (n = 50), or primary progressive aphasia (PPA) [25 non-fluent variant (nfvPPA), 27 semantic variant (svPPA), and 34 logopenic variant (lvPPA)] and 25 control participants. Between-group differences in clustering, switching, lexical frequency (LF), age of acquisition (AoA), neighborhood density (ND), and word length (WL) were examined in the category and letter fluency with analysis of variance adjusted for age, sex, and the total number of words. Associations with other cognitive functions were explored with linear regression analysis. The results showed that the verbal fluency performance of patients with svPPA could be distinguished from controls and other patient groups by fewer and smaller clusters, more switches, higher LF, and lower AoA (all p < 0.05). Patients with lvPPA specifically produced words with higher ND than the other patient groups (p < 0.05). Patients with bvFTD produced longer words than the PPA groups (p < 0.05). Clustering, switching, LF, AoA, and ND-but not WL-were differentially predicted by measures of language, memory, and executive functioning (range standardized regression coefficient 0.25-0.41). In addition to the total number of words, qualitative linguistic features differ between subtypes of FTD. These features provide additional information on lexical processing and semantic memory that may aid the differential diagnosis of FTD.

Comprehensive verbal fluency features predict executive function performance

Semantic verbal fluency (sVF) tasks are commonly used in clinical diagnostic batteries as well as in a research context. When performing sVF tasks to assess executive functions (EFs) the sum of correctly produced words is the main measure. Although previous research indicates potentially better insights into EF performance by the use of finer grained sVF information, this has not yet been objectively evaluated. To investigate the potential of employing a finer grained sVF feature set to predict EF performance, healthy monolingual German speaking participants (n = 230) were tested with a comprehensive EF test battery and sVF tasks, from which features including sum scores, error types, speech breaks and semantic relatedness were extracted. A machine learning method was applied to predict EF scores from sVF features in previously unseen subjects. To investigate the predictive power of the advanced sVF feature set, we compared it to the commonly used sum score analysis. Results revealed that 8 / 14 EF tests were predicted significantly using the comprehensive sVF feature set, which outperformed sum scores particularly in predicting cognitive flexibility and inhibitory processes. These findings highlight the predictive potential of a comprehensive evaluation of sVF tasks which might be used as diagnostic screening of EFs.

Contribution of the Cerebellum and the Basal Ganglia to Language Production: Speech, Word Fluency, and Sentence Construction-Evidence from Pathology

Evidence reported in recent decades increasingly confirms that both the cerebellum and the basal ganglia, which are primarily involved in movement control, also have a significant role in a vast range of cognitive and affective functions. Evidence from pathology indicates that the disorders of some aspects of language production which follow damage of the cerebellum or respectively basal ganglia, i.e., disorders of speech, word fluency, and sentence construction, have identifiable neuropsychological profiles and that most manifestations can be specifically attributed to the dysfunctions of mechanisms supported by one or the other of these structures. The cerebellum and the basal ganglia are reciprocally interconnected. Thus, it is plausible that some disorders observed when damage involves one of these structures could be remote effects of abnormal activity in the other. However, in a purely clinical-neuropsychological perspective, primary and remote effects in the network are difficult to disentangle. Functional neuroimaging and non-invasive brain stimulation techniques likely represent the indispensable support for achieving this goal.

Recruiting the right hemisphere: Sex differences in inter-hemispheric communication during semantic verbal fluency

Sex differences in cognitive functions are heavily debated. Recent work suggests that sex differences do stem from different processing strategies utilized by men and women. While these processing strategies are likely reflected in different brain networks, so far the link between brain networks and processing strategies remains speculative. In the present study we seek for the first time to link sex differences in brain activation patterns to sex differences in processing strategies utilizing a semantic verbal fluency task in a large sample of 35 men and 35 women, all scanned thrice. For verbal fluency, strategies of clustering and switching have been described. Our results show that men show higher activation in the brain network supporting clustering, while women show higher activation in the brain network supporting switching. Furthermore, converging evidence from activation results, lateralization indices and connectivity analyses suggests that men recruit the right hemisphere more strongly during clustering, but women during switching. These results may explain findings of differential performance and strategy-use in previous behavioral studies.

Association Between Toll-Like Receptor 4 (TLR4) and Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) Genetic Variants and Clinical Progression of Huntington's Disease

BACKGROUND

Although Huntington's disease (HD) is caused by a single dominant gene, it is clear that there are genetic modifiers that may influence the age of onset and disease progression.

OBJECTIVES

We sought to investigate whether new inflammation-related genetic variants may contribute to the onset and progression of HD.

METHODS

We first used postmortem brain material from patients at different stages of HD to look at the protein expression of toll-like receptor 4 (TLR4) and triggering receptor expressed on myeloid cells 2 (TREM2). We then genotyped the TREM2 R47H gene variant and 3 TLR4 single nucleotide polymorphisms in a large cohort of HD patients from the European Huntington's Disease Network REGISTRY.

RESULTS

We found an increase in the number of cells expressing TREM2 and TLR4 in postmortem brain samples from patients dying with HD. We also found that the TREM2 R47H gene variant was associated with changes in cognitive decline in the large cohort of HD patients, whereas 2 of 3 TLR4 single nucleotide polymorphisms assessed were associated with changes in motor progression in this same group.

CONCLUSIONS

These findings identify TREM2 and TLR4 as potential genetic modifiers for HD and suggest that inflammation influences disease progression in this condition. © 2019 International Parkinson and Movement Disorder Society.

Thought and language disturbance in bipolar disorder quantified via process-oriented verbal fluency measures

Bipolar disorder (BD) is characterized by speech abnormalities, reflected by symptoms such as pressure of speech in mania and poverty of speech in depression. Here we aimed at investigating speech abnormalities in different episodes of BD, including mixed episodes, via process-oriented measures of verbal fluency performance - i.e., word and error count, semantic and phonological clustering measures, and number of switches-, and their relation to neurocognitive mechanisms and clinical symptoms. 93 patients with BD - i.e., 25 manic, 12 mixed manic, 19 mixed depression, 17 depressed, and 20 euthymic-and 31 healthy controls were administered three verbal fluency tasks - free, letter, semantic-and a clinical and neuropsychological assessment. Compared to depression and euthymia, switching and clustering abnormalities were found in manic and mixed states, mimicking symptoms like flight of ideas. Moreover, the neuropsychological results, as well as the fact that error count did not increase whereas phonological associations did, showed that impaired inhibition abilities and distractibility could not account for the results in patients with manic symptoms. Rather, semantic overactivation in patients with manic symptoms, including mixed depression, may compensate for trait-like deficient semantic retrieval/access found in euthymia. "For those who are manic, or those who have a history of mania, words move about in all directions possible, in a three-dimensional 'soup', making retrieval more fluid, less predictable." Kay Redfield Jamison (2017, p. 279).

Automated Indices of Clustering and Switching of Semantic Verbal Fluency in Parkinson's Disease

OBJECTIVES

Deficits in semantic verbal fluency (SVF) can stem from dysfunction of an executive control system and/or of semantic knowledge. Previous analyses of SVF responses were devised to characterize these two components including switching and mean cluster size (MCS) indices, but these rely on subjective experimenter-based assessment of the words' relatedness. To address this limitation, computational data-driven SVF indices have been developed. Our aim is to assess the validity and usefulness of these automated indices in the context of cognitive decline in Parkinson's disease (PD).

METHODS

This is a retrospective study including 50 advanced PD patients with (n=28) or without (n=22) mild cognitive impairment (PD-MCI). We analyzed animal SVF outputs using an automated computational approach yielding switching, MCS, and cumulative relatedness (CuRel) indices. We compared these indices to the classic experimenter-based switching and MCS indices to assess concurrent validity, and against neuropsychological measures of executive functioning and semantic knowledge to assess construct validity. We also examined whether these indices were impaired and predicted PD-MCI.

RESULTS

Automated switching indices, but not MCS or CuRel, showed evidence of concurrent and construct validity, and characterized individual difference in advanced PD. Automated switching indices also outperformed the experimenter-dependent index in predicting the presence of PD-MCI.

CONCLUSION

Computational methods hold promise as fine-grained, unbiased indices reflecting the executive component of SVF, but none of the methods provided valid measures of semantic knowledge in PD. Our data also confirm that SVF are not adequate tests of semantic memory in patients with executive dysfunction such as PD. (JINS, 2018, 24, 1047-1056).

Motor and cognitive impairments in spinocerebellar ataxia type 7 and its correlations with cortical volumes

Spinocerebellar Ataxia Type 7 (SCA7) is a neurodegenerative disorder caused by cytosine-adenine-guanine (CAG) repeat expansion. It is clinically characterized by ataxia and visual loss. To date, little is known about SCA7 cognitive impairments and its relationship with grey matter volume (GMV) changes. The aim of this study was to explore SCA7 patients' performance in specific components of auditory-verbal neuropsychological tests and to correlate their scores with genetic mutation, severity of ataxia and GMV. We assessed verbal memory and verbal fluency proficiencies in 31 genetically confirmed SCA7 patients, and compared their results with 32 healthy matched volunteers; we also correlated CAG repeats and severity of motor symptoms with performance in the auditory-verbal tests. SCA7 patients exhibited deficiencies in several components of these cognitive tasks, which were independent of motor impairments and showed no relation to CAG repeats. Based on Resonance Images performed in 27 patients we found association between ataxia severity and GMV in "sensoriomotor" cerebellum, as well as correlations of impaired verbal memory and semantic fluency scores with GMV in association cortices, including the right parahippocampal gyrus. To our knowledge, this is the first report of deficits in the organization of semantic information and in the evocation of verbal material, as well as greater susceptibility to proactive interference in SCA7 patients. These findings bring novel information about specific cognitive abilities in SCA7 patients, particularly verbal memory and fluency, and their relation with GMV variations in circumscribed brain regions, including association cortices known to have functional relationships with the cerebellum.

Qualitative Assessment of Verbal Fluency Performance in Frontotemporal Dementia

BACKGROUND/AIMS

Verbal fluency is impaired in patients with frontotemporal dementia (FTD) and primary progressive aphasia (PPA). This study explored qualitative differences in verbal fluency (clustering of words, switching between strategies) between FTD and PPA variants.

METHODS

Twenty-nine patients with behavioral variant FTD (bvFTD) and 50 with PPA (13 nonfluent/agrammatic, 14 semantic, and 23 logopenic) performed a semantic and letter fluency task. Clustering (number of multiword strings) and switching (number of transitions between clustered and nonclustered words) were recorded by two independent raters. Between-group differences, associations with memory, language, and executive functioning, and longitudinal change (subsample) in clustering and switching were examined.

RESULTS

Interrater reliability was high (median 0.98). PPA patients generated (a) smaller (number of) clusters on semantic and letter fluency than bvFTD patients (p < 0.05). Semantic variant patients used more switches than nonfluent/agrammatic or logopenic variant patients (p < 0.05). Clustering in semantic fluency was significantly associated with memory and language (range standardized regression coefficients 0.24-0.38). Switching in letter fluency was associated with executive functioning (0.32-0.35).

CONCLUSION

Clustering and switching in verbal fluency differed between patients with subtypes of FTD and PPA. Qualitative aspects of verbal fluency provide additional information on verbal ability and executive control which can be used for clinically diagnostic purposes.

Developmental Trajectories of Executive and Verbal Processes in Children with Phenylketonuria

Phenylketonuria (PKU) is a hereditary disorder characterized by disrupted phenylalanine metabolism and cognitive impairment. However, the precise nature and developmental trajectory of this cognitive impairment remains unclear. The present study used a verbal fluency task to dissociate executive and verbal processes in children with PKU (n = 23; 7-18 years) and controls (n = 44; 7-19 years). Data were collected at three longitudinal timepoints over a three-year period, and the contributions of age, group, and their interaction to fluency performance were evaluated. Results indicated impairments in executive processes in children with PKU, which were exacerbated by declining metabolic control.

More expertise for a better perspective: Task and strategy-driven adaptive neurofunctional reorganization for word production in high-performing older adults

The suggestion that neurofunctional reorganization may contribute to preserved language abilities is still emerging in aging studies. Some of these abilities, such as verbal fluency (VF), are not unitary but instead rely on different strategic processes that are differentially changed with age. Younger (n = 13) and older adults (n = 13) carried out an overt self-paced semantic and orthographic VF tasks within mixed fMRI design. Our results suggest that patterns of brain activation sustaining equivalent performances could be underpinned by different strategies facing brain changes during healthy aging. These main findings suggest that temporally mediated semantic clustering and frontally mediated orthographic switching were driven by evolutive neurofunctional resources in high-performing older adults. These age-related activation changes can appear to be compatible with the idea that unique neural patterns expressing distinctive cognitive strategies are necessary to support older adults' performance on VF tasks.

Fractionating Executive Functions of Adults With ADHD

OBJECTIVE

To evaluate the performance of adults with ADHD considering the fractionation of executive functions into six different domains.

METHOD

Participants were adult ADHD patients who were not under the acute effects of medication ( n = 48). Their performance was compared with that of a healthy control group ( n = 20) of comparable age, education, and nonverbal intelligence quotient. The cognitive domains assessed were executive shifting, updating, inhibition of prepotent responses, dual-task performance, planning, and access to long-term memory. We also assessed the symptoms of inattention, hyperactivity/impulsivity, anxiety, and depression by validated questionnaires.

RESULTS

Compared with controls, patients reported more symptoms related to ADHD, anxiety and depression symptoms and were impaired in the shifting cost measure and phonemic fluency (measure of access to long-term memory).

CONCLUSION

ADHD in adults selectively impaired executive shifting and access to long-term memory, domains that may alter performance in a wide range of daily tasks.

Características del habla, el lenguaje y la deglución en la enfermedad de Huntington

La enfermedad de Huntington (EH) ha sido descrita como una afección de causa genética producida por una mutación en la repetición de la secuencia de nucleótidos CAG (citosina-adenina-guanina). Según el estadio que curse la enfermedad, las personas pueden presentar dificultades en el habla, el lenguaje y la deglución. El propósito de este artículo es exponer con detalle dichas dificultades, así como su tratamiento fonoaudiológico. Se destaca que en el habla se encuentran características propias de una disartria hipercinética debido a los movimientos coreicos subyacentes. En el lenguaje, las personas con EH realizan enunciados más cortos y con estructuras sintácticas mucho más simples y presentan dificultades en tareas que requieren procesamiento cognitivo complejo. En la deglución, se presenta una disfagia que progresa a medida que avanza la enfermedad. Una intervención fonoaudiológica oportuna, integral y eficaz es fundamental para mejorar la calidad de vida de las personas y contribuir a su bienestar comunicativo.

Non-Verbal and Verbal Fluency in Prodromal Huntington's Disease

BACKGROUND

This study examines non-verbal (design) and verbal (phonemic and semantic) fluency in prodromal Huntington's disease (HD). An accumulating body of research indicates subtle deficits in cognitive functioning among prodromal mutation carriers for HD.

METHODS

Performance was compared between 32 mutation carriers and 38 non-carriers in order to examine the magnitude of impairment across fluency tasks. The predicted years to onset (PYTO) in mutation carriers was calculated by a regression equation and used to divide the group according to whether onset was predicted as less than 12.75 years (HD+CLOSE; n = 16) or greater than 12.75 years (HD+DISTANT; n = 16).

RESULTS

The results indicate that both non-verbal and verbal fluency is sensitive to subtle impairment in prodromal HD. HD+CLOSE group produced fewer items in all assessed fluency tasks compared to non-carriers. HD+DISTANT produced fewer drawings than non-carriers in the non-verbal task. PYTO correlated significantly with all measures of non-verbal and verbal fluency.

CONCLUSION

The pattern of results indicates that subtle cognitive deficits exist in prodromal HD, and that less structured tasks with high executive demands are the most sensitive in detecting divergence from the normal range of functioning. These selective impairments can be attributed to the early involvement of frontostriatal circuitry and frontal lobes.

The role of tau in the pathological process and clinical expression of Huntington's disease

Tau has recently been implicated in Huntington’s disease, but the nature of its involvement is unclear. Vuono et al. reveal tau oligomers and hyperphosphorylated tau aggregates in post-mortem Huntington’s disease brains, including those from young-onset cases. Genotype-phenotype analysis of a large patient cohort shows that tau haplotypes influence cognitive decline.

Huntington’s disease is a neurodegenerative disorder caused by an abnormal CAG repeat expansion within exon 1 of the huntingtin gene HTT. While several genetic modifiers, distinct from the Huntington’s disease locus itself, have been identified as being linked to the clinical expression and progression of Huntington’s disease, the exact molecular mechanisms driving its pathogenic cascade and clinical features, especially the dementia, are not fully understood. Recently the microtubule associated protein tau, MAPT, which is associated with several neurodegenerative disorders, has been implicated in Huntington’s disease. We explored this association in more detail at the neuropathological, genetic and clinical level. We first investigated tau pathology by looking for the presence of hyperphosphorylated tau aggregates, co-localization of tau with mutant HTT and its oligomeric intermediates in post-mortem brain samples from patients with Huntington’s disease (n = 16) compared to cases with a known tauopathy and healthy controls. Next, we undertook a genotype–phenotype analysis of a large cohort of patients with Huntington’s disease (n = 960) with a particular focus on cognitive decline. We report not only on the tau pathology in the Huntington’s disease brain but also the association between genetic variation in tau gene and the clinical expression and progression of the disease. We found extensive pathological inclusions containing abnormally phosphorylated tau protein that co-localized in some instances with mutant HTT. We confirmed this related to the disease process rather than age, by showing it is also present in two patients with young-onset Huntington’s disease (26 and 40 years old at death). In addition we demonstrate that tau oligomers (suggested to be the most likely neurotoxic tau entity) are present in the Huntington’s disease brains. Finally we highlight the clinical significance of this pathology by demonstrating that the MAPT haplotypes affect the rate of cognitive decline in a large cohort of patients with Huntington’s disease. Our findings therefore highlight a novel important role of tau in the pathogenic process and clinical expression of Huntington’s disease, which in turn opens up new therapeutic avenues for this incurable condition.

The absoluteness of semantic processing: lessons from the analysis of temporal clusters in phonemic verbal fluency

Background

For word production, we may consciously pursue semantic or phonological search strategies, but it is uncertain whether we can retrieve the different aspects of lexical information independently from each other. We therefore studied the spread of semantic information into words produced under exclusively phonemic task demands.

Methods

42 subjects participated in a letter verbal fluency task, demanding the production of as many s-words as possible in two minutes. Based on curve fittings for the time courses of word production, output spurts (temporal clusters) considered to reflect rapid lexical retrieval based on automatic activation spread, were identified. Semantic and phonemic word relatedness within versus between these clusters was assessed by respective scores (0 meaning no relation, 4 maximum relation).

Results

Subjects produced 27.5 (±9.4) words belonging to 6.7 (±2.4) clusters. Both phonemically and semantically words were more related within clusters than between clusters (phon: 0.33±0.22 vs. 0.19±0.17, p<.01; sem: 0.65±0.29 vs. 0.37±0.29, p<.01). Whereas the extent of phonemic relatedness correlated with high task performance, the contrary was the case for the extent of semantic relatedness.

Conclusion

The results indicate that semantic information spread occurs, even if the consciously pursued word search strategy is purely phonological. This, together with the negative correlation between semantic relatedness and verbal output suits the idea of a semantic default mode of lexical search, acting against rapid task performance in the given scenario of phonemic verbal fluency. The simultaneity of enhanced semantic and phonemic word relatedness within the same temporal cluster boundaries suggests an interaction between content and sound-related information whenever a new semantic field has been opened.

Supporting physical activity engagement in people with Huntington's disease (ENGAGE-HD): study protocol for a randomized controlled feasibility trial

Background

Huntington’s disease (HD) is a complex, single-gene inherited neurodegenerative condition resulting in symptoms that occur across a wide range of neurological domains, including cognitive, behavioral and motor. The benefits of regular physical activity for people with HD are widely recognized. However, a number of factors can prohibit sustained exercise and activity. The purpose of this trial is to explore the feasibility, acceptability and effectiveness of a physical activity intervention program targeted for people with early- to mid-stage HD.

Methods/Design

The proposed trial is a single blind, multisite, exploratory, randomized controlled feasibility trial of a physical activity intervention. A total of 62 participants with genetically confirmed HD will be recruited. Each participant will be involved in the trial for 26 weeks. Participants will be randomized immediately following the baseline assessment into either a physical activity intervention or a social contact control intervention. The physical activity intervention is framed around self-determination theory placed within a broader behaviour change wheel framework. An HD-specific workbook and individual goal setting will be utilized over six 1:1 sessions, with interim telephone calls. All participants will be reassessed at 16 weeks following the baseline assessment, and then again at a final follow-up assessment 26 weeks later. At the end of the study, all participants will be offered a brief version of the alternative intervention, with one home visit and one follow-up telephone call.

Discussion

Engaging and supporting people with HD in a regular physical activity program raises a number of challenges. The physical activity intervention and the comparator social interaction intervention have been developed following consultation with people with HD and their families. Each are individually tailored and determined on individual needs and goals. The results from this trial will provide guidance for the development of definitive trials.

Trial registration

The trial was registered with ISRCTN ( http://www.isrctn.com/ISRCTN65378754) on 13 March 2014.

Taste perception analysis using a semantic verbal fluency task

A verbal fluency (VF) task is a test used to examine cognitive perception. The main aim of this study was to explore a possible relationship between taste perception in the basic taste categories (sweet, salty, sour, and bitter) and subjects' taste preferences, using a VF task in healthy and dysphagic subjects. In addition, we correlated the results of the VF task with body mass index (BMI). The hypothesis is that categorical preferences would be consistent with the number of verbal responses. We also hypothesized that higher BMI (>30 kg/m(2)) would correlate with more responses in either some or all four categories. VF tasks were randomly administered. Analysis criteria included number of verbally produced responses, number of clusters, number of switches, number and type of errors, and VF consistency with taste preferences. Sixty Greek-speaking individuals participated in this study. Forty-three healthy subjects were selected with a wide range of ages, sex, and education levels. Seventeen dysphagic patients were then matched with 17 healthy subjects according to age, sex, and BMI. Quantitative one-way analysis of variance (between groups as well as repeated measures), post hoc, and chi-square, and qualitative analyses were performed. In the healthy subjects' group, the differences among the mean number of responses for the four taste categories were statistically significant. When comparing the two matched groups of healthy and dysphagic subjects, there were no statistically significant differences in the mean number of responses in the four basic taste categories. However, for both groups, most responses were generated in the following descending order: sweet, salty, sour, and bitter. The bitter category presented the majority of errors for both groups. Obese subjects produced a greater mean number of responses for the "sweet," "sour," and "bitter" categories; conversely, underweight subjects produced a larger mean number of responses for the "salty" category, even though these differences were not statistically significant. The relationship of VF with taste perception and BMI could contribute to evidence-based knowledge that can be used for clinical practice.

Alpha-theta border EEG abnormalities in preclinical Huntington's disease

BACKGROUND

Brain dysfunction precedes clinical manifestation of Huntington's disease (HD) by decades. This study was aimed to determine whether resting EEG is altered in preclinical HD mutations carriers (pre-HD).

METHODS

We examined relative power of broad traditional EEG bands as well as 1-Hz sub-bands of theta and alpha from the resting-state EEG of 29 pre-HD individuals and of 29 age-matched normal controls.

RESULTS

The relative power of the narrow sub-band in the border of theta-alpha (7-8 Hz) was significantly reduced in pre-HD subjects as compared to normal controls, while the alterations in relative power of the broad frequency bands were not significant. In pre-HD subjects, the number of CAG repeats in the huntingtin (HTT) gene as well as the disease burden score (DBS) showed a positive correlation with relative power of the delta and theta frequency bands and their sub-bands and a negative correlation with alpha band relative power and the differences of relative power of the 7-8 Hz and 4-5 Hz frequency sub-bands.

CONCLUSION

The obtained results suggest that EEG alterations in pre-HD individuals may be related to the course of the pathological process and to HD endophenotype. Analysis of the narrow EEG bands was found to be more useful for assessing EEG alterations in pre-HD individuals than a more traditional approach using broad bandwidths.

Motor-Language Coupling in Huntington's Disease Families

Traditionally, Huntington’s disease (HD) has been known as a movement disorder, characterized by motor, psychiatric, and cognitive impairments. Recent studies have shown that motor and action–language processes are neurally associated. The cognitive mechanisms underlying this interaction have been investigated through the action compatibility effect (ACE) paradigm, which induces a contextual coupling of ongoing motor actions and verbal processing. The present study is the first to use the ACE paradigm to evaluate action–word processing in HD patients (HDP) and their families. Specifically, we tested three groups: HDP, healthy first-degree relatives (HDR), and non-relative healthy controls. The results showed that ACE was abolished in HDP as well as HDR, but not in controls. Furthermore, we found that the processing deficits were primarily linguistic, given that they did not correlate executive function measurements. Our overall results underscore the role of cortico-basal ganglia circuits in action–word processing and indicate that the ACE task is a sensitive and robust early biomarker of HD and familial vulnerability.

The nature of lexical-semantic access in bilingual aphasia

Background. Despite a growing clinical need, there are no clear guidelines on assessment of lexical access in the two languages in individuals with bilingual aphasia. Objective. In this study, we examined the influence of language proficiency on three tasks requiring lexical access in English and Spanish bilingual normal controls and in bilingual individuals with aphasia. Methods. 12 neurologically healthy Spanish-English bilinguals and 10 Spanish-English bilinguals with aphasia participated in the study. All participants completed three lexical retrieval tasks: two picture-naming tasks (BNT, BPNT) and a category generation (CG) task. Results. This study found that across all tasks, the greatest predictors for performance were the effect of group and language ability rating (LAR). Bilingual controls had a greater score or produced more correct responses than participants with bilingual aphasia across all tasks. The results of our study also indicate that normal controls and bilinguals with aphasia make similar types of errors in both English and Spanish and develop similar clustering strategies despite significant performance differences between the groups. Conclusions. Differences between bilingual patients and controls demonstrate a fundamental lexical retrieval deficit in bilingual individuals with aphasia, but one that is further influenced by language proficiency in the two languages.

The effect of Parkinson's disease subgroups on verbal and nonverbal fluency

BACKGROUND

Parkinson's disease (PD) leads to deficits in executive function, including verbal and nonverbal fluency, as a result of compromised frontostriatal circuits. It is unknown whether deficits in verbal and nonverbal fluency in PD are driven by certain subgroups of patients, or how strategy use may facilitate performance.

PARTICIPANTS

Sixty-five nondemented individuals with PD, including 36 with right-body onset (RPD; 20 with tremor as their initial symptom, 16 nontremor) and 29 with left-body onset (LPD; 14 with tremor as their initial symptom, 15 nontremor), and 52 normal control participants (NC) took part in the study.

MEASUREMENTS

Verbal fluency was assessed using the FAS and Animals tests. Nonverbal fluency was assessed using the Ruff Figural Fluency Test.

RESULTS

Both RPD and LPD were impaired in generating words and in using clustering and switching strategies on phonemic verbal fluency, whereas different patterns of impairment were found on nonverbal fluency depending on the interaction of side of onset and initial motor symptom (tremor vs. nontremor). Strategy use correlated with number of correct responses on verbal fluency in LPD, RPD, and NC. By contrast, on nonverbal fluency, strategy use correlated with correct responses for RPD and LPD, but not for NC.

CONCLUSION

Our findings demonstrate the importance of considering subgroups in PD and analyzing subcomponents of verbal and nonverbal fluency (correct responses, errors, and strategies), which may depend differently on the integrity of dorsolateral prefrontal cortex, inferior frontal cortex, and anterior cingulate cortex.

Utility of a computerized, paced semantic verbal fluency paradigm in differentiating schizophrenia and healthy subjects

Functional magnetic resonance imaging (fMRI) paradigms designed to study word generation traditionally utilize a computerized paced version of the verbal fluency task (VFT) comprising 'blocks' of word generation and a baseline word repetition task. The utility of the above paced VFT paradigm in differentiating neuropsychiatric patients from healthy subjects has not been systematically examined. We administered a computerized, paced version of the semantic VFT comprising word generation and word repetition blocks to 24 schizophrenia and 24 matched healthy subjects, both before and during fMRI acquisition. The performance of patients with schizophrenia was significantly inferior to that of healthy control subjects in both the 'pre-scan' and 'intra-scan' sessions of the computerized paced semantic VFT. Specifically, schizophrenia patients generated significantly fewer total responses (VFTR) as well as correct responses (VFCR), but a larger number of 'no response' trials. However, there were no significant group differences in perseverative responses in the pre-scan session or 'intra-scan' sessions. The above computerized task has been reported by us previously to generate a behavioral performance index with hemodynamic correlates (John et al., 2011). Thus, our findings support the use of computerized paced VFT comprising word generation and word repetition blocks in both clinical and research settings.

Evidence of semantic clustering in letter-cued word retrieval

Letter-cued word fluency is conceptualized as a phonemically guided word retrieval process. Accordingly, word clusters typically are defined solely by their phonemic similarity. We investigated semantic clustering in two letter-cued (P and S) word fluency task performances by 315 healthy adults, each for 1 min. Singular value decomposition (SVD) and generalized topological overlap measure (GTOM) were applied to verbal outputs to conservatively extract clusters of high-frequency words. The results generally confirmed phonemic clustering. However, we also found considerable semantic/associative clusters of words (e.g., pen, pencil, and paper), and some words showed both phonemic and semantic associations within a single cluster (e.g., pair, pear, peach). We conclude that letter-cued fluency is not necessarily a purely phonemic word retrieval process. Strong automatic semantic activation mechanisms play an important role in letter-cued lexical retrieval. Theoretical conceptualizations of the word retrieval process with phonemic cues may also need to be reexamined in light of these analyses.

A computational linguistic measure of clustering behavior on semantic verbal fluency task predicts risk of future dementia in the nun study

Generative semantic verbal fluency (SVF) tests show early and disproportionate decline relative to other abilities in individuals developing Alzheimer's disease. Optimal performance on SVF tests depends on the efficiency of using clustered organization of semantically related items and the ability to switch between clusters. Traditional approaches to clustering and switching have relied on manual determination of clusters. We evaluated a novel automated computational linguistic approach for quantifying clustering behavior. Our approach is based on Latent Semantic Analysis (LSA) for computing strength of semantic relatedness between pairs of words produced in response to SVF test. The mean size of semantic clusters (MCS) and semantic chains (MChS) are calculated based on pairwise relatedness values between words. We evaluated the predictive validity of these measures on a set of 239 participants in the Nun Study, a longitudinal study of aging. All were cognitively intact at baseline assessment, measured with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery, and were followed in 18-month waves for up to 20 years. The onset of either dementia or memory impairment were used as outcomes in Cox proportional hazards models adjusted for age and education and censored at follow-up waves 5 (6.3 years) and 13 (16.96 years). Higher MCS was associated with 38% reduction in dementia risk at wave 5 and 26% reduction at wave 13, but not with the onset of memory impairment. Higher [+1 standard deviation (SD)] MChS was associated with 39% dementia risk reduction at wave 5 but not wave 13, and association with memory impairment was not significant. Higher traditional SVF scores were associated with 22-29% memory impairment and 35-40% dementia risk reduction. SVF scores were not correlated with either MCS or MChS. Our study suggests that an automated approach to measuring clustering behavior can be used to estimate dementia risk in cognitively normal individuals.

Component analysis of verbal fluency scores in severe traumatic brain injury

PRIMARY OBJECTIVE

This study set out to examine the sensitivity of verbal fluency component scores in severe traumatic brain injury (TBI).

RESEARCH DESIGN

A retrospective cross-sectional design was used, with control participants chosen at random from the community and TBI patients from litigation cases.

METHODS AND PROCEDURES

Fifty-four healthy controls and 28 patients who had incurred a severe TBI were included in the study. The Controlled Oral Word Association test was rescored to include clustering and switching scores for phonemic and semantic fluency separately. The scores were compared between controls and TBI patients using independent samples t-tests.

MAIN OUTCOMES AND RESULTS

The findings demonstrate that component scores for semantic fluency yielded the largest effect sizes overall (d = 1.32 and d = 1.53), but not phonemic fluency. Total words generated in phonemic fluency yielded the largest effect size, although still modest (d = 0.62).

CONCLUSIONS

While verbal fluency may be a useful test tool to elicit evidence of neuropsychological impairment after TBI, these findings are consistent with previous research demonstrating that component scores are more sensitive indices. There is potential clinical utility in using component scores for examining the specific severity of verbal fluency impairment in TBI and guiding rehabilitation efforts.

Combined effects of aging and HIV infection on semantic verbal fluency: a view of the cortical hypothesis through the lens of clustering and switching

The profile of HIV-associated neurocognitive disorders (HAND) has classically been characterized as "subcortical," but questions have arisen as to whether aging with HIV in the antiretroviral therapy era has subtly shifted the expression of HAND into a more "cortical" disorder (e.g., decay of semantic memory stores). We evaluated this hypothesis by examining semantic fluency and its component processes (i.e., clustering and switching) in 257 individuals across four groups stratified by age (<40 and ≥50 years) and HIV serostatus. Jonckheere-Terpstra tests revealed significant monotonic trends for the combined effects of HIV and aging on overall semantic (and letter) fluency and switching, but not cluster size, with greatest deficits evident in the older adults with HIV infection. Within the older HIV-infected cohort, poorer switching was uniquely associated with self-reported declines in instrumental activities of daily living and deficits in learning and executive functions, but not semantic memory. Results suggest that HIV infection and aging may confer adverse additive effects on the executive components of semantic fluency (i.e., switching), rather than a degradation of semantic memory stores (i.e., cluster size), which is a profile that is most consistent with combined frontostriatal neuropathological burden of these two conditions.

Semantic cueing improves category verbal fluency in persons living with HIV infection

HIV-associated neurocognitive disorders (HAND) remain highly prevalent in the era of combination antiretroviral therapies, but there are no validated psychological interventions aimed at improving cognitive outcomes. This study sought to determine the potential benefit of semantic cueing on category fluency deficits, which are prevalent in HIV and affect daily functioning. A group of 86 HIV-infected individuals and 87 demographically-matched seronegative participants were administered a standard (i.e., uncued) and a cued category fluency task. Results revealed significant improvements in cued versus uncued performance in HIV, particularly for persons with lower levels of education. The cueing benefit observed may inform rehabilitation efforts aimed at ameliorating HAND.

Component analysis of verbal fluency in patients with mild traumatic brain injury

We set out to examine the sensitivity of switching and clustering component scores of verbal fluency in patients with mild traumatic brain injury (mTBI). Clustering and switching scores were compared between patients with mTBI and healthy normal controls as well as those with moderate TBI and severe TBI. Fifty-four healthy controls along with 20 mild TBI, 8 moderate TBI, and 12 severe TBI patients were included in the study. Our findings demonstrate that component score effect sizes were larger than those of total words generated for both phonemic and semantic fluency. This pattern of finding held true regardless of comparison group. In addition, semantic fluency component scores were found to correspond to larger component score effect sizes than did phonemic fluency component scores. Our findings demonstrate that component scores derived from the Controlled Oral Word Association Test may be sufficient to reliably capture the effects of unremitting injury (i.e., more than 3 months post status) to the frontal and temporal brain as evinced in cases of unremitting mTBI. This differential pattern of performance provides preliminary evidence for the potential usefulness of switching and clustering in the assessment of mTBI. Given the small sample sizes employed in our study, however, future studies are needed to determine whether component measures of verbal fluency have discriminative ability.

Executive strategic processing during verbal fluency performance in children with phenylketonuria

In the current study, we examined a specific aspect of executive abilities, strategic processing, in 32 children with early-treated phenylketonuria (PKU) and 41 typically-developing control children. To do so, clustering and switching were assessed during semantic (animal, food/drink) and phonemic (S, F) fluency tasks. Specifically, number of words generated, number of subcategory clusters, number of words in subcategory clusters, and number of switches between subcategories were analyzed to provide a refined analysis of strategic processing. Compared with controls, children with PKU generated significantly fewer words and made significantly fewer switches between subcategories in the food/drink trial and the phonemic fluency condition. Number of switches was associated with number of words generated in these tasks. In addition, a significant interaction between age and group in number of switches for the food/drink trial reflected a greater increase in number of switches for the control than PKU group as a function of increasing age. These results suggest impairment in frontally-mediated aspects of strategic processing in children with early-treated PKU and indicate that strategic processing should be evaluated carefully as these children age.

The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

Deficits in verbal fluency associated with ecstasy use have been well established; however, the mechanisms underlying this impairment have yet to be elucidated. In this study we investigated for the first time whether there was a disproportionate impairment in two cognitive subcomponents of verbal fluency: clustering (ability to generate words within the same subcategory) and switching (ability to change the subcategory). We also investigated a possible association between ecstasy use and verbal fluency in subjects genotyped for 5-HTT (5-HTTLPR and 5-HTTVNTR) and COMT (val(108/158)met, rs165599 and rs2097603) polymorphisms, in order to find a potential implication of genetic factors. Ecstasy polydrug users (n = 30) and non-ecstasy users (n = 41) were evaluated in both semantic and phonemic fluency. Results showed that ecstasy users had poorer semantic (but not phonemic) fluency performance than controls. Detailed analysis of clustering and switching performance revealed that this impairment was associated with poorer clustering mechanisms. Clustering was also modulated by the COMT rs165599 polymorphism independently of the group. A specific effect of the 5-HTTLPR polymorphism on switching performance was also found, with ss carriers performing significantly worse than ls and ll carriers, suggesting a serotonin modulation of frontal-executive flexibility. Based on the impaired clustering and switching strategies observed in ecstasy users, it might be proposed that both semantic knowledge and retrieval are impaired in this population. The verbal fluency deficit in ecstasy users may be attributable to a disruption of frontal-striatal circuits directly related with the serotonin function as well as a depletion of lexical-semantic stores mediated by temporal structures.

Verbal Fluency Component Analysis in Adults with HIV/AIDS

The present study examined the impact of HIV disease severity, depressed mood, and highly-active antiretroviral therapy (HAART) on verbal fluency components in a sample of adults with HIV-infection. Switching and clustering have been identified as dissociable components that contribute to performance on tests of phonemic and semantic verbal fluency. Advanced HIV-infection was predicted to differentially impair switching. Switching has been shown to be reduced in disorders affecting frontal-striatal systems (e.g., Parkinson's disease). Verbal fluency protocols (FAS and Animals) of 217 adults with HIV-infection were scored for total switches and average cluster size following the method of Troyer, et al. (1998). Component scores were compared to published norms. Analysis of variance (ANOVA) was used to examine the impact on switching and clustering performance of (1) HIV disease severity (presence of AIDS diagnosis) and depressed mood, and (2) AIDS diagnosis and medication status (current HAART therapy). FAS switching was more often impaired in participants with AIDS. Depressed mood did not affect switching. Neither AIDS diagnosis nor depressed mood was associated with clustering performance. Participants with an AIDS diagnosis who were receiving HAART showed better performance on FAS switching relative to participants with AIDS who were not taking antiretroviral medication. FAS switching appears to be sensitive to cognitive changes associated with advanced HIV-infection. Further research is needed to determine if switching is a specific marker of frontal-striatal dysfunction in this population.