Verbal and design fluency in patients with frontal lobe lesions

Executive function and underlying brain network distinctions for callous-unemotional traits and conduct problems in adolescents

The complexity of executive function (EF) impairments in youth antisocial phenotypes of callous-unemotional (CU) traits and conduct problems (CP) challenge identifying phenotypic specific EF deficits. We can redress these challenges by (1) accounting for EF measurement error and (2) testing distinct functional brain properties accounting for differences in EF. Thus, we employed a latent modeling approach for EFs (inhibition, shifting, fluency, common EF) and extracted connection density from matching contemporary EF brain models with a sample of 112 adolescents (ages 13-17, 42 % female). Path analysis indicated CU traits associated with lower inhibition. Inhibition network density positively associated with inhibition, but this association was strengthened by CU and attenuated by CP. Common EF associated with three-way interactions between density*CP by CU for the inhibition and shifting networks. This suggests those higher in CU require their brain to work harder for lower inhibition, whereas those higher in CP have difficulty engaging inhibitory brain responses. Additionally, those with CP interacting with CU show distinct brain patterns for a more general EF capacity. Importantly, modeling cross-network connection density in contemporary EF models to test EF involvement in core impairments in CU and CP may accelerate our understanding of EF in these phenotypes.

Normative Data for the Alternating and Orthographic Constraint Semantic Fluency Tests in the Adult French-Quebec Population and Validation Study in Mild Cognitive Impairment and Alzheimer's Disease

Verbal fluency tests, known to elicit executive functions (EFs), have proven useful in distinguishing healthy individuals from those with cognitive impairment. The present study addresses two new tests of verbal fluency that elicit EFs, namely, extradimensional alternating fluency (EAF) and extradimensional orthographic constraint semantic fluency (EOCSF). The aim of Study 1 was to provide normative data in the adult and elderly population of French Québec for the two fluency tests. The aim of Study 2 was to determine their psychometric value. The normative sample consisted of 338 healthy controls (HCs) aged 50-89 years. Multiple linear regressions were used to generate equations for calculating Z-scores. Convergent validity was established by administering the two verbal fluency tests and the Letter-Number Sequence (LNS) subtest of the WAIS-III. To assess predictive validity, the performance of 19 HCs was compared with that of 19 participants with mild cognitive impairment (MCI) and 19 participants with Alzheimer's disease (AD). To determine test-retest reliability, the test was administered twice, 3 months apart, to a subsample of 20 HCs. Age and educational level were significantly related to performance in the EAF and the EOCSF. The two tests correlated significantly and positively with the LNS. The EAF and the EOCSF distinguished the performance of HCs from that of participants with MCI or AD. A test-retest analysis showed that scores on the two tests were stable over time. The norms and psychometric data for the EAF and the EOCSF will help clinicians and researchers better identify executive impairments associated with pathological conditions.

Correlation of early-phase β-amyloid positron-emission-tomography and neuropsychological testing in patients with Alzheimer's disease

PURPOSE

Clinical staging in individuals with Alzheimer's disease (AD) typically relies on neuropsychological testing. Recognizing the imperative for an objective measure of clinical AD staging, regional perfusion in early-phase β-amyloid-PET may aid as a cost-efficient index for the assessment of neurodegeneration severity in patients with Alzheimer's disease.

METHODS

Regional perfusion deficits in early-phase β-amyloid-PET as well as neuropsychological testing (max. 90 days delay) were evaluated in 82 patients with biologically defined AD according to the ATN classification. In reference to the Braak staging system patients were classified into the groups stage0, stageI-II+, stageI-IV+, stageI-VI+, and stageatypical+ according to regional perfusion deficits in regions of interest (ROIs) published by the Alzheimer's Disease Neuroimaging Initiative. Multiple regression analysis controlling for age, gender, and education was used to evaluate the association of regional z-scores on perfusion-phase PET with clinical scores for all patients and with annual decline of cognitive performance in 23 patients with follow-up data.

RESULTS

Patients classified as stage0 and stageI-II+ demonstrated significantly superior neuropsychological performance compared to those classified as stageI-IV+ and stageI-VI+. Lower cognitive performance was associated with decreased perfusion in early-phase β-amyloid-PET globally and regionally, with the most pronounced association identified in the left temporal lobe. Mean z-scores on early-phase PET in temporal and parietal regions offered a robust prediction of future annual decline in MMSE and sum scores of the CERAD-Plus (Consortium to Establish a Registry for Alzheimer's Disease) test battery.

CONCLUSION

Regional and global perfusion deficits in early-phase β-amyloid-PET can serve as an objective index of neurodegeneration severity and may act as prognostic markers of future cognitive decline in AD.

Reduced frontotemporal connectivity during a verbal fluency task in patients with anxiety, sleep, and major depressive disorders

Background

It has been well established that psychiatric disorders are often accompanied by cognitive dysfunction. Previous studies have investigated the verbal fluency task (VFT) for detecting executive function impairment in different psychiatric disorders, but the sensitivity and specificity of this task in different psychiatric disorders have not been explored. Furthermore, clarifying the mechanisms underlying variations in executive function impairments across multiple psychiatric disorders will enhance our comprehension of brain activity alternations among these disorders. Therefore, this study combined the VFT and the functional near-infrared spectroscopy (fNIRS) to investigate the neural mechanisms underlying the impairment of executive function across psychiatric disorders including anxiety disorder (AD), sleep disorder (SD) and major depressive disorder (MDD).

Methods

Two hundred and eight participants were enrolled including 52 AD, 52 SD, 52 MDD and 52 healthy controls (HCs). All participants completed the VFT while being monitored using fNIRS to measure changes in brain oxygenated hemoglobin (Oxy-Hb).

Results

Our results demonstrated that MDD, AD and SD exhibited decreased overall connectivity strength, as well as reduced connected networks involving the frontal and temporal regions during the VFT comparing to HC. Furthermore, the MDD group showed a reduction in connected networks, specifically in the left superior temporal gyrus and precentral gyrus, compared to the AD group.

Conclusion

Our study offers neural evidence that the VFT combined with fNIRS could effectively detect executive function impairment in different psychiatric disorders.

Phonemic word fluency is related to temporal and striatal gray matter volume in healthy older adults

Word fluency (WF) tasks that tap verbal and executive function show deteriorating performance by advancing age. To address the scarcely studied age-related brain correlates of WF, we employed whole-brain voxel-based morphometry to examine gray matter (GM) correlates of semantic and phonemic WF in 46 healthy older adults. Lower phonemic WF score was related to smaller anterior medial temporal GM volume as well as smaller GM volume in the putamen bilaterally. A disproportionally weak score on phonemic WF in relation to semantic WF was associated with smaller GM volume in the left inferior frontal cortex, the right anterior medial temporal lobe, and the right striatum. There were no significant associations for semantic WF. The fact that our temporal and subcortical findings were bilateral and right-lateralized, may reflect age-related compensation by these brain areas.

Cognitive profiles in the acute phase of traumatic brain injury according to injury severity

Although several studies have documented the chronic phase of traumatic brain injury (TBI), few verified the nature and severity of cognitive impairments during the acute phase. Among the studies carried out during the acute phase, instrumental functions were rarely examined compared to attention, memory, and executive functions. This study aimed to compare the nature and intensity of cognitive problems in the acute phase according to TBI severity and age. It was hypothesized that cognitive impairments would increase in line with TBI severity and age, and that instrumental functions would be less affected in victims of mild or moderate TBI than in those with severe TBI. The Brief Cognitive Exam in Traumatology (EXACT), a new and reliable test specifically designed and validated to briefly assess global cognitive functioning during the acute phase, was administered to 319 mild to severe TBI victims (aged 16 to 96 years), within three months post-accident. The EXACT evaluates five domains: Language, Instrumental functions (other than language), Attention and working memory, Episodic memory, and Executive functions and behavioral regulation. Results confirmed the negative influence of TBI severity and age on global cognitive functioning. Also, compared to victims with a mild or moderate TBI, a higher proportion of those with a severe TBI presented impaired instrumental functions (calculation, praxis, and gnosis). Thus, during the acute phase, the nature and severity of cognitive impairments vary according to TBI severity.

Dual-task costs in speed tasks: a comparison between elite ice hockey, open-skill and closed-skill sports athletes

Introduction

Ice hockey is a high pace sports game that requires players to integrate multiple skills. Players face perceptive, cognitive, and motor tasks concurrently; hence, players are regularly exposed to dual- or multi-task demands. Dual-tasking has been shown to lead to decreased performance in one or both performed tasks. The degree of performance reductions might be modulated by the exhaustion of cognitive resources. Literature on dual-task paradigms that combine sport-relevant elements is scarce. Therefore, a novel paradigm combining cyclical speed of the lower extremities and concurrent visuo-verbal speed reading was tested and validated. Additionally, to understand the nature of dual-task costs, the relationship between these costs and cognitive performance was assessed. We hypothesized occurrence of dual-task costs in all athletes without relationship to single task performance. Differences in dual-task cost were expected between open-skill and closed-skill sports, as well as differing expertise levels. Level of cognitive function was expected to explain some variance in dual-task cost.

Methods

A total of 322 elite athletes (120 ice hockey, 165 other team sports, 37 closed-skill sports) participated in this study. Each athlete performed a tapping task, a visuo-verbal speed-reading task, and both tasks simultaneously. All ice hockey athletes performed additional cognitive tests assessing processing speed, spatial working memory, sustained attention, two choice reaction time, and motor inhibition.

Results

The results of paired-sample t-tests confirmed significant dual-task costs for all sport groups (p < 0.001). Single-task performance and dual-task costs correlated weakly in a positive direction. A one-way ANOVA revealed significantly greater costs in closed-skill sports athletes than in ice hockey and other sports athletes. No significant differences in dual-task costs were found between teams of differing expertise levels. Lastly, no significant regression model was found to predict dual-task costs from cognitive test performance.

Discussion

Our study suggests that this novel dual-task paradigm was successful in inducing dual-task costs for all elite athletes. Since it distinguishes between closed-skill and open-skill sports athletes, it might be a valuable diagnostic tool for performance and for talent development of open-skill athletes. Dual-task costs could not be relevantly predicted via cognitive performance measures, questioning cognitive resource theories as an explanation for dual-task costs.

Exploring behavioural and cognitive dysexecutive syndrome in patients with focal prefrontal cortex damage

This study's objectives were to characterize the frequency and profile of behavioral and cognitive dysexecutive syndromes in patients with focal prefrontal cortex damage and how these syndromes overlap. We also examined the contribution of the prefrontal brain regions to these syndromes. Therefore, thirty patients with prefrontal cortex damage and thirty control subjects were compared on their performances using the GREFEX battery assessing the dysexecutive syndromes. The results showed that combined behavioral and cognitive dysexecutive syndrome was observed in 53.33%, while pure cognitive dysexecutive syndrome was observed in 20% and behavioral in 26.67%. Also, almost all behavioral and cognitive dysexecutive disorders discriminated frontal patients from controls. Moreover, correlations and regression analyses between task scores in both domains of dysexecutive syndromes showed that the spectrum of behavioral disorders was differentially associated with cognitive impairment of initiation, inhibition, generation, deduction, coordination, flexibility and the planning process. Furthermore, the patterns of cognitive and behavioral dysexecutive syndrome were both predictors of impairment in daily living activities and loss of autonomy. Finally, frontal regions contributing to different dysexecutive syndromes assessed by MRI voxel lesion symptom analysis indicate several overlapping regions centered on the ventromedial and dorsomedial prefrontal cortex for both domains of dysexecutive syndrome. This study concludes that damage to the frontal structures may lead to a diverse set of changes in both cognitive and behavioral domains which both contribute to loss of autonomy. The association of the ventromedial and dorsomedial prefrontal regions to both domains of dysexecutive syndrome suggests a higher integrative role of these regions in processing cognition and behavior.

Executive functions in patients with bilateral and unilateral peripheral vestibular dysfunction

Previous research suggests that patients with peripheral vestibular dysfunction (PVD) suffer from nonspatial cognitive problems, including executive impairments. However, previous studies that assessed executive functions are conflicting, limited to single executive components, and assessments are confounded by other cognitive functions. We compared performance in a comprehensive executive test battery in a large sample of 83 patients with several conditions of PVD (34 bilateral, 29 chronic unilateral, 20 acute unilateral) to healthy controls who were pairwise matched to patients regarding age, sex, and education. We assessed basic and complex executive functions with validated neuropsychological tests. Patients with bilateral PVD performed worse than controls in verbal initiation and working memory span, while other executive functions were preserved. Patients with chronic unilateral PVD had equal executive performance as controls. Patients with acute unilateral PVD performed worse than controls in the exact same tests as patients with bilateral PVD (verbal initiation, working memory span); however, this effect in patients with acute PVD diminished after correcting for multiple comparisons. Hearing loss and affective disorders did not influence our results. Vestibular related variables (disease duration, symptoms, dizziness handicap, deafferentation degree, and compensation) did not predict verbal initiation or working memory span in patients with bilateral PVD. The results suggest that bilateral PVD not only manifests in difficulties when solving spatial tasks but leads to more general neurocognitive deficits. This understanding is important for multidisciplinary workgroups (e.g., neurotologists, neurologists, audiologists) that are involved in diagnosing and treating patients with PVD. We recommend screening patients with PVD for executive impairments and if indicated providing them with cognitive training or psychoeducational support.

Examining the validity of the Delis-Kaplan Executive Function System (D-KEFS) in traumatic brain injury

This study examines the validity of the Delis-Kaplan Executive Function System (D-KEFS) in a traumatic brain injury (TBI) population compared to participants with orthopaedic injuries and normative controls. The utility of the D-KEFS was examined using a between groups design. One hundred patients with mild uncomplicated to severe TBI were recruited from a consecutive cohort of patients admitted as inpatients to a UK Major Trauma Centre and compared to 823 participants from the D-KEFS normative sample and 26 participants with orthopaedic injuries. Data were filtered for performance validity. Sample discrimination was calculated from D-KEFS subtest scores and derived index scores. Sensitivity to TBI severity was established. The TBI participants performed significantly lower on the D-KEFS Trail Making Test, Colour Word Interference, Colour Word Switching, Letter Fluency and Verbal Fluency Category Switching Total Words Correct. The D-KEFS index scores discriminated between TBI, orthopaedic and normative participants with large and moderate effect sizes, respectively. The D-KEFS demonstrated a dose-response relationship with TBI severity. These effects were robust to differences in premorbid intellectual functioning; however, D-KEFS performance was sensitive to performance on tests of mental processing speed. The use of a D-KEFS index score provides a robust and reliable discrimination of TBI patients from healthy control participants. This discrimination is not accounted for by premorbid intellect or the non-specific effects of trauma. The clinical and conceptual implications of these findings are considered.

Differential contribution of language and executive functioning to verbal fluency performance in glioma patients

Glioma patients often suffer from deficits in language and executive functioning. Performance in verbal fluency (generating words within one minute according to a semantic category-category fluency, or given letter-letter fluency) is typically impaired in this patient group. While both language and executive functioning play a role in verbal fluency, the relative contribution of both domains remains unclear. We aim to retrospectively investigate glioma patients' performance on verbal and nonverbal fluency and to explore the influence of language and executive functioning on verbal fluency. Sixty-nine adults with gliomas in eloquent areas underwent a neuropsychological test battery (verbal fluency, nonverbal fluency, language, and executive functioning tests) before surgery (T1) and a subgroup of 31 patients also at three (T2) and twelve months (T3) after surgery. Preoperatively, patients were impaired in all verbal fluency tasks and dissociations were found based on tumour location. In contrast, nonverbal fluency was intact. Different language and executive functioning tests predicted performance on category fluency animals and letter fluency, while no significant predictors for category fluency professions were found. The longitudinal results indicated that category fluency professions deteriorated after surgery (T1-T2, T1-T3) and that nonverbal fluency improved after surgery (T1-T3, T2-T3). Verbal fluency performance can provide information on different possible underlying deficits in language and executive functioning in glioma patients, depending on verbal fluency task selection. Efficient task (order) selection can be based on complexity. Category fluency professions can be selected to detect more permanent long-term deficits.

HD-tDCS over the left DLPFC increases cued recall and subjective question familiarity rather than other aspects of memory and metamemory

When retrieving information from memory there is an interplay between memory and metamemory processes, and the prefrontal cortex has been implicated in both memory and metamemory. Previous work shown that High Definition transcranial Direct Current Stimulation (HD-tDCS) over the dorsolateral prefrontal cortex (DLPFC) can lead to improvements in memory and metamemory monitoring, but findings are mixed. Our original design targeted metamemory, but because the prefrontal cortex plays a role in both memory and metamemory, we tested for effects of HD-tDCS on multiple memory tasks (e.g., recall, cued recall, and recognition) and multiple aspects of metamemory (e.g., once-knew-it ratings, feeling-of-knowing ratings, metamemory accuracy, and metamemory control). There were HD-tDCS-related improvements in cued recall performance, but not other memory tasks. For metamemory, there were HD-tDCS-related increases in subjective once-knew-it ratings, but not other aspects of metamemory. These results highlight the need to consider the effects of HD-tDCS on memory and metamemory at different timepoints during retrieval, as well as specific conditions that show benefits from HD-tDCS.

Executive function and underlying brain network distinctions for callous-unemotional traits and conduct problems in adolescents

The complexity of executive function (EF) impairments in youth antisocial phenotypes of callous-unemotional (CU) traits and conduct problems (CP) challenge identifying phenotypic specific EF deficits. We can redress these challenges by (1) accounting for EF measurement error and (2) testing distinct functional brain properties accounting for differences in EF. Thus, we employed a latent modeling approach for EFs (inhibition, shifting, fluency, common EF) and extracted connection density from matching contemporary EF brain models with a sample of 112 adolescents (ages 13-17, 42% female). Path analysis indicated CU traits associated with lower inhibition. Inhibition network density positively associated with inhibition, but this association was strengthened by CU and attenuated by CP. Common EF associated with three-way interactions between density*CP by CU for the inhibition and shifting networks. This suggests those higher in CU require their brain to work harder for lower inhibition, whereas those higher in CP have difficulty engaging inhibitory brain responses. Additionally, those with CP interacting with CU show distinct brain patterns for a more general EF capacity. Importantly, modeling cross-network connection density in contemporary EF models to test EF involvement in core impairments in CU and CP may accelerate our understanding of EF in these phenotypes.

Serum glial fibrillary acidic protein and neurofilament light chain in treatment-naïve patients with unipolar depression

BACKGROUND

Unipolar depression has been associated with increased levels of glial dysfunction and neurodegeneration biomarkers, such as Glial Fibrillary Acidic Protein (GFAP) and Neurofilament light chain (NfL). However, previous studies were conducted on patients taking psychotropic medication and did not monitor longitudinal associations between disease status and GFAP/NfL.

METHODS

Treatment-naïve patients with unipolar depression (n = 110) and healthy controls (n = 33) were included. GFAP/NfL serum levels were analyzed by Single Molecule Array at baseline and 3-month follow-up. The primary endpoint was GFAP/NfL levels in patients with depression compared with healthy controls. The secondary endpoint was the associations between GFAP/NfL with depression severity and cognitive function.

RESULTS

The patients' mean HAM-D17 score was 18.9 (SD 3.9) at baseline and improved by 7.9 (SD 6.8) points during follow-up. GFAP/NfL was quantified in all individuals. At baseline, the adjusted GFAP levels were -16.8 % (95 % CI: -28.8 to -1.9, p = 0.03) lower among patients with depression compared to healthy controls, while NfL levels were comparable between the groups (p = 0.57). In patients with depression, mean NfL levels increased from baseline to follow-up (0.68 pg/ml, p = 0.03), while GFAP levels were unchanged (p = 0.24). We did not find consistent associations between NfL/GFAP with depression scores or cognitive function.

CONCLUSION

This largest study of serum NfL/GFAP levels in patients with depression did not support previous findings of elevated GFAP/NfL in patients with depression or positive associations with depression severity. Although limited by a small control group, our study may support the presence of glial dysfunction but not damage to neurons in depression.

Triangulating evidence from observational and Mendelian randomization studies of ketone bodies for cognitive performance

BACKGROUND

Ketone bodies (KBs) are an alternative energy supply for brain functions when glucose is limited. The most abundant ketone metabolite, 3-β-hydroxybutyrate (BOHBUT), has been suggested to prevent or delay cognitive impairment, but the evidence remains unclear. We triangulated observational and Mendelian randomization (MR) studies to investigate the association and causation between KBs and cognitive function.

METHODS

In observational analyses of 5506 participants aged ≥ 45 years from the Whitehall II study, we used multiple linear regression to investigate the associations between categorized KBs and cognitive function scores. Two-sample MR was carried out using summary statistics from an in-house KBs meta-analysis between the University College London-London School of Hygiene and Tropical Medicine-Edinburgh-Bristol (UCLEB) Consortium and Kettunen et al. (N = 45,031), and publicly available summary statistics of cognitive performance and Alzheimer's disease (AD) from the Social Science Genetic Association Consortium (N = 257,841), and the International Genomics of Alzheimer's Project (N = 54,162), respectively. Both strong (P < 5 × 10-8) and suggestive (P < 1 × 10-5) sets of instrumental variables for BOHBUT were applied. Finally, we performed cis-MR on OXCT1, a well-known gene for KB catabolism.

RESULTS

BOHBUT was positively associated with general cognitive function (β = 0.26, P = 9.74 × 10-3). In MR analyses, we observed a protective effect of BOHBUT on cognitive performance (inverse variance weighted: βIVW = 7.89 × 10-2, PIVW = 1.03 × 10-2; weighted median: βW-Median = 8.65 × 10-2, PW-Median = 9.60 × 10-3) and a protective effect on AD (βIVW =  - 0.31, odds ratio: OR = 0.74, PIVW = 3.06 × 10-2). Cis-MR showed little evidence of therapeutic modulation of OXCT1 on cognitive impairment.

CONCLUSIONS

Triangulation of evidence suggests that BOHBUT has a beneficial effect on cognitive performance. Our findings raise the hypothesis that increased BOHBUT may improve general cognitive functions, delaying cognitive impairment and reducing the risk of AD.

The Role of Apathy in Spontaneous Verbal and Nonverbal Behaviors: A Transdiagnostic Pilot Study in Neurodegeneration

BACKGROUND

Apathy, characterized by a quantifiable reduction in motivation or goal-directed behavior, is a multidimensional syndrome that has been observed across many neurodegenerative diseases.

OBJECTIVE

To develop a novel task measuring spontaneous action initiation (ie, a nonverbal equivalent to spontaneous speech tasks) and to investigate the association between apathy and executive functions such as the voluntary initiation of speech and actions and energization (ie, ability to initiate and sustain a response).

METHOD

We compared the energization and executive functioning performance of 10 individuals with neurodegenerative disease and clinically significant apathy with that of age-matched healthy controls (HC). We also investigated the association between self-reported scores on the Apathy Evaluation Scale (AES) and performance on energization tasks.

RESULTS

The individuals with apathy made significantly fewer task-related actions than the HC on the novel spontaneous action task, and their scores on the AES were negatively correlated with spontaneous task-related actions, providing preliminary evidence for the task's construct validity. In addition, the individuals with apathy performed more poorly than the HC on all of the energization tasks, regardless of task type or stimulus modality, suggesting difficulty in sustaining voluntary responding over time. Most of the tasks also correlated negatively with the AES score. However, the individuals with apathy also performed more poorly on some of the executive function tasks, particularly those involving self-monitoring.

CONCLUSION

Our work presents a novel experimental task for measuring spontaneous action initiation-a key symptom of apathy-and suggests a possible contribution of apathy to neuropsychological deficits such as poor energization.

Arousal deregulation in the co-shaping of neuropsychological dysfunction in frontal and mesial temporal lobe epilepsy

OBJECTIVE

Our work aims to investigate the role of physiological arousal in the expression of neuropsychological deficits in frontal lobe epilepsy (FLE) and mesial temporal lobe epilepsy (mTLE), by drawing on the Lurian theory of brain function.

METHODS

For this study a total of 43 patients with focal onset epilepsy has been taken; twenty-four patients with FLE, 19 patients with mTLE and 26 healthy controls, all matched for age and education. Participants underwent a comprehensive neuropsychological assessment including various cognitive domains, such as attention, episodic memory, speed of information processing, response inhibition and mental flexibility, working memory, verbal fluency (phonological & semantic).

RESULTS

There were no significant differences between FLE and mTLE patients in terms of neuropsychological performance. However, both FLE and mTLE patients showed significantly worse performance in several cognitive domains than HCs. The results seem to support our hypothesis that aberrant physiological arousal, as reflected in patients' worse performance in vigilance and attention, response inhibition, and processing speed, along with other disease-specific variables, may co-determine neuropsychological dysfunction and/or impairment in both FLE and mTLE.

CONCLUSION

Identifying a differential arousal-related neuropsychological affection in FLE and mTLE, among the known deleterious effects of the functional deficit zone and other disease-related variables, may further our understanding of the underlying cognitive-pathophysiological mechanisms in focal epilepsy syndromes.

Altered brain network centrality in Parkinson's disease patients after deep brain stimulation: a functional MRI study using a voxel-wise degree centrality approach

OBJECTIVE

After deep brain stimulation (DBS), patients with Parkinson's disease (PD) show improved motor symptoms and decreased verbal fluency, an effect that occurs before the initiation of DBS in the subthalamic nucleus. However, the underlying mechanism remains unclear. This study aimed to evaluate the effects of DBS on whole-brain degree centrality (DC) and seed-based functional connectivity (FC) in PD patients.

METHODS

The authors obtained resting-state functional MRI data of 28 PD patients before and after DBS surgery. All patients underwent MRI scans in the off-stimulation state. The DC method was used to evaluate the effects of DBS on whole-brain FC at the voxel level. Seed-based FC analysis was used to examine network function changes after DBS.

RESULTS

After DBS surgery, PD patients showed significantly weaker DC values in the left middle temporal gyrus, left supramarginal gyrus, and left middle frontal gyrus, but significantly stronger DC values in the midbrain, left precuneus, and right precentral gyrus. FC analysis revealed decreased FC values within the default mode network (DMN).

CONCLUSIONS

This study demonstrated that the DC of DMN-related brain regions decreased in PD patients after DBS surgery, whereas the DC of the motor cortex increased. These findings provide new evidence for the neural effects of DBS on voxel-based whole-brain networks in PD patients.

Gray matter volume and within-task verbal fluency performance among older adults

The current study examined the relationship between gray matter volume (GMV) and rate of word generation over the course of three consecutive 20-sec intervals in 60-sec letter and category verbal fluency (VF) tasks. Attenuated rate of within-person word generation in VF provides incremental information beyond total scores and predicts increased risk of incident Mild Cognitive Impairment (MCI). No studies to date, however, have determined the structural neural substrates underlying word generation rate in VF. Participants were 70 community-residing adults ≥ 65 years, who completed the letter and category VF tasks and a 3 T structural MRI scan. Linear mixed effects models (LMEMs) were used to determine the moderating effect of GMV on word generation rate. Whole brain voxel-wise LMEMs, adjusted for age, gender, education, Wide-Range Achievement Test - reading subtest score (WRAT3), and global health score, were run using permutation methods to correct for multiple comparisons. Lower GMV, primarily in frontal regions (superior frontal, rostral middle frontal, frontal pole, medial orbitofrontal, and pars orbitalis), were related to attenuated word generation rate, especially for letter VF. We propose that lower frontal GMV underlies inefficient executive word search processes reflected by attenuated word generation slope in letter VF amongst older adults.

Effect of interactive multitouch game-based cognitive intervention on cognitive function in older adults: A randomized controlled trial

Purpose

This study investigated the effects of an interactive multitouch game-based cognitive intervention (ICI) on cognitive function in community-dwelling older adults.

Methods

Thirty-two older adults (19 women) between 65 and 84 years of age (mean age, 74.47 ± 4.30 years) without a history of neurological disease participated. They were randomized into two groups: intervention and control. The intervention group took part in ICI sessions using HAPPYTABLE® (Spring Soft Co. Ltd, Seoul, Korea) (ICI group), and the control group underwent a traditional paper-and-pencil-based cognitive intervention (TCI group). Both groups completed 10 intervention sessions over four consecutive weeks. Cognitive function was assessed before (pre-intervention) and after (post-intervention) intervention. Executive function was evaluated through the Color-Word Stroop Test (CWST) and Controlled Oral Word Association Test (COWAT). Memory was assessed through the Verbal Learning Test (VLT) and Rey Complex Figure Test (RCFT).

Results

The ICI and TCI groups showed significant improvements in some cognitive functions after the intervention. Both groups showed substantial improvements in VLT and RCFT (P < 0.05), reflecting memory function. Regarding the executive role, the ICI group showed significant post-intervention improvements in the conditions of the CWST incongruent (ICI 76.31 ± 23.82; P = 0.004) compared to the pre-intervention scores. ANCOVA with pre-intervention scores and gender as covariates revealed improved results in the ICI group compared with the VLT delayed (ICI 9.18 ± 1.68, TCI 7.56 ± 2.13; P = 0.015) and VLT recognition task (ICI 22.81 ± 1.22, TCI 21.38 ± 1.09; P = 0.035).

Conclusions

These findings revealed that both ICI and TCI helped increase cognitive performance in community-dwelling older persons; nevertheless, ICI showed better improvement in memory function than TCI. Thus, the ICI can be used to improve cognitive performance among older adults living in the community.

The Use of Executive Fluency Tasks to Detect Cognitive Impairment in Individuals with Subjective Cognitive Decline

OBJECTIVE

Although evidence has indicated that subjective cognitive decline (SCD) may be an early sign of Alzheimer's disease (AD), the objectification of cognitive impairment in SCD is challenging, mainly due to the lack of sensitivity in assessment tools. The present study investigated the potential contribution of two verbal fluency tasks with high executive processing loads to the identification of cognitive impairment in SCD.

METHODS

A total of 60 adults with SCD and 60 healthy controls (HCs) performed one free action (verb) fluency task and two fluency tasks with more executive processing load-an alternating fluency task and an orthographic constraint fluency task-and the results were compared.

RESULT

In the free action fluency task, the performance of the participants with SCD and the HCs was similar. However, HCs performed significantly better than SCD in the alternating fluency task, which required mental flexibility, and the orthographic constraint fluency task, which required inhibition.

DISCUSSION

The study findings suggest that verbal fluency tasks with high executive processing load could be useful in detecting cognitive deficits at the preclinical stage of AD. The inclusion of such tests in assessment batteries should be considered in order to improve the detection of subtle cognitive impairment in preclinical major neurocognitive disorder populations.

Executive functioning and verbal fluency performance in youth with Down syndrome

BACKGROUND

Executive functioning (EF) is an area of challenge for individuals with Down syndrome (DS) associated with a variety of downstream difficulties. Verbal fluency performance is one potential downstream effect that is commonly assessed in individuals with DS due to the measure's utility as a predictor of dementia. Verbal fluency requires individuals to inhibit irrelevant responses, shift between groupings of related words, and monitor to prevent repetition, all skills related to EF.

AIMS

This study aimed to determine the association between semantic verbal fluency performance and three EF subdomains (inhibition, shifting, and working memory) in youth with DS after taking into account vocabulary and cognitive ability.

METHODS AND PROCEDURES

Neuropsychological assessments (verbal and visuospatial), and parent reports of EF, were completed at one time point by 69 youth with DS 6-17 years old and their caregivers. Expressive and receptive vocabulary skills and cognitive ability were also assessed.

OUTCOMES AND RESULTS

The results revealed that verbal fluency performance was significantly associated with neuropsychological assessments of EF and parent report of inhibition even after controlling for the effects of vocabulary and cognitive ability.

CONCLUSIONS AND IMPLICATIONS

The findings highlight the underlying importance of EF in verbal fluency tasks in youth with DS.

Functional connectivity of brain networks during semantic processing in older adults

The neural systems underlying semantic processing have been characterized with functional neuroimaging in young adults. Whether the integrity of these systems degrade with advanced age remains unresolved. The current study examined functional connectivity during abstract and concrete word processing. Thirty-eight adults, aged 55–91, engaged in semantic association decision tasks during a mixed event-related block functional magnetic resonance imaging (fMRI) paradigm. During the semantic trials, the task required participants to make a judgment as to whether pairs were semantically associated. During the rhyme trials, the task required participants to determine if non-word pairs rhymed. Seeds were placed in putative semantic hubs of the left anterior middle temporal gyrus (aMTG) and the angular gyrus (AG), and also in the left inferior frontal gyrus (IFG), an area considered important for semantic control. Greater connectivity between aMTG, AG, and IFG and multiple cortical areas occurred during semantic processing. Connectivity from the three seeds differed during semantic processing: the left AG and aMTG were strongly connected with frontal, parietal, and occipital areas bilaterally, whereas the IFG was most strongly connected with other frontal cortical areas and the AG in the ipsilateral left hemisphere. Notably, the strength and extent of connectivity differed for abstract and concrete semantic processing; connectivity from the left aMTG and AG to bilateral cortical areas was greater during abstract processing, whereas IFG connectivity with left cortical areas was greater during concrete processing. With advanced age, greater connectivity occurred only between the left AG and supramarginal gyrus during the processing of concrete word-pairs, but not abstract word-pairs. Among older adults, robust functional connectivity of the aMTG, AG, and IFG to widely distributed bilateral cortical areas occurs during abstract and concrete semantic processing in a manner consistent with reports from past studies of young adults. There was not a significant degradation of functional connectivity during semantic processing between the ages of 55 and 85 years. As the study focused on semantic functioning in older adults, a comparison group of young adults was not included, limiting generalizability. Future longitudinal neuroimaging studies that compare functional connectivity of young and older adults under different semantic demands will be valuable.

Design and Verbal Fluency in Alzheimer's Disease and Frontotemporal Dementia: Clinical and Metabolic Correlates

OBJECTIVE

Cognitive processes underlying verbal and design fluency, and their neural correlates in patients with Alzheimer's disease (AD) and behavioural variant Frontotemporal Dementia (bvFTD) remain unclear. We hypothesised that verbal and design fluency may be associated with distinct neuropsychological processes in AD and FTD, showing different patterns of impairment and neural basis.

METHODS

We enrolled 142 participants including patients with AD (n = 80, mean age = 74.71), bvFTD (n = 34, mean age = 68.18), and healthy controls (HCs) (n = 28, mean age = 71.14), that underwent cognitive assessment and ¹⁸F-fluorodeoxyglucose positron emission tomography imaging.

RESULTS

Semantic and phonemic fluency showed the largest effect sizes between groups, showing lower scores in bvFTD than AD and HCs, and lower scores in AD than HC. Both AD and bvFTD showed a lower number of unique designs in design fluency in comparison to HC. Semantic fluency was correlated with left frontotemporal lobe in AD, and with left frontal, caudate, and thalamus in bvFTD. Percentage of unique designs in design fluency was associated with the metabolism of the bilateral fronto-temporo-parietal cortex in AD, and the bilateral frontal cortex with right predominance in bvFTD. Repetitions in AD were correlated with bilateral frontal, temporal, and parietal lobes, and with left prefrontal cortex in bvFTD.

CONCLUSIONS

Our findings demonstrate differential underlying cognitive processes in verbal and design fluency in AD and bvFTD. While memory and executive functioning associated with fronto-temporo-parietal regions were key in AD, attention and executive functions correlated with the frontal cortex and played a more significant role in bvFTD during fluency tasks.

Segregated circuits for phonemic and semantic fluency: A novel patient-tailored disconnection study

Phonemic and semantic fluency are neuropsychological tests widely used to assess patients' language and executive abilities and are highly sensitive tests in detecting language deficits in glioma patients. However, the networks that are involved in these tasks could be distinct and suggesting either a frontal (phonemic) or temporal (semantic) involvement. 42 right-handed patients (26 male, mean age = 52.5 years, SD=±13.3) were included in this retrospective study. Patients underwent awake (54.8%) or asleep (45.2%) surgery for low-grade (16.7%) or high-grade-glioma (83.3%) in the frontal (64.3%) or temporal lobe (35.7%) of the left (50%) or right (50%) hemisphere. Pre-operative tractography was reconstructed for each patient, with segmentation of the inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), third branch of the superior longitudinal fasciculus (SLF-III), frontal aslant tract (FAT), and cortico-spinal tract (CST). Post-operative percentage of damage and disconnection of each tract, based on the patients' surgical cavities, were correlated with verbal fluencies scores at one week and one month after surgery. Analyses of differences between fluency scores at these timepoints (before surgery, one week and one month after surgery) were performed; lesion-symptom mapping was used to identify the correlation between cortical areas and post-operative scores. Immediately after surgery, a transient impairment of verbal fluency was observed, that improved within a month. Left hemisphere lesions were related to a worse verbal fluency performance, being a damage to the left superior frontal or temporal gyri associated with phonemic or semantic fluency deficit, respectively. At a subcortical level, disconnection analyses revealed that fluency scores were associated to the involvement of the left FAT and the left frontal part of the IFOF for phonemic fluency, and the association was still present one month after surgery. For semantic fluency, the correlation between post-surgery performance emerged for the left AF, UF, ILF and the temporal part of the IFOF, but disappeared at the follow-up. This approach based on the patients' pre-operative tractography, allowed to trace for the first time a dissociation between white matter pathways integrity and verbal fluency after surgery for glioma resection. Our results confirm the involvement of a frontal anterior pathway for phonemic fluency and a ventral temporal pathway for semantic fluency. Finally, our longitudinal results suggest that the frontal executive pathway requires a longer interval to recover compared to the semantic one.

LSD, afterglow and hangover: Increased episodic memory and verbal fluency, decreased cognitive flexibility

Psychedelics acutely impair cognitive functions, but these impairments decline with growing experiences with psychedelics and microdoses may even exert opposing effects. Given the recent evidence that psychedelics induce neuroplasticity, this explorative study aimed at investigating the potential of psychedelics to sub-acutely change cognition. For this, we applied a randomized, double-blind, placebo-controlled, crossover study with 24 healthy volunteers receiving 50 μg lysergic acid diethylamide (LSD) or an inactive placebo. Sub-acute changes in cognition were measured 24 h after dosing, including memory (Rey-Osterrieth Complex Figure, ROCF; 2D Object-Location Memory Task, OLMT; Rey Auditory-Verbal Learning Test, RAVLT), verbal fluency (phonological; semantic; switch), design fluency (basic; filter; switch), cognitive flexibility (Wisconsin Card Sorting Test, WCST), sustained and switching attention (Trail Making Test, TMT), inhibitory control (Stroop Task) and perceptual reasoning (Block Design Test, BDT). The results show that when compared to placebo and corrected for Body Mass Index (BMI) and abstinence period from psychedelics, LSD sub-acutely improved visuospatial memory (ROCF immediate recall points and percentage, OLMT consolidation percentage) and phonological verbal fluency and impaired cognitive flexibility (WCST: fewer categories achieved; more perseveration, errors and conceptual level responses). In conclusion, the low dose of LSD moderately induced both "afterglow" and "hangover". The improvements in visuospatial memory and phonological fluency suggest that LSD-assisted therapy should be explored as a novel treatment perspective in conditions involving memory and language declines such as brain injury, stroke or dementia.

Altered Interhemispheric Functional Connectivity Associated With Early Verbal Fluency Decline After Deep Brain Stimulation in Parkinson’s Disease

Background

Patients with Parkinson’s disease (PD) experience a decline in verbal fluency (VF) immediately after undergoing deep brain stimulation (DBS) of the subthalamic nucleus (STN). This phenomenon is thought to be related to surgical microlesions.

Purpose

We investigated the alterations in interhemispheric functional connectivity after STN-DBS in PD patients. We also evaluated the correlation between these changes and decreased VF scores.

Method

Overall, 30 patients with PD were enrolled in the study. Resting-state functional magnetic resonance imaging scans were performed twice, once before and once after DBS, in PD patients. Voxel-mirrored homotopic connectivity (VMHC) was applied in order to evaluate the synchronicity of functional connectivity between the hemispheres.

Result

After undergoing STN-DBS, PD patients demonstrated reduced VMHC value in the posterior cerebellum lobe, angular gyrus, precuneus/posterior cingulate gyrus (PCC), supramarginal gyrus, superior frontal gyrus (SFG) (medial and dorsolateral) and middle frontal gyrus (MFG). In addition, we observed a significant positive correlation between the altered VMHC value in the SFG and MFG and the change of phonemic VF scores.

Conclusion

PD patients demonstrated an interhemispheric coordination disorder in the prefrontal cortex, cerebellum, supramarginal gyrus and DMN after undergoing STN-DBS. The positive correlation between reduced VMHC value in the SFG and MFG and the changes of VF scores provides a novel understanding with regard to the decline of VF after DBS.

Capturing Subtle Neurocognitive Differences in Children with and without Tourette Syndrome through a Fine-Grained Analysis of Design Fluency Profiles

BACKGROUND

Tourette syndrome (TS) can be accompanied by neurocognitive impairment. Only a few studies have focused on executive function assessment in TS using design fluency, providing preliminary results. This study aimed to characterize the detailed design fluency profile of children with TS compared with neurotypical children, while addressing the central concern of frequent comorbidities in studies on TS by considering tic severity and attention-deficit/hyperactivity disorder (ADHD) symptoms and diagnosis.

METHODS

Sixty-one children aged between 6 and 15 years participated and were divided into a TS group (n = 28 (with ADHD n = 15)) and a control group (n = 33). Our objective was addressed by examining a wide range of measures of the Five-Point-Test, presumably sensitive to frontostriatal dysfunction. The total number of designs, repetitions, repetition ratio, unique designs, and numerical, spatial, and total strategies were examined for the total duration of the test (global measures) and at five equal time intervals (process measures).

RESULTS

The TS group produced significantly fewer numerical strategies. Groups did not differ in other global or process measures. ADHD did not affect performance.

CONCLUSIONS

Children with TS do not inherently show general executive dysfunction but may present with subtle neurocognitive characteristics here revealed by comprehensive design fluency profiles.

Verbal Fluency in Metabolic Syndrome

Metabolic syndrome (MetS) or otherwise insulin resistance (IR) is described as a cluster of several commonly occurring disorders, including abdominal obesity; lipids disorders, such as hypertriglyceridemia; and low levels of high-density-lipoprotein cholesterol (HDL-C), hypertension (≥130/85 mmHg), and carbohydrates disorders, such as impaired fasting glucose or diabetes mellitus type 2. Type 2 diabetes (T2DM) constitutes insulin resistance, which is a strong risk factor for strokes. Patients with MetS are often prone to cognitive decline. Metabolic risk factors, hypertension, and diabetes, amongst them, have been hypothesized to play a great role in the pathogenesis of Alzheimer’s disease (AD) and the development of vascular dementia. For neuropsychological diagnostic and theoretical purposes verbal fluency is defined as a cognitive function that facilitates information retrieval from memory. It engages executive control and other cognitive processes, such as selective attention, selective inhibition, mental set shifting, internal response generation, and self-monitoring, as well as imagination and psychomotor skills. A total of 90 subjects, divided into 2 groups, patients with MetS (45) and healthy controls (45), were assessed. A significant difference in performance was found between the patients and controls, both in the phonetic (p < 0.01) and semantic fluency trials (p < 0.001). The MetS patients produced less words in the letter K and animal categories. The analysis of descriptive statistics shows that the group of patients with metabolic syndrome generated fewer words in both the phonetic and semantic categories. Our study shows that there is an association between metabolic factors and the verbal fluency performance of MetS patients. This is true, especially for phonetic verbal fluency, which is traditionally connected with the frontal cortex. Lower switching signifies possible executive dysfunctions amongst people with MetS. Subjects with this condition generated more diverse words and created less standard associations. This further implies the existence of dysexecutive syndrome and the need for diagnosing patients in this direction and involving this group of people in therapy. The proper correction of MetS components may improve cognitive function.

A scoping review of near infrared spectroscopy studies employing a verbal fluency task in bipolar disorder

BACKGROUND

Deficits in cognitive functioning, including attention, memory, and executive functions, along with impairments in language production, are present in patients with bipolar disorder (BD) patients during mood phases, but also during euthymia.Verbal fluency tasks (VFTs), being able to evaluate integrity of a wide range of cognitive domains and represent, can be used to screen for these disturbances. Neuroimaging studies, including Near-InfraRed Spectroscopy (NIRS), have repeatedly showed widespread alterations in the prefrontal and temporal cortex during the performance of VFTs in BD patients. This review aims to summarize the results of NIRS studies that evaluated hemodynamic responses associated with the VFTs in prefrontal and temporal regions in BD patients.

METHODS

We performed a scoping review of studies evaluating VFT-induced activation in prefrontal and temporal regions in BD patients, and the relationship between NIRS data and various clinical variables.

RESULTS

15 studies met the inclusion criteria. In BD patients, compared to healthy controls, NIRS studies showed hypoactivation of the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex and anterior temporal regions. Moreover, clinical variables, such as depressive and social adaptation scores, were negatively correlated with hemodynamic responses in prefrontal and temporal regions, while a positive correlation were reported for measures of manic symptoms and impulsivity.

LIMITATIONS

The heterogeneity of the studies in terms of methodology, study design and clinical characteristics of the samples limited the comparability of the findings.

CONCLUSIONS

Given its non-invasiveness, good time-resolution and no need of posturalconstraint, NIRS technique could represent a useful tool for the evaluation of prefrontal and temporal haemodynamic correlates of cognitive performances in BD patients.

The promising fNIRS: Uncovering the function of prefrontal working memory networks based on multi-cognitive tasks

The diversity of cognitive task paradigms using functional near-infrared spectroscopy (fNIRS) and the lack of theoretical explanations for these functional imaging atlases have greatly hindered the application of fNIRS in psychiatry. The fNIRS brain imaging based on multiple cognitive tasks could generally reflect the working patterns and neurovascular coupling changes in the prefrontal working memory network. By alternating the stimulation patterns of resting and task states, six typical symptom-related functional brain imaging waveforms related to psychiatric disorders are identified and three joint networks of the prefrontal working memory, namely, the attentional working memory primary coordination network, the perceptual content working memory secondary network, and the emotional-behavioral working memory executive network, are initially represented. This is the first attempt to characterize the cognitive, emotional, and behavioral regulation of the prefrontal working memory network using fNIRS, which may promote the application of fNIRS in clinical settings.

Polygenic risk score for bipolar disorder associates with divergent thinking and brain structures in the prefrontal cortex

It has been hypothesized that a higher genetic risk of bipolar disorder (BD) is associated with greater creativity. Given the clinical importance of bipolar disorder and the importance of creativity to human society and cultural development, it is essential to reveal their associations and the neural basis of the genetic risk of bipolar disorder to gain insight into its etiology. However, despite the previous demonstration of the associations of polygenic risk score (PRS) of BD and creative jobs, the associations of BD‐PRS and creativity measured by the divergent thinking (CMDT) and regional gray matter volume (rGMV) as well as regional white matter volume (rWMV) have not been investigated. Using psychological analyses and whole‐brain voxel‐by‐voxel analyses, we examined these potential associations in 1558 young, typically developing adult students. After adjusting for confounding variables and multiple comparisons, a greater BD‐PRS was associated with a greater total CMDT fluency score, and a significant relationship was found in fluency subscores. A greater BD‐PRS was also associated with lower total mood disturbance. Neuroimaging analyses revealed that the BD‐PRS was associated with greater rGMV in the right inferior frontal gyrus, which is a consistently affected area in BD, as well as a greater rWMV in the left middle frontal gyrus, which has been suggested to play a central role in the increased creativity associated with the risk of BD with creativity. These findings suggest a relationship between the genetic risk of BD and CMDT and prefrontal cortical structures among young educated individuals.

Fluency test generation and errors in focal frontal and posterior lesions

The number produced on fluency tasks is widely used to measure voluntary response generation. To further evaluate the relationship between generation, errors, and the area of anatomical damage we administered eight fluency tasks (word, design, gesture, ideational) to a large group of focal frontal (n = 69) and posterior (n = 43) patients and controls (n = 150). Lesions were analysed by a finer-grained frontal localisation method, and traditional subdivisions (anterior/posterior, left/right frontal). Thus, we compared patients with Lateral lesions to patients with Medial lesions. Our results show that all fluency tasks are sensitive to frontal lobe damage for the number of correct responses and, for the first time, we provide evidence that seven fluency tasks show frontal sensitivity in terms of errors (perseverations, rule-breaks). Lateral (not Medial) patients produced the highest error rates, indicative of task-setting or monitoring difficulties. There was a right frontal effect for perseverative errors when retrieving known or stored items and rule-break errors when creating novel responses. Left lateral effects were specific to phonemic word fluency rule-breaks and perseverations for meaningless gesture fluency. In addition, our generation output and error findings support a frontal role in novelty processes. Finally, we confirm our previous generation findings suggesting critical roles of the superior medial region in energization and the left inferior frontal region in selection (Robinson et al., 2012). Overall, these results support the notion that frontal functions comprise a set of highly specialised cognitive processes, supported by distinct frontal regions.

Amyloid and anatomical correlates of executive functioning in middle-aged offspring of patients with late-onset Alzheimer's disease

A traditional hallmark of cognitive impairment associated with late-onset Alzheimer´s disease (LOAD) is episodic memory impairment. However, early alterations have been identified in brain regions associated with executive function in asymptomatic, middle-age offspring of patients with LOAD (O-LOAD) compared to those with no family history. We hypothesized that executive function among O-LOAD would correlate with structural and amyloid brain imaging differently from those without a family history of LOAD (control subjects, CS). Executive function, cortical thickness, and in-vivo Aβ deposits were quantified in 30 O-LOAD and 25 CS. Associations were observed among O-LOAD only. Cortical thickness in the left lateral orbitofrontal cortex was positively associated with Design Fluency. The Stroop Color and Word Test, correlated positively with right rostral mid-frontal cortex thickness. Trails Making Test-B was inversely related to left medial orbitofrontal thickness. Tower of London total time was positively associated with β-amyloid deposition in the right precuneus. These results support previous evidence that early executive dysfunction might reflect subtle, early changes in persons at risk of LOAD and suggests that executive function alterations deserve further exploration in the LOAD literature.

Objective Measures of Cognitive Performance in Sleep Disorder Research

Neurocognitive tests offer objective and reliable assessment of patients' status and progress. However, there is no consensus on how to use neurocognitive assessment in sleep disorder research. An effective use of neurocognitive assessment must be based on standardized practices and have a firm theoretic basis. The aim of this review is to offer an overview of how different tests have been used in the field, mapping each test onto a corresponding cognitive domain and propose how to move forward with a suggested cognitive battery of tests covering all major cognitive domains.

Proposed diagnostic criteria for mild cognitive impairment in Down syndrome population

BACKGROUND

Despite presenting higher risk of dementia, mild cognitive impairment (MCI) is not well defined in Down syndrome population.

OBJECTIVE

We aimed to describe cognitive and neuropsychological patterns associated with MCI in Down syndrome individuals.

METHOD

Two groups of adults with Down syndrome (control and prodromal) were studied throughout 3 years. Two linear mixed models and a model including the variables that best predicted group membership were built.

RESULTS

Behavioural Regulation Index (BRI) (Behaviour Rating Inventory of Executive Function test) and the model composed of BRI, abstraction and delayed verbal memory were the variable and model best predicting group membership, respectively.

CONCLUSION

Suggest a diagnosis of MCI when BRI is the earliest change perceived by caregivers and this is combined with low scores in abstract thinking, and when an amnesic pattern in delayed verbal memory is observed, but adaptive skills are preserved.

Using fiber tractography and diffusion kurtosis imaging to evaluate neuroimaging changes in patients with cerebrotendinous xanthomatosis after stopping chenodeoxycholic acid treatment for three years

BACKGROUND

The aim of this study was to use tractography and diffusion kurtosis imaging (DKI) to evaluate cerebral white matter (WM) changes in patients with cerebrotendinous xanthomatosis (CTX) after stopping chenodeoxycholic acid (CDCA) treatment.

MATERIAL AND METHODS

Two siblings with CTX aged 40 and 38 years, respectively, who had been diagnosed with CTX for 16 years were enrolled. They had received CDCA treatment from 2005 until 2015, after which CDCA was no longer available in Taiwan. Serial brain magnetic resonance imaging (MRI) studies were used to record brain changes, and a series of neuropsychiatric tests were used to evaluate cognitive changes 3 years after stopping CDCA treatment.

RESULTS

The conventional MRI studies revealed progressive changes in dentate nuclei and surrounding cerebellar hemispheres, but no obvious changes in cerebral white matter (WM). Tractography captured in 2018 showed a general reduction in fiber density, especially involving frontal lobe fibers, compared to 2015. In addition, the DKI studies performed in 2018 showed a decreased axonal water fraction in diffuse WM structures and increased RadEAD in frontal WM. Comparisons of the neuropsychiatric test results between 2015 and 2018 showed a marked decline in executive function including design fluency, digit backward span and digit forward span, and this cognitive impairment highly suggested frontal lobe dysfunction.

CONCLUSIONS

This study may suggest that cerebral tractography and DKI study results can identify changes in cerebral WM in CTX patients shortly after stopping CDCA treatment, and that they may have a better correlation with the results of neuropsychiatric tests.

Brain structure associations with phonemic and semantic fluency in typically-developing children

Verbal fluency is the ability to retrieve lexical knowledge quickly and efficiently and develops during childhood and adolescence. Few studies have investigated associations between verbal fluency performance and brain structural variation in children. Here we examined associations of verbal fluency performance with structural measures of frontal and temporal language-related brain regions and their connections in 73 typically-developing children aged 7-13 years. Tract-based spatial statistics was used to extract fractional anisotropy (FA) from the superior longitudinal fasciculus/arcuate fasciculus (SLF/AF), and the white matter underlying frontal and temporal language-related regions. FreeSurfer was used to extract cortical thickness and surface area. Better semantic and phonemic fluency performance was associated with higher right SLF/AF FA, and phonemic fluency was also modestly associated with lower left SLF/AF FA. Explorative voxelwise analyses for semantic fluency suggested associations with FA in other fiber tracts, including corpus callosum and right inferior fronto-occipital fasciculus. Overall, our results suggest that verbal fluency performance in children may rely on right hemisphere structures, possibly involving both language and executive function networks, and less on solely left hemisphere structures as often is observed in adults. Longitudinal studies are needed to clarify whether these associations are mediated by maturational processes, stable characteristics and/or experience.

Metacognition: ideas and insights from neuro- and educational sciences

Metacognition comprises both the ability to be aware of one's cognitive processes (metacognitive knowledge) and to regulate them (metacognitive control). Research in educational sciences has amassed a large body of evidence on the importance of metacognition in learning and academic achievement. More recently, metacognition has been studied from experimental and cognitive neuroscience perspectives. This research has started to identify brain regions that encode metacognitive processes. However, the educational and neuroscience disciplines have largely developed separately with little exchange and communication. In this article, we review the literature on metacognition in educational and cognitive neuroscience and identify entry points for synthesis. We argue that to improve our understanding of metacognition, future research needs to (i) investigate the degree to which different protocols relate to the similar or different metacognitive constructs and processes, (ii) implement experiments to identify neural substrates necessary for metacognition based on protocols used in educational sciences, (iii) study the effects of training metacognitive knowledge in the brain, and (iv) perform developmental research in the metacognitive brain and compare it with the existing developmental literature from educational sciences regarding the domain-generality of metacognition.

Network reorganization during verbal fluency task in fronto-temporal epilepsy: A functional near-infrared spectroscopy study

This is the first study to use functional near-infrared spectroscopy (fNIRS) to investigate how the lateralization of the epileptogenic zone affects the reconfiguration of task-related network patterns. Eleven left fronto-temporal epilepsy (L-FTE) and 11 right fronto-temporal epilepsy (R-FTE), as well as 22 age- and gender-matched controls, were enrolled. Signals from 52-channel fNIRS were recorded while the subject was undertaking verbal fluency tasks (VFTs), which included categorical (CFT) and letter (LFT) fluency tasks. Three analytic methods were used to study the network topology: network-based analysis, hub identification, and proportional threshold to select the top 20% strongest connections for both graph theory parameters and clinical correlation. Performance of CFT is accomplished primarily using the ventral pathway, and bilateral ventral pathways are augmented in fronto-temporal epilepsy patients by strengthening the inter-hemispheric connections, especially for R-FTE. LFT mainly employed the dorsal pathway, and further prioritized the left dorsal pathway in strengthening intra-hemispheric connections in fronto-temporal epilepsy, especially L-FTE. The top 20% of the strongest connections only present differences in CFT network compared with the controls. R-FTE increased inter-hemispheric network density, while L-FTE decreased inter-hemispheric average characteristic path length. Accumulative seizure burden only affects L-FTE network. Better LFT performance and longer educational years seem to promote left fronto-temporal networks, and decreased the demand from RR intra-hemispheric connectivity in L-FTE. LFT scores in R-FTE are maintained by preserved RR intra-hemispheric networks. However, CFT scores and educational years seem to have no effect on the CFT network topology in both FTE.

Association of General Cognitive Functions with Gaming Use in Young Adults: A Comparison among Excessive Gamers, Regular Gamers and Non-Gamers

This study aimed to examine the relationship of general cognitive function with gaming use, and to identify elements of intelligence predicting increased gaming use. In total, 160 young adults participated in this study. Two clinical groups (n = 97) were defined: excessive gaming users diagnosed with internet gaming disorder (IGD) (n = 64) and the high-risk users (n = 33). The control group (n = 63) was also divided into regular gamers (n = 14) and non-gamers (n = 49). Participants completed the Wechsler Adult Intelligence Scale-IV and self-reported questionnaires regarding IGD severity and gaming hours. The IGD group had significantly lower Full Scale Intelligence Quotient (FSIQ), Verbal Comprehension Index (VCI), and Processing Speed Index (PSI) scores, compared with regular gamers and non-gamers. The IGD group also exhibited lower Working Memory Index (WMI) scores, compared with non-gamers. The high-risk group demonstrated significantly lower PSI score, compared with non-gamers. Furthermore FSIQ, VCI, WMI, and PSI scores were significant predictors of gaming hours in the IGD group. For the high-risk group, FSIQ, WMI, and VCI scores were negatively associated with gaming hours. Our study demonstrates the need to address the importance of enhancing working memory and verbal ability, thus, preventing the development of gaming addiction among individuals at high-risk gamers.

Nonverbal fluency assessed by the five-point test in epilepsy patients with unilateral mesial temporal sclerosis-a Brazilian study

OBJECTIVE

To investigate the performance of epilepsy patients diagnosed with unilateral mesial temporal sclerosis (MTS) on a nonverbal fluency measure using the five-point test (FPT). Our secondary aim was to investigate any differences in FPT and verbal fluency test (VFT) scores between left and right MTS. We hypothesized that scores on the FPT, commonly utilized in the assessment of individuals with presumed frontal lobe damage, would be lower in patients with temporal lobe dysfunction.

METHOD

One hundred eighty patients diagnosed with temporal lobe epilepsy (TLE) and 150 healthy controls (HCs) were included in this retrospective study. We analyzed correlations between scores obtained from FPT and phonemic and semantic VFT, and scores according to the lateralization of epileptogenic focus in the TLE group.

RESULTS

Overall, the TLE patients had lower performance than the HCs on the FPT, but no differences were observed on perseverance rates (p = 0.992). Statistically significant difference was found in both sections of the VFT in association with the lateralization of the epileptogenic zone (p < 0.001). As for the FPT, differences did not reach statistical significance (p = 0.0857).

CONCLUSIONS

Our results support the hypothesis of involvement of the temporal areas on tasks such as the FPT, despite the lack of a lateralizing effect. Our findings also contribute to better understanding of the role of the FPT in assessment of executive function in patients with unilateral MTS, and provide further psychometric data on a native Brazilian population.

Characteristics of resting-state functional connectivity in older adults after the PICMOR intervention program: a preliminary report

BACKGROUND

The present study aimed to provide a basis for future research examining the neural mechanisms that underlie the beneficial effect of an intervention program, Photo-Integrated Conversation Moderated by Robots (PICMOR), on verbal fluency in older adults as identified in our previous randomized controlled trial. In this preliminary report, we conducted an additional experiment using resting-state functional magnetic resonance imaging (rsfMRI) after the intervention period. Specifically, we investigated the resting-state functional connectivity (rsFC) characteristics of the intervention group (INT) compared to the control group (CONT).

METHODS

rsfMRI data were acquired from 31 and 30 participants in INT and CONT, respectively, after the intervention. In the analyses, two of the most important regions in verbal fluency, the left inferior and middle frontal gyri, were selected as seed regions, and the rsFCs were compared between groups. We also conducted regression analyses for rsFCs using the difference in individual phonemic verbal fluency task (PVFT) scores between the pre- and post-intervention periods (i.e., post- minus pre-intervention) as an independent variable.

RESULTS

We found higher rsFC in INT than in CONT between the left inferior frontal gyrus as a seed region and the temporal pole and middle frontal gyrus. The rsFC strength between the left inferior frontal gyrus and temporal pole positively correlated with an increased PVFT score between the pre- and post-intervention periods. In contrast, we found lower rsFC in INT than in CONT between the left middle frontal gyrus as a seed region and the posterior cingulate cortex, precuneus, and postcentral gyrus.

CONCLUSIONS

Our findings suggest that the beneficial intervention effect of PICMOR on verbal fluency is characterized by enhanced rsFC of the left inferior frontal gyrus with semantic and executive control-related regions and suppressed rsFC between the left middle frontal gyrus and posterior cortical midline structures. No definitive conclusions can be made because of a lack of rsfMRI data before the intervention. However, this pilot study provides the candidates for rsFCs, reflecting the beneficial effects of PICMOR on the brain network involved in verbal fluency.

TRIAL REGISTRATION

The trial was retrospectively registered at the UMIN Clinical Trials Registry ( UMIN000036667 ) (May 7th, 2019).

Cognition in Vascular Aging and Mild Cognitive Impairment

Cardiovascular health declines with age, due to vascular risk factors, and this leads to an increasing risk of cognitive decline. Mild cognitive impairment (MCI) is defined as the negative cognitive changes beyond what is expected in normal aging. The purpose of the study was to compare older adults with vascular risk factors (VRF), MCI patients, and healthy controls (HC) in main dimensions of cognitive control. The sample comprised a total of 109 adults, aged 50 to 85 (M = 66.09, S.D. = 9.02). They were divided into three groups: 1) older adults with VRF, 2) MCI patients, and 3) healthy controls (HC). VRF and MCI did not differ significantly in age, educational level, or gender as was the case with HC. The tests used mainly examine inhibition, cognitive flexibility, and working memory processing. Results showed that the VRF group had more Set Loss Errors in drawing designs indicating deficits in establishing cognitive set and in cognitive shifting. MCI patients displayed lower performance in processing. Hence, different types of specific impairments emerge in vascular aging and MCI, and this may imply that discrete underlying pathologies may play a role in the development of somewhat different profiles of cognitive decline.

Drumming Motor Sequence Training Induces Apparent Myelin Remodelling in Huntington's Disease: A Longitudinal Diffusion MRI and Quantitative Magnetization Transfer Study

Background:

Impaired myelination may contribute to Huntington’s disease (HD) pathogenesis.

Objective:

This study assessed differences in white matter (WM) microstructure between HD patients and controls, and tested whether drumming training stimulates WM remodelling in HD. Furthermore, it examined whether training-induced microstructural changes are related to improvements in motor and cognitive function.

Methods:

Participants undertook two months of drumming exercises. Working memory and executive function were assessed before and post-training. Changes in WM microstructure were investigated with diffusion tensor magnetic resonance imaging (DT-MRI)-based metrics, the restricted diffusion signal fraction (Fr) from the composite hindered and restricted model of diffusion (CHARMED) and the macromolecular proton fraction (MPF) from quantitative magnetization transfer (qMT) imaging. WM pathways linking putamen and supplementary motor areas (SMA-Putamen), and three segments of the corpus callosum (CCI, CCII, CCIII) were studied using deterministic tractography. Baseline MPF differences between patients and controls were assessed with tract-based spatial statistics.

Results:

MPF was reduced in the mid-section of the CC in HD subjects at baseline, while a significantly greater change in MPF was detected in HD patients relative to controls in the CCII, CCIII, and the right SMA-putamen post-training. Further, although patients improved their drumming and executive function performance, such improvements did not correlate with microstructural changes. Increased MPF suggests training-induced myelin changes in HD.

Conclusion:

Though only preliminary and based on a small sample size, these results suggest that tailored behavioural stimulation may lead to neural benefits in early HD, that could be exploited for delaying disease progression.