Mild behavioral impairment as a potential marker of predementia risk states in motor neuron diseases.

BACKGROUND AND PURPOSE: Mild behavioral impairment (MBI) has been increasingly regarded as the neurobehavioral axis of predementia risk states, but a specific investigation of its detection as a potential marker of prodromal dementia in motor neuron diseases (MNDs) is still lacking. The aims of our study were therefore to explore MBI in MNDs both at onset and over the disease course, and to evaluate its relationship with baseline and longitudinal cognitive features. METHODS: Sixty MND patients with cognitive/behavioral, mood, and motor examinations were recruited and followed longitudinally for up to 15 months. Associations between baseline MBI symptoms and clinical features were tested using the Spearman correlation coefficient. Based on longitudinal data, relative deltas of variation for each cognitive measure were generated, and linear regression models were then used to evaluate the role of baseline MBI symptoms in predicting longitudinal rates of cognitive decline. RESULTS: At disease onset, the most impaired MBI domain was affective/emotional dysregulation, followed by impulse dyscontrol, apathy, and social inappropriateness. Greater MBI symptoms correlated with more severe baseline motor, cognitive/behavioral, and mood disturbances (p values from <0.001 to 0.05). Longitudinally, the greatest decline was observed in the affective/emotional dysregulation domain, followed by impulse dyscontrol, apathy, and social inappropriateness. Greater MBI symptoms at onset were significant predictors of more severe longitudinal cognitive decline in both amyotrophic lateral sclerosis (ALS)-specific and ALS-nonspecific functions (p values from <0.001 to 0.03). CONCLUSIONS: MBI represents a valuable clinical marker of incident cognitive decline in MNDs, and its evaluation has good potential for detecting dementia in its preclinical/prodromal phase.

Age at symptom onset influences cortical thinning distribution and survival in amyotrophic lateral sclerosis.

PURPOSE: The lifetime risk of developing amyotrophic lateral sclerosis (ALS) increases in the elderly, and greater age at symptom onset has been identified as a negative prognostic factor in the disease. However, the underlying neurobiological mechanisms are still poorly investigated. We hypothesized that older age at symptom onset would have been associated with greater extra-motor cortical damage contributing to worse prognosis, so we explored the relationship between age at symptom onset, cortical thinning (CT) distribution, and clinical markers of disease progression. METHODS: We included 26 ALS patients and 29 healthy controls with T1-weighted magnetic resonance imaging (MRI). FreeSurfer 6.0 was used to identify regions of cortical atrophy (CA) in ALS, and to relate age at symptom onset to CT distribution. Linear regression analyses were then used to investigate whether MRI metrics of age-related damage were predictive of clinical progression. MRI results were corrected using the Monte Carlo simulation method, and regression analyses were further corrected for disease duration. RESULTS: ALS patients exhibited significant CA mainly encompassing motor regions, but also involving the cuneus bilaterally and the right superior parietal cortex (p < 0.05). Older age at symptom onset was selectively associated with greater extra-motor (frontotemporal) CT, including pars opercularis bilaterally, left middle temporal, and parahippocampal cortices (p < 0.05), and CT of these regions was predictive of shorter survival (p = 0.004, p = 0.03). CONCLUSION: More severe frontotemporal CT contributes to shorter survival in older ALS patients. These findings have the potential to unravel the neurobiological mechanisms linking older age at symptom onset to worse prognosis in ALS.

Predictors of self-perceived health worsening over COVID-19 emergency in ALS.

INTRODUCTION: Factors influencing self-perceived health status over Corona Virus Disease 2019 (COVID-19) emergency in vulnerable populations, such as patients with chronic neurological diseases, are still unknown. In this work, we aimed at testing whether clinical care changes imposed by the quarantine, together with certain demographic and disease-specific features, might have determined a self-perceived worsening of health status in patients with amyotrophic lateral sclerosis (ALS). METHODS: A brief web-based questionnaire investigating self-perceived anxiety, depression, and motor worsening, as well as clinical care changes over COVID-19 emergency, was administered to ALS patients currently followed at San Martino Hospital. Ordinal and logistic regression analyses were applied to identify significant predictors of health status. RESULTS: Fifty-seven ALS patients completed the questionnaire. A total of 35.08% of cases reported anxiety symptoms, 36.84% depressive symptoms, and 35.08% reported worsening of motor symptoms. Significant predictors of anxiety symptoms severity included female gender, greater motor impairment, more aggressive disease course, and rehabilitation therapy suspension. The only significant predictor of depressive symptoms severity was a more aggressive disease course. Significant predictors of motor worsening were shorter disease duration and exams/visits cancelation. DISCUSSION: COVID-19 emergency and its management exerted a significant impact on self-perceived health status in patients with ALS, particularly in those cases in the earliest disease phases and with a more aggressive disease course. These findings have potential to improve personalized medicine strategies in the next phase.

Brain MRI shows white matter sparing in Kennedy's disease and slow-progressing lower motor neuron disease.

The extent of central nervous system involvement in Kennedy's disease (KD) relative to other motor neuron disease (MND) phenotypes still needs to be clarified. In this study, we investigated cortical and white matter (WM) MRI alterations in 25 patients with KD, compared with 24 healthy subjects, 25 patients with sporadic amyotrophic lateral sclerosis (ALS), and 35 cases with lower motor neuron-predominant disease (LMND). LMND patients were clinically differentiated into 24 fast and 11 slow progressors. Whole-brain cortical thickness, WM tract-based spatial statistics and corticospinal tract (CST) tractography analyses were performed. No significant difference in terms of cortical thickness was found between groups. ALS patients showed widespread decreased fractional anisotropy and increased mean (MD) and radial diffusivity (radD) in the CST, corpus callosum and fronto-temporal extra-motor tracts, compared with healthy controls and other patient groups. CST tractography showed significant alterations of DT MRI metrics in ALS and LMND-fast patients whereas KD and LMND-slow patients were comparable with healthy controls. Our study demonstrated the absence of WM abnormalities in patients with KD and LMND-slow, in contrast with diffuse WM damage in ALS and focal CST degeneration in LMND-fast, supporting the use of DT MRI measures as powerful tools to differentiate fast- and slow-progressing MND syndromes, including KD.

TBK1 mutations in Italian patients with amyotrophic lateral sclerosis: genetic and functional characterisation.

BACKGROUND: TANK-binding kinase 1 (TBK1) gene has been recently identified as a causative gene of amyotrophic lateral sclerosis (ALS). METHODS: We sequenced the TBK1 gene in a cohort of 154 Italian patients with ALS with unclear genetic aetiology. We subsequently assessed the pathogenic potential of novel identified TBK1 variants using functional in vitro studies: expression, targeting and activity were evaluated in patient-derived fibroblasts and in cells transfected with mutated-TBK1 plasmids. RESULTS: We identified novel genomic TBK1 variants including two loss-of-function (LoF) (p.Leu59Phefs*16 and c.358+5G>A), two missense (p.Asp118Asn and p.Ile397Thr) and one intronic variant (c.1644-5_1644-2delAATA), in addition to two previously reported pathogenetic missense variants (p.Lys291Glu and p.Arg357Gln). Functional studies in patient-derived fibroblasts revealed that the c.358+5G>A causes aberrant pre-mRNA processing leading TBK1 haploinsufficiency. Biochemical studies in cellular models showed that the truncating variant p.Leu59Phefs*16 abolishes TBK1 protein expression, whereas the p.Asp118Asn variant severely impairs TBK1 phosphorylation activity. Conversely, the p.Ile397Thr variant displayed enhanced phosphorylation activity, whose biological relevance is not clear. CONCLUSION: The observed frequency of TBK1 LoF variants was 1.3% (2/154), increasing up to 3.2% (5/154) by taking into account also the functional missense variants that we were able to classify as potentially pathogenic, supporting the relevance of TBK1 in the Italian population with ALS.

Structural brain correlates of cognitive and behavioral impairment in MND.

OBJECTIVE: To assess the structural correlates of cognitive and behavioral impairment in motor neuron diseases (MND) using multimodal MRI. METHODS: One hundred one patients with sporadic MND (56 classic amyotrophic lateral sclerosis, 31 upper motor neuron phenotype, and 14 lower motor neuron phenotype) and 51 controls were enrolled. Patients were classified into MND with a pure motor syndrome (MND-motor) and with cognitive/behavioral symptoms (MND-plus). Cortical thickness measures and diffusion tensor (DT) metrics of white matter (WM) tracts were assessed. A random forest approach was used to explore the independent role of cortical and WM abnormalities in explaining major cognitive and behavioral symptoms. RESULTS: There were 48 MND-motor and 53 MND-plus patients. Relative to controls, both patient groups showed a distributed cortical thinning of the bilateral precentral gyrus, insular and cingulate cortices, and frontotemporal regions. In all regions, there was a trend toward a more severe involvement in MND-plus cases, particularly in the temporal lobes. Both patient groups showed damage to the motor callosal fibers, which was more severe in MND-plus. MND-plus patients also showed a more severe involvement of the extra-motor WM tracts. The best predictors of executive and non-executive deficits and behavioral symptoms in MND were diffusivity abnormalities of the corpus callosum and frontotemporal tracts, including the uncinate, cingulum, and superior longitudinal fasciculi. CONCLUSIONS: Cortical thinning and WM degeneration are highly associated with neuropsychological and behavioral symptoms in patients with MND. DT MRI metrics seem to be the most sensitive markers of extra-motor deficits within the MND spectrum.

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.

MRI signatures of the frontotemporal lobar degeneration continuum.

OBJECTIVE: To identify overlapping and unique grey (GM) and white matter (WM) signatures within the frontotemporal lobar degeneration (FTLD) continuum, and discriminate likely FTLD-TAU and FTLD-TDP patients using structural and diffusion tensor (DT) magnetic resonance imaging (MRI). METHODS: T1-weighted and DT MRI were collected from 121 subjects: 35 motor neuron disease (MND), 14 behavioral variant of frontotemporal dementia, 12 semantic and 11 nonfluent primary progressive aphasia, 21 progressive supranuclear palsy syndrome patients, and 28 healthy controls. Patterns of GM atrophy were established using voxel-based morphometry. Tract-based spatial statistics was used to perform a WM voxelwise analysis of mean diffusivity and fractional anisotropy. RESULTS: In all clinical FTLD phenotypes, the pattern of WM damage was more distributed than that of GM atrophy. All patient groups, with the exception of MND cases with a pure motor syndrome, shared a focal GM atrophy centered around the dorsolateral and medial frontal cortex and a largely overlapping pattern of WM damage involving the genu and body of the corpus callosum and ventral frontotemporal and dorsal frontoparietal WM pathways. Surrounding this common area, phenotype (symptom)-specific GM and WM regions of damage were found in each group. CONCLUSIONS: In the FTLD spectrum, WM disruption is more severe than GM damage. Frontal cortex and WM pathways represent the common target of neurodegeneration in these conditions. The topographic pattern of damage supports a "prion-like" protein propagation through WM connections as underlying mechanism of the stereotyped progression of FTLD.

Differentiation between Subtypes of Primary Progressive Aphasia by Using Cortical Thickness and Diffusion-Tensor MR Imaging Measures.

PURPOSE: To test a multimodal magnetic resonance (MR) imaging-based approach composed of cortical thickness and white matter (WM) damage metrics to discriminate between variants of primary progressive aphasia (PPA) that are nonfluent and/or agrammatic (NFVPPA) and semantic (SVPPA). MATERIALS AND METHODS: This study was approved by the local ethics committees on human studies, and written informed consent from all patients was obtained before their enrollment. T1-weighted and diffusion-tensor (DT) MR images were obtained from 13 NFVPPA patients, 13 SVPPA patients, and 23 healthy control participants. Cortical thickness and DT MR imaging indices from the long-associative and interhemispheric WM tracts were obtained. A random forest (RF) analysis was used to identify the image features associated with each clinical syndrome. Individual patient classification was performed by using receiver operator characteristic curve analysis with cortical thickness, DT MR imaging, and a combination of the two modalities. RESULTS RF analysis showed that the best markers to differentiate the two PPA variants at an individual patient level among cortical thickness and DT MR imaging metrics were diffusivity abnormalities of the left inferior longitudinal and uncinate fasciculi and cortical thickness measures of the left temporal pole and inferior frontal gyrus. A combination of cortical thickness and DT MR imaging measures (the so-called gray-matter-and-WM model) was able to distinguish patients with NFVPPA and SVPPA with the following classification pattern: area under the curve, 0.91; accuracy, 0.89; sensitivity, 0.92; specificity, 0.85. Leave-one-out analysis demonstrated that the gray matter and WM model is more robust than the single MR modality models to distinguish PPA variants (accuracy was 0.86, 0.73, and 0.68 for the gray matter and WM model, the gray matter-only model, and the WM-only model, respectively). CONCLUSION: A combination of structural and DT MR imaging metrics may provide a quantitative procedure to distinguish NFVPPA and SVPPA patients at an individual patient level. The discrimination accuracies obtained suggest that the gray matter and WM model is potentially relevant for the differential diagnosis of the PPA variants in clinical practice.

Psychological resilience is protective against cognitive deterioration in motor neuron diseases.

OBJECTIVES: Recent studies suggest that psychological resilience (PR) is associated with more well-preserved cognition in healthy subjects (HS), but an investigation of such phenomenon in patients with motor neuron diseases (MNDs) is still lacking. The aim of our study was therefore to evaluate PR and its relationship with baseline cognitive/behavioral and mood symptoms, as well as longitudinal cognitive functioning, in MNDs. METHODS: 94 MND patients and 87 demographically matched HS were enrolled. PR was assessed using the Connor-Davidson Resilience Scale (CD-RISC). Patients were further evaluated both at baseline and every 6 months for cognitive/behavioral disturbances using the Edinburgh Cognitive and Behavioral ALS Screen (ECAS), and for mood symptoms using the Hospital Anxiety and Depression Scale (HADS). CD-RISC scores were compared between patients and HS using the Mann-Whitney U test, and regression models were applied to evaluate the role of CD-RISC scores in predicting baseline cognitive/behavioral and mood measures, as well as longitudinal cognitive performances, in MND patients. RESULTS: MND cases showed significantly greater PR compared to HS (p from <0.001 to 0.02). In MNDs, higher PR levels were significant predictors of both greater cognitive performance (p from 0.01 to 0.05) and milder mood symptoms (p from <0.001 to 0.04) at baseline, as well as less severe memory decline (p from 0.001 to 0.04) longitudinally. CONCLUSIONS: PR is an important protective factor against the onset and evolution of cognitive/mood disturbances in MNDs, suggesting the usefulness of resilience enhancement psychological interventions to prevent or delay cognitive and mood disorders in these neurodegenerative conditions.

Dog-assisted physiotherapy in amyotrophic lateral sclerosis: a randomized controlled pilot study.

BACKGROUND: Animal-assisted therapy (AAT) is an intervention in which the animal acts as a co-therapist. It has been mainly used in the context of patients with dementia, showing positive effects on psychological symptoms, but its potential as a physiotherapy treatment for patients with neuromuscular disorders, amyotrophic lateral sclerosis (ALS) in particular, has not yet been investigated. AIM: The aim of the study was to evaluate the impact of AAT, specifically of dog-assisted therapy, on motor functions and psychological status in patients with ALS. DESIGN: This study was a randomized controlled pilot study. SETTING: The study was carried out at the Rehabilitation Unit NEuroMuscular Omnicenter (NEMO) of Arenzano, Genoa. POPULATION: Sixty hospitalized ALS patients were enrolled. METHODS: All patients ran a regular two-weeks neurorehabilitation program twice a day. For three days a week, in place of the morning traditional treatment, the AAT group performed a rehabilitation session with a simultaneous interaction with the therapy-dog, while the control group performed a traditional rehabilitation session. The outcome measures were the Timed Up and Go Test, the Short Physical Performance Battery (SPPB), the Six Minutes Walk Test, the Ten Meters walking Test and the Hospital Anxiety and Depression Scale. RESULTS: Both groups showed an amelioration in motor scales. However, SPPB subscales as well as HADS scores showed a statistically significant improvement only in the AAT group (P values from <0.0001 to 0.0004). Additionally, across almost all motor and psychological measures, post-treatments values were significantly better for the AAT group (P values from <0.0001 to 0.01). CONCLUSIONS: The obtained results not only suggest that AAT is comparable to traditional physiotherapy treatments, but also evidence that this type of treatment has greater beneficial effects on motor and psychological symptoms in patients with ALS. CLINICAL REHABILITATION IMPACT: This study provides first evidence that AAT is a powerful rehabilitation strategy in patients with ALS, improving both motor and psychological symptoms, and therefore possibly ameliorating quality of life.

Comparing the Impact of COVID-19 on Vaccinated and Unvaccinated Patients Affected by Myasthenia Gravis.

We evaluated 13 patients affected by myasthenia gravis (MG) who had coronavirus disease 2019 (COVID-19) before vaccination and 14 myasthenic patients who contracted severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection after vaccination to evaluate factors related to different COVID-19 outcomes. We compared the two groups' previous stability of MG and the severity of SARS-CoV-2 infection. Vaccinated and non-vaccinated patients were comparable in terms of severity of the previous MG course (mean maximum myasthenia gravis Foundation of America-MGFA-Class III) and during SARS-CoV-2 infection (mean MGFA Class II). In non-vaccinated patients, the hospitalization and severe course percentages were 61.5%, while the mortality reached 30.8%. The hospitalization, severe course, and mortality percentages in vaccinated patients were 7.1%. In deceased, non-vaccinated patients, greater myasthenia severity in the past clinical history, but not at the time of infection, was observed. Similarly, older age at MG onset and at the time of infection correlated with a more severe COVID-19 course in non-vaccinated patients (p = 0.03 and p = 0.04), but not in the group of vaccinated patients. In summary, our data support a protective role of vaccination in myasthenic patients, even if anti-CD20 therapy might be associated with a poor immune response to vaccines.

MND Phenotypes Differentiation: The Role of Multimodal Characterization at the Time of Diagnosis.

Pure/predominant upper motor neuron (pUMN) and lower motor neuron (pLMN) diseases have significantly better prognosis compared to amyotrophic lateral sclerosis (ALS), but their early differentiation is often challenging. We therefore tested whether a multimodal characterization approach embedding clinical, cognitive/behavioral, genetic, and neurophysiological data may improve the differentiation of pUMN and pLMN from ALS already by the time of diagnosis. Dunn's and chi-squared tests were used to compare data from 41 ALS, 34 pLMN, and 19 pUMN cases with diagnoses confirmed throughout a 2-year observation period. Area under the curve (AUC) analyses were implemented to identify the finest tools for phenotypes discrimination. Relative to ALS, pLMN showed greater lower limbs weakness, lower UMN burden, and progression rate (p < 0.001−0.04). PUMN showed a greater frequency of lower limbs onset, higher UMN burden, lower ALSFRS-r and MRC progression rates (p < 0.001−0.03), and greater ulnar compound muscle action potential (CMAP) amplitude and tibial central motor conduction time (CMCT) (p = 0.05−0.03). The UMN progression rate was the finest measure to identify pLMN cases (AUC = 90%), while the MRC progression rate was the finest tool to identify pUMN (AUC = 82%). Detailed clinical and neurophysiological examinations may significantly improve MNDs differentiation, facilitating prognosis estimation and ameliorating stratification strategies for clinical trials enrollment.

18F-FDG-PET correlates of aging and disease course in ALS as revealed by distinct PVC approaches.

PURPOSE: The partial volume effect (PVE) complicates PET studies of neurodegenerative diseases, since a decreased 18F-FDG retention might be influenced by atrophy-related changes of cortical regions. Multiple partial volume correction (PVC) methods have been therefore developed, but their application in amyotrophic lateral sclerosis (ALS) is still rare. Additionally, even if metabolic changes have been established in ALS, no study yet has investigated how these may be influenced by aging and disease course. The aim of the present study was therefore to apply and compare multiple PVC approaches to explore aging and disease course-related hypometabolism in ALS. METHODS: PET and MRI data from 15 ALS patients were analyzed using PETSurfer to implement 4 distinct PVC methods: noPVC, Meltzer (MZ), Müller-Gärtner (MG) and Symmetric Geometric Transfer Matrix (SGTM). For each method and Region of Interest (ROI), the 18F-FDG value was regressed against subject age and disease duration. RESULTS: MG/SGTM application almost halved the number of regions showing a significant age-related hypometabolism, while the same effect was not observed for disease course, where only the distribution of identified regions varied. Three distinct patterns emerged: regions showing a significant age/disease course-related effect across all the different methods, regions yielding significance only with MG/SGTM application, and regions maintaining significance only with noPVC/MZ application. CONCLUSIONS: Significant changes in the distribution of aging and disease course-related hypometabolism were observed when the effect of the underlying structural status was considered, supporting the need for investigate the impact of PVE on PET-assessed metabolic changes in clinical and research settings.

Northwestern Anagram Test-Italian (Nat-I) for primary progressive aphasia.

OBJECTIVES: To test the ability of the Northwestern Anagram Test-Italian (NAT-I) to distinguish between the non-fluent/agrammatic (nfv-) and phonological/logopenic (lv-) variants of primary progressive aphasia (PPA), and to determine the relationship between NAT-I variables and brain integrity in PPA patients. METHODS: 13 nfvPPA and 8 lvPPA patients underwent the 44-item-version of NAT-I and brain MRI. The NAT-I was also administered to six patients with the semantic variant (sv) PPA to sample performance in cases with no grammatical deficits. Performances were recorded and compared between patient groups. Receiver Operating Characteristic curve analysis assessed the ability of NAT-I to discriminate nfvPPA and lvPPA. The correlation between anatomical changes and NAT-I variables were assessed. A shortened (22-item)-version of NAT-I was also tested for classification ability. RESULTS: Participants with NfvPPA performed more poorly than lvPPA patients on canonical and non-canonical sentences. NAT-I non-canonical sentence and total scores achieved the highest diagnostic accuracy in discriminating the two patient groups (area under the curve: .93 and .91, respectively). SvPPA participants showed performances similar to lvPPA. NAT-I variables correlated with the integrity of the left inferior frontal gyrus and the body of the corpus callosum. The NAT-I 22-item-version total and non-canonical sentences scores reached diagnostic accuracy comparable to the full version. CONCLUSIONS: The NAT-I, in particular the measure of non-canonical syntax, is an effective tool for distinguishing nfvPPA and lvPPA patients and correlated with the integrity of crucial brain regions implicated in syntactic processing. The 22-item-brief version of NAT-I is suitable for clinical practice and research.

UNC13A polymorphism contributes to frontotemporal disease in sporadic amyotrophic lateral sclerosis.

The majority (90%-95%) of amyotrophic lateral sclerosis (ALS) is sporadic, and ∼50% of patients develop symptoms of frontotemporal degeneration (FTD) associated with shorter survival. The genetic polymorphism rs12608932 in UNC13A confers increased risk of sporadic ALS and sporadic FTD and modifies survival in ALS. Here, we evaluate whether rs12608932 is also associated with frontotemporal disease in sporadic ALS. We identified reduced cortical thickness in sporadic ALS with T1-weighted magnetic resonance imaging (N = 109) relative to controls (N = 113), and observed that minor allele (C) carriers exhibited greater reduction of cortical thickness in the dorsal prefrontal, ventromedial prefrontal, anterior temporal, and middle temporal cortices and worse performance on a frontal lobe-mediated cognitive test (reverse digit span). In sporadic ALS with autopsy data (N = 102), minor allele homozygotes exhibited greater burden of phosphorylated tar DNA-binding protein-43 kda (TDP-43) pathology in the middle frontal, middle temporal, and motor cortices. Our findings demonstrate converging evidence that rs12608932 may modify frontotemporal disease in sporadic ALS and suggest that rs12608932 may function as a prognostic indicator and could be used to define patient endophenotypes in clinical trials.

Perfusion alterations converge with patterns of pathological spread in transactive response DNA-binding protein 43 proteinopathies.

Amyotrophic lateral sclerosis (ALS) and the behavioral variant of frontotemporal dementia (bvFTD) commonly share the presence of transactive response DNA-binding protein 43 (TDP-43) inclusions. Structural magnetic resonance imaging studies demonstrated evidence for TDP-43 pathology spread, but while structural imaging usually reveals overt neuronal loss, perfusion imaging may detect more subtle neural activity alterations. We evaluated perfusion as an early marker for incipient pathology-associated brain alterations in TDP-43 proteinopathies. Cortical thickness (CT) and perfusion measurements were obtained in ALS (N = 18), pathologically and/or genetically confirmed bvFTD-TDP (N = 12), and healthy controls (N = 33). bvFTD showed reduced frontotemporal CT, hypoperfusion encompassing orbitofrontal and temporal cortices, and hyperperfusion in motor and occipital regions. ALS did not show reduced CT, but exhibited hypoperfusion in motor and temporal regions, and hyperperfusion in frontal and occipital cortices. Frontotemporal hypoperfusion and reduced CT correlated with cognitive and behavioral impairments as investigated using Mini-Mental State Examination and Philadelphia Brief Assessment of Cognition in bvFTD, and hypoperfusion in motor regions correlated with motor disability as measured by the ALS Functional Rating Scale-Revised in ALS. Hypoperfusion marked early pathologically involved regions, while hyperperfusion characterized regions of late pathological involvement. Distinct perfusion patterns may provide early markers of pathology distribution in TDP-43 proteinopathies.

Multimodal structural MRI in the diagnosis of motor neuron diseases.

This prospective study developed an MRI-based method for identification of individual motor neuron disease (MND) patients and test its accuracy at the individual patient level in an independent sample compared with mimic disorders. 123 patients with amyotrophic lateral sclerosis (ALS), 44 patients with predominantly upper motor neuron disease (PUMN), 20 patients with ALS-mimic disorders, and 78 healthy controls were studied. The diagnostic accuracy of precentral cortical thickness and diffusion tensor (DT) MRI metrics of corticospinal and motor callosal tracts were assessed in a training cohort and externally proved in a validation cohort using a random forest analysis. In the training set, precentral cortical thickness showed 0.86 and 0.89 accuracy in differentiating ALS and PUMN patients from controls, while DT MRI distinguished the two groups from controls with 0.78 and 0.92 accuracy. In ALS vs controls, the combination of cortical thickness and DT MRI metrics (combined model) improved the classification pattern (0.91 accuracy). In the validation cohort, the best accuracy was reached by DT MRI (0.87 and 0.95 accuracy in ALS and PUMN vs mimic disorders). The combined model distinguished ALS and PUMN patients from mimic syndromes with 0.87 and 0.94 accuracy. A multimodal MRI approach that incorporates motor cortical and white matter alterations yields statistically significant improvement in accuracy over using each modality separately in the individual MND patient classification. DT MRI represents the most powerful tool to distinguish MND from mimic disorders.