Verbal fluency deficits in Parkinson's disease: a meta-analysis

Cortical structural involvement and cognitive dysfunction in early Parkinson's disease

Magnetic resonance imaging (MRI) studies in early Parkinson's disease (PD) have shown promise in the detection of disease-related brain changes in the white and deep grey matter. We set out to establish whether intrinsic cortical involvement in early PD can be detected with quantitative MRI. We collected a rich, multi-modal dataset, including diffusion MRI, T₁ relaxometry and cortical morphometry, in 20 patients with early PD (disease duration, 1.9 ± 0.97 years, Hoehn & Yahr 1-2) and in 19 matched controls. The cortex was reconstructed using FreeSurfer. Data analysis employed linked independent component analysis (ICA), a novel data-driven technique that allows for data fusion and extraction of multi-modal components before further analysis. For comparison, we performed standard uni-modal analysis with a general linear model (GLM). Linked ICA detected multi-modal cortical changes in early PD (p = 0.015). These comprised fractional anisotropy reduction in dorsolateral prefrontal, cingulate and premotor cortex and the superior parietal lobule, mean diffusivity increase in the mesolimbic, somatosensory and superior parietal cortex, sparse diffusivity decrease in lateral parietal and right prefrontal cortex, and sparse changes to the cortex area. In PD, the amount of cortical dysintegrity correlated with diminished cognitive performance. Importantly, uni-modal analysis detected no significant group difference on any imaging modality. We detected microstructural cortical pathology in early PD using a data-driven, multi-modal approach. This pathology is correlated with diminished cognitive performance. Our results indicate that early degenerative processes leave an MRI signature in the cortex of patients with early PD. The cortical imaging findings are behaviourally meaningful and provide a link between cognitive status and microstructural cortical pathology in patients with early PD.

A cross-linguistic comparison of category and letter fluency: Mandarin and English

Verbal fluency tasks are widely applied in a variety of languages, but whether the quality and quantity of responses are comparable across structurally different writing systems is debatable. For example, since there are no letters in a logographic, non-alphabetic language such as Chinese, the mechanisms speakers use to generate a list of words in a letter fluency task might be structurally different than those used by speakers of alphabetic languages. In this study, we investigated lexical retrieval strategies and approaches in letter and category fluency tasks among monolingual Mandarin speakers compared to monolingual English speakers. We found that the responses of Mandarin speakers are both qualitatively and quantitatively different in letter fluency, and qualitatively different in category fluency. These results suggest that differences in task completion among non-English-speaking populations are important to consider when using this extensively utilised cognitive and linguistic measure in research and clinic.

Overcoming duality: the fused bousfieldian function for modeling word production in verbal fluency tasks

Word production is generally assumed to occur as a function of a broadly interconnected language system. In terms of verbal fluency tasks, word production dynamics can be assessed by analyzing respective time courses via curve fitting. Here, a new generalized fitting function is presented by merging the two dichotomous classical Bousfieldian functions into one overarching power function with an adjustable shape parameter. When applied to empirical data from verbal fluency tasks, the error of approximation was significantly reduced while also fulfilling the Bayesian information criterion, suggesting a superior overall application value. Moreover, the approach identified a previously unknown logarithmic time course, providing further evidence of an underlying lexical network structure. In view of theories on lexical access, the corresponding modeling differentiates task-immanent lexical suppression from automatic lexical coactivation. In conclusion, our approach indicates that process dynamics result from an increasing cognitive effort to suppress automatic network functions.

Cognitive and behavioral disorders in Parkinson's disease: an update. I: cognitive impairments

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by motor symptoms such as rigidity, rest tremor, and bradykinesia. However, a growing body of evidence demonstrated that PD encompasses several non-motor disturbances as well, such as cognitive impairment. Cognitive defects can be present since early stages of the disease but tend to dominate the clinical picture as the disease progresses. Around 40% of patients with PD present with cognitive impairments in several cognitive domains including attention, working memory and executive functions, language, visuospatial skills, and episodic memory; in later stages of the disease, cognitive defects and associated behavioral disorders concur to determine clinically relevant PD-associated dementia. Part of these defects is ascribed to a dopamine-dependent dysfunction of fronto-striatal pathways, but there is a considerable heterogeneity in the cognitive impairments as well as a suggestion of the role of other neurotransmitter systems, such as the cholinergic one, mainly responsible for Parkinson-dementia syndrome. In this paper, we review recent literature with particular attention to the last 5 years on the main cognitive deficits described in PD patients as well as on the hypothesized neuro-functional substrate of such impairments. Finally, we provide some suggestions on how to test cognitive functions in PD appropriately.

Multifaceted Communication Problems in Everyday Conversations Involving People with Parkinson's Disease

It is known that Parkinson's disease is often accompanied by a motor speech disorder, which results in impaired communication. However, people with Parkinson's disease may also have impaired word retrieval (anomia) and other communicative problems, which have a negative impact on their ability to participate in conversations with family as well as healthcare staff. The aim of the present study was to explore effects of impaired speech and language on communication and how this is managed by people with Parkinson's disease and their spouses. Using a qualitative method based on Conversation Analysis, in-depth analyses were performed on natural conversational interaction in five dyads including elderly men who were at different stages of Parkinson's disease. The findings showed that the motor speech disorder in combination with word retrieval difficulties and adaptations, such as using communication strategies, may result in atypical utterances that are difficult for communication partners to understand. The coexistence of several communication problems compounds the difficulties faced in conversations and individuals with Parkinson's disease are often dependent on cooperation with their communication partner to make themselves understood.

Verbal monitoring in Parkinson's disease: A comparison between internal and external monitoring

Patients with Parkinson's disease (PD) display a variety of impairments in motor and non-motor language processes; speech is decreased on motor aspects such as amplitude, prosody and speed and on linguistic aspects including grammar and fluency. Here we investigated whether verbal monitoring is impaired and what the relative contributions of the internal and external monitoring route are on verbal monitoring in patients with PD relative to controls. Furthermore, the data were used to investigate whether internal monitoring performance could be predicted by internal speech perception tasks, as perception based monitoring theories assume. Performance of 18 patients with Parkinson's disease was measured on two cognitive performance tasks and a battery of 11 linguistic tasks, including tasks that measured performance on internal and external monitoring. Results were compared with those of 16 age-matched healthy controls. PD patients and controls generally performed similarly on the linguistic and monitoring measures. However, we observed qualitative differences in the effects of noise masking on monitoring and disfluencies and in the extent to which the linguistic tasks predicted monitoring behavior. We suggest that the patients differ from healthy subjects in their recruitment of monitoring channels.

Presence or absence of cognitive complaints in Parkinson's disease: mood disorder or anosognosia?

We intended to evaluate whether non-demented Parkinsons's disease (PD) patients, with or without subjective cognitive complaint, demonstrate differences between them and in comparison to controls concerning cognitive performance and mood. We evaluated 77 subjects between 30 and 70 years, divided as follows: PD without cognitive complaints (n = 31), PD with cognitive complaints (n = 21) and controls (n = 25). We applied the following tests: SCOPA-Cog, Trail Making Test-B, Phonemic Fluency, Clock Drawing Test, Boston Naming Test, Neuropsychiatric Inventory, Hospital Anxiety and Depression Scale (HADS) and Beck Depression Inventory. PD without complaints presented lower total score on Scales for outcome of Parkinson's disease-cognition as compared to controls (p = 0.048). PD with complaints group showed higher scores on HADS (p = 0.011). PD without complaints group showed poorer cognitive performance compared to controls, but was similar to the PD with complaints group. Moreover, this group was different from the PD without complaints and control groups concerning mood.

Present and future selves in Parkinson's disease

The study of the self in neuropsychological patients raises not only theoretical questions on the relationships between the self, autobiographical memory (AM), and episodic future thinking but also clinical issues for patients' daily life and care. We addressed this issue in Parkinson's disease patients for whom AM and future thinking impairments have been documented. All patients and controls generated and dated up past and future self-images and provided associated past and future events. Our findings suggest a subtle pattern of preservation/impairment of different dimensions (quantitative and qualitative) of self-images, which rely partially on the episodic quality of past and future events.

Anticholinergic drug use is associated with episodic memory decline in older adults without dementia

Anticholinergic drug use is common in older adults and has been related to increased dementia risk. This suggests that users of these drugs may experience accelerated cognitive decline. So far, however, longitudinal data on this topic are absent and the available evidence is inconclusive with respect to effects on specific cognitive domains due to suboptimal control of confounding variables. We investigated whether anticholinergic medication use is associated with cognitive decline over 6 years in a population-based study of older adults (aged 60-90; n = 1473) without dementia. We found that users (n = 29) declined more on episodic memory over 6 years compared to nonusers (n = 1418). These results were independent of age, sex, education, overall drug intake, physical activity, depression, cardiovascular risk burden, and cardiovascular disease. By contrast, anticholinergic drug use was unrelated to performance in processing speed, semantic memory, short-term memory, verbal fluency, and global cognition (the Mini-Mental-State Examination). Our results suggest that effects of anticholinergics may be particularly detrimental to episodic memory in older adults, which supports the assertion that the cholinergic system plays an important role in episodic memory formation.

A Neurophysiological Study of Semantic Processing in Parkinson's Disease

OBJECTIVES

Cognitive-linguistic impairments in Parkinson's disease (PD) have been well documented; however, few studies have explored the neurophysiological underpinnings of semantic deficits in PD. This study investigated semantic function in PD using event-related potentials.

METHODS

Eighteen people with PD and 18 healthy controls performed a semantic judgement task on written word pairs that were either congruent or incongruent.

RESULTS

The mean amplitude of the N400 for new incongruent word pairs was similar for both groups, however the onset latency was delayed in the PD group. Further analysis of the data revealed that both groups demonstrated attenuation of the N400 for repeated incongruent trials, as well as attenuation of the P600 component for repeated congruent trials.

CONCLUSIONS

The presence of N400 congruity and N400 repetition effects in the PD group suggests that semantic processing is generally intact, but with a slower time course as evidenced by the delayed N400. Additional research will be required to determine whether N400 and P600 repetition effects are sensitive to further cognitive decline in PD. (JINS, 2017, 23, 78-89).

The Interaction of Lexical Characteristics and Speech Production in Parkinson's Disease

PURPOSE

This study sought to investigate the interaction of speech movement execution with higher order lexical parameters. The authors examined how lexical characteristics affect speech output in individuals with Parkinson's disease (PD) and healthy control (HC) speakers.

METHOD

Twenty speakers with PD and 12 healthy speakers read sentences with target words that varied in word frequency and neighborhood density. The formant transitions (F2 slopes) of the diphthongs in the target words were compared across lexical categories between PD and HC groups.

RESULTS

Both groups of speakers produced steeper F2 slopes for the diphthongs in less frequent words and words from sparse neighborhoods. The magnitude of the increase in F2 slopes was significantly less in the PD than HC group. The lexical effect on the F2 slope differed among the diphthongs and between the 2 groups.

CONCLUSIONS

PD and healthy speakers varied their acoustic output on the basis of word frequency and neighborhood density. F2 slope variations can be traced to higher level lexical differences. This lexical effect on articulation, however, appears to be constrained by PD.

Computerized Analysis of Verbal Fluency: Normative Data and the Effects of Repeated Testing, Simulated Malingering, and Traumatic Brain Injury

In verbal fluency (VF) tests, subjects articulate words in a specified category during a short test period (typically 60 s). Verbal fluency tests are widely used to study language development and to evaluate memory retrieval in neuropsychiatric disorders. Performance is usually measured as the total number of correct words retrieved. Here, we describe the properties of a computerized VF (C-VF) test that tallies correct words and repetitions while providing additional lexical measures of word frequency, syllable count, and typicality. In addition, the C-VF permits (1) the analysis of the rate of responding over time, and (2) the analysis of the semantic relationships between words using a new method, Explicit Semantic Analysis (ESA), as well as the established semantic clustering and switching measures developed by Troyer et al. (1997). In Experiment 1, we gathered normative data from 180 subjects ranging in age from 18 to 82 years in semantic ("animals") and phonemic (letter "F") conditions. The number of words retrieved in 90 s correlated with education and daily hours of computer-use. The rate of word production declined sharply over time during both tests. In semantic conditions, correct-word scores correlated strongly with the number of ESA and Troyer-defined semantic switches as well as with an ESA-defined semantic organization index (SOI). In phonemic conditions, ESA revealed significant semantic influences in the sequence of words retrieved. In Experiment 2, we examined the test-retest reliability of different measures across three weekly tests in 40 young subjects. Different categories were used for each semantic ("animals", "parts of the body", and "foods") and phonemic (letters "F", "A", and "S") condition. After regressing out the influences of education and computer-use, we found that correct-word z-scores in the first session did not differ from those of the subjects in Experiment 1. Word production was uniformly greater in semantic than phonemic conditions. Intraclass correlation coefficients (ICCs) of correct-word z-scores were higher for phonemic (0.91) than semantic (0.77) tests. In semantic conditions, good reliability was also seen for the SOI (ICC = 0.68) and ESA-defined switches in semantic categories (ICC = 0.62). In Experiment 3, we examined the performance of subjects from Experiment 2 when instructed to malinger: 38% showed abnormal (p< 0.05) performance in semantic conditions. Simulated malingerers with abnormal scores could be distinguished with 80% sensitivity and 89% specificity from subjects with abnormal scores in Experiment 1 using lexical, temporal, and semantic measures. In Experiment 4, we tested patients with mild and severe traumatic brain injury (mTBI and sTBI). Patients with mTBI performed within the normal range, while patients with sTBI showed significant impairments in correct-word z-scores and category shifts. The lexical, temporal, and semantic measures of the C-VF provide an automated and comprehensive description of verbal fluency performance.

Semantic Verbal Fluency: Normative Data in Older Spanish Adults From NEDICES Population-Based Cohort

OBJECTIVE

We aimed to provide the normative data stratified by age, sex and educational attainment for two semantic categories (animal and fruits) in older Spanish adults.

METHOD

A representative sample of 2,744 non-demented older individuals with different socioeconomic background was selected from the Neurological Disorders in Central Spain (NEDICES), a population-based study. Normative data are presented in percentile ranks and divided into four age-tables with different midpoints, using the overlapping interval procedure.

RESULTS

Correlation analyses showed that age, education and sex influence significantly the scores in both semantic tasks. Normative data presented here covered two urban (Margaritas & Lista) and one rural areas (Arévalo).

CONCLUSION

These norms may provide useful data for screening cognitive impairment more accurately in Spanish older adults.

Worsening of Verbal Fluency After Deep Brain Stimulation in Parkinson's Disease: A Focused Review

Worsening of verbal fluency after treatment with deep brain stimulation in Parkinson's disease patients is one of the most often reported cognitive adverse effect. The underlying mechanisms of this decline are not well understood. The present focused review assesses the evidence for the reliability of the often-reported decline of verbal fluency, as well as the evidence for the suggested mechanisms including disease progression, reduced medication levels, electrode positions, and stimulation effect vs. surgical effects. Finally, we highlight the need for more systematic investigations of the large degree of heterogeneity in the prevalence of verbal fluency worsening after DBS, as well as provide suggestions for future research.

Changes in Verbal Fluency in Parkinson's Disease

Background

The test for semantic verbal fluency is quick and easy to administer. Decreases in semantic verbal fluency would suggest executive dysfunction among individuals with Parkinson's disease (PD).

Methods

The National Parkinson Foundation's Outcomes Project is a multicenter study that seeks to determine best practices in PD management. We analyzed data from the baseline and two annual follow-up visits to determine the annual rate of verbal fluency change and determinants of that change. Linear mixed modeling was used to assess relationships between verbal fluency, clinical characteristics, quality of life, and caregiver burden.

Results

There were 1,322 participants with an average age of 67.3 years, of whom 37% were women. Mean baseline verbal fluency scores at baseline were 18.81 (standard deviation = 6.25). Verbal fluency scores did not change among patients who were at our cohort's average age and average PD duration (8.4 years) and who had no other associated conditions (beta = -0.02; P = 0.80). Verbal fluency, however, did decrease for individuals with PD duration greater than the average (beta = -0.25; P = 0.03), age greater than the average (beta = -0.022; P < 0.01), a Hoehn and Yahr >=3 (beta = -0.31; P = 0.04), and in those with cardiovascular disease (beta = -0.32; P = 0.01) or psychiatric symptomatology (beta = -0.34; P = 0.01). Individuals with higher verbal fluency scores had better quality of life (P < 0.01) and decreased caregiver burden (P < 0.01).

Conclusions

Clinicians should monitor verbal fluency scores to evaluate cognitive decline among individuals with PD. Modifiable risk factors for verbal fluency changes include psychiatric symptomatology and cardiovascular disease. Clinicians may use verbal fluency testing to identify individuals at risk for decreased quality of life and increased caregiver burden, allowing for focused interventions.

Use of an automated mobile application to assess effects of nicotine withdrawal on verbal fluency: A pilot study

Mild-to-moderate impairment in frontally mediated functions such as sustained attention, working memory, and inhibition have been found to occur during tobacco withdrawal and may present a barrier to successful cessation. These findings have led to studies evaluating cessation treatments that target nicotine withdrawal related cognitive impairment. The instruments currently used to assess cognitive function provide detailed and specific information but have limitations including being time consuming, cumbersome, anxiety provoking, and having poor ecological validity. The authors examined the feasibility of using a mobile computer application to test verbal fluency (VF) as a quick, easy-to-administer, and more ecologically valid method of measuring the effects of short-term smoking abstinence on frontally mediated cognitive functions. Thirty participants completed 2 assessments-1 during ad lib smoking and 1 after overnight abstinence. At each assessment, semantic and phonemic VF tests were administered using a mobile application and nicotine craving and withdrawal symptom severity was assessed. In repeated assessments, performance on both semantic and phonemic VF tests is expected to improve due to practice effects; however, significant improvements were observed only in semantic (p = .012) but not phonemic (p = .154) VF. In addition, the change between assessments in phonemic (but not semantic) score was significantly associated with withdrawal (p = .006) and craving (p = .037) severity measured postabstinence. This study demonstrates that nicotine withdrawal has differential effects on semantic versus phonemic VF suggesting impairments of working memory, attention, and inhibition. These effects were measured using methods easily used in large groups of participants, potentially with remote test administration and automated scoring. (PsycINFO Database Record

Deep Brain Stimulation of the Subthalamic Nucleus Improves Lexical Switching in Parkinsons Disease Patients

Objective

Reduced verbal fluency (VF) has been reported in patients with Parkinson’s disease (PD), especially those treated by Deep Brain Stimulation of the subthalamic nucleus (STN DBS). To delineate the nature of this dysfunction we aimed at identifying the particular VF-related operations modified by STN DBS.

Method

Eleven PD patients performed VF tasks in their STN DBS ON and OFF condition. To differentiate VF-components modulated by the stimulation, a temporal cluster analysis was performed, separating production spurts (i.e., ‘clusters’ as correlates of automatic activation spread within lexical fields) from slower cluster transitions (i.e., ‘switches’ reflecting set-shifting towards new lexical fields). The results were compared to those of eleven healthy control subjects.

Results

PD patients produced significantly more switches accompanied by shorter switch times in the STN DBS ON compared to the STN DBS OFF condition. The number of clusters and time intervals between words within clusters were not affected by the treatment state. Although switch behavior in patients with DBS ON improved, their task performance was still lower compared to that of healthy controls.

Discussion

Beyond impacting on motor symptoms, STN DBS seems to influence the dynamics of cognitive procedures. Specifically, the results are in line with basal ganglia roles for cognitive switching, in the particular case of VF, from prevailing lexical concepts to new ones.

Verbal fluency tests: Normative data for the Latin American Spanish speaking adult population

OBJECTIVE

To generate normative data for the Verbal Fluency Tests across 11 countries in Latin America, with country-specific adjustments for gender, age, and education, where appropriate.

METHOD

The sample consisted of 3,977 healthy adults who were recruited from Argentina, Bolivia, Chile, Cuba, El Salvador, Guatemala, Honduras, Mexico, Paraguay, Peru, and, Puerto Rico. Each subject was administered the Verbal Fluency Test as part of a larger neuropsychological battery. A standardized five-step statistical procedure was used to generate the norms.

RESULTS

The final multiple linear regression models for the letter F explained 8-30% of the variance, 7-32% for letter A, 8-32% for the letter S, and 16-43% for the animal category in Verbal Fluency Test scores. Although t-tests showed significant differences between men and women on the Verbal Fluency Test, they did not have an effect size larger than 0.3. As a result, gender-adjusted norms were not generated.

CONCLUSIONS

This is the first normative multicenter study conducted in Latin America aiming to create norms for the Verbal Fluency Test; this study will have important outcomes for the future of neuropsychology in the region.

Speech and gait in Parkinson's disease: When rhythm matters

INTRODUCTION

Speech disturbances in Parkinson's disease (PD) are heterogeneous, ranging from hypokinetic to hyperkinetic types. Repetitive speech disorder has been demonstrated in more advanced disease stages and has been considered the speech equivalent of freezing of gait (FOG). We aimed to verify a possible relationship between speech and FOG in patients with PD.

METHODS

Forty-three consecutive PD patients and 20 healthy control subjects underwent standardized speech evaluation using the Italian version of the Dysarthria Profile (DP), for its motor component, and subsets of the Battery for the Analysis of the Aphasic Deficit (BADA), for its procedural component. DP is a scale composed of 7 sub-sections assessing different features of speech; the rate/prosody section of DP includes items investigating the presence of repetitive speech disorder. Severity of FOG was evaluated with the new freezing of gait questionnaire (NFGQ).

RESULTS

PD patients performed worse at DP and BADA compared to healthy controls; patients with FOG or with Hoehn-Yahr >2 reported lower scores in the articulation, intellibility, rate/prosody sections of DP and in the semantic verbal fluency test. Logistic regression analysis showed that only age and rate/prosody scores were significantly associated to FOG in PD. Multiple regression analysis showed that only the severity of FOG was associated to rate/prosody score.

CONCLUSIONS

Our data demonstrate that repetitive speech disorder is related to FOG and is associated to advanced disease stages and independent of disease duration. Speech dysfluency represents a disorder of motor speech control, possibly sharing pathophysiological mechanisms with FOG.

Increased subcortical neural activity among HIV+ individuals during a lexical retrieval task

BACKGROUND

Deficits in lexical retrieval, present in approximately 40% of HIV+ patients, are thought to reflect disruptions to frontal-striatal functions and may worsen with immunosuppression. Coupling frontal-striatal tasks such as lexical retrieval with functional neuroimaging may help delineate the pathophysiologic mechanisms underlying HIV-associated neurological dysfunction.

OBJECTIVE

We examined whether HIV infection confers brain functional changes during lexical access and retrieval. It was expected that HIV+ individuals would demonstrate greater brain activity in frontal-subcortical regions despite minimal differences between groups on neuropsychological testing. Within the HIV+ sample, we examined associations between indices of immunosuppression (recent and nadir CD4+ count) and task-related signal change in frontostriatal structures. Method16 HIV+ participants and 12 HIV- controls underwent fMRI while engaged in phonemic/letter and semantic fluency tasks. Participants also completed standardized measures of verbal fluency

RESULTS

HIV status groups performed similarly on phonemic and semantic fluency tasks prior to being scanned. fMRI results demonstrated activation differences during the phonemic fluency task as a function of HIV status, with HIV+ individuals demonstrating significantly greater activation in BG structures than HIV- individuals. There were no significant differences in frontal brain activation between HIV status groups during the phonemic fluency task, nor were there significant brain activation differences during the semantic fluency task. Within the HIV+ group, current CD4+ count, though not nadir, was positively correlated with increased activity in the inferior frontal gyrus and basal ganglia.

CONCLUSION

During phonemic fluency performance, HIV+ patients recruit subcortical structures to a greater degree than HIV- controls despite similar task performances suggesting that fMRI may be sensitive to neurocompromise before overt cognitive declines can be detected. Among HIV+ individuals, reduced activity in the frontal-subcortical structures was associated with lower CD4+ count.

Screening for Cognitive Impairment in Parkinson's Disease: Improving the Diagnostic Utility of the MoCA through Subtest Weighting

Background

Given the high prevalence of cognitive impairment in Parkinson’s disease (PD), cognitive screening is important in clinical practice. The Montreal Cognitive Assessment (MoCA) is a frequently used screening test in PD to detect mild cognitive impairment (PD-MCI) and Parkinson’s disease dementia (PD-D). However, the proportion in which the subtests are represented in the MoCA total score does not seem reasonable. We present the development and preliminary evaluation of an empirically based alternative scoring system of the MoCA which aims at increasing the overall diagnostic accuracy.

Methods

In study 1, the MoCA was administered to 40 patients with PD without cognitive impairment (PD-N), PD-MCI, or PD-D, as defined by a comprehensive neuropsychological test battery. The new MoCA scoring algorithm was developed by defining Areas under the Curve (AUC) for MoCA subtests in a Receiver Operating Characteristic (ROC) and by weighting the subtests according to their sensitivities and specificities. In study 2, an independent sample of 24 PD patients (PD-N, PD-MCI, or PD-D) was tested with the MoCA. In both studies, diagnostic accuracy of the original and the new scoring procedure was calculated.

Results

Diagnostic accuracy increased with the new MoCA scoring algorithm. In study 1, the sensitivity to detect cognitive impairment increased from 62.5% to 92%, while specificity decreased only slightly from 77.7% to 73%; in study 2, sensitivity increased from 68.8% to 81.3%, while specificity stayed stable at 75%.

Conclusion

This pilot study demonstrates that the sensitivity of the MoCA can be enhanced substantially by an empirically based weighting procedure and that the proposed scoring algorithm may serve the MoCA’s actual purpose as a screening tool in the detection of cognitive dysfunction in PD patients better than the original scoring of the MoCA. Further research with larger sample sizes is necessary to establish efficacy of the alternate scoring system.

Impaired functional default mode network in patients with mild neurological Wilson's disease

Wilson's disease (WD) is an autosomal recessive metabolic disorder characterized by cognitive, psychiatric and motor signs and symptoms that are associated with structural and pathological brain abnormalities, in addition to liver changes. However, functional brain connectivity pattern of WD patients remains largely unknown. In the present study, we investigated functional brain connectivity pattern of WD patients using resting state functional magnetic resonance imaging. Particularly, we studied default mode network (DMN) using posterior cingulate cortex (PCC) based seed functional connectivity analysis and graph theoretic functional brain network analysis tools, and investigated the relationship between the DMN's functional connectivity pattern of WD patients and their attention functions examined using the attention network test (ANT). Our results demonstrated that WD patients had altered DMN's functional connectivity and lower local and global network efficiency compared with normal controls (NCs). In addition, the functional connectivity between left inferior temporal cortex and right lateral parietal cortex was correlated with altering function, one of the attention functions, across WD and NC subjects. These findings indicated that the DMN's functional connectivity was altered in WD patients, which might be correlated with their attention dysfunction.

Delayed recall memory impairment in patients with Parkinson's disease

Age is one of the risk factors for dementia in patients with Parkinson's disease (PDD). Distinct cognitive syndromes of Parkinson's disease (PD) have been identified in previous studies. Questions about the role of such cognitive disorders in PD outcomes, especially memory dysfunction, in patients with PD remain unanswered.

OBJECTIVE

To establish possible correlations between delayed recall memory (episodic memory), age, and other demographic variables in patients with PD.

METHODS

A two-stage protocol was applied. Patients with delayed recall memory compromise, selected based on a brief battery of tests (BBRC-Edu), were classified as dementia cases and submitted to the Mattis Dementia Rating Scale (MDRS). Data from patients with memory disturbances were compared against individuals without episodic memory impairment, and correlated with age and demographic variables.

RESULTS

Except for identification and naming, all subtests in the screening battery showed a significant difference (p≤0.0001) between the memory-compromised group (case) and the group without memory impairment (no case). The results also correlated negatively with age (p≤0.0001) and positively with level of education (p=0.0874) in patients with PD.

CONCLUSION

The analysis showed a significant relationship between age and dementia characterized by impaired episodic memory. The findings support reports of a wide spectrum of neuropsychological performance impairment in PD with age, particularly dementia associated with memory deterioration. No correlations between disease duration and cognitive dysfunction were evident.

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.

Normative data for phonemic and semantic verbal fluency test in the adult French-Quebec population and validation study in Alzheimer's disease and depression

OBJECTIVE

Verbal fluency tasks are principally used to assess lexical access and have shown usefulness for differential diagnosis. The purpose of Study 1 was to provide normative data in the adult French-Quebec population (Canada) for semantic verbal fluency (animals), for two sets of phonemic verbal fluency (TNP and PFL), and for letter P alone (60 seconds per category/letter). The objectives of Study 2 were to establish the diagnostic and predictive validity of the present tasks and normative data in Alzheimer's disease (AD) and major depressive episode (MDE).

METHOD

The normative sample consisted of 932 participants aged 19-91 years. Based on multiple linear regressions, equations to calculate Z-scores were provided. To assess validity, performance of 62 healthy participants was compared to 62 participants with AD and 41 with MDE aged over 50.

RESULTS

Age and education, but not gender, predicted performance on each verbal fluency task. Healthy adults aged 50 and younger had a better performance on semantic than phonemic verbal fluency. In comparison to MDE, AD participants had lower performance on animals and TNP, but not on letter P. Ninety percent of people with a Z-score ≤ -1.50 on semantic verbal fluency had AD and the global accuracy was 76.6%. Test-retest reliability over one year was high for both animals (r = .711) and TNP (r = .790) in healthy older participants, but dropped for animals in people with AD (r = .493).

CONCLUSIONS

These data will strengthen accurate detection of verbal fluency deficits in French-Quebec adults.

Construct Validity of Fluency and Implications for the Factorial Structure of Memory

Fluency is an important construct in clinical assessment and in cognitive taxonomies. In the Cattell–Horn–Carroll (CHC) model, Fluency is represented by several narrow factors that form a subset of the long-term memory encoding and retrieval (Glr) broad factor. The CHC broad classification of Fluency was evaluated in five data sets, and the CHC narrow classification was evaluated in an additional two data sets. The results suggest that Fluency tests are more strongly related to processing speed (Gs) and acquired knowledge (Gc) than to Glr, but Fluency may also be represented as a distinct broad factor. In the two additional data sets with a large number of Fluency tests, the CHC Fluency narrow factors failed to replicate with confirmatory factor analysis. An alternative and simpler narrow structure of Fluency was found, supporting the factorial distinction of semantic versus orthographic Fluency. The results have important implications for the factorial structure of memory, the classification of Fluency tests, and the assessment of Fluency.

Mindfulness for Motor and Nonmotor Dysfunctions in Parkinson's Disease

Background. Motor and nonmotor symptoms negatively influence Parkinson's disease (PD) patients' quality of life. Mindfulness interventions have been a recent focus in PD. The present study explores effectiveness of a manualized group mindfulness intervention tailored for PD in improving both motor and neuropsychiatric deficits in PD. Methods. Fourteen PD patients completed an 8-week mindfulness intervention that included 6 sessions. The Five Facet Mindfulness Questionnaire (FFMQ), Geriatric Anxiety Inventory, Hamilton Depression Rating Scale, PD Cognitive Rating Scale, Unified PD Rating Scale, PD Quality of Life Questionnaire, and Outcome Questionnaire (OQ-45) were administered before and after the intervention. Participants also completed the FFMQ-15 at each session. Gains at postassessment and at 6-month follow-up were compared to baseline using paired t-tests and Wilcoxon nonparametric tests. Results. A significant increase in FFMQ-Observe subscale, a reduction in anxiety, depression, and OQ-45 symptom distress, an increase in PDCRS-Subcortical scores, and an improvement in postural instability, gait, and rigidity motor symptoms were observed at postassessment. Gains for the PDCRS were sustained at follow-up. Conclusion. The mindfulness intervention tailored for PD is associated with reduced anxiety and depression and improved cognitive and motor functioning. A randomised controlled trial using a large sample of PD patients is warranted.

Verbal Fluency in Parkinson's Patients with and without Bilateral Deep Brain Stimulation of the Subthalamic Nucleus: A Meta-analysis

OBJECTIVES

Patients with Parkinson's disease often experience significant decline in verbal fluency over time; however, deep brain stimulation of the subthalamic nucleus (STN-DBS) is also associated with post-surgical declines in verbal fluency. The purpose of this study was to determine if Parkinson's patients who have undergone bilateral STN-DBS have greater impairment in verbal fluency compared to Parkinson's patients treated by medication only.

METHODS

A literature search yielded over 140 articles and 10 articles met inclusion criteria. A total of 439 patients with Parkinson's disease who underwent bilateral STN-DBS and 392 non-surgical patients were included. Cohen's d, a measure of effect size, was calculated using a random effects model to compare post-treatment verbal fluency in patients with Parkinson's disease who underwent STN-DBS versus those in the non-surgical comparison group.

RESULTS

The random effects model demonstrated a medium effect size for letter fluency (d=-0.47) and a small effect size for category fluency (d=-0.31), indicating individuals with bilateral STN-DBS had significantly worse verbal fluency performance than the non-surgical comparison group.

CONCLUSIONS

Individuals with Parkinson's disease who have undergone bilateral STN-DBS experience greater deficits in letter and category verbal fluency compared to a non-surgical group.

Chinese character fluency test: an investigation of psychometric properties

OBJECTIVE

Verbal fluency test (VFT), one of the most commonly used tests to evaluate executive function (EF), can be subdivided into letter fluency (LF) and semantic fluency (SF). Although SF tasks have been established in Eastern societies, it is difficult to develop a LF task (Non-SF task) in Mandarin. This study thus aims to examine the psychometric properties of the Chang Gung University Orthographical Fluency Test (CGUOFT), a non-SF task with Chinese characters.

METHOD

A total of 290 participants were recruited from the community. Thirty participants were retested for the test-retest reliability. Three tests of EFs were used for the criterion-related validity.

RESULTS

CGUOFT has fair internal consistency and good test-retest reliability. The concurrent validity of CGUOFT is also acceptable. An exploratory factor analysis showed a one-factor structure, and the CGUOFT scores significantly correlated with sex, age and educational level.

CONCLUSIONS

This study might be the first one considering the Chinese characters to establish a VFT. Based on good psychometric properties, it merits evaluations of the CGUOFT from clinical samples in future studies.

Cognitive and Psychiatric Effects of STN versus GPi Deep Brain Stimulation in Parkinson's Disease: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Deep brain stimulation (DBS) of either the subthalamic nucleus (STN) or the globus pallidus interna (GPi) can reduce motor symptoms in patients with Parkinson's disease (PD) and improve their quality of life. However, the effects of STN DBS and GPi DBS on cognitive functions and their psychiatric effects remain controversial. The present meta-analysis was therefore performed to clarify these issues.

METHODS

We searched the PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials databases. Other sources, including internet-based clinical trial registries and grey literature sources, were also searched. After searching the literature, two investigators independently performed literature screens to assess the quality of the included trials and to extract the data. The outcomes included the effects of STN DBS and GPi DBS on multiple cognitive domains, depression, anxiety, and quality of life.

RESULTS

Seven articles related to four randomized controlled trials that included 521 participants were incorporated into the present meta-analysis. Compared with GPi DBS, STN DBS was associated with declines in selected cognitive domains after surgery, including attention, working memory and processing speed, phonemic fluency, learning and memory, and global cognition. However, there were no significant differences in terms of quality of life or psychiatric effects, such as depression and anxiety, between the two groups.

CONCLUSIONS

A selective decline in frontal-subcortical cognitive functions is observed after STN DBS in comparison with GPi DBS, which should not be ignored in the target selection for DBS treatment in PD patients. In addition, compared to GPi DBS, STN DBS does not affect depression, anxiety, and quality of life.

Task-dependent and polarity-specific effects of prefrontal transcranial direct current stimulation on cortical activation during word fluency

Targeted modulation of cortical functions by non-invasive brain stimulation is widely used for the investigation of the neurophysiological signatures of executive functions and put forward as a potential specific treatment for its disorders. To further investigate the underlying mechanisms, we performed two experiments involving 46 subjects that performed a semantic and a phonological verbal fluency task (VFT) as well as a simple speech-production task after application of 1mA anodal or cathodal transcranial direct current stimulation (tDCS) to the left inferior frontal gyrus (IFG). Brain activation was measured by functional near-infrared spectroscopy (fNIRS) during task performance. Neither preceding anodal nor cathodal tDCS was found to modulate VFT performance of either difficulty. However, preconditioning with anodal tDCS increased brain activity during the VFT whereas a trendwise decrease of activation was found after cathodal stimulation. Notably, this difference was not found with simple speech production. These findings support the notion of a polarity-specific malleability of neuronal network activity underlying speech production by tDCS. Most importantly, the task-specificity of the modulatory effect observed after the end of stimulation demonstrates lasting neurophysiological effects of tDCS that are reflected in modifications of cortical excitability by challenging cognitive tasks.

Using Automatic Speech Recognition to Assess Spoken Responses to Cognitive Tests of Semantic Verbal Fluency

Cognitive tests of verbal fluency (VF) consist of verbalizing as many words as possible in one minute that either start with a specific letter of the alphabet or belong to a specific semantic category. These tests are widely used in neurological, psychiatric, mental health, and school settings and their validity for clinical applications has been extensively demonstrated. However, VF tests are currently administered and scored manually making them too cumbersome to use, particularly for longitudinal cognitive monitoring in large populations. The objective of the current study was to determine if automatic speech recognition (ASR) could be used for computerized administration and scoring of VF tests. We examined established techniques for constraining language modeling to a predefined vocabulary from a specific semantic category (e.g., animals). We also experimented with post-processing ASR output with confidence scoring, as well as with using speaker adaptation to improve automated VF scoring. Audio responses to a VF task were collected from 38 novice and experienced professional fighters (boxing and mixed martial arts) participating in a longitudinal study of effects of repetitive head trauma on brain function. Word error rate, correlation with manual word count and distance from manual word count were used to compare ASR-based approaches to scoring to each other and to the manually scored reference standard. Our study's results show that responses to the VF task contain a large number of extraneous utterances and noise that lead to relatively poor baseline ASR performance. However, we also found that speaker adaptation combined with confidence scoring significantly improves all three metrics and can enable use of ASR for reliable estimates of the traditional manual VF scores.

Biomarker validation of a decline in semantic processing in preclinical Alzheimer's disease

OBJECTIVE

Differentially worse performance on category versus letter fluency suggests greater semantic versus retrieval difficulties. This discrepancy, combined with reduced episodic memory, has widespread clinical utility in diagnosing Alzheimer's disease (AD). Our objective was to investigate whether changes in semantic processing, as measured by the discrepancy between category and letter fluency, was detectable in preclinical AD: in clinically normal older adults with abnormal β-amyloid (Aβ) deposition on positron emission tomography (PET) neuroimaging.

METHOD

Clinically normal older adults (mean Mini Mental State Exam (MMSE) score = 29) were classified as Aβ+ (n = 70) or Aβ- (n = 205) using Pittsburgh Compound B-(PET) imaging. Participants completed letter fluency (FAS; word generation to letters F-A-S) and category fluency (CAT; word generation to animals, vegetables, fruits) annually (mean follow-up = 2.42 years). The effect of Aβ status on fluency over time was examined using linear mixed models controlling for age, sex, and education. To dissociate effects related to semantic (CAT) versus retrieval processes (CAT and FAS), we repeated models predicting CAT over time, controlling for FAS and likewise for CAT controlling for FAS.

RESULTS

At baseline, the Aβ+ group performed better on FAS compared with the Aβ- group but comparably on CAT. Longitudinally, the Aβ+ group demonstrated greater decline on CAT compared with the Aβ- group (p = .0011). This finding remained significant even when covarying for FAS (p = .0107). Aβ+ participants similarly declined compared with Aβ- participants on FAS (p = .0112), but this effect became insignificant when covarying for CAT (p = .1607).

CONCLUSION

These findings provide biomarker validation for the greater specificity of declines in category versus letter fluency to underlying AD pathology. Our results also suggest that changes in semantic processing occur earlier in the AD trajectory than previously hypothesized. (PsycINFO Database Record

Language Impairment in Adolescents With Sydenham Chorea

BACKGROUND

Neuropsychiatric comorbidities are frequent in Sydenham chorea. However, cognitive impairment in Sydenham chorea has not been sufficiently described. The objective of this study was to evaluate expressive and receptive language deficits in adolescents with Sydenham chorea.

METHODS

Twenty patients with Sydenham chorea were compared with 20 patients with rheumatic fever without chorea and 20 healthy controls. Participants were matched for age and gender. Participants were assessed with verbal fluency tasks (phonemic and semantic) and with verbal comprehension tasks (Token Test). Patients with Sydenham chorea were also assessed with the Universidade Federal de Minas Gerais Sydenham Chorea Rating Scale.

RESULTS

Performance in verbal fluency and in verbal comprehension tasks differed significantly (P < 0.01) among the three groups. Patients with Sydenham chorea performed significantly worse than healthy control group in phonemic and semantic verbal fluency tasks as well as in the Token Test. The group with rheumatic fever also performed worse than healthy controls in phonemic verbal fluency. Severity of motor signs in Sydenham chorea inversely correlated with performance in phonemic verbal fluency (words beginning with letter S, and total sum of words beginning with letters F, A, and S).

CONCLUSIONS

Adolescents with Sydenham chorea show difficulties in verbal fluency and in verbal comprehension. Patients with rheumatic fever also have some degree of language impairment. Future studies must investigate language impairment in difference stages of Sydenham chorea (acute, persistent, and remission) and putative biological markers.

Vocal learning, prosody, and basal ganglia: don't underestimate their complexity

Ackermann et al.'s arguments in the target article need sharpening and rethinking at both mechanistic and evolutionary levels. First, the authors' evolutionary arguments are inconsistent with recent evidence concerning nonhuman animal rhythmic abilities. Second, prosodic intonation conveys much more complex linguistic information than mere emotional expression. Finally, human adults' basal ganglia have a considerably wider role in speech modulation than Ackermann et al. surmise.

Gray and white matter imaging: A biomarker for cognitive impairment in early Parkinson's disease?

BACKGROUND

The aim of this work was to investigate the cortical and white matter changes that underlie cognitive impairment in patients with incident Parkinson's disease (PD) disease using voxel-based morphometry and diffusion tensor imaging.

METHODS

Newly diagnosed nondemented PD (n = 125) and control subjects (n = 50) were recruited from the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease Study and completed cognitive assessments and 3T structural and diffusion tensor MR imaging. Voxel-based morphometry was performed to investigate the relationship between gray matter volume and cognitive ability. Microstructural white matter changes were assessed with diffusion tensor imaging measures of fractional anisotropy and mean diffusivity using tract-based spatial statistics.

RESULTS

Increased mean diffusivity was observed bilaterally in subjects with PD, relative to controls (P = 0.019). Increased mean diffusivity was associated with performance on the semantic fluency and Tower of London tasks in frontal and parietal white matter tracts, including the cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. There was no difference in total gray matter volume between groups; however, bilateral reductions in frontal and parietal gray matter volume were associated with reduced performance on measures of executive function in PD subjects.

CONCLUSIONS

At the earliest stages of PD, regionally specific increases in central white matter mean diffusivity are present and suggest early axonal damage. Such changes are not accompanied by significant gray matter volume loss and are consistent with proposed models of pathological progression of the disease. Structural MRI, especially diffusion tensor imaging analysis, offers potential as a noninvasive biomarker reflecting cognitive impairment in PD.

Verbal Fluency: Language or Executive Function Measure?

Measures of phonemic and semantic verbal fluency, such as FAS and Animal Fluency (Benton, Hamsher, & Sivan, 1989), are often thought to be measures of executive functioning (EF). However, some studies (Henry & Crawford, 2004a , 2004b , 2004c ) have noted there is also a language component to these tasks. The current exploratory factor-analytic study examined the underlying cognitive structure of verbal fluency. Participants were administered language and EF measures, including the Controlled Oral Word Association Test (FAS version), Animal Fluency, Boston Naming Test (BNT), Vocabulary (Wechsler Adult Intelligence Scale-III), Wisconsin Card-Sorting Test (WCST, perseverative responses), and Trail-Making Test-Part B (TMT-B). A 2-factor solution was found with the 1st factor, language, having significant loadings for BNT and Vocabulary, while the second factor was labeled EF because of significant loading from the WCST and TMT-B. Surprisingly, FAS and Animal Fluency loaded exclusively on to the language factor and not EF. The current results do not exclude EF as a determinant of verbal fluency, but they do suggest that language processing is the critical component for this task, even without significant aphasic symptoms. Thus, the results indicated that both letter (phonemic) and category (semantic) fluency are related to language, but the relationship to EF is not supported by the results.