Magnetoencephalography resting-state correlates of executive and language components of verbal fluency

Verbal fluency (VF) is a heterogeneous cognitive function that requires executive as well as language abilities. The purpose of this study was to elucidate the specificity of the resting state MEG correlates of the executive and language components. To this end, we administered a VF test, another verbal test (Vocabulary), and another executive test (Trail Making Test), and we recorded 5-min eyes-open resting-state MEG data in 28 healthy participants. We used source-reconstructed spectral power estimates to compute correlation/anticorrelation MEG clusters with the performance at each test, as well as with the advantage in performance between tests, across individuals using cluster-level statistics in the standard frequency bands. By obtaining conjunction clusters between verbal fluency scores and factor loading obtained for verbal fluency and each of the two other tests, we showed a core of slow clusters (delta to beta) localized in the right hemisphere, in adjacent parts of the premotor, pre-central and post-central cortex in the mid-lateral regions related to executive monitoring. We also found slow parietal clusters bilaterally and a cluster in the gamma 2 and 3 bands in the left inferior frontal gyrus likely associated with phonological processing involved in verbal fluency.

Performance on verbal fluency tasks depends on the given category/letter: Preliminary data from a multivariable analysis

Verbal fluency tasks are often used in neuropsychological research and may have predictive and diagnostic utility in psychiatry and neurology. However, researchers using verbal fluency have uncritically assumed that there are no category- or phoneme-specific effects on verbal fluency performance. We recruited 16 young adult subjects and administered two semantic (animals, trees) and phonemic (K, M) fluency tasks. Because of the small sample size, results should be regarded as preliminary. On the animal compared to the tree task, subjects produced significantly more legal words, had a significantly lower intrusion rate, significantly shorter first-response latencies and final silence periods, as well as significantly shorter between-cluster response latencies. These differences may be explained by differences in the category sizes, integrity of the categories' borders, and efficiency of the functional connectivity between subcategories. On the K compared to the M task, subjects produced significantly more legal words and had significantly shorter between-cluster response times. Counterintuitively, a corpus analysis revealed there are more words starting with m compared to k in the experimental language. Our results have important implications for research utilizing verbal fluency, including decreased reproducibility, unreliability of diagnostic and predictive tools based on verbal fluency, and decreased knowledge accumulation.

Clustering and switching in verbal fluency: a comparison between control and individuals with brain damage

ABSTRACT Purpose The aim of this study is to analyze and compare the performance and strategies used by control subjects and patients with unilateral brain damage on phonemic and semantic Verbal Fluency tasks. Methods The sample consisted of 104 participants divided into four groups (26 with left hemisphere damage and aphasia- LHDa, 28 with left hemisphere damage and no aphasia- LHDna, 25 with right hemisphere damage- RHD and 25 neurologically healthy control subjects). All participants were administered the phonemic (“M” letter-based) and semantic (animals) verbal fluency tasks from the Montreal-Toulouse Language Assessment Battery (MTL-BR). Results Patients in the LHDa group showed the worst performance (fewer words produced, fewer clusters and switches) in both types of fluency task. RHD group showed fewer switching productions when compared with controls and LHDna had fewer words productions than controls in the first 30 seconds block. Conclusion Our findings suggest that the LHDa group obtained lower scores in most measures of SVF and PVF when compared to the other groups.

Cognitive ageing: 20 years process

Background: People with normal functionality have normal cognitive changes associated with the ageing process while many people age without cognitive decline. The most exact effects of age are cognitive impairments in learning, memory, and problem solving. These age-related effects slightly increase or do not change for many years, and do not affect the daily life activities of the person. Methods: To investigate age-related cognitive effects, detailed cognitive evaluations were compared with 20 years intervals in 7 (seven) elderly individuals at Haydarpaşa Numune Training and Research Hospital in 2019. These individuals are continuing daily life activities and sociocultural relations independently. Mini-mental state examination, verbal memory processes test and visual memory test-Wechsler memory scale for memory processes, digit span test for attention function, verbal fluency, similarities, stroop, and trail-making test for the evaluation of frontal lobe functions, Benton’s line direction determination test for the visuospatial organization have been applied to individuals. Results: In comparison with the cognitive test results applied twenty years ago; immediate memory impairment is evident, abstraction and attention function are relatively less affected. The tests showing the frontal lobe function, the verbal fluency which also reflects the vocabulary information is less affected, while the cognitive impairment is more in consecutive-complex processes. Conclusion: Cognitive functions based on attention, vocabulary and knowledge are substantially preserved with mild improvement in normal ageing. The most important improvement is on executive functions due to the decrease in motor and cognitive processing speed in cases where complex information needs to be processed.

Semantic Verbal Fluency in Youth with Down Syndrome: Analysis of Conventional and Contextual Cluster Formation

Expressive language delays and executive functioning challenges are common in youth with Down syndrome (DS). Verbal fluency is one method to investigate these constructs. We examined semantic verbal fluency responses to determine patterns in response generation and the psychometric properties of coded cluster formations. Participants were 97 children and adolescents with DS ranging in age from 6 to 19 years old. The semantic verbal fluency task was administered at two time points, two weeks apart. Heterogeneity in performance was observed for responses when coded either with conventional or contextual classifications. Overall, the number of switches in conventional classifications was greater than contextual classifications. This implies that participants did not use traditional (conventional) categories to organize their semantic verbal fluency responses, but may have been using contextual strategies. However, the number of switches and cluster size variables had poor to moderate test–retest reliability, which indicated that participants did not stay consistent with their performance over the two-week testing interval, regardless of the strategies used. Therefore, conventional and contextual clusters and switches as a measure of executive control may not be appropriate for all individuals with DS and additional attention is warranted to determine the utility of response coding in this population.

Repetitive Transcranial Magnetic Stimulation as a Treatment for Veterans with Cognitive Impairment and Multiple Comorbidities

Background: Despite decades of research efforts, current treatments for Alzheimer’s disease (AD) are of limited effectiveness and do not halt the progression of the disease and associated cognitive decline. Studies have shown that repetitive transcranial magnetic stimulation (rTMS) may improve cognition. Objective: We conducted a pilot study to investigate the effect of rTMS on cognitive function in Veterans with numerous medical comorbidities. Methods: Participants underwent 20 sessions, over the course of approximately 4 weeks, of 10 Hz rTMS at the left dorsolateral prefrontal cortex with intensity of 120% resting motor threshold. Outcome measures including memory, language, verbal fluency, and executive functions were acquired at baseline, end of treatment, and 4 months after the last rTMS session. Twenty-six Veterans completed the study (13 in the active rTMS group, 13 in the sham rTMS group). Results: The study protocol was well-tolerated. Active, compared to sham, rTMS showed improved auditory-verbal memory at the end of treatment and at 4-month follow-up. However, the active rTMS group demonstrated a trend in decreased semantic verbal fluency at the end of treatment and at 4-month follow up. Conclusion: These preliminary results show rTMS is safe in general in this elderly Veteran population with multiple co-morbidities. Patients in the sham group showed an expected, slight decline in the California Verbal Learning Test scores over the course of the study, whereas the active treatment group showed a slight improvement at the 4-month post-treatment follow up. These effects need to be confirmed by studies of larger sample sizes.

Is Old Age Just a Number in Language Skills? Language Performance and Its Relation to Age, Education, Gender, Cognitive Screening, and Dentition in Very Old Finnish Speakers

Purpose: This study reports on how very old (VO) Finnish people without dementia perform in the Western Aphasia Battery (WAB) and two verbal fluency tasks and which demographic factors predict the performance. Method: The study included fifty 80- to 100-year-old community-dwelling Finnish speakers with no dementing illnesses or speech-language disabilities, who completed the WAB and two verbal fluency tasks. Multifactorial statistical analyses with recursive partitioning were carried out to determine the significant predictors out of five predictor variables (age, gender, education, dentition, and Mini-Mental State Examination [MMSE]) for four response variables (WAB Aphasia Quotient [AQ], Language Quotient [LQ], semantic, and phonemic word fluencies). Results: Overall, individual variation was notable in VO speakers. All predictor variables were statistically significantly associated with one or more of the language skills. Age was the most significant predictor; the critical age of 85–86 years was associated with a decline in WAB-AQ and semantic fluency. Poor dentition and the MMSE score both predicted a decline in WAB-LQ and phonemic fluency. A high level of education was positively associated with the skills of the best-performing individuals in WAB-AQ, WAB-LQ, and semantic fluency. Conclusions: VO age is a significant factor contributing to language performance. However, a younger age, a good cognitive performance, intact teeth, and a higher educational level also seem to have a preservative power as regards language skills. Gender differences should be interpreted with caution. The results of this study provide culture- and language-specific normative data, which aids in differentiating typical aging from the signs of acute or degenerative neuropathology to ensure appropriate medical and therapeutic interventions.

Substance Use-Related Cognitive Decline in Families with Autosomal Dominant Alzheimer’s Disease: A Cohort Study

Background: Cigarette smoking is a known risk factor for Alzheimer’s disease (AD). However, the association between neurodegeneration and other substances has not been fully determined. It is of vital importance to evaluate this relationship in populations at high risk of dementia. Since substance use possibly modifies the progression rate of cognitive decline, we studied this association in a unique and well-phenotyped cohort from the University of Antioquia: carriers of the PSEN1-E280A genetic variant. Objective: To determine the association between substance use and cognitive decline in carriers of the PSEN1-E280A genetic variant. Methods: A retrospective cohort study was conducted with 94 carriers and 69 noncarriers recruited between January 2019 and April 2020. A psychiatrist interviewed the participants using the Consumption of Alcohol, Cigarettes and other Substances questionnaire. The participants were also submitted to cognitive evaluation. The relationship between cognitive decline and substance use was explored through a mixed effects regression model. Results: There was an association between cigarettes and better performance on tasks related to perceptual organization, verbal fluency, and memory in carriers. Alcohol had a positive or negative effect on memory according to the type of alcoholic beverage. Results on marijuana use were no conclusive. Coffee was associated with progressive improvements in executive function and verbal fluency. Conclusion: Cigarette and alcohol were associated with an improvement of some cognitive assessments, possibly by a survival bias. In addition, coffee was related to improvements in executive function and language; therefore, its short-term neuroprotective potential should be studied.