Frontal and temporal lobe involvement on verbal fluency measures in amyotrophic lateral sclerosis

Verbal and nonverbal fluency in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a multi-system disorder that commonly affects cognition and behaviour. Verbal fluency impairments are consistently reported in ALS patients, and we aimed to investigate whether this deficit extends beyond the verbal domain. We further aimed to determine whether deficits are underpinned by a primary intrinsic response generation impairment (i.e., a global reduction across tasks), potentially related to apathy, or an inability to maintain responding over time (i.e., a 'drop off' pattern). Twenty-two ALS patients and 21 demographically-matched controls completed verbal and nonverbal fluency tasks (phonemic/semantic word fluency, design fluency, gesture fluency and ideational fluency), requiring the generation of responses over a specified time period. Fluency performance was analysed in terms of the overall number of novel items produced, as well as the number of items produced in the first 'initiation' and the remaining 'maintenance' time periods. ALS patients' overall performance was not globally reduced across tasks. Patients were impaired only on meaningful gesture fluency, which requires the generation of gestures that communicate meaning (e.g., waving). On phonemic fluency, ALS patients showed a 'drop off' pattern of performance, where they had difficulty maintaining responding over time, but this pattern was not evident on the other fluency tasks. Apathy did not appear to be related to fluency performance. The selective meaningful gesture fluency deficit, in the context of preserved meaningless gesture fluency, highlights that the retrieval of action knowledge may be weakened in early ALS.

The Spectrum of Cognitive Dysfunction in Amyotrophic Lateral Sclerosis: An Update

Cognitive dysfunction is an important non-motor symptom in amyotrophic lateral sclerosis (ALS) that has a negative impact on survival and caregiver burden. It shows a wide spectrum ranging from subjective cognitive decline to frontotemporal dementia (FTD) and covers various cognitive domains, mainly executive/attention, language and verbal memory deficits. The frequency of cognitive impairment across the different ALS phenotypes ranges from 30% to 75%, with up to 45% fulfilling the criteria of FTD. Significant genetic, clinical, and pathological heterogeneity reflects deficits in various cognitive domains. Modern neuroimaging studies revealed frontotemporal degeneration and widespread involvement of limbic and white matter systems, with hypometabolism of the relevant areas. Morphological substrates are frontotemporal and hippocampal atrophy with synaptic loss, associated with TDP-43 and other co-pathologies, including tau deposition. Widespread functional disruptions of motor and extramotor networks, as well as of frontoparietal, frontostriatal and other connectivities, are markers for cognitive deficits in ALS. Cognitive reserve may moderate the effect of brain damage but is not protective against cognitive decline. The natural history of cognitive dysfunction in ALS and its relationship to FTD are not fully understood, although there is an overlap between the ALS variants and ALS-related frontotemporal syndromes, suggesting a differential vulnerability of motor and non-motor networks. An assessment of risks or the early detection of brain connectivity signatures before structural changes may be helpful in investigating the pathophysiological mechanisms of cognitive impairment in ALS, which might even serve as novel targets for effective disease-modifying therapies.

Inhibitory dysfunction may cause prospective memory impairment in temporal lobe epilepsy (TLE) patients: an event-related potential study

Introduction

Prospective memory (PM) is the ability to remember future intentions, and PM function is closely related to independence in daily life, particularly in patients with temporal lobe epilepsy (TLE). As PM involves various cognitive components of attention, working memory, inhibition and other executive functions, this study investigated how TLE may affect PM components and the underlying neural mechanisms.

Methods

Sixty-four subjects were recruited, including 20 refractory TLE patients, 18 well-controlled TLE patients and 26 age-matched healthy controls. A set of neuropsychological tests was administered to assess specific brain functions. An event-related potential (ERP) task was used to further explore how PM and its components would be differentially affected in the two TLE types.

Results

Our findings revealed that: (1) refractory TLE patients scored lower than the healthy controls in the digit span, Verbal Fluency Test and Symbol Digit Modalities Test; (2) refractory TLE patients exhibited impaired PM performance and reduced prospective positivity amplitudes over the frontal, central and parietal regions in ERP experiments when compared to the healthy controls; and (3) decreased P3 amplitudes in the nogo trials were observed over the frontal-central sites in refractory but not in well-controlled TLE patients.

Discussion

To our knowledge, this is the first ERP study on PM that has specifically identified PM impairment in refractory but not in well-controlled TLE patients. Our finding of double dissociation in PM components suggests that inhibition dysfunction may be the main reason for PM deficit in refractory TLE patients. The present results have clinical implications for neuropsychological rehabilitation in TLE patients.

Effects of probiotic supplements on cognition, anxiety, and physical activity in subjects with mild and moderate Alzheimer's disease: A randomized, double-blind, and placebo-controlled study

Probiotics have been suggested as an effective adjuvant treatment for Alzheimer's disease (AD) due to their modulating effect on the gut microbiota, which may affect the gut-brain axis. Therefore, we aimed to evaluate the effects of two different single-strain probiotics on cognition, physical activity, and anxiety in subjects with mild and moderate AD. Eligible patients (n = 90) with AD were randomly assigned to either of two interventions [Lactobacillus rhamnosus HA-114 (1015 CFU) or Bifidobacterium longum R0175 (1015 CFU)] or placebo group, receiving probiotic supplement twice daily for 12 weeks. The primary outcome of the study was cognitive function measured by using the two tests, namely, the Mini-Mental State Examination (MMSE) and the categorical verbal fluency test (CFT). Secondary outcomes included a performance in Activities of Daily Living (ADL), the Lawton Instrumental Activities of Daily Living (IADL) scale, and the Generalized Anxiety Disorder (GAD-7) scale. Linear mixed-effect models were used to investigate the independent effects of probiotics on clinical outcomes. After 12 weeks, MMSE significantly improved cognition (P Interaction < 0.0001), with post hoc comparisons identifying significantly more improvement in the B. longum intervention group (differences: 4.86, 95% CI: 3.91-5.81; P < 0.0001) compared with both the placebo and L. rhamnosus intervention groups (differences: 4.06, 95% CI: 3.11-5.01; P < 0.0001). There was no significant difference between the two intervention groups (differences: -0.8, 95% CI: -1.74 to 0.14; P = 0.09). In conclusion, this trial demonstrated that 12-week probiotic supplementation compared with placebo had beneficial effects on the cognition status of patients with AD.

Adaptation and norming of the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS) for three language groups in South Africa

Objectives: To adapt and translate the Edinburgh Cognitive and behavioural amyotrophic lateral sclerosis screen (ECAS); to generate preliminary normative data for three language groups in South Africa (SA); to assess the convergent validity of the ECAS in SA samples. Methods: The ECAS was linguistically and culturally adapted for Afrikaans-, isiXhosa-, and English-speaking SA adults (n = 108, 100, and 53, respectively). Each language group was stratified by age and educational level. Cutoff scores for cognitive impairment were set at the group mean minus two standard deviations (SDs). A pilot sample of ALS patients and controls (n = 21 each) were administered the ECAS and an extensive neuropsychological evaluation (NPE) and the Montreal Cognitive Assessment (MoCA) to assess convergent validity. Results: Across the three language groups, the total ECAS cutoff scores ranged from 68 to 97. The ECAS score correlated significantly positively with educational level (p < 0.001) and negatively with age (p < 0.005). The restricted letter fluency task demonstrated a floor effect, particularly in Afrikaans-speakers. The mean total ECAS score (±SD) was similar in ALS patients (103.52 ± 11.90) and controls (100.67 ± 20.49; p = 0.58). Three (14.3%) ALS patients scored below the cutoff for cognitive impairment. Correlations between individual ECAS subtests and analogous NPE tests ranged from weak to moderate. The MoCA score was significantly positively correlated with the ECAS total score (r = 0.59; p = < 0.001). Conclusions: The adapted ECAS and associated normative data will aid cognitive screening of African ALS patients. Larger participant numbers are needed to assess the validity of the adapted instrument.

Cognitive and behavioural impairment in amyotrophic lateral sclerosis

PURPOSE OF REVIEW

The current review provides an up to date overview of the nature and progression of the cognitive and behavioural impairment in amyotrophic lateral sclerosis (ALS). Understanding these symptoms has implications for the management of the disease and the design of clinical trials, in addition to the support of patient and caregiver regarding mental capacity and end of life decision-making.

RECENT FINDINGS

Cognitive and behavioural change in ALS are best characterized as the consequence of extensive network dysfunction. 35-45% of ALS patients present with mild-moderate cognitive impairment and comorbid dementia occurs in approximately 14% of patients, the majority of these meeting diagnostic criteria for frontotemporal dementia (FTD). Cognitive change in ALS manifests most commonly as executive dysfunction and language impairment. Behavioural change in the form of apathy, disinhibition, loss of sympathy and empathy, stereotyped behaviours and dietary changes occur.

SUMMARY

Cognitive and behavioural impairment is an important feature of ALS, and reflects broad network dysfunction of frontostriatal and frontotemporal systems. Cognition and behaviour should be assessed early in the diagnostic process, and data driven approaches should be developed to enable reliable quantitative outcome assessment suitable for clinical trials.

Intrusion errors during verbal fluency task in amyotrophic lateral sclerosis

BACKGROUND

Numerous studies have noted the presence of a dysexecutive component of the ALS-FTD. The most widely replicated result refers to the significantly reduced verbal fluency of ALS patients when compared to healthy people. As ALS patients have motor alterations that interfere with production, qualitative studies have the advantage of being independent of the degree of motor disability and revealing patients' cognitive state. This study examined the production differences between 42 ALS patients who presented with different degrees of dementia and motor impairment and 42 healthy people. Production processes were studied by extending the administration time of a letter fluency task to 2 minutes for the phonemic verbal fluency (PVF) and semantic verbal fluency (SVF) categories. This ensured that the qualitative aspects of verbal fluency were addressed, paying special attention to the new perseverations and intrusions, as well as any clinical correlates that may exist.

RESULTS

The ALS patients produced a significantly lower number of responses in PVF (p = .017) and SVF (p = .008). The rest of the indicators for frontal lobe alteration also suggested the existence of a dysfunction. The most remarkable results were the number of intrusions on the PVF task, which was much higher in the ALS group (p = .002). However, the number of perseverations did not differ significantly.

CONCLUSIONS

This study highlights the value of intrusions in addressing cognitive deterioration in ALS patients. This deterioration seems to be independent of the degree of motor impairment and of behavioural alterations. Therefore, the value of the intromissions on the verbal fluency task was highlighted as an indicator of a new cognitive alteration, which can be easily evaluated, even retrospectively.

Spectroscopic markers of neurodegeneration in the mesial prefrontal cortex predict survival in ALS

Background and objective: N-acetylaspartate (NAA) and myo-inositol (mIns) are spectroscopic markers of neuronal integrity and astrogliosis, respectively. We performed a survival analysis to determine the prognostic value of the NAA/mIns metabolite ratio in ALS after a period of two and five years. Methods: Twenty-four patients with ALS (two with ALS-FTD) were recruited to participate in a high-field MR spectroscopy study of the mesial prefrontal cortex. Univariate and multivariate Cox proportional hazards analyses were used to assess NAA/mIns as a predictor of survival alongside other demographic and clinical measures. Census dates were set at two and five years after the time of MR scan for each patient. Survival curves were calculated using the Kaplan-Meier method. Results: After a five-year observation period, 19 patients had died and five were still alive. Median survival time from date of scan was 1.95 years. Univariate and multivariate Cox analysis showed NAA/mIns to be a significant independent predictor of survival at two years after scanning, but not at five years. Conclusion: Cerebral degeneration in the mesial prefrontal cortex as detected by the NAA/mIns metabolite ratio is predictive of survival in ALS in a time-dependent manner.

Abnormal Functional Connectivity Density in Amyotrophic Lateral Sclerosis

Purpose: Amyotrophic lateral sclerosis (ALS) is a motor neuro-degenerative disorder that also damages extra-motor neural pathways. A significant proportion of existing evidence describe alterations in the strengths of functional connectivity, whereas the changes in the density of these functional connections have not been explored. Therefore, our study seeks to identify ALS-induced alternations in the resting-state functional connectivity density (FCD).

Methods: Two groups comprising of 38 ALS patients and 35 healthy participants (age and gender matched) were subjected to the resting-state functional magnetic resonance imaging (MRI) scanning. An ultra-fast graph theory method known as FCD mapping was utilized to calculate the voxel-wise short- and long-range FCD values of the brain for each participant. FCD values of patients and controls were compared based on voxels in order to discern cerebral regions that possessed significant FCD alterations. For areas demonstrating a group effect of atypical FCD in ALS, seed-based functional connectivity analysis was then investigated. Partial correlation analyses were carried out between aberrant FCDs and several clinical variables, controlling for age, gender, and total intracranial volume.

Results: Patients with ALS were found to have decreased short-range FCD in the primary motor cortex and increased long-range FCD in the premotor cortex. Extra-motor areas that also displayed extensive FCD alterations encompassed the temporal cortex, insula, cingulate gyrus, occipital cortex, and inferior parietal lobule. Seed-based correlation analysis further demonstrated that these regions also possessed disrupted functional connectivity. However, no significant correlations were identified between aberrant FCDs and clinical variables.

Conclusion: FCD changes in the regions identified represent communication deficits and impaired functional brain dynamics, which might underlie the motor, motor control, language, visuoperceptual and high-order cognitive deficits in ALS. These findings support the fact that ALS is a disorder affecting multiple systems. We gain a deeper insight of the neural mechanisms underlying ALS.

Brain MR Imaging in Patients with Lower Motor Neuron-Predominant Disease

Purpose To investigate the patterns of cortical thinning and white matter tract damage in patients with lower motor neuron (LMN)-predominant disease compared with healthy control subjects and those with classic amyotrophic lateral sclerosis (ALS) and to evaluate the relationship between brain structural changes and clinical and cognitive features in these patients. Materials and Methods This study was approved by the local ethical committee, and written informed consent was obtained from all subjects before enrollment. Twenty-eight patients with LMN-predominant disease were compared with 55 patients with ALS and 56 healthy control subjects. Patients underwent a clinical and neuropsychological assessment and T1-weighted and diffusion-tensor magnetic resonance (MR) imaging. Surface-based morphometry was used to assess cortical thickness. Tract-based spatial statistics and tractography were used to study white matter tract damage. Results Patients with LMN-predominant disease did not show differences compared with healthy control subjects in cortical thickness and diffusion-tensor MR imaging metrics. Patients with ALS showed cortical thinning of the motor-related cortices and a distributed involvement of the prefrontal, temporal, and parietal gyri (P < .05, false discovery rate corrected). Patients with ALS also showed white matter damage along motor and extramotor tracts compared with control subjects and patients with LMN-predominant disease (tract-based spatial statistics: P < .05, family-wise error corrected; tractography: P values < .001 to .05, false discovery rate corrected). In patients with LMN-predominant disease, cognitive deficits correlated with alterations in diffusivity in the left cingulum (r = -0.66, P = .01) and superior longitudinal fasciculus (r = -0.65, P = .05). Conclusion Motor and extramotor cortical thinning and diffusion-tensor MR imaging alterations were specific for motor neuron disease phenotypes, with clinically overt upper motor neuron involvement. However, the lack of significant differences in cortical thickness between subjects with LMN-predominant disease and those with ALS and cognitive deficits associated with alterations in diffusivity in patients with LMN-predominant disease suggest that investigating brain structural and microstructural MR imaging features may provide markers of central nervous system damage in patients with rare motor neuron disease. (©) RSNA, 2016 Online supplemental material is available for this article.

Gait control and executive dysfunction in early schizophrenia

Dysexecutive functioning, which is described as an enduring core feature of schizophrenia, has been associated with gait disorders. However, few studies have reported gait disorders in schizophrenia patients. The objective of this study was to examine the association between executive dysfunction and gait performance in recent-onset schizophrenia patients using the dual task paradigm. Thirty-two subjects participated to the study: 17 with recent-onset schizophrenia and 15 healthy age-matched controls. Executive functions were evaluated using the Frontal Assessment Battery, Stroop and Trail-Making tests. Mean values and coefficients of variation (CV) of the temporal gait parameters while single tasking (just walking) and while dual tasking (walking and forward counting, walking and backward counting, walking and verbal fluency) were measured using the SMTEC(®)-footswitch system. We focused on the CV of stride time as this measure has been shown to be the most representative parameter of higher gait control. A strong effect of the stride time was found in the group factor for the verbal fluency dual-task when compared to controls (Cohen's d mean = 1.28 and CV = 1.05). The effect was lower in the other dual tasks, and insignificant in the single task of walking. This study shows that patients exhibit higher stride-to-stride variability while dual tasking than controls. It also shows a stronger impact of verbal fluency on gait regularity compared to the other dual tasks revealing a relationship between the executive dysfunction and gait modification. Those results are in line with the idea that schizophrenia implies not only cognitive but also motor functioning and coordination impairment.

Molecular imaging of microglial activation in amyotrophic lateral sclerosis

There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, ¹⁸F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of ¹⁸F-DPA-714 was increased in ALS patients during the “time of diagnosis” phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation.

A systematic review of behavioural changes in motor neuron disease

Motor neuron disease (MND) and the behavioural variant of frontotemporal dementia (bvFTD) are thought to be part of a disease spectrum. There is uncertainty about the frequency and characteristics of behavioural changes in MND, and similarly, about a relation between bvFTD and the site of onset of MND. Our aim was to perform a systematic review of the publications on behavioural changes in MND. An extensive search for articles on behavioural changes in MND patients was performed. First, cohort studies of MND patients were reviewed to summarize the prevalence of bvFTD and mild behavioural changes. Secondly, data on bvFTD symptoms (mostly from case reports) of individual MND-bvFTD patients were used to analyse characteristics and pooled prevalences of bvFTD symptoms. In addition, site of onset, survival and demographic variables of MND-bvFTD patients were analysed. Results showed that in cohorts, 8.1% (95% CI 5.6 - 11.5%) of MND patients had bvFTD. In 170 individual patients with MND-bvFTD, perseveration (40%), apathy (29%) and disinhibition (26%) were the most frequently reported behavioural changes; 43% had memory disturbances and bulbar onset was found in 48%. In conclusion, 8% of MND patients have bvFTD, with perseveration being reported most frequently. MND-bvFTD is often accompanied by memory disturbances and is related to bulbar onset.

Verbal fluency: Effect of time on item generation

The distribution of item generation/time in the performance of elderly on verbal fluency (VF) remains unknown.