SNAFU: The Semantic Network and Fluency Utility

The verbal fluency task—listing words from a category or words that begin with a specific letter—is a common experimental paradigm that is used to diagnose memory impairments and to understand how we store and retrieve knowledge. Data from the verbal fluency task are analyzed in many different ways, often requiring manual coding that is time intensive and error-prone. Researchers have also used fluency data from groups or individuals to estimate semantic networks—latent representations of semantic memory that describe the relations between concepts—that further our understanding of how knowledge is encoded. However computational methods used to estimate networks are not standardized and can be difficult to implement, which has hindered widespread adoption. We present SNAFU: the Semantic Network and Fluency Utility, a tool for estimating networks from fluency data and automatizing traditional fluency analyses, including counting cluster switches and cluster sizes, intrusions, perseverations, and word frequencies. In this manuscript, we provide a primer on using the tool, illustrate its application by creating a semantic network for foods, and validate the tool by comparing results to trained human coders using multiple datasets.

Electrocorticography reveals spatiotemporal neuronal activation patterns of verbal fluency in patients with epilepsy

Verbal fluency is commonly used to evaluate cognitive dysfunction in a variety of neuropsychiatric diseases, yet the neurobiology underlying performance of this task is incompletely understood. Electrocorticography (ECoG) provides a unique opportunity to investigate temporal activation patterns during cognitive tasks with high spatial and temporal precision. We used ECoG to study high gamma activity (HGA) patterns in patients undergoing presurgical evaluation for intractable epilepsy as they completed an overt, free-recall verbal fluency task. We examined regions demonstrating changes in HGA during specific timeframes relative to speech onset. Early pre-speech high gamma activity was present in left frontal regions during letter fluency and in bifrontal regions during category fluency. During timeframes typically associated with word planning, a distributed network was engaged including left inferior frontal, orbitofrontal and posterior temporal regions. Peri-Rolandic activation was observed during speech onset, and there was post-speech activation in the bilateral posterior superior temporal regions. Based on these observations in the context of prior studies, we propose a model of neocortical activity patterns underlying verbal fluency.

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

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

Word retrieval across the biomarker-confirmed Alzheimer's disease syndromic spectrum

Alzheimer's disease (AD) is now conceptualized as a biological entity defined by amyloid and tau deposition and neurodegeneration, with heterogeneous clinical presentations. With the aid of in vivo biomarkers, clinicians are better poised to examine clinical syndromic variability arising from a common pathology. Word retrieval deficits, measured using verbal fluency and confrontation naming tests, are hallmark features of the early clinical stages of the amnestic presentations of AD, specifically in category fluency and naming with relatively spared letter fluency. As yet, there is no consensus regarding performance on these tests in atypical clinical phenotypes of AD, including posterior cortical atrophy (PCA) and logopenic primary progressive aphasia (lvPPA), in individuals who are amyloid-positive (Aβ+) but present with different clinical profiles and patterns of neurodegeneration compared to amnestic AD. The goal of the current study is to determine how Aβ+ individuals across the syndromic spectrum of AD perform on three different word retrieval tasks. A secondary goal is to determine the neuroanatomical substrates underlying word retrieval performance in these Aβ+ individuals. Thirty-two Aβ+ participants with the amnestic presentation, 16 with Aβ+ PCA, 22 with Aβ+ lvPPA, and 99 amyloid-negative (Aβ-) control participants were evaluated with verbal fluency and visual confrontation naming tests as well as high-resolution MRI. The Aβ+ patient groups were rated at very mild or mild levels of severity (CDR 0.5 or 1) and had comparable levels of global cognitive impairment (average MMSE = 23.7 ± 3.9). Behaviorally, we found that the word retrieval profile of PCA patients is comparable to that of amnestic patients, characterized by intact letter fluency but impaired category fluency and visual confrontation naming, while lvPPA patients demonstrated impairment across all tests of word retrieval. Across all AD variants, we observed that letter fluency was associated with cortical thickness in prefrontal, central precuneus, lateral parietal and temporal cortex, while category fluency and naming were associated with cortical thickness in left middle frontal gyrus, posterior middle temporal gyrus, and lateral parietal cortex. Visual confrontation naming was uniquely associated with atrophy in inferior temporal and visual association cortex. We conclude that a better understanding of the word retrieval profiles and underlying neurodegeneration across the AD syndromic spectrum will help improve interpretation of neuropsychological profiles with regard to the localization of neurodegeneration, particularly in the atypical AD variants.

Verbal Fluency Development Across Childhood: Normative Data from Brazilian-Portuguese Speakers and Underlying Cognitive Processes

OBJECTIVE

Verbal fluency (VF) tasks are widely used to investigate children's lexical knowledge and executive functions skills. Consistency of measurement of the strategic retrieval components is still an issue and performance of Brazilian-Portuguese speaking children are currently not available. A cross-sectional study investigated the effects of age, school type (public × private) and the influence of language, memory and inhibitory control on VF.

METHOD

We assessed 414 Brazilian children, aged 6-12, in the number of words produced and both clustering and switching components, with two measures of VF: letter (LVF) and semantic (SVF).

RESULTS

Analysis of the number of words produced showed a significant increase between 6-8-year-olds, 9-10-year-olds and 11-12-year-olds in SVF, while in LVF, the differences were significant only in the later age group. In SVF, the numbers of clusters and switches increased with age, whereas in LVF, the number of switches increased in all age groups, but clusters increased only in the older group. Structural equation model analyses showed that oral and written language, verbal memory and inhibitory control are associated with VF performance and IQ, while age mediated VF performance.

CONCLUSIONS

The results indicate a different development pattern between LVF and SVF in the number of words produced and in clustering and switching, with the latter predicting VF performance in words produced. VF development is shown to depend on language, memory and inhibitory control. Our results have important implications to clinical neuropsychology.

Association of rs1059004 polymorphism in the OLIG2 locus with whole-brain functional connectivity in first-episode schizophrenia

The rs1059004 in the oligodendrocyte lineage transcription factor 2 (OLIG2) gene has been reported to be a candidate single nucleotide polymorphism (SNP) for schizophrenia (SZ). A variety of functional magnetic resonance imaging (fMRI) studies have revealed disconnection in SZ. We aimed to investigate the association of rs1059004 polymorphism with whole-brain functional connectivity (FC) and to further explore the correlation between altered FC and cognitive behavioral scales. Fifty-five SZ patients and fifty-three matched healthy controls were included in this study. The general linear model was used to test the role of rs1059004 polymorphism in whole-brain FC based on resting-state fMRI. Spearman's rank correlation test was used to calculate the correlation coefficient between FC strength and behavior score. In the whole-brain FC analysis, we found that the FC pattern in SZ patients differs from healthy controls. Furthermore, compared to homozygous C carriers, risk A allele carriers have reduced FC strength in both SZ patients and healthy controls. For the correlation analysis in risk A allele carriers, we found a positive correlation between FC strength and verbal fluency score in SZ patients, while healthy controls appeared to have the opposite result. Our results revealed that participants carrying the risk A allele show FC patterns differing from those of homozygous C carriers. This result suggests that rs1059004 polymorphism and SZ have synergistic effects on brain connections. The correlation analysis result suggests that special attention should be paid to SZ patients who carry the risk A allele because the patients perform worse in verbal fluency.

The therapeutic effect of treatment with RehaCom software on verbal performance in patients with multiple sclerosis

Multiple sclerosis (MS) is characterized by central nervous system lesions that lead to neurological dysfunctions including fatigue, depression and anxiety. MS is affecting almost 2.3 million people around the world, with the significant highest prevalence in the North America. MS also affects different cognitive abilities, such as attention, memory and executive functions. Furthermore, a significant impairment in verbal fluency and naming abilities in patients with MS has been reported. RehaCom, is a software that has improvement effects on cognitive functions. The goal of this research is to investigate the effect of treatment with RehaCom on verbal performance in patients with MS. To select the participants, 60 patients with MS who referred to our clinic were chosen randomly and divided into Control (n = 30) and Experimental (n = 30) groups. The participants in the experimental group were treated by RehaCom software for 10 sessions during 5 weeks (2 sessions per week and each session was 1 h). Controlled Oral Word Association Test (COWAT) and California Verbal Learning Test - Second Edition (CVLT-II), were used to assess verbal performance (verbal fluency, and verbal learning and memory) at weeks 0 (baseline), 5 (post-test) and 10 (follow-up). The results showed that, treatment with RehaCom improved verbal performance in patient with MS, at both post-test and follow-up stages. In conclusion, treatment with RehaCom cognitive rehabilitation software can improve verbal fluency, and verbal learning and memory in patient with MS, possibly by affecting the brain regions involved in language performance.

Can semantic fluency be used as an alternative or additional measure in the abbreviated Minimal Assessment of Cognitive Function in Multiple Sclerosis (aMACFIMS)?

BACKGROUND

The abbreviated Minimal Assessment of Cognitive Function in Multiple Sclerosis (aMACFIMS) was designed using four shortened measures from the MACFIMS. Semantic fluency was suggested as an alternative task; however, its equivalency as part of this battery has yet to be examined.

OBJECTIVES

1) To determine the optimal semantic fluency raw score cut-offs; 2) compare the modified aMACFIMS (with semantic fluency) to the standard aMACFIMS (with phonemic fluency); and 3) compare the expanded aMACFIMS (with both verbal fluency measures) to the Brief International Cognitive Assessment in MS (BICAMS).

METHODS

Receiver-operating-characteristic curves were used to identify the optimal cut-off at -1.5 and - 2.0 standard deviation (SD) impairment criteria (n = 335). The diagnostic accuracies were compared between the different versions of the aMACFIMS and BICAMS (n = 146).

RESULTS

The raw score cut-offs for semantic fluency (13 and 11 words) had high sensitivity (100%) and specificity (96.6% - 98.6%). The modified aMACFIMS did not significantly differ from the standard aMACFIMS. The expanded aMACFIMS had stronger specificity (84.8%) and positive predictive value (85.9%) than the BICAMS.

CONCLUSIONS

Semantic fluency can be used as an alternative, though including both measures results in the most effective aMACFIMS version. Using semantic fluency may be especially valuable when evaluating older PwMS.

Effects of stress on functional connectivity during verbal processing

Effects of stress on functional connectivity (FC) in specific language processing regions of the brain during verbal fluency tasks were explored. Roles of gender and serotonin transporter gene polymorphisms (5-HTTLPR), associated with stress susceptibility, were also examined to understand their effect. Forty-five healthy volunteers (Mean age: 19.6 ± 1.6 years; 28 females) participated. Functional magnetic resonance imaging was carried out while participants performed letter and category fluency tasks. These tasks were interposed with the Montreal Imaging Stress Test to induce stress or a no-stress control task. Buccal swabs collected were used to genotype for the presence of polymorphisms on the SLC6A4 gene known to contribute to atypical stress responses. Significant variations in strength of FC were noted between several ROIs, including left inferior frontal gyrus and left middle temporal gyrus. Overall, males showed regional increases in FC strength over long and short distances during task under stress. Additionally, variability in effects of stress on task performance was associated with effects of stress on FC. Results suggest that long distance FC may be strengthened to compensate for additional cognitive load of the stressor but that specific short distance functional connections may be strengthened in a gender specific manner. Additionally, FC may serve as a marker for effects of stress on performance. This is the first study exploring stress effects on language tasks with imaging markers. Future studies will need to explore stress susceptible populations and establish the role of FC as a marker, with implications for targeted therapeutic interventions.

Verbal fluency in three Spanish-English bilingual speakers with TBI

This study investigated differences between healthy bilingual participants and bilingual participants with traumatic brain injury (TBI) on verbal fluency tasks. The performance of three Spanish-English bilingual speakers with traumatic brain injury was compared to the performance of 30 neurotypical bilingual speakers on tasks of category and letter verbal fluency in English and Spanish. Responses were analyzed for total number of correct productions, differences in correct productions between languages, average cluster size, total number of switches, and rates of language choice errors. The data were analyzed using predicted scores from regression equations based on neurotypical data and modified t-tests. Analyses revealed significantly lower total output than predicted by the regression equations for both task types and in both languages for one TBI participant. The same participant demonstrated significantly lower total number of switches than the neurotypical group. Two participants demonstrated higher rates of language choice errors than the neurotypical group. There were no significant differences between TBI participants and the neurotypical group for average cluster size. There were no significant differences between predicted and obtained values for differences between English and Spanish total number correct in each task type. Results are discussed in the context of individual cognitive and linguistic profiles of the TBI participants.

Preliminary findings of four-week, task-based anodal prefrontal cortex transcranial direct current stimulation transferring to other cognitive improvements in schizophrenia

Most transcranial Direct Current Stimulation (tDCS) trials of schizophrenia administer few sessions and do not assess transfer effects to other cognitive domains. In a randomized, double-blind, sham-controlled, parallel groups trial, we determined the extent to which 4-weeks of 2 mA tDCS at 20 min/day totalling 20 tDCS sessions administered during a spatial working memory test, with anodal right dorsolateral prefrontal cortex (DLPFC) and cathodal left tempo-parietal junction (TPJ) placement, as an adjunct to antipsychotics reduced auditory hallucinations and improved cognition in 12 outpatients with schizophrenia. Anodal tDCS significantly improved language-based working memory after 2 weeks and verbal fluency after 2 and 4 weeks. Thus, four weeks of tDCS appears to be safe and elicits transfer benefits to other prefrontal-dependent cognitive abilities in schizophrenia.

Metabolic syndrome is negatively associated with cognition among endothelial nitric oxide synthase (eNOS)- 786C carriers in schizophrenia-spectrum disorders

Although metabolic syndrome and cognitive inefficiencies are well-described common complications of schizophrenia, their association remains inconsistent, potentially due to poorly understood mechanisms underlying their relationship. Variability in the endothelial nitric oxide synthase (eNOS) gene, specifically the T-786C variant, has been separately associated with cognition and metabolic syndrome, with worse outcomes for eNOS-786C carriers likely occurring via negative effects on blood vessel functioning. However, the interaction between eNOS and metabolic syndrome in cognition among adults with schizophrenia is unknown. This study aimed to test the main and interaction effects of the eNOS-786C allele in cognition using hierarchical regression analyses controlling for age, sex, education, race, and antipsychotic exposure. Metabolic syndrome, eNOS T-786C genotype, and cognitive performance were assessed in 226 community-dwelling participants with chronic schizophrenia-spectrum disorders. Results demonstrated a significant interaction between metabolic syndrome and the eNOS-786C allele. Specifically, among eNOS-786C carriers only, metabolic syndrome was independently associated with lower scores in processing speed and verbal fluency, and predicted 12.5% and 15.8% of variance in performance, respectively. These results suggest that the additive negative effects of eNOS-786C and metabolic syndrome on blood vessel functioning may be severe enough to negatively impact cognition. The finding that metabolic syndrome is associated with worse cognition only in the presence of the eNOS-786C allele may clarify extant inconsistencies in the literature. These findings provide preliminary evidence that may inform interventions to reduce cognitive morbidity among adults with schizophrenia.

Characteristics and progression of cognitive deficits in progressive supranuclear palsy vs. multiple system atrophy and Parkinson's disease

Cognitive impairment is frequent in progressive supranuclear palsy (PSP) and less common in multiple system atrophy (MSA), but characteristics and progression compared with Parkinson's disease (PD) need to be properly defined. We evaluated 35 PSP with Richardson's syndrome (PSP-RS), 30 MSA as well as 65 age-, sex-, and education-matched PD with an extensive clinical and neuropsychological assessment, allowing Level II cognitive diagnosis. Eighteen PSP, 12 MSA and 30 PD had a second evaluation between 12 and 18 months (mean 15 months) after the first assessment. PSP performance at Montreal Cognitive Assessment (MoCA), verbal fluencies (phonemic and semantic tasks), Stroop test (Error and Time), Digit Span Sequencing (DSS), incomplete letters of Visual Object and Space Perception (VOSP) and Benton's Judgment of Line Orientation (JLO) performance were significantly poorer at baseline compared to PD and MSA. Executive, language and visuospatial abilities declined longitudinally in PSP, but not in PD and MSA. After 1.5 year, 16% of PSP converted to dementia. Our study provides evidence that cognitive progression is more severe and rapid in PSP-RS than PD and MSA. Further, we observed that MoCA, verbal fluency (particularly semantic), DSS and Benton's JLO are valuable tests to detect cognitive progression in PSP-RS and may be proposed as possible biomarker to assess efficacy of disease modification strategies.

Verbal fluency in Mexican Spanish-speaking subjects with high educational level: Ranking of letters and semantic categories

Introduction: Verbal fluency tasks are useful tools in clinical practice and research studies across languages and contexts, but specific data obtained using Spanish phonological tasks and semantic tasks with different levels of difficulty are lacking. The present study aimed to determine the difficulty level of a phonological tasks and semantic tasks among Spanish-speakers. Method: Both tasks were ordered across five difficulty levels based on the frequency of use in Mexican Spanish (phonological) and the number of elements given by a group of participants (semantic). One hundred healthy Mexican Spanish-speaking participants (aged 24-63 years; 55 females) were presented with five phonological and five semantic categories. The participants also underwent a neuropsychological test and sociodemographic interview. The number of words correctly produced in each category within one minute was calculated. An ANOVA and a Kruskal-Wallis analysis were conducted in order to know if there were different levels of difficulty in the tasks. Additionally, correlation analyzes were performed to test the effect of the sociodemographic and cognitive variables on the participants' responses. Results: According to the analyzes, there were different levels of difficulty in the categories; P was the easiest and O was the most difficult category in the phonological tasks, and body parts and precious stones were the easiest and most difficult, respectively, in the semantic tasks. Age had a negative correlation with four-legged animals and a positive correlation with O; Positive correlations were also found between education and professions, vegetables, and alcoholic beverages; and between IQ and D, N, musical instruments, sports, vegetables, and trees. Conclusions: Both tasks offer categories with different level of difficulty based on the performance of a highly educated Mexican population. These data may be useful for clinical and research purposes.

Schizophrenia, cannabis use and Catechol-O-Methyltransferase (COMT): Modeling the interplay on cognition

Cognitive impairments are considered core features of schizophrenia and are recognized as the most important predictors of functional outcome and quality of life. A better study of the mechanisms underlying the cognition is of extreme relevance. Literature has shown that several genetic and environmental factors affect cognitive performance. In particular, the interaction between Catechol-O-Methyltransferase (COMT) gene and cannabis use has gained increasing attention in the past years. Based on these premises, the present study, aimed to analyze the interplay between cannabis use and COMT polymorphism on cognitive performance in a sample of 135 patients with chronic schizophrenia. Patients were assessed for neurocognitive measures with a broad battery, genotyped for COMT Val158Met polymorphism from peripheral blood sample, and evaluated with a semi-structured interview in order to establish the history of cannabis abuse. Results showed a significant interaction effect between COMT polymorphism and cannabis use on verbal fluency and speed of processing. The analysis revealed significant differences between subjects COMT Val/Val homozygous and Met carriers with history of cannabis use, with a better performance on both tasks among the Met carriers group. These data are in line with literature on healthy subjects that suggests a more detrimental effect of cannabis among subjects with Val/Val genotype. In conclusions, results highlight the need to better disentangle the biological pathways in which cannabis use and COMT are converging, as possible treatment targets, as well as the importance to assess these factors in clinical to optimize individualized interventions.

Regional neuropathology distribution and verbal fluency impairments in Parkinson's disease

BACKGROUND

Verbal fluency deficits are common in patients with Parkinson's disease. The association of these impairments with regional neuropathological changes is unexplored.

OBJECTIVES

Determine if patients with verbal fluency impairments have greater neuropathological burden in frontal, temporal, and limbic regions and if Lewy bodies or neurofibrillary tangles were associated with verbal fluency impairments.

METHODS

Data was derived from the Arizona Study of Aging and Neurodegenerative Disorders. 47 individuals who completed phonemic and semantic verbal fluency tasks and met clinicopathological criteria for Parkinson's disease (with and without comorbid Alzheimer's disease) were included. Impairment on fluency tasks was defined by normative data, and the density of neuropathology in temporal, limbic, and frontal regions was compared between groups.

RESULTS

Individuals with semantic fluency impairments had greater total pathology (Lewy bodies + neurofibrillary tangles) in limbic structures (W = 320.0, p = .033, r_pb = .33), while those who had phonemic fluency impairments had increased total neuropathology in frontal (W = 364.5, p = .011, r_pb = .37), temporal (W = 356.5, p = .022, r_pb = .34), and limbic regions (W = 357.0, p = .024, r_pb = .34). Greater Lewy body density was found in those with verbal fluency impairments, though trends for greater neurofibrillary tangle density were noted as well.

CONCLUSIONS

Impaired phonemic fluency was associated with higher Lewy body and tangle burden in frontal, temporal, and limbic regions, while impaired semantic fluency was associated with greater limbic pathology. Though neurofibrillary tangles trended higher in several regions in those with impaired verbal fluency, higher Lewy body density in general was associated with verbal fluency deficits. Implications for research and clinical practice are discussed.

Dissociating frontal and temporal correlates of phonological and semantic fluency in a large sample of left hemisphere stroke patients

Previous lesion studies suggest that semantic and phonological fluency are differentially subserved by distinct brain regions in the left temporal and the left frontal cortex, respectively. However, as of yet, this often implied double dissociation has not been explicitly investigated due to mainly two reasons: (i) the lack of sufficiently large samples of brain-lesioned patients that underwent assessment of the two fluency variants and (ii) the lack of tools to assess interactions in factorial analyses of non-normally distributed behavioral data. In addition, previous studies did not control for task resource artifacts potentially introduced by the generally higher task difficulty of phonological compared to semantic fluency.

We addressed these issues by task-difficulty adjusted assessment of semantic and phonological fluency in 85 chronic patients with ischemic stroke of the left middle cerebral artery. For classical region-based lesion-behavior mapping patients were grouped with respect to their primary lesion location. Building on the extension of the non-parametric Brunner-Munzel rank-order test to multi-factorial designs, ANOVA-type analyses revealed a significant two-way interaction for cue type (semantic vs. phonological) by lesion location (left temporal vs. left frontal vs. other as stroke control group). Subsequent contrast analyses further confirmed the proposed double dissociation by demonstrating that (i) compared to stroke controls, left temporal lesions led to significant impairments in semantic but not in phonological fluency, whereas left frontal lesions led to significant impairments in phonological but not in semantic fluency, and that (ii) patients with frontal lesions showed significantly poorer performance in phonological than in semantic fluency, whereas patients with temporal lesions showed significantly poorer performance in semantic than in phonological fluency.

The anatomical specificity of these findings was further assessed in voxel-based lesion-behavior mapping analyses using the multi-factorial extension of the Brunner-Munzel test. Voxel-wise ANOVA-type analyses identified circumscribed parts of left inferior frontal gyrus and left superior and middle temporal gyrus that significantly double-dissociated with respect to their differential contribution to phonological and semantic fluency, respectively. Furthermore, a main effect of lesion with significant impairments in both fluency types was found in left inferior frontal regions adjacent to but not overlapping with those showing the differential effect for phonological fluency.

The present study hence not only provides first explicit evidence for the anatomical double dissociation in verbal fluency at the group level but also clearly underlines that its formulation constitutes an oversimplification as parts of left frontal cortex appear to contribute to both semantic and phonological fluency.

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Lesion study on neural correlates of phonological and semantic fluency

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Evidence for dissociable and for overlapping contributions

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Left superior and middle temporal gyri specifically crucial for semantic fluency

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Left IFG pars opercularis specifically crucial for phonological fluency

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Left IFG pars triangularis critical for both semantic and phonological fluency

Responses to executive demand in young adulthood differ by APOE genotype

Despite evidence of a relationship between Apolipoprotein E (APOE) ε4+ and later-life cognitive decline, the lifespan effects of carrying an ε4+ allele on cognitive ageing are not well understood. Evidence of ε4+ advantages in early-life are inconsistent, but not inconsiderable. We explored the proposal that APOE ε4+ cognitive advantages arise only in response to complex and sensitive tasks targeting specific executive functions. We systematically manipulated executive demand within verbal fluency, decision-making, prospective memory, and sustained attention tasks. Participants aged 18-25 years (21 ε4+, 63 ε33) also completed a measure of subjective effort. Under low executive demand, ε4+ made fewer verbal fluency word repeats compared to ε33 carriers. Under high executive demand, ε4+ showed lower costs associated with performing concurrent tasks, greater switching errors, and more verbal fluency root repetition errors. Overall, ε4+ appeared to be showing working memory updating advantages under conditions of low executive demand, more effective resource allocation under elevated levels of executive demand, and errors indicating different strategy use compared to ε33 carriers, including speed-accuracy trade-offs.

Abnormal relationships between local and global brain measures in subjects at clinical high risk for psychosis: a pilot study

We examined whether abnormal volumes of several brain regions as well as their mutual associations that have been observed in patients with schizophrenia, are also present in individuals at clinical high-risk (CHR) for developing psychosis. 3T magnetic resonance imaging was acquired in 19 CHR and 20 age- and handedness-matched controls. Volumes were measured for the body and temporal horns of the lateral ventricles, hippocampus and amygdala as well as total brain, cortical gray matter, white matter, and subcortical gray matter volumes. Relationships between volumes as well as correlations between volumes and cognitive and clinical measures were explored. Ratios of lateral ventricular volume to total brain volume and temporal horn volume to total brain volume were calculated. Volumetric abnormalities were lateralized to the left hemisphere. Volumes of the left temporal horn, and marginally, of the body of the left lateral ventricle were larger, while left amygdala but not hippocampal volume was significantly smaller in CHR participants compared to controls. Total brain volume was also significantly smaller and the ratio of the temporal horn/total brain volume was significantly higher in CHR than in controls. White matter volume correlated positively with higher verbal fluency score while temporal horn volume correlated positively with a greater number of perseverative errors. Together with the finding of larger temporal horns and smaller amygdala volumes in the left hemisphere, these results indicate that the ratio of temporal horns volume to brain volume is abnormal in CHR compared to controls. These abnormalities present in CHR individuals may constitute the biological basis for at least some of the CHR syndrome.

Intact verbal fluency abilities in the Broad Autism Phenotype

This study attempted to replicate the findings of Camodeca and Voelker (2016), who demonstrated that controlled processing weaknesses were evident in the Broad Autism Phenotype (BAP), and that these weaknesses were predictive of real-world pragmatic language problems. One hundred eighty-two undergraduates completed the Delis-Kaplan Executive Function System Verbal Fluency (D-KEFS-VF) test and the Broad Autism Phenotype Questionnaire (BAPQ). Results were partially replicated. Contrary to the previous study, the BAP group (n = 31) did not demonstrate comparative weaknesses in controlled processing, nor were controlled processing abilities predictive of BAPQ Pragmatic Language score. Similar to the previous study, controlled processing did not predict pragmatic language abilities for Non-BAP (n = 151) subjects. For each group, letter fluency score predicted 2nd 15″ interval score (controlled processing abilities); automatic processing (1st 15″ interval) did not. Results suggest that verbal fluency skills in the BAP are similar to controls, and that controlled processing does not account for significant variance in real-world social language in the BAP.

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).

Phonemic and Semantic Verbal Fluency in Sex Chromosome Aneuploidy: Contrasting the Effects of Supernumerary X versus Y Chromosomes on Performance

OBJECTIVES

Past research suggests that youth with sex chromosome aneuploidies (SCAs) present with verbal fluency deficits. However, most studies have focused on sex chromosome trisomies. Far less is known about sex chromosome tetrasomies and pentasomies. Thus, the current research sought to characterize verbal fluency performance among youth with sex chromosome trisomies, tetrasomies, and pentasomies by contrasting how performance varies as a function of extra X number and X versus Y status.

METHODS

Participants included 79 youth with SCAs and 42 typically developing controls matched on age, maternal education, and racial/ethnic background. Participants completed the phonemic and semantic conditions of a verbal fluency task and an abbreviated intelligence test.

RESULTS

Both supernumerary X and Y chromosomes were associated with verbal fluency deficits relative to controls. These impairments increased as a function of the number of extra X chromosomes, and the pattern of impairments on phonemic and semantic fluency differed for those with a supernumerary X versus Y chromosome. Whereas one supernumerary Y chromosome was associated with similar performance across fluency conditions, one supernumerary X chromosome was associated with relatively stronger semantic than phonemic fluency skills.

CONCLUSIONS

Verbal fluency skills in youth with supernumerary X and Y chromosomes are impaired relative to controls. However, the degree of impairment varies across groups and task condition. Further research into the cognitive underpinnings of verbal fluency in youth with SCAs may provide insights into their verbal fluency deficits and help guide future treatments. (JINS, 2018, 24, 917-927).

Cognitive control ability mediates prediction costs in monolinguals and bilinguals

In this study, we examined the role that cognitive control and language regulation ability play in mediating readers' susceptibility to prediction error costs when reading in the native language (L1) or a second language (L2). Twenty-four English monolinguals (Experiment 1) and 28 Chinese-English bilinguals (Experiment 2) read sentences in English while their EEG was recorded. The sentences varied in the predictability of an upcoming expected word and in whether that prediction was confirmed. Monolinguals showed sensitivity to sentence contexts in which expectations were not met (i.e., when unexpected words were encountered) in the form of a late, frontally-distributed positivity, but for bilinguals this effect was more complex. For both groups, performance on the prediction task was modulated by individual differences on the AX-CPT, a measure of inhibitory control. However, the bilinguals' reading performance in the L2 was affected not only by inhibitory control, but also by their performance on an L1 verbal fluency task that indexed language regulation and production capability, related to their language dominance and immersion context. Bilinguals with better regulation of the L1 generated a larger frontal positivity in response to unexpected words in the L2, an effect that was attenuated by inhibitory control ability. In contrast, bilinguals with lower regulatory ability generated a larger, late negativity, which was also mediated by control. These findings suggest that the ability to regulate the native language when immersed in a second language environment can influence mechanisms underlying the prediction process when reading in the L2. In addition, cognitive control ability, specifically inhibitory control, appears to mediate the difficulty readers incur when predictions are disconfirmed, not only in the native language, but also for proficient bilinguals reading in the L2. We argue that the mechanisms engaged during prediction in the L1 and L2 are fundamentally the same, and that what differs for bilinguals are the additional demands imposed by their language experience and language use.

Decreased hemodynamic response in inferior frontotemporal regions in elderly with mild cognitive impairment

The verbal fluency task (VFT) is a well-established cognitive marker for mild cognitive impairment (MCI) in the prodromal stage of Alzheimer´s dementia (AD). The behavioral VFT performance of patients allows the prediction of dementia two years later. But effective compensatory mechanism might cover or reduce the predictive value of the VFT. Therefore the aim of this study is to measure the hemodynamic response during VFT in patients with mild cognitive impairment (MCI) to establish the hemodynamic response during the VFT as a screening instrument for the prediction of dementia. One method which allows measuring the hemodynamic response during speech production without severe problems with moving artifacts like in functional magnetic resonance imaging (fMRI) is the functional near-infrared spectroscopy (fNIRS). It is optimal as a screening instrument, as it is easy to apply and without any contraindications. In this study we assessed the hemodynamic response in prefrontal and temporal regions in patients with MCI as well as matched healthy controls with fNIRS. We found a decreased hemodynamic response in the inferior frontotemporal cortex for the MCI group. Our results indicate that a frontotemporal decreased hemodynamic response could serve as a diagnostic biomarker for dementia.

Hypofunction of left dorsolateral prefrontal cortex in depression during verbal fluency task: A multi-channel near-infrared spectroscopy study

BACKGROUND

Previous functional neuroimaging studies of depression have demonstrated frontotemporal dysfunction, including the dorsolateral prefrontal cortex, while patients perform working memory and language comprehension tasks. Recent near-infrared spectroscopy (NIRS) studies have shown frontotemporal hypofunction in depression by verbal fluency task, but the regions of impairment affecting respective depressive symptoms still remain unclear. We investigated frontotemporal function during word production task in depression with multi-channel NIRS. Further, we aimed to clarify whether any depressive symptoms affect frontotemporal dysfunction.

METHODS

One hundred seventy-seven major depressive patients and 50 healthy control volunteers participated in this study. Their cerebral activations were compared during verbal fluency task.

RESULTS

Although performance was not significantly different, hypoactivation in the bilateral frontotemporal regions was significantly observed in depressed patients, compared with controls. Left lateral frontotemporal activation was significantly reduced in the group with mandatory symptom, which is depressed mood, or loss of interest or pleasure, compared with the group that still has residual depressive symptoms in spite MDD having been remitted.

LIMITATION

the MDD group had significantly higher age and education level than the controls. Conclusions Our findings indicate hypofunction of the bilateral frontotemporal regions in depression during verbal fluency task. Further, hypofunction of these regions in the left hemisphere by this task could reflect whether the subjects recovered from depressed mood, or loss of interest or pleasure.