The effects of executive and behavioral dysfunction on the course of ALS

Healthcare Professionals’ Views on the provision of Gastrostomy and Noninvasive Ventilation to Amyotrophic Lateral Sclerosis Patients in England, Wales, and Northern Ireland

Gastrostomy and noninvasive ventilation (NIV) are recommended interventions for the management of symptoms associated with amyotrophic lateral sclerosis (ALS). This study aimed to quantify the views of a range of healthcare professionals (HCPs) on the provision of these interventions in the United Kingdom. A total of 177 HCPs participated in an online survey. Significant differences were found between medical and allied HCPs’ views on: whether HCPs adhere to policy and accept legal constraints when it comes to making gastrostomy available to people with ALS; the impressions that HCPs receive of the way patients and caregivers understand the effects of gastrostomy and NIV on symptoms and quality of life; and the challenges HCPs face when caring for patients who have refused gastrostomy. More widely available guidelines for the provision of gastrostomy and advice on the best way to impart information to patients and caregivers about gastrostomy and NIV appear to be needed.

Clinical and Radiological Markers of Extra-Motor Deficits in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is now universally recognized as a complex multisystem disorder with considerable extra-motor involvement. The neuropsychological manifestations of frontotemporal, parietal, and basal ganglia involvement in ALS have important implications for compliance with assistive devices, survival, participation in clinical trials, caregiver burden, and the management of individual care needs. Recent advances in neuroimaging have been instrumental in characterizing the biological substrate of heterogeneous cognitive and behavioral deficits in ALS. In this review we discuss the clinical and radiological aspects of cognitive and behavioral impairment in ALS focusing on the recognition, assessment, and monitoring of these symptoms.

Distinct Clinical Features and Outcomes in Motor Neuron Disease Associated with Behavioural Variant Frontotemporal Dementia

AIM

To determine the motor phenotype and outcome in a clinically ascertained group of patients with motor neuron disease (MND) and frontotemporal dementia (FTD).

METHODS

This is an observational retrospective clinical study of patients fulfilling the clinical criteria for MND-FTD. A contemporary series of patients with amyotrophic lateral sclerosis (ALS) without dementia were included for comparison. Demographic, clinical, genetic, and neuropathological data were collected. A descriptive and comparative data analysis was performed.

RESULTS

We identified 22 patients with MND-FTD. Selective distal upper limb muscle weakness and atrophy with non-significant lower limb weakness during follow-up was the most frequent motor pattern, present in 18 patients - in 15 of them associated with severe dysphagia. Aspiration pneumonia was the most common cause of death (12/19; 63%) despite gastrostomy. One-third of the patients did not develop upper motor neuron dysfunction. When compared to classic ALS without dementia (n = 162), these features were significantly different. A neuro-pathological examination was performed on 7 patients, and it confirmed the presence of MND with TDP43 protein aggregates in all patients.

CONCLUSIONS

The MND-FTD patients frequently displayed a distinctive motor pattern characterized by weakness and atrophy in distal upper limb muscles and dysphagia, with no or little spreading to other regions. These features may help to define specific subgroups of patients, which is important with regard to clinical management, outcome, and research.

The burden of apathy for caregivers of patients with amyotrophic lateral sclerosis

OBJECTIVES

Apathy is the most common behavioral symptom of amyotrophic lateral sclerosis (ALS). Despite its known impact on caregiver wellbeing, apathy is typically considered a unitary construct making assessment and targeting treatment problematic. The aim of this study was to explore the relationship between caregiver burden and the behavioral, cognitive, and emotional symptoms of apathy in ALS.

METHODS

Fifty-one ALS patient-caregiver dyads from an ALS/frontotemporal dementia Clinic were assessed with the Apathy Evaluation Scale which measured the cognitive, behavioral, emotional, and nonspecific symptoms of apathy as well as the Zarit Burden Interview, a measure of perceived burden among caregivers of cognitively impaired older adults. The relationship between apathy and caregiver burden were analyzed using univariate and multivariate methods.

RESULTS

Apathy was identified in 18% of ALS patients. Greater behavioral (p = 0.011) and nonspecific (p = 0.010) symptoms of apathy exhibited by patients were reported by caregivers with higher levels of burden compared to caregivers with lower levels of burden. Of the cognitive, behavioral, emotional, and nonspecific symptoms of apathy, only the behavioral symptoms explained a significant amount of variance in caregiver burden (p = 0.031).

CONCLUSIONS

Apathy, specifically the behavioral symptoms of apathy was associated with higher burden of care among ALS caregivers, highlighting the importance of multidimensional assessment of apathy and provision of behavior management support as part of ALS care.

Apathy Is Correlated with Widespread Diffusion Tensor Imaging (DTI) Impairment in Amyotrophic Lateral Sclerosis

Apathy is recognized as the most common behavioral change in several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), a multisystem neurodegenerative disorder. Particularly, apathy has been reported to be associated with poor ALS prognosis. However, the brain microstructural correlates of this behavioral symptom, reported as the most common in ALS, have not been completely elucidated. Using diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS), here we aimed to quantify the correlation between brain microstructural damage and apathy scores in the early stages of ALS. Twenty-one consecutive ALS patients, in King's clinical stage 1 or 2, and 19 age- and sex-matched healthy controls (HCs) underwent magnetic resonance imaging and neuropsychological examination. Between-group comparisons did not show any significant difference on cognitive and behavioral variables. When compared to HCs, ALS patients exhibited a decreased fractional anisotropy (FA) [p < .05, threshold-free cluster enhancement (TFCE) corrected] in the corpus callosum and in bilateral anterior cingulate cortices. Self-rated Apathy Evaluation Scale (AES) scores and self-rated apathy T-scores of the Frontal Systems Behavior (FrSBe) scale were found inversely correlated to FA measures (p < .05, TFCE corrected) in widespread white matter (WM) areas, including several associative fiber tracts in the frontal, temporal, and parietal lobes. These results point towards an early microstructural degeneration of brain areas biologically involved in cognition and behavior regulation in ALS. Moreover, the significant correlations between apathy and DTI measures in several brain areas may suggest that subtle WM changes may be associated with mild behavioral symptoms in ALS even in the absence of overt cognitive and behavioral impairment.

Evaluating the cerebral correlates of survival in amyotrophic lateral sclerosis

Objective

To evaluate cerebral degenerative changes in ALS and their correlates with survival using 3D texture analysis.

Methods

A total of 157 participants were included in this analysis from four neuroimaging studies. Voxel-wise texture analysis on T1-weighted brain magnetic resonance images (MRIs) was conducted between patients and controls. Patients were divided into long- and short-survivors using the median survival of the cohort. Neuroanatomical differences between the two survival groups were also investigated.

Results

Whole-brain analysis revealed significant changes in image texture (FDR P < 0.05) bilaterally in the motor cortex, corticospinal tract (CST), insula, basal ganglia, hippocampus, and frontal regions including subcortical white matter. The texture of the CST correlated (P < 0.05) with finger- and foot-tapping rate, measures of upper motor neuron function. Patients with a survival below the media of 19.5 months demonstrated texture change (FDR P < 0.05) in the motor cortex, CST, basal ganglia, and the hippocampus, a distribution which corresponds to stage 4 of the distribution TDP-43 pathology in ALS. Patients with longer survival exhibited texture changes restricted to motor regions, including the motor cortex and the CST.

Interpretation

Widespread gray and white matter pathology is evident in ALS, as revealed by texture analysis of conventional T1-weighted MRI. Length of survival in patients with ALS is associated with the spatial extent of cerebral degeneration.

ALS-specific cognitive and behavior changes associated with advancing disease stage in ALS

Objective

To elucidate the relationship between disease stage in amyotrophic lateral sclerosis (ALS), as measured with the King's Clinical Staging System, and cognitive and behavioral change, measured with the Edinburgh Cognitive and Behavioural ALS Screen (ECAS).

Methods

A large multicenter observational cohort of 161 cross-sectional patients with ALS and 80 healthy matched controls were recruited across 3 research sites (Dublin, Edinburgh, and London). Participants were administered the ECAS and categorized into independent groups based on their King's clinical disease stage at time of testing.

Results

Significant differences were observed between patients and controls on all subtests of the ECAS except for visuospatial functioning. A significant cross-sectional effect was observed across disease stages for ALS-specific functions (executive, language, letter fluency) and ECAS total score but not for ALS-nonspecific functions (memory, visuospatial). Rates of ALS-specific impairment and behavioral change were also related to disease stage. The relationship between cognitive function and disease stage may be due to letter fluency impairment, whereas higher rates of all behavioral domains were seen in later King's stage. The presence of bulbar signs, but not site of onset, was significantly related to ALS-specific, ECAS total, and behavioral scores.

Conclusion

ALS-specific cognitive deficits and behavioral impairment are more frequent with more severe disease stage. By end-stage disease, only a small percentage of patients are free of neuropsychological impairment. The presence of bulbar symptoms exaggerates the differences observed between disease stages. These findings suggest that cognitive and behavioral change should be incorporated into ALS diagnostic criteria and should be included in future staging systems.

Self-Regulation and Executive Functioning as Related to Survival in Motor Neuron Disease: Preliminary Findings

OBJECTIVE

Disease progression varies widely among patients with motor neuron disease (MND). Patients with MND and coexisting dementia have shorter survival. However, implications of mild cognitive and behavioral difficulties are unclear. The present study examined the relative contribution of executive functioning and self-regulation difficulties on survival over a 6-year period among patients with MND, who scored largely within normal limits on cognitive and behavioral indices.

METHODS

Patients with MND (N = 37, age = 59.97 ± 11.57, 46% female) completed the Wisconsin Card Sorting Task as an executive functioning perseveration index. The Behavior Rating Inventory of Executive Functions (BRIEF-A) was used as a behavioral measure of self-regulation in two subdomains self-regulatory behavior (Behavioral Regulation) and self-regulatory problem-solving (Metacognition). Cox proportional hazard regression analyses were used.

RESULTS

In total, 23 patients died during follow-up. In Cox proportional hazard regressions adjusted for a priori covariates, each 10-point t-score increment in patient-reported BRIEF-A self-regulatory behavior and problem-solving difficulties increased mortality risk by 94% and 103%, respectively (adjusted HR = 1.94, 95% CI = 1.07-3.52; adjusted HR = 2.03, 95% CI = 1.19-3.48). In sensitivity analyses, patient-reported self-regulatory problem-solving remained significant independent of disease severity and a priori covariates (adjusted HR = 1.68, 95% CI = 1.01-2.78), though the predictive value of self-regulatory behavior was attenuated in adjusted models (HR = 1.67, 95% CI = 0.85-3.27). Caregiver-reported BRIEF-A ratings of patients and Wisconsin Card Sorting Task perseverative errors did not significantly predict survival.

CONCLUSIONS

Preliminary evidence suggests patient-reported self-regulatory problem-solving difficulties indicate poorer prognosis in MND. Further research is needed to uncover mechanisms that negatively impact patient survival.

Respiratory Assessment of ALS Patients: A Nationwide Survey of Current Dutch Practice

BACKGROUND AND OBJECTIVE

Non-invasive ventilation (NIV) is an established treatment for respiratory failure in patients with amyotrophic lateral sclerosis (ALS). Several studies have shown room for improvement with regard to respiratory care for ALS patients, including latency of referral. These studies focused on the time period starting at the moment of referral to a home ventilation service (HVS) onwards. In the current study we performed a nationwide survey to gain insight in the trajectory before referral. We questioned the assessment of respiratory impairment by ALS physicians/care teams, including criteria for referral to an HVS.

METHODS

We requested 40 ALS care teams in the Netherlands to fill in an online questionnaire on respiratory management in ALS patients.

RESULTS

Thirty-two ALS care teams (80%) responded. Forced vital capacity was the most frequently used test at each outpatient visit (72%) and often served as a criterion (78%) for referral to an HVS. Other respiratory function measurements that were performed less often included peak cough flow (50%), maximum inspiratory/expiratory pressure (31% /28%) and sniff nasal inspiratory pressure (13%). Morning headache was the most frequently questioned complaint (94%), followed by daytime sleepiness (91%). Dyspnoea and orthopnoea were reported by 38% and 59% as important complaints. Out of all patients under the care of the ALS care teams, the mean estimated proportion of patients that was referred to an HVS was 69% (range 20-100%). When physicians refrained from referral, the most often cited reasons were patient's decision to withhold NIV (94%) and cognitive impairment (50%). Sixteen percent of the respondents stated bulbar impairment as a reason to refrain from referral.

CONCLUSION

Despite findings in previous studies on the superiority of SNIP and PCF as compared to FVC, our study shows that a majority of ALS care teams still prefers to use FVC for the assessment of respiratory dysfunction and for the timing of referral to an HVS. Another finding is that bulbar impairment is not an obstacle for referral for NIV.

Physical therapy for individuals with amyotrophic lateral sclerosis: current insights

Amyotrophic lateral sclerosis (ALS) is a progressive, neurodegenerative, and inevitably fatal disease. There is no cure for ALS and life expectancy is typically 2–5 years after symptom onset. Despite the lack of a cure and the rapidly progressive nature of the disease, ALS is considered a “treatable disease” and rehabilitation is integral to optimal, comprehensive care. In addition to the other health care professions making up the health care team, physical therapy provides a critical role in the overall management in individuals with ALS. Physical therapy that is tailored to the individual’s needs and goals and focused on addressing symptoms and maximizing function and participation enables people with ALS to live their lives to the fullest and with quality. The purpose of this paper is to review some of the recent ALS research findings that have implications for physical therapy practice.

The Clinical and Radiological Spectrum of Hippocampal Pathology in Amyotrophic Lateral Sclerosis

Hippocampal pathology in Amyotrophic Lateral Sclerosis (ALS) remains surprisingly under recognized despite compelling evidence from neuropsychology, neuroimaging and neuropathology studies. Hippocampal dysfunction contributes significantly to the clinical heterogeneity of ALS and requires structure-specific cognitive and neuroimaging tools for accurate in vivo evaluation. Recent imaging studies have generated unprecedented insights into the presymptomatic and longitudinal processes affecting this structure and have contributed to the characterisation of both focal and network-level changes. Emerging neuropsychology data suggest that memory deficits in ALS may be independent from executive dysfunction. In the era of precision medicine, where the development of individualized care strategies and patient stratification for clinical trials are key priorities, the comprehensive review of hippocampal dysfunction in ALS is particularly timely.

mTh1 driven expression of hTDP-43 results in typical ALS/FTLD neuropathological symptoms

Transgenic mouse models are indispensable tools to mimic human diseases and analyze the effectiveness of related new drugs. For a long time amyotrophic lateral sclerosis (ALS) research depended on only a few mouse models that exhibit a very strong and early phenotype, e.g. SOD1 mice, resulting in a short treatment time window. By now, several models are available that need to be characterized to highlight characteristics of each model. Here we further characterized the mThy1-hTDP-43 transgenic mouse model TAR6/6 that overexpresses wild type human TARDBP, also called TDP-43, under control of the neuronal Thy-1 promoter presented by Wils and colleagues, 2010, by using biochemical, histological and behavioral readouts. Our results show that TAR6/6 mice exhibit a strong TDP-43 expression in the hippocampus, spinal cord, hypothalamus and medulla oblongata. Apart from prominent protein expression in the nucleus, TDP-43 protein was found at lower levels in the cytosol of transgenic mice. Additionally, we detected insoluble TDP-43 in the cortex, motoneuron loss, and increased neuroinflammation in the central nervous system of TAR6/6 animals. Behavioral analyses revealed early motor deficits in the clasping- and wire suspension test as well as decreased anxiety in the elevated plus maze. Further motor tests showed differences at later time points compared to non-transgenic littermates, thus allowing the observation of onset and severity of such deficits. Together, TAR6/6 mice are a valuable tool to test new ALS/FTLD drugs that target TDP-43 expression and insolubility, neuroinflammation, motoneuron loss or other TDP-43 related downstream signaling pathways since these mice exhibit a later pathology as previously used ALS/FTLD mouse models.

Phosphorylation of Threonine 175 Tau in the Induction of Tau Pathology in Amyotrophic Lateral Sclerosis-Frontotemporal Spectrum Disorder (ALS-FTSD). A Review

Approximately 50–60% of all patients with amyotrophic lateral sclerosis (ALS) will develop a deficit of frontotemporal function, ranging from frontotemporal dementia (FTD) to one or more deficits of neuropsychological, speech or language function which are collectively known as the frontotemporal spectrum disorders of ALS (ALS-FTSD). While the neuropathology underlying these disorders is most consistent with a widespread alteration in the metabolism of transactive response DNA-binding protein 43 (TDP-43), in both ALS with cognitive impairment (ALSci) and ALS with FTD (ALS-FTD; also known as MND-FTD) there is evidence for alterations in the metabolism of the microtubule associated protein tau. This alteration in tau metabolism is characterized by pathological phosphorylation at residue Thr¹⁷⁵ (pThr¹⁷⁵ tau) which in vitro is associated with activation of GSK3β (pTyr²¹⁶GSK3β), phosphorylation of Thr²³¹tau, and the formation of cytoplasmic inclusions with increased rates of cell death. This putative pathway of pThr¹⁷⁵ induction of pThr²³¹ and the formation of pathogenic tau inclusions has been recently shown to span a broad range of tauopathies, including chronic traumatic encephalopathy (CTE) and CTE in association with ALS (CTE-ALS). This pathway can be experimentally triggered through a moderate traumatic brain injury, suggesting that it is a primary neuropathological event and not secondary to a more widespread neuronal dysfunction. In this review, we discuss the neuropathological underpinnings of the postulate that ALS is associated with a tauopathy which manifests as a FTSD, and examine possible mechanisms by which phosphorylation at Thr¹⁷⁵tau is induced. We hypothesize that this might lead to an unfolding of the hairpin structure of tau, activation of GSK3β and pathological tau fibril formation through the induction of cis-Thr²³¹ tau conformers. A potential role of TDP-43 acting synergistically with pathological tau metabolism is proposed.

Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases

Neurodegenerative diseases are a common cause of morbidity and cognitive impairment in older adults. Most clinicians who care for the elderly are not trained to diagnose these conditions, perhaps other than typical Alzheimer's disease (AD). Each of these disorders has varied epidemiology, clinical symptomatology, laboratory and neuroimaging features, neuropathology, and management. Thus, it is important that clinicians be able to differentiate and diagnose these conditions accurately. This review summarizes and highlights clinical aspects of several of the most commonly encountered neurodegenerative diseases, including AD, frontotemporal dementia (FTD) and its variants, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and Huntington's disease (HD). For each condition, we provide a brief overview of the epidemiology, defining clinical symptoms and diagnostic criteria, relevant imaging and laboratory features, genetics, pathology, treatments, and differential diagnosis.

Prion-like mechanisms in amyotrophic lateral sclerosis

The prion hypothesis - a protein conformation capable of replicating without a nucleic acid genome - was heretical at the time of its discovery. However, the characteristics of the disease-misfolded prion protein and its ability to transmit disease, replicate, and spread are now widely accepted throughout the scientific community. In fact, in the last decade a wealth of evidence has emerged supporting similar properties observed for many of the misfolded proteins implicated in other neurodegenerative diseases, such as Alzheimer disease, Parkinson disease, tauopathies, and as described in this chapter, amyotrophic lateral sclerosis (ALS). Multiple studies have now demonstrated the ability for superoxide dismutase-1, 43-kDa transactive response (TAR) DNA-binding protein, fused-in sarcoma, and most recently, C9orf72-encoded polypeptides to display properties similar to those of prions. The majority of these are cell-free and in vitro assays, while superoxide dismutase-1 remains the only ALS-linked protein to demonstrate several prion-like properties in vivo. In this chapter, we provide an introduction to ALS and review the recent literature linking several proteins implicated in the familial forms of the disease to properties of the prion protein.

Measuring reliable change in cognition using the Edinburgh Cognitive and Behavioural ALS Screen (ECAS)

Background: Cognitive impairment affects approximately 50% of people with amyotrophic lateral sclerosis (ALS). Research has indicated that impairment may worsen with disease progression. The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) was designed to measure neuropsychological functioning in ALS, with its alternate forms (ECAS-A, B, and C) allowing for serial assessment over time. Objective: The aim of the present study was to establish reliable change scores for the alternate forms of the ECAS, and to explore practice effects and test-retest reliability of the ECAS’s alternate forms. Method: Eighty healthy participants were recruited, with 57 completing two and 51 completing three assessments. Participants were administered alternate versions of the ECAS serially (A-B-C) at four-month intervals. Intra-class correlation analysis was employed to explore test-retest reliability, while analysis of variance was used to examine the presence of practice effects. Reliable change indices (RCI) and regression-based methods were utilized to establish change scores for the ECAS alternate forms. Results: Test-retest reliability was excellent for ALS Specific, ALS Non-Specific, and ECAS Total scores of the combined ECAS A, B, and C (all > .90). No significant practice effects were observed over the three testing sessions. RCI and regression-based methods produced similar change scores. Conclusion: The alternate forms of the ECAS possess excellent test-retest reliability in a healthy control sample, with no significant practice effects. The use of conservative RCI scores is recommended. Therefore, a change of ≥8, ≥4, and ≥9 for ALS Specific, ALS Non-Specific, and ECAS Total score is required for reliable change.

ECAS A-B-C: alternate forms of the Edinburgh Cognitive and Behavioural ALS Screen

BACKGROUND

The Edinburgh Cognitive and Behavioural ALS Screen (ECAS) is a short assessment by which neuropsychological symptoms can be detected and quantified in people with ALS. To avoid potential practice effects with repeated administration, here we present alternative versions of the ECAS suitable for measuring change over time.

OBJECTIVE

To develop two alternate versions of the ECAS: ECAS-B and ECAS-C.

METHOD

One hundred and forty-nine healthy adult participants were recruited. Thirty participants completed a pilot study in developing the alternate versions. Two groups of 40 participants were administered the ECAS-B or ECAS-C and compared to published data of the original ECAS (ECAS-A) to determine equivalence. An additional 39 participants were administered the ECAS consecutively, either repeating the original version (ECAS-A-A-A) serially or the different versions (ECAS-A-B-C) to determine potential practice effects. Recordings of assessments were scored by a second researcher to determine inter-rater reliability.

RESULTS

No significant differences were found between versions (A, B, C) of the composite performance measures of ALS Specific, ALS Non-Specific, and ECAS Total scores. Repeated serial administration of ECAS-A (A-A-A) produced some practice effects for composite scores, whereas no such effects were found when alternate versions were administered serially (A-B-C). Exceptionally high intra-class correlations were found for all three versions of the ECAS suggesting a high degree of rater agreement.

CONCLUSION

The newly developed alternate forms of the ECAS are both highly equitable to the original ECAS-A and enable avoidance of practice effects, thus supporting their use in measuring cognition and behaviour over time.

Progression and effect of cognitive-behavioral changes in patients with amyotrophic lateral sclerosis

Background

To prospectively evaluate the progression of cognitive-behavioral function in amyotrophic lateral sclerosis (ALS) and examine the association of cognitive-behavioral deficits with disease progression, patient quality of life (QOL), and caregiver burden.

Methods

We evaluated cognitive-behavioral function using the Amyotrophic Lateral Sclerosis Cognitive Behavioral Screen at enrollment and after 7 months in a cohort of patients with ALS. Paired t tests were used to evaluate the change in the 2 assessments. Linear regression and Kruskal-Wallis tests were applied to investigate how initial cognitive or behavioral status related to outcomes.

Results

The mean test-retest interval was 6.8 months (SD 1.6). Cognitive status of the study population (n = 49) overall did not change over the study period (p = 0.06) despite progression of motor weakness (p < 0.001), though small subsets of the sample demonstrate cognitive change. Patients initially classified as behaviorally normal showed increased behavioral problems over time (t = -2.8, p = 0.009). Decline in cognitive (β = -1.3, p = 0.03) and behavioral (β = -0.76, p = 0.002) status predicted increasing caregiver burden. Behavioral abnormalities predicted decline in forced vital capacity and ALS Functional Rating Scale-Revised score (p = 0.008, 0.012) in the study population and patient QOL in the most severely affected group (t = 4.3, p = 0.003).

Conclusions

Cognitive-behavioral change is a key aspect of disease heterogeneity in ALS. Executive function in ALS overall remains stable over 7 months as detected by an administered screening tool. However, patients may develop caregiver-reported behavioral symptoms in that time period. Screening for caregiver-reported symptoms has a particular utility in predicting future clinical decline, increased caregiver burden, and worsening patient QOL.

Comorbidity of dementia with amyotrophic lateral sclerosis (ALS): insights from a large multicenter Italian cohort

To assess the association, at diagnosis, between amyotrophic lateral sclerosis (ALS) and dementia in a large cohort of well-characterized Italian patients. We investigated the phenotypic profile of 1638 incident patients with definite, probable or laboratory-supported probable ALS, diagnosed from January 2009 to December 2013 in 13 Italian Referral Centers, located in 10 Italian Regions, and classified in two independent subsamples accounting for presence or not of dementia. The collected ALS features, including survival and other follow-up data, were compared between the two subgroups using a one-way analysis of variance and Chi-square test, as appropriate, logistic regression models and Kaplan-Meier survival analysis. Between-subgroup comparisons showed an older age at clinical observation (p = .006), at onset and at diagnosis (p = .002) in demented versus non demented ALS patients. After adjustment for these variables, diagnosis of dementia was significantly associated with higher odds of family history of ALS (p = .001) and frontotemporal dementia (p = .003) and of bulbar onset (p = .004), and lower odds of flail leg phenotype (p = .019) and spinal onset (p = .008). The median survival time was shorter in demented versus non-demented patients, especially in case of classical, bulbar and flail limb phenotypes and both bulbar and spinal onset. Our multicenter study emphasized the importance of an early diagnosis of comorbid dementia in ALS patients, which may have clinical impact and prognostic relevance. Moreover, our results may give further inputs to validation of ALS-specific tools for the screening of cognitive impairment in clinical practice.

Clinical Spectrum of Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is primarily characterized by progressive loss of motor neurons, although there is marked phenotypic heterogeneity between cases. Typical, or "classical," ALS is associated with simultaneous upper motor neuron (UMN) and lower motor neuron (LMN) involvement at disease onset, whereas atypical forms, such as primary lateral sclerosis and progressive muscular atrophy, have early and predominant involvement in the UMN and LMN, respectively. The varying phenotypes can be so distinctive that they would seem to have differing biology. Because the same phenotypes can have multiple causes, including different gene mutations, there may be multiple molecular mechanisms causing ALS, implying that the disease is a syndrome. Conversely, multiple phenotypes can be caused by a single gene mutation; thus, a single molecular mechanism could be compatible with clinical heterogeneity. The pathogenic mechanism(s) in ALS remain unknown, but active propagation of the pathology neuroanatomically is likely a primary component.

Frontotemporal Dementia

Frontotemporal dementia (FTD) is a heterogeneous disorder with distinct clinical phenotypes associated with multiple neuropathologic entities. Presently, the term FTD encompasses clinical disorders that include changes in behavior, language, executive control, and often motor symptoms. The core FTD spectrum disorders include behavioral variant FTD, nonfluent/agrammatic variant primary progressive aphasia, and semantic variant PPA. Related FTD disorders include frontotemporal dementia with motor neuron disease, progressive supranuclear palsy syndrome, and corticobasal syndrome. In this article, the authors discuss the clinical presentation, diagnostic criteria, neuropathology, genetics, and treatments of these disorders.

Decision-making for tracheostomy in amyotrophic lateral sclerosis (ALS): a retrospective study

BACKGROUND

ALS patients should discuss the issue of tracheostomy before the onset of terminal respiratory failure. While the process of shared decision-making is desirable, there are few data on the practical application of this real-life situation.

AIM OF THE STUDY

To determine how a decision-making process is actually carried out, we analysed the episodes of acute respiratory failure preceding tracheostomy.

METHODS

We studied the charts of a group of ALS patients after tracheostomy. An interview focusing on the existence of anticipated directives was carried out. Tracheostomies were classified as planned or unplanned according to the presence of a decision plan.

RESULTS

A total of 209 ALS patients were cared for during a three-year period. Of these patients, 34 (16%) were tracheotomised. In 38% of cases, tracheostomy was planned, 41% were unplanned, and 21% remained undiagnosed.

CONCLUSIONS

A minority of ALS patients make a voluntary decision for tracheostomy before the procedure is conducted. The advising process of care still presents limits that have been thus far poorly addressed. In the future, we will need to develop guidelines for the timing and content of the shared-decision making process.

Survival prediction in Amyotrophic lateral sclerosis based on MRI measures and clinical characteristics

Background

Amyotrophic lateral sclerosis (ALS) a highly heterogeneous neurodegenerative condition. Accurate diagnostic, monitoring and prognostic biomarkers are urgently needed both for individualised patient care and clinical trials. A multimodal magnetic resonance imaging study is presented, where MRI measures of ALS-associated brain regions are utilised to predict 18-month survival.

Methods

A total of 60 ALS patients and 69 healthy controls were included in this study. 20% of the patient sample was utilised as an independent validation sample. Surface-based morphometry and diffusion tensor white matter parameters were used to identify anatomical patterns of neurodegeneration in 80% of the patient sample compared to healthy controls. Binary logistic ridge regressions were carried out to predict 18-month survival based on clinical measures alone, MRI features, and a combination of clinical and MRI data. Clinical indices included age at symptoms onset, site of disease onset, diagnostic delay from first symptom to diagnosis, and physical disability (ALSFRS-r). MRI features included the average cortical thickness of the precentral and paracentral gyri, the average fractional anisotropy, radial-, medial-, and axial diffusivity of the superior and inferior corona radiata, internal capsule, cerebral peduncles and the genu, body and splenium of the corpus callosum.

Results

Clinical data alone had a survival prediction accuracy of 66.67%, with 62.50% sensitivity and 70.84% specificity. MRI data alone resulted in a prediction accuracy of 77.08%, with 79.16% sensitivity and 75% specificity. The combination of clinical and MRI measures led to a survival prediction accuracy of 79.17%, with 75% sensitivity and 83.34% specificity.

Conclusion

Quantitative MRI measures of ALS-specific brain regions enhance survival prediction in ALS and should be incorporated in future clinical trial designs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0854-x) contains supplementary material, which is available to authorized users.

Longitudinal assessment of the Edinburgh Cognitive and Behavioural Amyotrophic Lateral Sclerosis Screen (ECAS): lack of practice effect in ALS patients?

OBJECTIVE

The study objective was to assess whether controls and ALS patients show a practice effect in the Edinburgh Cognitive and Behavioural ALS Screen (ECAS) on repeated longitudinal testing and if the ECAS detects progression of cognitive or behavioural changes over time.

METHODS

The ECAS was administered serially to ALS patients (n = 24 after six months, n = 10 after 12-18 months) and controls (n = 21 after six months). The ECAS was fully performed by all participants. For comparison purposes the Frontal Assessment Battery (FAB) was administered to a subgroup of 14 patients and 14 controls.

RESULTS

After six months controls showed a significantly higher overall score (p < 0.001) and significantly higher scores in all subdomains of the ECAS, except for visuospatial function and fluency. ALS patients showed no significant difference in any score of the ECAS after six months and up to18 months. Behavioural changes were increasingly, but not statistically, significant, noted by patient carers. The FAB was no longer applicable due to progressive motor deficits in 20% of ALS patients.

CONCLUSIONS

In conclusion, in contrast to healthy controls, ALS patients show no practice effects. This could reflect 'pre-symptomatic' cognitive decline and progressive behavioural symptoms.

A clinical tool for predicting survival in ALS

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive and usually fatal neurodegenerative disease. Survival from diagnosis varies considerably. Several prognostic factors are known, including site of onset (bulbar or limb), age at symptom onset, delay from onset to diagnosis and the use of riluzole and non-invasive ventilation (NIV). Clinicians and patients would benefit from a practical way of using these factors to provide an individualised prognosis.

METHODS

575 consecutive patients with incident ALS from a population-based registry in South-East England register for ALS (SEALS) were studied. Their survival was modelled as a two-step process: the time from diagnosis to respiratory muscle involvement, followed by the time from respiratory involvement to death. The effects of predictor variables were assessed separately for each time interval.

FINDINGS

Younger age at symptom onset, longer delay from onset to diagnosis and riluzole use were associated with slower progression to respiratory involvement, and NIV use was associated with lower mortality after respiratory involvement, each with a clinically significant effect size. Riluzole may have a greater effect in younger patients and those with longer delay to diagnosis. A patient's survival time has a roughly 50% chance of falling between half and twice the predicted median.

INTERPRETATION

A simple and clinically applicable graphical method of predicting an individual patient's survival from diagnosis is presented. The model should be validated in an independent cohort, and extended to include other important prognostic factors.

Eye-Tracking Control to Assess Cognitive Functions in Patients with Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder with pathological involvement of upper and lower motoneurons, subsequently leading to progressive loss of motor and speech abilities. In addition, cognitive functions are impaired in a subset of patients. To evaluate these potential deficits in severely physically impaired ALS patients, eye-tracking is a promising means to conduct cognitive tests. The present article focuses on how eye movements, an indirect means of communication for physically disabled patients, can be utilized to allow for detailed neuropsychological assessment. The requirements, in terms of oculomotor parameters that have to be met for sufficient eye-tracking in ALS patients are presented. The properties of stimuli, including type of neuropsychological tests and style of presentation, best suited to successfully assess cognitive functioning, are also described. Furthermore, recommendations regarding procedural requirements are provided. Overall, this methodology provides a reliable, easy to administer and fast approach for assessing cognitive deficits in patients who are unable to speak or write such as patients with severe ALS. The only confounding factor might be deficits in voluntary eye movement control in a subset of ALS patients.

The frontotemporal syndrome of ALS is associated with poor survival

Thirty percent of ALS patients have a frontotemporal syndrome (FS), defined as behavioral changes or cognitive impairment. Despite previous studies, there are no firm conclusions on the effect of the FS on survival and the use of non-invasive ventilation (NIV) in ALS. We examined the effect of the FS on survival and the start and duration of NIV in ALS. Behavioral changes were defined as >22 points on the ALS-Frontotemporal-Dementia-Questionnaire or ≥3 points on ≥2 items of the Neuropsychiatric Inventory. Cognitive impairment was defined as below the fifth percentile on ≥2 tests of executive function, memory or language. Classic ALS was defined as ALS without the frontotemporal syndrome. We performed survival analyses from symptom onset and time from NIV initiation, respectively, to death. The impact of the explanatory variables on survival and NIV initiation were examined using Cox proportional hazards models. We included 110 ALS patients (76 men) with a mean age of 62 years. Median survival time was 4.3 years (95 % CI 3.53–5.13). Forty-seven patients (43 %) had an FS. Factors associated with shorter survival were FS, bulbar onset, older age at onset, short time to diagnosis and a C9orf72 repeat expansion. The adjusted hazard ratio (HR) for the FS was 2.29 (95 % CI 1.44–3.65, p < 0.001) in a multivariate model. Patients with an FS had a shorter survival after NIV initiation (adjusted HR 2.70, 95 % CI 1.04–4.67, p = 0.04). In conclusion, there is an association between the frontotemporal syndrome and poor survival in ALS, which remains present after initiation of NIV.

Pathogenesis of FUS-associated ALS and FTD: insights from rodent models

Disruptions to genes linked to RNA processing and homeostasis are implicated in the pathogenesis of two pathologically related but clinically heterogeneous neurodegenerative diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Mutations in the Fused-in-Sarcoma (FUS) gene encoding a 526 amino-acid RNA-binding protein are found in a small subset of ALS cases, but FUS mutations do not appear to be a direct cause of FTD. Structural and functional similarities between FUS and another ALS-related RNA-binding protein, TDP-43, highlight the potential importance of aberrant RNA processing in ALS/FTD, and this pathway is now a major focus of interest. Recently, several research groups have reported transgenic vertebrate models of FUSopathy, with varying results. Here, we discuss the evidence for FUS pathogenicity in ALS/FTD, review the experimental approaches used and phenotypic features of FUS rodent models reported to date, and outline their contribution to our understanding of pathogenic mechanisms. Further refinement of vertebrate models will likely aid our understanding of the role of FUS in both diseases.

Executive dysfunction and survival in patients with amyotrophic lateral sclerosis: Preliminary report from a Serbian centre for motor neuron disease

Our objective was to determine whether the presence of executive dysfunction in non-demented amyotrophic lateral sclerosis (ALS) patients might affect the longevity of survival. Forty-eight consecutive non-demented ALS patients (mean age = 52.93 ± 12.37) were followed for five years. All patients underwent clinical and neuropsychological assessments at baseline visit. Further, a yearly follow-up check for associated dementia (ALS-Dem) was completed and the time of death was recorded, when applicable. Executive deficits were shown in 49.5% of ALS patients, with the most striking differences found on the tests of verbal fluency (both phonemic and category, p < 0.01); as well as inefficient strategy on a working memory test (p < 0.05); as on the more demanding levels of the planning and problem solving task (p < 0.01). It appears that the baseline executive status might predict survival in ALS (p = 0.075), and the patients presenting executive dysfunction could have up to three times greater risk of death, after adjustment by several potential confounding factors. In conclusion, this study suggests that executive dysfunction could potentially influence survival in ALS patients. The cognitive testing might give us important clues about the prognosis of the disease. Further studies with larger sample size are necessary.

The cognitive profile of ALS: a systematic review and meta-analysis update

Cognitive impairment is present in approximately 30% of patients with amyotrophic lateral sclerosis (ALS) and, especially when severe, has a negative impact on survival and caregiver burden. Our 2010 meta-analysis of the cognitive profile of ALS showed impairment of fluency, executive function, language and memory. However, the limited number of studies resulted in large confidence intervals. To obtain a more valid assessment, we updated the meta-analysis and included methodological improvements (controlled data extraction, risk of bias analysis and effect size calculation of individual neuropsychological tests). Embase, Medline and PsycInfo were searched for neuropsychological studies of non-demented patients with ALS and age-matched and education-matched healthy controls. Neuropsychological tests were categorised in 13 cognitive domains and effect sizes (Hedges' g) were calculated for each domain and for individual tests administered in ≥5 studies. Subgroup analyses were performed to assess the influence of clinical and demographic variables. Forty-four studies were included comprising 1287 patients and 1130 healthy controls. All cognitive domains, except visuoperceptive functions, showed significant effect sizes compared to controls. Cognitive domains without bias due to motor impairment showed medium effect sizes (95% CI): fluency (0.56 (0.43 to 0.70)), language (0.56 (0.40 to 0.72)), social cognition (0.55 (0.34 to 0.76)), or small effect sizes: delayed verbal memory 0.47 (0.27 to 0.68)) and executive functions (0.41 (0.27 to 0.55)). Individual neuropsychological tests showed diverging effect sizes, which could be explained by bias due to motor impairment. Subgroup analyses showed no influence of bulbar disease onset and depression and anxiety on the cognitive outcomes. The cognitive profile of ALS consists of deficits in fluency, language, social cognition, executive functions and verbal memory. Social cognition is a new cognitive domain with a relatively large effect size, highlighting the overlap between ALS and frontotemporal dementia. The diverging effect sizes for individual neuropsychological tests show the importance of correction for motor impairment in patients with ALS. These findings have implications for bedside testing, the design of cognitive screening measures and full neuropsychological examinations.

The validation of the Italian Edinburgh Cognitive and Behavioural ALS Screen (ECAS)

This study presents the Italian validation of the recently developed Edinburgh Cognitive and Behavioural ALS Screen (ECAS), a short screen for cognitive/behavioural alterations in patients with amyotrophic lateral sclerosis (ALS). We evaluated the psychometric properties of the ECAS Italian version in terms of reliability and convergent validity for both cognitive and behavioural features. Furthermore, we investigated the relationship with affective and clinical variables, in addition to ECAS usability and patients' insight into cognitive/behaviour changes. Finally, correlations between genetic and cognitive/behavioural data were analysed. We recruited 107 patients with ALS. Normative data were collected on 248 healthy subjects. Participants were administered the ECAS and two standard cognitive screening tools (FAB, MoCA), two psychological questionnaires (BDI, STAI/Y) and an ad hoc usability questionnaire. The FBI was also carried out with caregivers. Results showed that the ECAS Italian version discriminated well between patients and controls. The most prevalent deficit occurred in executive functions and fluency. Correlations were observed between the ECAS and standard cognitive screening tools and between the ECAS carer interview and the FBI, supporting its full convergent validity. In conclusion, the ECAS Italian version provides clinicians with a rapid, feasible and sensitive tool, useful to identify different profiles of cognitive-behavioural impairment in ALS.

Associations between neuropsychiatric symptoms and cognition in Chinese patients with amyotrophic lateral sclerosis

Our objective was to explore features of the neuropsychiatric symptoms in Chinese patients with amyotrophic lateral sclerosis (ALS) and the associations between these neuropsychiatric symptoms and cognition. A total of 91 ALS patients were evaluated using three recommended scales including the Neuropsychiatric Inventory (NPI), Addenbrooke's Cognitive Examination Revised (ACE-R), and Frontal Assessment Battery (FAB) tests. The mean age of onset was 52.5 ± 10.8 years. The median NPI score of all patients was 2.0. The most common neuropsychiatric symptom was dysphoria/depression (59.3%), followed by anxiety (41.8%) and irritability/lability (26.4%). There were no significant differences in the frequency of neuropsychiatric symptoms in terms of gender, age of onset, onset form and disease duration. There were no significant differences in NPI total score, ACE-R total score and FAB total score in terms of gender, age of onset, onset form and disease duration, except for a higher ACE-R score observed in patients with a shorter disease duration. The NPI score had a strong correlation with the ACE-R score but not with the FAB score. In conclusion, neuropsychiatric symptoms appear to be quite common in Chinese ALS patients, who were likely to present with the emotional states of depression or anxiety. The neuropsychiatric symptoms in ALS are closely related to global cognition dysfunction.

Cognitive-behavioral screening reveals prevalent impairment in a large multicenter ALS cohort

OBJECTIVES

To characterize the prevalence of cognitive and behavioral symptoms using a cognitive/behavioral screening battery in a large prospective multicenter study of amyotrophic lateral sclerosis (ALS).

METHODS

Two hundred seventy-four patients with ALS completed 2 validated cognitive screening tests and 2 validated behavioral interviews with accompanying caregivers. We examined the associations between cognitive and behavioral performance, demographic and clinical data, and C9orf72 mutation data.

RESULTS

Based on the ALS Cognitive Behavioral Screen cognitive score, 6.5% of the sample scored below the cutoff score for frontotemporal lobar dementia, 54.2% scored in a range consistent with ALS with mild cognitive impairment, and 39.2% scored in the normal range. The ALS Cognitive Behavioral Screen behavioral subscale identified 16.5% of the sample scoring below the dementia cutoff score, with an additional 14.1% scoring in the ALS behavioral impairment range, and 69.4% scoring in the normal range.

CONCLUSIONS

This investigation revealed high levels of cognitive and behavioral impairment in patients with ALS within 18 months of symptom onset, comparable to prior investigations. This investigation illustrates the successful use and scientific value of adding a cognitive-behavioral screening tool in studies of motor neuron diseases, to provide neurologists with an efficient method to measure these common deficits and to understand how they relate to key clinical variables, when extensive neuropsychological examinations are unavailable. These tools, developed specifically for patients with motor impairment, may be particularly useful in patient populations with multiple sclerosis and Parkinson disease, who are known to have comorbid cognitive decline.

Cognitive and Behavioral Symptoms in ALSFTD: Detection, Differentiation, and Progression

Brief screening tools that detect and differentiate patients with amyotrophic lateral sclerosis and frontotemporal dementia (ALSFTD) from those more subtle cognitive or behavioral symptoms (ALS plus) and motor symptoms only (ALS pure) is pertinent in a clinical setting. The utility of 2 validated and data-driven tests (Mini-Addenbrooke's Cognitive Examination [M-ACE] and Motor Neuron Disease Behavioral Scale [MiND-B]) was investigated in 70 ALS patients (24 ALSFTD, 19 ALS plus, and 27 ALS pure). More than 90% of patients with ALSFTD scored at or below the cutoff on the M-ACE, whereas this was seen in only about 20% of ALS patients without dementia. The MiND-B differentiated between ALS pure and ALS plus diagnostic categories. Rasch modeling of M-ACE and MiND-B items revealed early cognitive (fluency, memory recall) and behavioral (apathy) symptoms in ALSFTD. The combined use of the M-ACE and MiND-B detects patients with ALSFTD, differentiates along the ALS continuum, and offers insight into the progression of nonmotor symptomatology in ALSFTD.

Epidemiology of amyotrophic lateral sclerosis: A review of literature

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death occurs from respiratory failure. The incidence of ALS in European populations is two to three people per year per 100,000 of the general population. In Europe, crude prevalences range from 1.1/100,000 population in Yugoslavia to 8.2/100,000 in the Faroe Islands. Major advances have been made in our understanding of the genetic causes of ALS, whereas the contribution of environmental factors has been more difficult to assess and large-scale studies have not yet revealed a replicable, definitive environmental risk factor. The only established risk factors to date are older age, male gender and a family history of ALS. Median survival time from onset to death is usually 3 years from the first appearance of symptoms. Older age and bulbar onset are consistently reported to have poorer outcomes. However, there are conflicting data regarding gender, diagnostic delay and El Escorial criteria. The rate of symptom progression has been revealed to be an independent prognostic factor. Psychosocial factors and impaired cognitive function are negatively related to ALS outcome, while nutritional status and respiratory function are also related to ALS prognosis. The effect of enteral nutrition on survival is still unclear, although noninvasive positive pressure ventilation (NIPPV) has been found to improve survival. These findings have relevant implications for the design of future trials.

Executive Dysfunctions and Event-Related Brain Potentials in Patients with Amyotrophic Lateral Sclerosis

A growing body of evidence implies psychological disturbances in amyotrophic lateral sclerosis (ALS). Specifically, executive dysfunctions occur in up to 50% of ALS patients. The recently shown presence of cytoplasmic aggregates (TDP-43) in ALS patients and in patients with behavioral variants of frontotemporal dementia suggests that these two disease entities form the extremes of a spectrum. The present study aimed at investigating behavioral and electrophysiological indices of conflict processing in patients with ALS. A non-verbal variant of the flanker task demanded two-choice responses to target stimuli that were surrounded by flanker stimuli which either primed the correct response or the alternative response (the latter case representing the conflict situation). Behavioral performance, event-related potentials (ERP), and lateralized readiness potentials (LRP) were analyzed in 21 ALS patients and 20 controls. In addition, relations between these measures and executive dysfunctions were examined. ALS patients performed the flanker task normally, indicating preserved conflict processing. In similar vein, ERP and LRP indices of conflict processing did not differ between groups. However, ALS patients showed enhanced posterior negative ERP waveform deflections, possibly indicating increased modulation of visual processing by frontoparietal networks in ALS. We also found that the presence of executive dysfunctions was associated with more error-prone behavior and enhanced LRP amplitudes in ALS patients, pointing to a prefrontal pathogenesis of executive dysfunctions and to a potential link between prefrontal and motor cortical functional dysregulation in ALS, respectively.

Symptom Management and End-of-Life Care in Amyotrophic Lateral Sclerosis

The number of available symptomatic treatments has markedly enhanced the care of patients with amyotrophic lateral sclerosis (ALS). Once thought to be untreatable, patients with ALS today clearly benefit from multidisciplinary care. The impact of such care on the disease course, including rate of progression and mortality, has surpassed the treatment effects commonly sought in clinical drug trials. Unfortunately, there are few randomized controlled trials of medications or interventions addressing symptom management. In this review, the authors provide the level of evidence, when available, for each intervention that is currently considered standard of care by consensus opinion.

Modeling ALS and FTD with iPSC-derived neurons

Recent advances in genetics and neuropathology support the idea that amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTD) are two ends of a disease spectrum. Although several animal models have been developed to investigate the pathogenesis and disease progression in ALS and FTD, there are significant limitations that hamper our ability to connect these models with the neurodegenerative processes in human diseases. With the technical breakthrough in reprogramming biology, it is now possible to generate patient-specific induced pluripotent stem cells (iPSCs) and disease-relevant neuron subtypes. This review provides a comprehensive summary of studies that use iPSC-derived neurons to model ALS and FTD. We discuss the unique capabilities of iPSC-derived neurons that capture some key features of ALS and FTD, and underscore their potential roles in drug discovery. There are, however, several critical caveats that require improvements before iPSC-derived neurons can become highly effective disease models. This article is part of a Special Issue entitled SI: Exploiting human neurons.

Frontotemporal Dysfunction and Dementia in Amyotrophic Lateral Sclerosis

Although amyotrophic lateral sclerosis (ALS) is classically considered a disorder exclusively affecting motor neurons, there is substantial clinical, neuroimaging, and neuropathologic evidence that more than half of patients have an associated syndrome of frontotemporal dysfunction. These syndromes range from frontotemporal dementia to behavioral or cognitive syndromes. Neuroimaging and neuropathologic findings are consistent with frontotemporal lobar degeneration that underpins alterations in network connectivity. Future clinical trials need to be stratified based on the presence or absence of frontotemporal dysfunction on the disease course of ALS.