Cognitive impairment in patients with multiple system atrophy and progressive supranuclear palsy

Influence of cognitive reserve on cognitive and motor function in α-synucleinopathies: A systematic review and multilevel meta-analysis

Cognitive reserve has shown promise as a justification for neuropathologically unexplainable clinical outcomes in Alzheimer's disease. Recent evidence suggests this effect may be replicated in conditions like Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. However, the relationships between cognitive reserve and different cognitive abilities, as well as motor outcomes, are still poorly understood in these conditions. Additionally, it is unclear whether the reported effects are confounded by medication. This review analysed studies investigating the relationship between cognitive reserve and clinical outcomes in these α-synucleinopathy cohorts, identified from MEDLINE, Scopus, psycINFO, CINAHL, and Web of Science. 85 records, containing 176 cognition and 31 motor function effect sizes, were pooled using multilevel meta-analysis. There was a significant, positive association between higher cognitive reserve and both better cognition and motor function. Cognition effect sizes differed by disease subtype, cognitive reserve measure, and outcome type; however, no moderators significantly impacted motor function. Review findings highlight the clinical implications of cognitive reserve and importance of engaging in reserve-building behaviours.

Impaired sequence manipulation in non-demented patients with progressive supranuclear palsy

PURPOSE

Sequential working memory is the ability to maintain and manipulate sequential information at a second time scale. Patients with progressive supranuclear palsy (PSP) or Parkinson's disease (PD) perform poorly in tests that require the flexible arrangement of thoughts or actions. This study investigated whether sequential working memory is differently impaired in patients with PSP versus PD.

METHOD

Twenty-nine patients with PSP Richardson's syndrome (PSP-RS), 36 patients with PD, and 36 healthy controls (HC) completed 3 well-established neuropsychological tests, including digit span forward (DST-F), digit span backward (DST-B), and adaptive digit ordering tests (DOT-A). The DST-F required maintaining digit sequences, and the DST-B and DOT-A required maintaining and manipulating digit sequences.

FINDING

The PSP-RS group scored lower than the PD and HC groups in the DST-B and DOT-A but not in the DST-F, indicating that the ability to manipulate sequences was impaired, but the maintenance ability was preserved in PSP-RS patients. Moreover, in PSP-RS, the DST-B score negatively correlated with the severity of motor symptoms. The actual levodopa dose positively correlated with the DST-B ordering cost (DST-F score vs. DST-B score). The PSP patients who took a greater dose of levodopa tended to have higher DST-B ordering cost. There was no effect of levodopa on DST-B or DOT-A in PD.

CONCLUSION

These results suggested that the ability to manipulate sequence was already reduced in patients with PSP-RS and was worse than in patients with PD.

Phenotypic Spectrum of Progressive Supranuclear Palsy: Clinical Study and Apolipoprotein E Effect

OBJECTIVE

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disorder encompassing several phenotypes with various motor and cognitive deficits. We aimed to study motor and cognitive characteristics across PSP phenotypes and to assess the influence of apolipoprotein E (APOE) gene variants on PSP phenotypic expression.

METHODS

In this 20-year cross-sectional study, we retrospectively reviewed the charts of all patients classified as PSP patients and recategorized them according to phenotype using the Movement Disorder Society criteria (2017). Phenotypes were divided into three subgroups, Richardson's syndrome (PSP-RS), PSP-cortical (PSP with predominant frontal presentation [PSP-F] + PSP with predominant speech/language disorder [PSP-SL] + PSP with predominant corticobasal syndrome [PSP-CBS]) and PSP-subcortical (PSP with predominant parkinsonism [PSP-P] + PSP with progressive gait freezing [PSP-PGF] + PSP with predominant postural instability [PSP-PI] + PSP with predominant ocular motor dysfunction [PSP-OM] + PSP with cerebellar ataxia [PSP-C] + PSP with primary lateral sclerosis [PSP-PLS]), based on clinical presentation during the first 3 years after symptom onset, which defines the early disease stage. Clinical and neuropsychological assessment data were collected. Genotyping of APOE was performed using restriction fragment length polymorphism polymerase chain reaction and verified by Sanger sequencing.

RESULTS

We included 112 PSP patients comprising 10 phenotypes classified into 48 PSP-RS, 34 PSP-cortical (PSP-CBS, 17.6%; PSP-F, 9.4%; PSP-SL, 8.2%) and 30 PSP-subcortical (PSP-P, 11.6%; PSP-PI, 8%; PSP-OM, 2.7%; PSP-PGF, 1.8%; PSP-C, 1.8%; PSP-PLS, 0.9%) subgroups. PSP-RS patients were older at disease onset (p = 0.009) and had more akinetic-rigid and levodopa-resistant parkinsonism (p = 0.006), while PSP-cortical patients had more tremors and asymmetric and/or levodopa-responsive parkinsonism (p = 0.025). Cognitive domains were significantly less altered in the PSP-subcortical subgroup. Overall, PSP-APOEε4 carriers developed parkinsonism earlier (p = 0.038), had earlier oculomotor dysfunction (p = 0.052) and had more altered cognitive profiles. The APOEε4 allele was also associated with a younger age of parkinsonism onset in the PSP-RS phenotype group (p = 0.026).

CONCLUSION

This study demonstrated the wide phenotypic spectrum of PSP among Tunisians. Disease onset and akinetic-rigid and levodopa-resistant parkinsonism were the hallmarks of the PSP-RS phenotype, while milder cognitive impairment was characteristic of the PSP-subcortical subgroup. The APOEε4 allele was associated with earlier parkinsonism and oculomotor dysfunction and seemed to play a role in defining a more altered cognitive profile in PSP patients.

Synchronous monitoring of brain-heart electrophysiology using heart rate variability coupled with rapid quantitative electroencephalography in orthostatic hypotension patients with α-synucleinopathies: Rapid prediction of orthostatic hypotension and preliminary exploration of brain stimulation therapy

BACKGROUND

In α-synucleinopathies, the dysfunction of the autonomic nervous system which typically manifests as orthostatic hypotension (OH) often leads to severe consequences and poses therapeutic challenges. This study aims to discover the brain-cardiac electrophysiological changes in OH patients with α-synucleinopathies using the rapid quantitative electroencephalography (qEEG) coupled with heart rate variability (HRV) technique to identify rapid, noninvasive biomarkers for early warning and diagnosis, as well as shed new light on complementary treatment approaches such as brain stimulation targets.

METHODS

In this study, 26 subjects of α-synucleinopathies with OH (α-OH group), 21 subjects of α-synucleinopathies without OH (α-NOH group), and 34 healthy controls (control group) were included from September 2021 to August 2023 (NCT05527067). The heart rate-blood pressure variations in supine and standing positions were monitored, and synchronization parameters of seated resting-state HRV coupled with qEEG were collected. Time-domain and frequency-domain of HRV measures as well as peak frequency and power of the brainwaves were extracted. Differences between these three groups were compared, and correlations between brain-heart parameters were analyzed.

RESULTS

The research results showed that the time-domain parameters such as MxDMn, pNN50, RMSSD, and SDSD of seated resting-state HRV exhibited a significant decrease only in the α-OH group compared to the healthy control group (p < 0.05), while there was no significant difference between the α-NOH group and the healthy control group. Several time-domain and frequency-domain parameters of seated resting-state HRV were found to be correlated with the blood pressure changes within the first 5 min of transitioning from supine to standing position (p < 0.05). Differences were observed in the power of beta1 waves (F4 and Fp2) and beta2 waves (Fp2 and F4) in the seated resting-state qEEG between the α-OH and α-NOH groups (p < 0.05). The peak frequency of theta waves in the Cz region also showed a difference (p < 0.05). The power of beta2 waves in the Fp2 and F4 brain regions correlated with frequency-domain parameters of HRV (p < 0.05). Additionally, abnormal electrical activity in the alpha, theta, and beta1 waves was associated with changes in heart rate and blood pressure within the first 5 min of transitioning from supine to standing position (p < 0.05).

CONCLUSION

Rapid resting-state HRV with certain time-domain parameters below normal levels may serve as a predictive indicator for the occurrence of orthostatic hypotension (OH) in patients with α-synucleinopathies. Additionally, the deterioration of HRV parameters correlates with synchronous abnormal qEEG patterns, which can provide insights into the brain stimulation target areas for OH in α-synucleinopathy patients.

A Systematic Review of the Spectrum and Prevalence of Non-motor Symptoms in Multiple System Atrophy

BACKGROUND

Patients with Multiple System Atrophy (MSA) frequently report non-motor symptoms, and several research groups have highlighted this.

OBJECTIVE

We systematically searched for and reviewed papers assessing prevalence of non-motor symptoms (NMS) in MSA patients as reported in the scientific literature.

METHODS

We performed a systematic review of studies of subjects with MSA (involving > 10 patients) who were assessed for NMS, published in the English literature in PUBMED and EMBASE databases from 1947-2022.

RESULTS

23 research papers, with data from 2648 clinically diagnosed and 171 pathologically verified cases of MSA were included, along with 238 controls. Mean age for MSA cases was 61.3 (9.2) years, mean disease duration 3.6 (2.7) years. 57.9% were male. Our analysis showed that the prevalence of cognitive issues in MSA varied widely (between 15-100%); dementia per se was uncommon, but assessment in advanced stages of MSA is impacted by unintelligible speech (which may be noted in a quarter of cases). The prevalence of depressive symptoms in MSA was between 44-88%. Sleep disturbances were reported by 17-89%, with REM-sleep behaviour disorder (RBD) rates as high as 75%. Pain was reported by 40-47% of patients: rheumatic or musculoskeletal sources of pain being commonest. Fatigue was reported by 29-60% of patients. Symptoms of autonomic failure in MSA were seen in 34-96.5% patients at baseline.

CONCLUSION

In routine clinical practice, NMS in MSA are under-recognised by clinicians. These impact hugely on patient quality of life and contribute to their overall morbidity. A methodical ascertainment of these complaints will address an unmet need, and lead to a more holistic approach of care for individuals with MSA.

[Cognitive impairment in multiple system atrophy - exclusion criteria or an integral part of the clinical picture?]

Multiple system atrophy (MSA) is a severe, orphan disease characterized by a steady increase in symptoms of parkinsonism, cerebellar disorders, and autonomic failure. In addition to autonomic failure, which is considered the defining symptom of this type of atypical parkinsonism, there are a range of other non-motor clinical manifestations, such as sleep disorders, pain syndrome, anxiety-depressive disorders, cognitive impairment (CI). CI, especially severe CI, has long been considered as a distinctive feature of MCA. Recently, there have been many clinical studies with pathomorphological or neuroimaging confirmation, indicating a high prevalence of cognitive disorders in MCA. In this article, we discuss the pathogenetic mechanisms of the development of MCA and CI in MCA, as well as the range of clinical manifestations of cognitive dysfunction.

Quantitative cellular changes in multiple system atrophy brains

Multiple system atrophy (MSA) is a neurodegenerative disorder characterised by a combined symptomatology of parkinsonism, cerebellar ataxia, autonomic failure and corticospinal dysfunction. In brains of MSA patients, the hallmark lesion is the aggregation of misfolded alpha-synuclein in oligodendrocytes. Even though the underlying pathological mechanisms remain poorly understood, the evidence suggests that alpha-synuclein aggregation in oligodendrocytes may contribute to the neurodegeneration seen in MSA. The primary aim of this review is to summarise the published stereological data on the total number of neurons and glial cell subtypes (oligodendrocytes, astrocytes and microglia) and volumes in brains from MSA patients. Thus, we include in this review exclusively the reports of unbiased quantitative data from brain regions including the neocortex, nuclei of the cerebrum, the brainstem and the cerebellum. Furthermore, we compare and discuss the stereological results in the context of imaging findings and MSA symptomatology. In general, the stereological results agree with the common neuropathological findings of neurodegeneration and gliosis in brains from MSA patients and support a major loss of nigrostriatal neurons in MSA patients with predominant parkinsonism (MSA-P), as well as olivopontocerebellar atrophy in MSA patients with predominant cerebellar ataxia (MSA-C). Surprisingly, the reports indicate only a minor loss of oligodendrocytes in sub-cortical regions of the cerebrum (glial cells not studied in the cerebellum) and negligible changes in brain volumes. In the past decades, the use of stereological methods has provided a vast amount of accurate information on cell numbers and volumes in the brains of MSA patients. Combining different techniques such as stereology and diagnostic imaging (e.g. MRI, PET and SPECT) with clinical data allows for a more detailed interdisciplinary understanding of the disease and illuminates the relationship between neuropathological changes and MSA symptomatology.

Structural correlates of survival in progressive supranuclear palsy

INTRODUCTION

Many studies of the Richardson's syndrome phenotype of progressive supranuclear palsy (PSP) have elucidated regions of progressive atrophy and neural correlates of clinical severity. However, the neural correlates of survival and how these differ according to variant phenotypes are poorly understood. We set out to identify structural changes that predict severity and survival from scanning date to death.

METHODS

Structural magnetic resonance imaging data from 112 deceased people with clinically defined 'probable' or 'possible' PSP were analysed. Neuroanatomical regions of interest volumes, thickness and area were correlated with 'temporal stage', defined as the ratio of time from symptom onset to death, time from scan to death ('survival from scan'), and in a subset of patients, clinical severity, adjusting for age and total intracranial volume. Forty-nine participants had post mortem confirmation of the diagnosis.

RESULTS

Using T1-weighted magnetic resonance imaging, we confirmed the midbrain, and bilateral cortical structural correlates of contemporary disease severity. Atrophy of the striatum, cerebellum and frontotemporal cortex correlate with temporal stage and survival from scan, even after adjusting for severity. Subcortical structure-survival relationships were stronger in Richardson's syndrome than variant phenotypes.

CONCLUSIONS

Although the duration of PSP varies widely between people, an individual's progress from disease onset to death (their temporal stage) reflects atrophy in striatal, cerebellar and frontotemporal cortical regions. Our findings suggest magnetic resonance imaging may contribute to prognostication and stratification of patients with heterogenous clinical trajectories and clarify the processes that confer mortality risk in PSP.

Mild cognitive impairment in multiple system atrophy: a brain network disorder

Cognitive impairment (CI), previously considered as a non-supporting feature of multiple system atrophy (MSA), according to the second consensus criteria, is not uncommon in this neurodegenerative disorder that is clinically characterized by a variable combination of autonomic failure, levodopa-unresponsive parkinsonism, motor and cerebellar signs. Mild cognitive impairment (MCI), a risk factor for dementia, has been reported in up to 44% of MSA patients, with predominant impairment of executive functions/attention, visuospatial and verbal deficits, and a variety of non-cognitive and neuropsychiatric symptoms. Despite changing concept of CI in this synucleinopathy, the underlying pathophysiological mechanisms remain controversial. Recent neuroimaging studies revealed volume reduction in the left temporal gyrus, and in the dopaminergic nucleus accumbens, while other morphometric studies did not find any gray matter atrophy, in particular in the frontal cortex. Functional analyses detected decreased functional connectivity in the left parietal lobe, bilateral cuneus, left precuneus, limbic structures, and cerebello-cerebral circuit, suggesting that structural and functional changes in the subcortical limbic structures and disrupted cerebello-cerebral networks may be associated with early cognitive decline in MSA. Whereas moderate to severe CI in MSA in addition to prefrontal-striatal degeneration is frequently associated with cortical Alzheimer and Lewy co-pathologies, neuropathological studies of the MCI stage of MSA are unfortunately not available. In view of the limited structural and functional findings in MSA cases with MCI, further neuroimaging and neuropathological studies are warranted in order to better elucidate its pathophysiological mechanisms and to develop validated biomarkers as basis for early diagnosis and future adequate treatment modalities in order to prevent progression of this debilitating disorder.

Waiting impulsivity in progressive supranuclear palsy-Richardson's syndrome

Background

Waiting impulsivity in progressive supranuclear palsy-Richardson's syndrome (PSP-RS) is difficult to assess, and its regulation is known to involve nucleus accumbens (NAc) subregions. We investigated waiting impulsivity using the "jumping the gun" (JTG) sign, which is defined as premature initiation of clapping before the start signal in the three-clap test and compared clinical features of PSP-RS patients with and without the sign and analyzed neural connectivity and microstructural changes in NAc subregions.

Materials and methods

A positive JTG sign was defined as the participant starting to clap before the start sign in the three-clap test. We classified participants into the JTG positive (JTG +) and JTG negative (JTG-) groups and compared their clinical features, microstructural changes, and connectivity between NAc subregions using diffusion tension imaging. The NAc was parcellated into core and shell subregions using data-driven connectivity-based methods.

Results

Seventy-seven patients with PSP-RS were recruited, and the JTG + group had worse frontal lobe battery (FAB) scores, more frequent falls, and more occurrence of the applause sign than the JTG- group. A logistic regression analysis revealed that FAB scores were associated with a positive JTG sign. The mean fiber density between the right NAc core and right medial orbitofrontal gyrus was higher in the JTG + group than the JTG- group.

Discussion

We show that the JTG sign is a surrogate marker of waiting impulsivity in PSP-RS patients. Our findings enrich the current literature by deepening our understanding of waiting impulsivity in PSP patients and introducing a novel method for its evaluation.

Neuropathological analysis of cognitive impairment in progressive supranuclear palsy

BACKGROUND

Cognitive impairment is an important symptom in progressive supranuclear palsy (PSP), but the pathological changes underlying the cognitive impairment are unclear. This study aimed to elucidate relationships between the severity of cognitive impairment and PSP-related pathology.

METHODS

We investigated the clinicopathological characteristics of 10 autopsy cases of PSP, including neuronal loss/gliosis and the burden of PSP-related tau pathology by using a semiquantitative score in 17 brain regions. Other concurrent pathologies such as Braak neurofibrillary tangle stage, Thal amyloid phase, Lewy-related pathology, argyrophilic grains, and TDP-43-related pathology were also assessed. We retrospectively divided the patients into a normal cognition group (PSP-NC) and cognitive impairment group (PSP-CI) based on antemortem clinical information about cognitive impairment and compared the pathological changes between these groups.

RESULTS

Seven patients were categorized into the PSP-CI group (men = 4) and three into the PSP-NC group (men = 3). The severity of neuronal loss/gliosis and concurrent pathologies were not different between the two groups. However, the total load of tau pretangles/neurofibrillary tangles was higher in the PSP-CI group than in the PSP-NC group. In addition, the burden of tufted astrocytes in the subthalamic nucleus and medial thalamus was higher in the PSP-CI group than in the PSP-NC group.

CONCLUSION

Cognitive impairment in PSP may be associated with the amount of tufted astrocyte pathology in the subthalamic nucleus and medial thalamus.

Automatic classification of MSA subtypes using Whole-brain gray matter function and Structure-Based radiomics approach

BACKGROUND

This study aims to develop a radiomics method based on the function and structure of whole-brain gray matter to accurately classify multiple system atrophy with predominant Parkinsonism (MSA-P) or predominant cerebellar ataxia (MSA-C).

METHODS

We enrolled 30 MSA-C and 41 MSA-P cases for the internal cohort and 11 MSA-C and 10 MSA-P cases for the external test cohort. We extracted 7,308 features, including gray matter volume (GMV), mean amplitude of low-frequency fluctuation (mALFF), mean regional homogeneity (mReHo), degree of centrality (DC), voxel-mirrored homotopic connectivity (VMHC), and resting-state functional connectivity (RSFC) from 3D-T1 and Rs-fMR data. Feature selection was conducted with t-test and least absolute shrinkage and selection operator (Lasso). Classification was performed using the support vector machine with linear and RBF kernel (SVM-linear/SVM-RBF), random forest and logistic regression. Model performance was assessed via receiver operating characteristic (ROC) curve and compared with DeLong's test.

RESULTS

Feature selection resulted in 12 features, including 1 ALFF, 1 DC and 10 RSFC. All the classifiers showed remarkable classification performance, especially the RF model which exhibited AUC values of 0.91 and 0.80 in the validation and test datasets, respectively. The brain functional activity and connectivity in the cerebellum, orbitofrontal lobe and limbic system were important features to distinguish MSA subtypes with the same disease severity and duration.

CONCLUSION

Radiomics approach has the potential to support clinical diagnostic systems and to achieve high classification accuracy for distinguishing between MSA-C and MSA-P patients at the individual level.

Characteristics of Mild Cognitive Impairment and Associated Factors in MSA Patients

Mild cognitive impairment (MCI) in multiple-system atrophy (MSA) patients is common but remains poorly characterized, and the related factors are unclear. This retrospective study included 200 consecutive patients with a clinical diagnosis of possible or probable MSA, 102 MSA patients with MCI (MSA-MCI), and 98 MSA patients with normal cognition (MSA-NC). Cognitive profiles were compared between MSA-MCI and MSA-NC patients using the MoCA. In addition, demographic as well as major motor and nonmotor symptom differences were compared between MSA-MCI and MSA-NC patients. The median MMSE score was 26 points. Overall, MSA-MCI was observed in 51% of patients, with predominant impairment in visuospatial, executive, and attention functions compared with MSA-NC patients. MSA-MCI patients were older (p = 0.015) and had a later onset age (p = 0.024) and a higher frequency of hypertension, motor onset, and MSA with the predominant parkinsonism (MSA-P) phenotype than MSA-NC patients. The positive rate of orthostatic hypotension (OH) in MSA-MCI patients was significantly decreased and depression/anxiety was significantly increased compared with MSA-NC patients (p = 0.004). Multivariate logistic analysis showed that motor onset was independently associated with MCI in MSA patients. MSA-MCI patients had impairment in visuospatial, executive, and attention functions. More prominent memory impairment was observed in MSA-P than in MSA-C patients. Motor onset was independently associated with MCI in MSA patients. MCI was commonly presented in MSA with more prominent memory impairment in MSA-P. Future follow-up studies are warranted to identify more factors that influence cognitive impairment in MSA.

Motor assessment of patients with multiple system atrophy: underuse of the Unified Multiple System Atrophy Rating Scale (UMSARS)

PURPOSE

Despite the availability of the Unified Multiple System Atrophy (MSA) Rating Scale (UMSARS) for almost two decades, studies still use scales developed for Parkinson's disease (PD) or ataxia (ATX). Our aim was to evaluate the use of UMSARS (part II, motor) compared to other motor rating scales in patients with MSA.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant literature search was conducted concerning studies of patients with MSA, reporting motor assessment with clinical rating scales, and focusing on the frequency of UMSARS use.

RESULTS

We included 261 articles, of which 42.9% did not use UMSARS, but rather scales for PD (59.8%), ATX (24.1%), or both (14.3%). Although UMSARS use increased with time, misuse of PD and ATX scales persists, with no evidence of a decremental trend.

CONCLUSIONS

Although higher in observational studies, the misuse of PD and ATX-related scales in MSA patients persists in prospective (planned) trials. Reasons for that must be addressed.

Cognitive Impairment in Neurodegenerative Movement Disorders

Patients with neurodegenerative movement disorders can develop cognitive impairment during the disease. Cognitive symptoms have been associated with decreased quality of life, higher caregiver burden, and earlier institutionalization, and are therefore critical for physicians to understand and address. The evaluation of cognitive performance of patients with neurodegenerative movement disorders is important for providing adequate diagnosis, management, prognosis, and support patients and their caregivers. In this review, we discuss the features of the cognitive impairment profile of commonly encountered movement disorders: Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal syndrome, and Huntington's disease. In addition, we provide neurologists with practical guidance and evaluation tools for the assessment and management of these challenging patients.

Multiple system atrophy

This is a practical guide to diagnosing and managing multiple system atrophy (MSA). We explain the newly published Movement Disorders Society Consensus Diagnostic Criteria, which include new 'Clinically Established MSA' and 'Possible Prodromal MSA' categories, hopefully reducing time to diagnosis. We then highlight the key clinical features of MSA to aid diagnosis. We include a list of MSA mimics with suggested methods of differentiation from MSA. Lastly, we discuss practical symptom management in people living with MSA, including balancing side effects, with the ultimate aim of improving quality of life.

Association Between Orthostatic Hypotension and Dementia in Patients With Parkinson Disease and Multiple System Atrophy

BACKGROUND AND OBJECTIVES

Orthostatic hypotension (OH) increases dementia risk in patients with Parkinson disease (PD), although the underlying mechanisms and whether a similar association between OH and cognitive impairment exists in other synucleinopathies remain unknown. The aim is to evaluate the association between OH and dementia risk in patients with PD, and cognitive impairment risk in patients with multiple system atrophy (MSA), and to explore relevant clinical and neuropathologic factors to understand underlying pathogenic mechanisms.

METHODS

This is a retrospective cohort study. Medical records throughout the entire disease course of consecutive patients with neuropathology-confirmed PD and MSA from the Queen Square Brain Bank were systematically reviewed. Time of onset and severity of OH-related symptoms were documented, and their association with other clinical and neuropathologic variables was evaluated. Dementia risk for patients with PD and cognitive impairment risk for patients with MSA were estimated using multivariable hazard regression.

RESULTS

One hundred thirty-two patients with PD and 137 with MSA were included. Patients with MSA developed OH more frequently, earlier in the disease course and with more severe symptoms. Cumulative dementia prevalence was higher in patients with PD. Multivariable adjusted regression models showed that early OH, but not its symptom severity, increased dementia risk in patients with PD by 14% per year (hazard ratio [HR] = 0.86; 95% CI, 0.80-0.93) and cognitive impairment risk in patients with MSA by 41% per year (HR = 0.59; 95% CI, 0.42-0.83). Early OH was not associated with increased α-synuclein, β-amyloid, tau, Alzheimer, or cerebrovascular pathologies. No significant associations were found between severity of OH symptoms and other clinical or neuropathologic variables.

DISCUSSION

Early OH, but not its symptom severity, increases the risk of cognitive impairment in patients with PD and MSA. OH is not associated with more extensive Lewy, β-amyloid, tau, Alzheimer, or cerebrovascular pathologies. It is likely that OH contributes to cognitive impairment in patients with PD and MSA by hypoxia-induced nonspecific neurodegeneration. Further research should evaluate whether improving brain perfusion by treating OH may modify the risk of dementia in these conditions.

Pathomechanisms of cognitive impairment in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder characterized by early postural instability and falls, oculomotor dysfunction (vertical supranuclear gaze palsy), parkinsonism with poor response to levodopa, pseudobulbar palsy, and cognitive impairment. This four-repeat tauopathy is morphologically featured by accumulation of tau protein in neurons and glia causing neuronal loss and gliosis in the extrapyramidal system associated with cortical atrophy and white matter lesions. Cognitive impairment being frequent in PSP and more severe than in multiple system atrophy and Parkinson disease, is dominated by executive dysfunction, with milder difficulties in memory, and visuo-spatial and naming dysfunctions. Showing longitudinal decline, it has been related to a variety of pathogenic mechanisms associated with the underlying neurodegenerative process, such as involvement of cholinergic and muscarinergic dysfunctions, and striking tau pathology in frontal and temporal cortical regions associated with reduced synaptic density. Altered striatofrontal, fronto-cerebellar, parahippocampal, and multiple subcortical structures, as well as widespread white matter lesions causing extensive connectivity disruptions in cortico-subcortical and cortico-brainstem connections, support the concept that PSP is a brain network disruption disorder. The pathophysiology and pathogenesis of cognitive impairment in PSP, as in other degenerative movement disorders, are complex and deserve further elucidation as a basis for adequate treatment to improve the quality of life of patients with this fatal disease.

Morphological differences between the two major subtypes of multiple system atrophy with cognitive impairment

OBJECTIVE

To compare the neuropathology between two types of multiple system atrophy - parkinsonism-predominant (MSA-P) and cerebellar ataxia-predominant (MSA-C) with cognitive impairment.

MATERIAL & METHODS

35 cases of MSA-P (mean age at death 60.5 ± 7.8 years) and 15 cases of MSA-C (mean age at death 61.3 ± 6.8 years), 35.% of which associated with mild to moderate cognitive impairment and one with severe dementia, were examined neuropathologically with semiquantitative evaluation of both α-synuclein and Alzheimer pathologies, including cerebral amyloid angiopathy (CAA) and other co-pathologies.

RESULTS

While the mean age at death of both MSA subgroups was similar, the age at onset and duration of disease were slightly higher in the MSA-C group. In line with the classification, the αSyn pathology glial and neuronal inclusions in both the cortex and brainstem were significantly higher in the MSA-P group. With regard to the Alzheimer disease pathology, tau load in cases with mild to moderate cognitive impairment was slightly but not significantly higher in the MSA-P group, one with severe dementia showing fully developed Alzheimer co-pathology, while the amyloid-β (Aβ) load including the CAA was higher in the MSA-C group. The presence of Lewy co-pathology in this series (20%), being similar to that of other MSA cohorts, was more frequent in MSA cases with mild to severe cognitive impairment, but did not differ between the two subgroups and seems not essentially important for MCI in MSA.

CONCLUSIONS

In agreement with previous clinical studies that reported more severe cognitive dysfunction in patients with MSA-P, the present neuropathological study showed increased tau pathology in MSA-P and one with severe Alzheimer co-pathology, but only slightly increased amyloid pathology in the MSA-C group. Lewy co-pathology was more frequent in MSA-P cases with cognitive decline. In view of the limited data about the pathobiological basis of cognitive impairment in MSA, further studies to elucidate the differences between the two phenotypes are urgently needed.

Structural and metabolic correlates of neuropsychological profiles in multiple system atrophy and Parkinson's disease

BACKGROUND

Despite increased recognition of cognitive impairment in Multiple System Atrophy (MSA), its neuroanatomical correlates are not well defined. We aimed to explore cognitive profiles in MSA with predominant parkinsonism (MSA-P) and Parkinson's disease (PD) and their relationship to frontostriatal structural and metabolic changes.

METHODS

Detailed clinical and neuropsychological evaluation was performed together with diffusion tensor imaging (DTI) and [¹⁸F]-fluoro-deoxyglucose positron emission tomography ([¹⁸F]-FDG-PET) in patients with MSA-P (n = 11) and PD (n = 11). We compared clinical and neuropsychological data to healthy controls (n = 9) and correlated neuropsychological data with imaging findings in MSA-P and PD.

RESULTS

Patients with MSA-P showed deficits in executive function (Trail Making Test B-A) and scored higher in measures of depression and anxiety compared to those with PD and healthy controls. Widespread frontostriatal white matter tract reduction in fractional anisotropy was seen in MSA-P and PD compared to an imaging control group. Stroop Test interference performance correlated with [¹⁸F]-FDG uptake in the bilateral dorsolateral prefrontal cortex (DLPFC) and with white matter integrity between the striatum and left inferior frontal gyrus (IFG) in PD. Trail Making Test performance correlated with corticostriatal white matter integrity along tracts from the bilateral IFG in MSA-P and from the right DLPFC in both groups.

CONCLUSION

Executive dysfunction was more prominent in patients with MSA-P compared to PD. DLPFC metabolism and frontostriatal white matter integrity seem to be a driver of executive function in PD, whereas alterations in corticostriatal white matter integrity may contribute more to executive dysfunction in MSA-P.

Association between Cognitive Impairment and Hippocampal Subfield Volumes in Multiple System Atrophy

This study aimed to explore morphological changes of hippocampal subfields in patients with multiple system atrophy (MSA) with and without cognitive impairment using FreeSurfer-automated segmentation of hippocampal subfield techniques and their relationship with cognitive function. We enrolled 75 patients with MSA classified as cognitively impaired MSA (MSA-CI, n = 40) and cognitively preserved MSA (MSA-CP, n = 35), as well as 68 healthy controls. All participants underwent three-dimensional volume T1-weighted magnetic resonance imaging. The hippocampal subfield volume was measured using FreeSurfer version 7.2 and compared among groups. Regression analyses were performed between the hippocampal subfield volumes and cognitive variables. Compared with healthy controls, the volume of the right cornu ammonis (CA) 2/3 was significantly lower in the MSA-CI group (P=0.029) and that of the left fimbria was significantly higher in the MSA-CP group (P=0.046). Results of linear regression analysis showed that the right CA2/3 volume was significantly correlated with the Frontal Assessment Battery score in patients with MSA (adjusted R ² = 0.282, β = 0.227, and P=0.041). The hippocampal subfield volume decreased in patients with MSA-CI, even at the early disease stages. Specific structural changes in the hippocampus might be associated with cognitive deficits in MSA.

Prevalence and Clinical Characteristics of Dementia and Cognitive Impairment in Multiple System Atrophy: A Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment is a clinical feature of multiple system atrophy (MSA). However, the prevalence and factors influencing the prevalence of cognitive impairment and dementia in MSA patients remain unclear.

OBJECTIVE

We aim to provide an estimate of the prevalence of cognitive impairment and dementia in patients with MSA and to evaluate the possible effect of demographic, clinical and methodological factors on the prevalence.

METHODS

We systematically searched the PubMed, Embase, and Web of science databases to identify studies that report the prevalence of cognitive impairment or dementia in MSA published up to February 2022. We computed the estimates of the pooled prevalence using random-effects models. Heterogeneity was investigated by subgroup analyses and meta-regression. Differences between MSA patients with and without cognitive impairment in demographic and clinical features were explored.

RESULTS

A total of 23 studies comprising 2064 MSA patients were included in meta-analysis. The pooled prevalence of cognitive impairment in MSA patients was 37% (95% CI: 29% -45%), the prevalence of dementia was 11% (95% CI: 7% -15%). The subgroup analyses showed the prevalence of dementia in pathologically-confirmed MSA was 7% (95% CI: 0% -12%), in clinically diagnosed MSA was 14% (95% CI: 10% -18%). Cognitive impairment in MSA patients was associated with older age, lower education, longer disease duration and more severe motor symptoms.

CONCLUSION

Cognitive impairment is a common non-motor symptom in MSA. Dementia can develop in a few patients with MSA as well, but usually in the late stage.

The size and behavior of virtual objects have influence on functional exercise and motivation of persons with multiple sclerosis: a randomized study

The consequences of multiple sclerosis are problems with limb movement, coordination, and vision. Heretofore a combination of therapy and additional medications can alter the course of the disease and reduce upper extremity disability. We developed a virtual environment for pick-and-place tasks as a supportive tool to address the problem of challenging task in occupational therapy. The primary objective of the study was to investigate the influence of size and bounce on proximal and fine motor performance and intrinsic motivation. The secondary objective was to examine how the absence of challenge may decrease intrinsic motivation and heart rate. The randomized trial involved 84/107 eligible inpatients with multiple sclerosis. They were divided into 4 groups by computer randomization: Group 1 small and bouncing, Group 2 small and non-bouncing, Group 3 large and bouncing, and Group 4 large and non-bouncing virtual cubes. Each participant completed 50 sessions of up to 2 min each in approximately 14 days. Before commencement of the study the participants completed visuospatial and cognitive tests. Participants' subjective experiences were assessed daily using the intrinsic motivation inventory. Before and after the study, the box and block test and the 9-hole peg test were administered. Kinematic analysis showed significant differences between groups (average manipulation time p = 0.008, inserted cubes p = 0.004). Group 4 was the most successful (inserted cubes > 9) and the fastest (63.4 SD 25.8 s), but had low pressure/tension and heart rate. Group 1 was the slowest (88.9 SD 28.2 s) but had increased interest/enjoyment in the task under higher pressure/tension. There were substantial differences in intrinsic motivation between the 1st and last sessions within groups (Cohen's U3 < 0.3 or > 0.8). The size and behavior of virtual objects may be important for training proximal movements and fine motor skills in people with multiple sclerosis. Furthermore, the demonstrated approach proved to be effective and may reduce upper extremity disability in the long term if intrinsic motivation can be sustained longer with a challenging task.Trial registration The small scale randomized pilot trial has been registered at ClinicalTrials.gov Identifier: NCT04266444, 12/02/2020, https://clinicaltrials.gov/ct2/show/NCT04266444 .

Alterations of voxel-wise spontaneous activity and corresponding brain functional networks in multiple system atrophy patients with mild cognitive impairment

Emerging evidence has indicated that cognitive impairment is an underrecognized feature of multiple system atrophy (MSA). Mild cognitive impairment (MCI) is related to a high risk of dementia. However, the mechanism underlying MCI in MSA remains controversial. In this study, we conducted the amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity (FC) analyses to detect the characteristics of local neural activity and corresponding network alterations in MSA patients with MCI (MSA-MCI). We enrolled 80 probable MSA patients classified as cognitively normal (MSA-NC, n = 36) and MSA-MCI (n = 44) and 40 healthy controls. Compared with MSA-NC, MSA-MCI exhibited decreased ALFF in the right dorsal lateral prefrontal cortex (RDLPFC) and increased ALFF in the right cerebellar lobule IX and lobule IV-V. In the secondary FC analyses, decreased FC in the left inferior parietal lobe (IPL) was observed when we set the RDLPFC as the seed region. Decreased FC in the bilateral cuneus, left precuneus, and left IPL and increased FC in the right middle temporal gyrus were shown when we set the right cerebellar lobule IX as the seed region. Furthermore, FC of DLPFC-IPL and cerebello-cerebral circuit, as well as ALFF alterations, were significantly correlated with Montreal Cognitive Assessment scores in MSA patients. We also employed whole-brain voxel-based morphometry analysis, but no gray matter atrophy was detected between the patient subgroups. Our findings indicate that altered spontaneous activity in the DLPFC and the cerebellum and disrupted DLPFC-IPL, cerebello-cerebral networks are possible biomarkers of early cognitive decline in MSA patients.

The Cognitive Profile of Atypical Parkinsonism: A Meta-Analysis

Atypical Parkinsonism (AP) syndromes are characterized by a wide spectrum of non-motor symptoms including prominent attentional and executive deficits. However, the cognitive profile of AP and its differences and similarities with that of Parkinson's Disease (PD) are still a matter of debate. The present meta-analysis aimed at identifying patterns of cognitive impairment in AP by comparing global cognitive functioning, memory, executive functions, visuospatial abilities, language, non-verbal reasoning, and processing speed test performances of patients with AP relative to healthy controls and patients with PD. All investigated cognitive domains showed a substantial impairment in patients with AP compared to healthy controls. When AP syndromes were considered separately, their cognitive functioning was distributed along a continuum from Multiple Systemic Atrophy at one extreme, with the least impaired cognitive profile (similar to that observed in PD) to Progressive Supranuclear Palsy, with the greatest decline in global cognitive and executive functioning (similar to Corticobasal Syndrome). These findings indicate that widespread cognitive impairment could represent an important clinical indicator to distinguish AP from other movement disorders.

Naming in Older Adults: Complementary Auditory and Visual Assessment

OBJECTIVES

Naming difficulty is a common symptom of multiple age-related neurodegenerative disorders. As naming difficulty increases with age, valid, up-to-date naming assessment tools are crucial for differentiating between neurotypical changes in healthy aging and pathological naming difficulty. We aimed to develop and provide normative data for complementary auditory description naming and visual naming tests for older adults. Furthermore, these measures would include not only untimed accuracy, typically the sole naming performance measure, but also additional scores that incorporate features characteristic of actual word finding difficulty.

METHODS

A normative sample of 407 healthy older adults, aged 56-100 years, were administered the Auditory Naming Test (ANT) and Visual Naming Test (VNT), and other standardized measures.

RESULTS

Item analyses resulted in 36 stimuli for both tests. Age-stratified, education-based normative data are provided for accuracy, response time, tip-of-the-tongue (i.e., delayed, yet accurate responses plus correct responses following phonemic cueing), and multiple Summary Scores. Internal and test-retest reliability coefficients were reasonable (.59-.84). Untimed accuracy scores were high across age groups, seemingly reflecting stability of naming into late adulthood; however, time- and cue-based scores revealed reduced efficiency in word retrieval with increasing age.

CONCLUSIONS

These complementary auditory and visual naming test for older adults improve upon the current standard by providing more sensitive performance measures and the addition of an auditory-verbal component for assessing naming. Detection of subtle naming changes in healthy aging holds promise for capturing symptomatic naming changes during the early stages of neurocognitive disorders involving expressive language, potentially assisting in earlier diagnoses and more timely treatment.

Cognitive and Autonomic Dysfunction in Multiple System Atrophy Type P and C: A Comparative Study

Multiple System Atrophy (MSA) is a rare neurodegenerative disease, clinically defined by a combination of autonomic dysfunction and motor involvement, that may be predominantly extrapyramidal (MSA-P) or cerebellar (MSA-C). Although dementia is generally considered a red flag against the clinical diagnosis of MSA, in the last decade the evidence of cognitive impairment in MSA patients has been growing. Cognitive dysfunction appears to involve mainly, but not exclusively, executive functions, and may have different characteristics and progression in the two subtypes of the disease (i.e., MSA-P and MSA-C). Despite continued efforts, combining in-vivo imaging studies as well as pathological studies, the physiopathological bases of cognitive involvement in MSA are still unclear. In this view, the possible link between cardiovascular autonomic impairment and decreased cognitive performance, extensively investigated in PD, needs to be clarified as well. In the present study, we evaluated a cohort of 20 MSA patients (9 MSA-P, 11 MSA-C) by means of a neuropsychological battery, hemodynamic assessment (heart rate and arterial blood pressure) during rest and active standing and bedside autonomic function tests assessed by heart rate variability (HRV) parameters and sympathetic skin response (SSR) in the same experimental session. Overall, global cognitive functioning, as indicated by the MoCA score, was preserved in most patients. However, short- and long-term memory and attentional and frontal-executive functions were moderately impaired. When comparing MSA-P and MSA-C, the latter obtained lower scores in tests of executive functions and verbal memory. Conversely, no statistically significant difference in cardiovascular autonomic parameters was identified between MSA-P and MSA-C patients. In conclusion, moderate cognitive deficits, involving executive functions and memory, are present in MSA, particularly in MSA-C patients. In addition, our findings do not support the role of dysautonomia as a major driver of cognitive differences between MSA-P and MSA-C.

A Systematic Review of Apathy and Depression in Progressive Supranuclear Palsy

Depression and apathy can be significant problems in progressive supranuclear palsy (PSP). Using PRISMA guidelines, this systematic review examined prevalence estimates for depression and apathy in PSP, and, how different methods of definition may influence results. 29 studies meeting inclusion/exclusion criteria were identified: 12 on depression, 9 on apathy, and 8 on both. Studies were stratified according to whether a diagnostic criteria, rating scale or screening question methodology was employed. The weighted mean prevalence was 59.7% for depression (sample size = 473) and 58.3% for apathy (sample size = 858). Results for depression using diagnostic criteria or rating scales were similar whereas screening questions were associated with considerable inconsistency. Depression prevalence appeared to be influenced by apathy but not somatic symptoms. Most apathy studies relied only on a screening question method. Depression and apathy are common in PSP but there is a need for consensus on how they are defined (both tools and cut-off scores). In particular, more studies probing apathy in greater detail than a simple screening question are required.

The Profile and Evolution of Neuropsychiatric Symptoms in Multiple System Atrophy: Self- and Caregiver Report

OBJECTIVE

Recent research shows that patients with multiple system atrophy (MSA) have significant cognitive and neuropsychiatric comorbidities that can color the clinical presentation of the disease and affect their quality of life. The aims of this study were to determine the neuropsychiatric profile in a cohort of patients with the parkinsonian type of MSA (MSA-P) and their dynamic changes over a 1-year follow-up period and to compare rates of neuropsychiatric symptoms (NPSs) reported by caregivers and the patients themselves.

METHODS

Forty-seven patients were assessed at baseline; of these, 25 were assessed again after 1 year. NPS assessment tools included the Neuropsychiatric Inventory (NPI), the Beck Depression Inventory, the Hamilton Depression Rating Scale, the Hamilton Anxiety Rating Scale, and the Apathy Evaluation Scale.

RESULTS

The prevalence of NPSs in patients with MSA-P was very high, with depression, sleep disturbances, apathy, and anxiety being the most frequently occurring features. The evolution of NPSs was found to be independent of motor, autonomic, and cognitive symptoms. None of the scales measuring NPSs, including the NPI, were capable of detecting changes over the 1-year follow-up period. Although the overall prevalence of depression, apathy, and anxiety obtained from caregivers and the patients themselves was similar, reports from these two sources cannot be considered interchangeable.

CONCLUSIONS

The progression of neuropsychiatric symptoms was not a subject of rapid change in MSA-P, in contrast to the observed motor, autonomic, and cognitive deterioration. These findings suggest the need to investigate the utility of available instruments in capturing the evolution of NPSs in MSA over time.

Do patients with Progressive Supranuclear Palsy have episodic memory impairment? A systematic review

Background

Progressive supranuclear palsy (PSP) is the most common atypical parkinsonism and has executive dysfunction as a core feature. The magnitude of episodic memory disturbance in PSP is yet to be clarified.

Objectives

To investigate how impaired is episodic memory in PSP compared to healthy controls and other neuropsychiatric disorders. Also, we sought to identify the brain correlates underlying these memory disturbances.

Methods

We performed a systematic search on PubMed and Scopus, combining the terms "progressive supranuclear palsy" AND "memory". The search was limited to papers published in English, French, Portuguese or Spanish, with no chronological filters. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed.

Results

The initial search returned 464 results. After extraction of duplicates, 356 records were screened, leading to inclusion of 38 studies. Most studies found that PSP patients had lower scores on episodic memory compared to healthy controls. In addition, the majority of studies suggest that PSP does not differ from Parkinson's disease and from atypical parkinsonism in terms of episodic memory performance. The same is seen for PSP and frontotemporal dementia. Conversely, episodic memory impairment seems to be greater in typical Alzheimer's disease compared to PSP. Neuroimaging findings indicate that striatofrontal structures may be involved in PSP episodic memory dysfunction, while no associations with mesial structures (including hippocampi) were found.

Conclusions

Episodic memory is impaired in PSP. Whether this amnesia refers to executive dysfunction is still controversial. More studies are warranted to clarify the neural basis of memory impairment in PSP.

The Frontal and Cerebellar Metabolism Related to Cognitive Dysfunction in Multiple System Atrophy

Background

Cognitive dysfunctions have been reported in multiple system atrophy (MSA). However the underlying mechanisms remain to be elucidated. This study aimed to explore the possible cerebral metabolism associated with domain-specific cognitive performances in MSA.

Methods

A total of 84 patients were diagnosed as probable or possible MSA, comprised of 27 patients as MSA with predominant parkinsonism (MSA-P) and 57 patients as MSA with predominant cerebellar ataxia (MSA-C). The comprehensive neuropsychological tests and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) imaging were performed. Z-score was calculated to non-dimensionalize and unify indicators of different tests in the domains of executive function, attention, language, memory, and visuospatial function. Correlations between specific Z-score and cerebral ¹⁸F-FDG uptake were analyzed using statistical parametric mapping. The cognition-related metabolic differences between patients with MSA-P and MSA-C were analyzed using the post-hoc test.

Results

Z-scores of the domains including attention, executive function, and language correlated positively with the metabolism in the superior/inferior frontal gyrus and cerebellum, but negatively with that in the insula and fusiform gyrus (p < 0.001). No significant differences in neuropsychological performances and frontal metabolism were found between patients with MSA-P and MSA-C. Only lower metabolism in the cerebellum was observed in MSA-C.

Conclusion

Metabolic changes in the frontal lobe and cerebellum may participate in the cognitive impairments of patients with MSA. Nevertheless, cognitive and corresponding metabolic differences between the two subtypes of MSA still need more exploration.

OUP accepted manuscript

The progression of cognitive decline is heterogeneous in the three most common idiopathic parkinsonian diseases: Parkinson disease, multiple system atrophy and progressive supranuclear palsy. The causes for this heterogeneity are not fully understood, and there are no validated biomarkers that can accurately identify patients who will develop dementia and when. In this population-based, prospective study, comprehensive neuropsychological testing was performed repeatedly in new-onset, idiopathic parkinsonism. Dementia was diagnosed until 10 years and participants (N = 210) were deeply phenotyped by multimodal clinical, biochemical, genetic and brain imaging measures. At baseline, before the start of dopaminergic treatment, mild cognitive impairment was prevalent in 43.4% of the patients with Parkinson disease, 23.1% of the patients with multiple system atrophy and 77.8% of the patients with progressive supranuclear palsy. Longitudinally, all three diseases had a higher incidence of cognitive decline compared with healthy controls, but the types and severity of cognitive dysfunctions differed. In Parkinson disease, psychomotor speed and attention showed signs of improvement after dopaminergic treatment, while no such improvement was seen in other diseases. The 10-year cumulative probability of dementia was 54% in Parkinson disease and 71% in progressive supranuclear palsy, while there were no cases of dementia in multiple system atrophy. An easy-to-use, multivariable model that predicts the risk of dementia in Parkinson disease within 10 years with high accuracy (area under the curve: 0.86, P < 0.001) was developed. The optimized model adds CSF biomarkers to four easily measurable clinical features at baseline (mild cognitive impairment, olfactory function, motor disease severity and age). The model demonstrates a highly variable but predictable risk of dementia in Parkinson disease, e.g. a 9% risk within 10 years in a patient with normal cognition and CSF amyloid-β₄₂ in the highest tertile, compared with an 85% risk in a patient with mild cognitive impairment and CSF amyloid-β₄₂ in the lowest tertile. Only small or no associations with cognitive decline were found for factors that could be easily modifiable (such as thyroid dysfunction). Risk factors for cognitive decline in multiple system atrophy and progressive supranuclear palsy included signs of systemic inflammation and eye movement abnormalities. The predictive model has high accuracy in Parkinson disease and might be used for the selection of patients into clinical trials or as an aid to improve the prevention of dementia.

Development of a cognitive composite for measuring change in progressive supranuclear palsy

INTRODUCTION

Individuals with progressive supranuclear palsy (PSP) experience cognitive changes that are challenging to follow without a validated neuropsychological test battery to measure progression. This study describes a composite measure to evaluate cognition in individuals with PSP.

METHODS

Baseline cognitive test data from 486 participants with PSP in the PASSPORT (NCT03068468) study included the Repeatable Battery for Assessment of Neuropsychological Status (RBANS), Color Trails Test (CTT) parts 1 and 2, letter-number sequencing, and letter fluency. Data were analyzed using summary statistics and a matrix of Pearson correlations. A hypothetical factor structure was constructed and validated.

RESULTS

Observed correlations were highest for scores between story memory and story recall (correlation coefficient = 0.78) and lowest for scores between letter fluency and picture naming (correlation coefficient = 0.11), and picture naming and figure copy (correlation coefficient = 0.12). After excluding picture naming and Color Trails Test (CTT) parts 1 and 2, a 3-factor structure was hypothesized for the remaining 13 tests. Confirmatory factor analysis demonstrated goodness of fit within acceptable limits (comparative fit index and Tucker-Lewis index = 0.98, standardized root-mean-square residual and root-mean-square error of approximation = 0.05-0.06). Mixed-model repeated-measures analysis of change from baseline to week 52 in RBANS and PSP cognitive composite score produced mean-to-standard-deviation ratios of 0.418 and 0.780, respectively.

CONCLUSIONS

This novel composite endpoint, based on RBANS and designed to account for motor impairments in PSP, improves on current cognitive assessments PSP.

Parkinsonism and dementia

The aim of the present review is to summarize literature data on dementia in parkinsonian disorders. Cognitive decline and the gradual development of dementia are considered to be key features in the majority of parkinsonian conditions. The burden of dementia in everyday life of parkinsonian patients and their caregivers is vast and can be even more challenging to handle than the motor component of the disease. Common pathogenetic mechanisms involve the aggregation and spreading of abnormal proteins like alpha-synuclein, tau or amyloid in cortical and subcortical regions with subsequent dysregulation of multiple neurotransmitter systems. The degree of cognitive deterioration in these disorders is variable and ranges from mild cognitive impairment to severe cognitive dysfunction. There is also variation in the number and type of affected cognitive domains which can involve either a single domain like executive or visuospatial function or multiple ones. Novel genetic, biological fluid or imaging biomarkers appear promising in facilitating the diagnosis and staging of dementia in parkinsonian conditions. A significant part of current research in Parkinson's disease and other parkinsonian syndromes is targeted towards the cognitive aspects of these disorders. Stabilization or amelioration of cognitive outcomes represents a primary endpoint in many ongoing clinical trials for novel disease modifying treatments in this field. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Diagnostic contribution and therapeutic perspectives of transcranial magnetic stimulation in dementia

Transcranial magnetic stimulation (TMS) is a powerful tool to probe in vivo brain circuits, as it allows to assess several cortical properties such asexcitability, plasticity and connectivity in humans. In the last 20 years, TMS has been applied to patients with dementia, enabling the identification of potential markers of thepathophysiology and predictors of cognitive decline; moreover, applied repetitively, TMS holds promise as a potential therapeutic intervention. The objective of this paper is to present a comprehensive review of studies that have employed TMS in dementia and to discuss potential clinical applications, from the diagnosis to the treatment. To provide a technical and theoretical framework, we first present an overview of the basic physiological mechanisms of the application of TMS to assess cortical excitability, excitation and inhibition balance, mechanisms of plasticity and cortico-cortical connectivity in the human brain. We then review the insights gained by TMS techniques into the pathophysiology and predictors of progression and response to treatment in dementias, including Alzheimer's disease (AD)-related dementias and secondary dementias. We show that while a single TMS measure offers low specificity, the use of a panel of measures and/or neurophysiological index can support the clinical diagnosis and predict progression. In the last part of the article, we discuss the therapeutic uses of TMS. So far, only repetitive TMS (rTMS) over the left dorsolateral prefrontal cortex and multisite rTMS associated with cognitive training have been shown to be, respectively, possibly (Level C of evidence) and probably (Level B of evidence) effective to improve cognition, apathy, memory, and language in AD patients, especially at a mild/early stage of the disease. The clinical use of this type of treatment warrants the combination of brain imaging techniques and/or electrophysiological tools to elucidate neurobiological effects of neurostimulation and to optimally tailor rTMS treatment protocols in individual patients or specific patient subgroups with dementia or mild cognitive impairment.

Clinical progression of progressive supranuclear palsy: impact of trials bias and phenotype variants

Progressive supranuclear palsy causes diverse clinical presentations, including classical Richardson’s syndrome and several variant phenotypes. Clinical trials of disease-modifying therapies have recently been completed, with more planned for the next 2 years. However, many people with progressive supranuclear palsy do not meet eligibility criteria for these clinical trials. Understanding clinical progression with different phenotypes would improve trial design and enhance the accuracy of risk–benefit and cost–benefit assessments of new treatments for progressive supranuclear palsy. We set out to determine rates of motor and cognitive progression of possible, probable and definite progressive supranuclear palsy, with different phenotypes, from a representative cohort in a regional UK healthcare service. Longitudinal clinical data from people with Richardson’s syndrome and variant phenotypes were analysed using linear mixed-modelling, using both the full and modified versions of the Progressive Supranuclear Palsy Rating Scale, Mini-Mental State Examination and the revised Addenbrooke’s Cognitive Examination. Subgroup analyses considered patients meeting recent Phase II trial entry criteria and patients with neuropathological confirmation. Two hundred and twenty-seven patients [male = 59%, mean age (±standard deviation), 71.8 (±7.0) years] were followed for a mean 21.6 (±15.6) months. One hundred and seventy-four (77%) had Richardson’s syndrome at the outset, 25 had cortical variant presentations (13%, frontal, corticobasal, speech and language variants) and 28 had subcortical variant presentations (14%, parkinsonism, postural instability and gait freezing variants). Across all participants, annual progression in Richardson’s syndrome was faster than variant phenotypes on the Mini-Mental State Examination (−1.8 versus −0.9/year, P = 0.005) and revised Addenbrooke’s Cognitive Examination (−5.3 versus −3.0/year, P = 0.01) but not the Progressive Supranuclear Palsy Rating Scale (9.0 versus 7.1/year, P = 0.2) nor the modified Progressive Supranuclear Palsy Rating Scale (2.7 versus 2.3/year, P = 0.4). However, for those with more than 1 years’ follow-up, a significant difference was observed between Richardson’s syndrome and variant phenotypes in Progressive Supranuclear Palsy Rating Scale (8.7 versus 6.3/year, P = 0.04). Survival was longer in variant phenotypes than Richardson’s syndrome [7.3 (±3.9) versus 5.6 (±2.0) years, P = 0.02]. Pathologically confirmed cases (n = 49) supported these findings. Patients meeting basic trial-eligibility criteria (n = 129) progressed faster on the Progressive Supranuclear Palsy Rating Scale than trial-not-eligible patients (10.1 versus 6.1/year, P = 0.001). In conclusion, phenotypes other than Richardson’s syndrome show slower progression and longer survival. Trial criteria do not select representative progressive supranuclear palsy cases. This has implications for trial design, and application of trial results to clinically more diverse patient populations.

Relationship Between Orthostatic Hypotension and Cognitive Functions in Multiple System Atrophy: A Longitudinal Study

Introduction: The aim of this study is to investigate the impact of orthostatic hypotension (OH) on cognitive functions in patients with multiple system atrophy (MSA) followed over time. Methods: Thirty-two MSA patients were enrolled and underwent a comprehensive neuropsychological battery; at baseline (T₀) 15 out of 32 patients presented OH, assessed by means of orthostatic standing test. All patients underwent a follow-up (T₁) evaluation 12 months after baseline. Thirteen out of 32 patients also underwent a second follow-up (T₂) evaluation at 24 months. Changes over time on different neuropsychological tasks were compared between patients with and without OH by means of Mann-Whitney's U-test. Moreover, clinical categories of normal cognition, mild cognitive impairment, and dementia were determined, and changes at T₁ and T₂ in global cognitive status were compared between patients with and without OH. Results: At T₀, patients with OH had better performance on words/non-words repetition task (p = 0.02) compared to patients without OH. Compared to patients without OH, patients with OH performed worse on semantic association task (p < 0.01) at T₁ and on Stroop test-error effect (p = 0.04) at T₂. The percentage of patients with worsened cognitive status at T₁ was higher among patients with OH than among patients without OH (93 vs. 59%, p = 0.03). OH (β = -4.67, p = 0.01), education (β = 0.45, p = 0.02), age (β = 0.19, p = 0.03), and Montreal Cognitive Assessment battery (MOCA) score at T₀ (β = -0.26, p = 0.04) were significant predictors of global cognitive status worsening at T₁. Discussion: We found that global cognitive status worsened at 1-year follow-up in 93% of patients with OH, and OH, along with age, education, and MOCA score, predicted cognitive worsening over time. To clarify the relationship between OH and cognitive dysfunction in MSA, we suggest the use of clinical categories of normal cognition, mild cognitive impairment, and dementia in further longitudinal studies on MSA patients with and without OH.

[Neuropathology of dementia]

Demenz ist die klinische Folge verschiedener neurologischer Erkrankungen mit einer Vielzahl von Ätiologien. Dabei ist die genaue Kenntnis der zugrunde liegenden pathologischen Veränderungen entscheidend für die passgenaue Versorgung der Patienten und für die Entwicklung geeigneter Krankheitsbiomarker. Eine definitive Diagnose vieler dieser Erkrankungen, insbesondere der neurodegenerativen Formen, kann nur nach gründlicher postmortaler neuropathologischer Untersuchung gestellt werden. Dies unterstreicht die Wichtigkeit der Durchführung einer Gehirnautopsie und die Relevanz einer engen Zusammenarbeit zwischen Klinikern, Neuroradiologen und Neuropathologen sowie mit Grundlagenforschern. Ziel der vorliegenden Arbeit ist es, einen kurzen Überblick über die Neuropathologie der Demenz mit Schwerpunkt auf neurodegenerative Erkrankungen zu geben, um die interdisziplinäre Zusammenarbeit weiter zu fördern.

Cerebral Metabolism Related to Cognitive Impairments in Multiple System Atrophy

Objective: We aimed to characterize the cognitive profiles in multiple system atrophy (MSA) and explore the cerebral metabolism related to the cognitive decline in MSA using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) Positron Emission Tomography (PET).

Methods: In this study, 105 MSA patients were included for cognitive assessment and 84 of them were enrolled for ¹⁸F-FDG PET analysis. The comprehensive neuropsychological tests covered five main domains including execution, attention, memory, language, and visuospatial function. The cognitive statuses were classified to MSA with normal cognition (MSA-NC) and MSA with cognitive impairment (MSA-CI), including dementia (MSA-D), and mild cognitive impairment (MSA-MCI). With ¹⁸F-FDG PET imaging, the cerebral metabolism differences among different cognitive statuses were analyzed using statistical parametric mapping and post-hoc analysis.

Results: Among 84 MSA patients, 52 patients were found with MSA-CI, including 36 patients as MSA-MCI and 16 patients as MSA-D. In detail, the cognitive impairments were observed in all the five domains, primarily in attention, executive function and memory. In ¹⁸F-FDG PET imaging, MSA-D and MSA-MCI patients exhibited hypometabolism in left middle and superior frontal lobe compared with MSA-NC (p < 0.001). The normalized regional cerebral metabolic rate of glucose (rCMRglc) in left middle frontal lobe showed relative accuracy in discriminating MSA-CI and MSA-NC [areas under the curve (AUC) = 0.750; 95%CI = 0.6391–0.8609].

Conclusions: Cognitive impairments were not rare in MSA, and the hypometabolism in frontal lobe may contribute to such impairments.

Phonemic Verbal Fluency and Midbrain Atrophy in Progressive Supranuclear Palsy

BACKGROUND

The neuropsychological profile of progressive supranuclear palsy (PSP) patients is mainly characterized by executive dysfunction, but the relationship between the latter and midbrain atrophy is still unclear.

OBJECTIVE

The aims of the study were to investigate which test evaluating executive functioning is more frequently impaired in PSP patients and to evaluate the relationship between midbrain-based MRI morphometric measures and executive dysfunction.

METHODS

PSP patients who had undergone a neuropsychological battery assessing executive functioning with the Frontal Assessment Battery (FAB), the phonemic verbal fluency F-A-S, the Raven's Progressive Colored Matrix, and the Stroop word colors test (time and errors) were enrolled in the study. A group of Parkinson's disease (PD) patients matched by age, sex, education, and global cognitive status was selected. All the enrolled patients also underwent a volumetric T1-3D brain MRI.

RESULTS

Thirty-five PSP patients and 35 PD patients were enrolled. Patients with PSP as compared to patients with PD showed a significant greater impairment in verbal fluency (16.0±7.9 and 23.4±8.7 words/180 s; p < 0.001) and a significant lower score at the FAB total score (11.5±3.8 and 13.7±3.4; p = 0.013). Midbrain area was significantly smaller in PSP patients than in PD patients (83.9±20.1 and 134.5±19.9 mm2; p < 0.001). In PSP patients, a significant positive correlation between verbal fluency and the midbrain area (r = 0.421; p = 0.028) was observed.

CONCLUSION

Our findings suggest that the phonemic verbal fluency is among the most frequently impaired executive functions in PSP patients and is strongly correlated to midbrain atrophy.

Cognitive and behavioral profile of progressive supranuclear palsy and its phenotypes

BACKGROUND

Although several progressive supranuclear palsy (PSP) phenotypes have recently been described, studies identifying cognitive and neuropsychiatric differences between them are lacking.

METHODS

An extensive battery of cognitive and behavioural assessments was administered to 63 PSP patients, 25 PD patients with similar sociodemographic characteristics, and 25 healthy controls. We analysed differences in phenomenology, frequency and severity of cognitive and neuropsychiatric symptoms between PSP, PD and HC, and between PSP subtypes.

RESULTS

Regarding phenotypes, 64.6% met criteria for Richardson's syndrome (PSP-RS), 10.7% PSP with predominant Parkinsonism (PSP-P), 10.7% with PSP progressive gait freezing (PSP-PGF), and 10.7% PSP with predominant speech/language disorder (PSP-SL). Impairment was more severe in the PSP group than in the PD and HC groups regarding motor scores, cognitive testing and neuropsychiatric scales. Cognitive testing did not clearly differentiate between PSP phenotypes, but PSP-RS and PSP-SL appeared to have more cognitive impairment than PSP-PGF and PSP-P, mainly due to an increased impairment in frontal executive domains. Regarding neuropsychiatric disturbances, no specific behavior was more common in any of the PSP subtypes.

CONCLUSION

Motor deficits delineate the phenotypes included in currently accepted MDS-PSP criteria. Cognition and behavioural disturbances are common in PSP and allow us to distinguish this disorder from other neurological diseases, but they do not differentiate between PSP phenotypes.

Laboratory-Supported Multiple System Atrophy beyond Autonomic Function Testing and Imaging: A Systematic Review by the MoDiMSA Study Group

Background

Neuroimaging has been used to support a diagnosis of possible multiple system atrophy (MSA). Only blood pressure changes upon standing are included in the second consensus criteria but other autonomic function tests (AFT) are also useful to diagnose widespread and progressive autonomic failure typical of MSA. Additional diagnostic tools are of interest to improve accuracy of MSA diagnosis.

Objectives

To assess the utility of diagnostic tools beyond brain imaging and AFT in enhancing a laboratory-supported diagnosis of MSA to support the upcoming revision of the consensus criteria.

Methods

The International Parkinson and Movement Disorders Society MSA Study Group (MoDiMSA) performed a systematic review of original papers on biomarkers, sleep studies, genetic, neuroendocrine, neurophysiological, neuropsychological and other tests including olfactory testing and acute levodopa challenge test published before August 2019.

Results

Evaluation of history of levodopa responsiveness and olfaction is useful in patients in whom MSA-parkinsonian subtype is suspected. Neuropsychological testing is useful to exclude dementia at time of diagnosis. Applicability of sphincter EMG is limited. When MSA-cerebellar subtype is suspected, a screening for the common causes of adult-onset progressive ataxia is useful, including spinocerebellar ataxias in selected patients. Diagnosing stridor and REM sleep behavior disorder is useful in both MSA subtypes. However, none of these tools are validated in large longitudinal cohorts of postmortem confirmed MSA cases.

Conclusions

Despite limited evidence, additional laboratory work-up of patients with possible MSA beyond imaging and AFT should be considered to optimize the clinical diagnostic accuracy.

A study on the characteristics of cognitive function in patients with multiple system atrophy in China

Nonmotor symptoms in patients with multiple system atrophy (MSA) have received an increasing amount of attention in recent years, but no research on MSA patients' cognitive characteristics has been conducted in China. To evaluate the cognitive function of MSA patients in China. Using a case–control study design, 256 MSA patients and 64 controls were evaluated by the Montreal cognitive assessment (MoCA) scale to characterize their cognitive function. Like the controls, 60.5% of the patients with MSA had cognitive impairment, but the characteristics of cognitive impairment between the two groups were different. The cognitive impairment in MSA patients was prominent in the cognitive domains of visuospatial/executive functions, naming, attention, and orientation; particularly, the visuospatial/executive functions were the most significantly impaired, while impairment in language function was mainly seen in the controls. Besides, impairments in visuospatial/executive functions, attention, language, and orientation were more prominent in MSA-P (MSA with predominant Parkinsonism) patients than in MSA-C (MSA with predominant cerebellar ataxia). The cognitive impairments were more severe in patients with probable MSA than in patients with possible MSA. In addition, the results showed that the level of cognitive function was negatively correlated with the severity of MSA. This study, which characterized the cognitive function of MSA patients with the largest sample size known so far in China, found that patients with MSA do have cognitive impairment and display specific characteristics. Therefore, the cognitive impairment of MSA should be paid more attention.

The study has been registered in the Chinese Clinical Trial Registry (ChiCTR) (Registration No: ChiCTR1900022462).

Language impairment in progressive supranuclear palsy and corticobasal syndrome

Although commonly known as movement disorders, progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) may present with changes in speech and language alongside or even before motor symptoms. The differential diagnosis of these two disorders can be challenging, especially in the early stages. Here we review their impact on speech and language. We discuss the neurobiological and clinical-phenomenological overlap of PSP and CBS with each other, and with other disorders including non-fluent agrammatic primary progressive aphasia and primary progressive apraxia of speech. Because language impairment is often an early and persistent problem in CBS and PSP, there is a need for improved methods for language screening in primary and secondary care, and more detailed language assessments in tertiary healthcare settings. Improved language assessment may aid differential diagnosis as well as inform clinical management decisions.

Quantitative Cellular Changes in the Thalamus of Patients with Multiple System Atrophy

The thalamus is a brain region consisting of anatomical and functional connections between various spinal, subcortical, and cortical regions, which has a putative role in the clinical manifestation of Multiple System Atrophy (MSA). Previous stereological studies have reported significant anatomical alterations in diverse brain regions of MSA patients, including the cerebral cortex, basal ganglia and white matter, but no quantitative studies have examined the thalamus. To establish the extent of thalamic involvement, we applied stereological methods to estimate the total number of neurons and glial cells (oligodendrocytes, astrocytes and microglia) as well as the volume in two thalamic sub-regions, the mediodorsal nucleus (MDT) and the anterior principal nucleus (APn), in brains from ten MSA patients and 11 healthy control subjects. Compared to healthy controls, MSA patients had significantly fewer neurons (26%) in the MDT, but not the APn. We also found significantly more astrocytes (32%) and microglia (54%) in the MDT, with no such changes in the APn. Finally, we saw no group differences in the total number of oligodendrocytes. Our findings show a region-specific loss of thalamic neurons that occurs without loss of oligodendrocytes, whereas thalamic microgliosis seems to occur alongside astrogliosis. These pathological changes in the thalamus may contribute to the cognitive impairment seen in most patients with MSA.

Phonemic fluency quantity and quality: Comparing patients with PSP, Parkinson's disease and focal frontal and subcortical lesions

Progressive supranuclear palsy (PSP) can be difficult to distinguish from Parkinson's disease (PD), but has a much graver prognosis. PSP is characterised severely reduced output on measures of phonemic fluency, suggesting that it may be a specific marker of PSP. However, reduced phonemic fluency has also been noted in PD, and very few studies have actually compared phonemic fluency in PSP and PD. Although anecdotal reports suggest that phonemic fluency output in PSP may have specific characteristics, with more low-frequency words and perseverative errors, no study to date has formally explored this. Further investigation into phonemic fluency output and its cognitive and neuroanatomical correlates is now critical for improving our understanding of the verbal fluency in PSP. In this study, we compared phonemic fluency characteristics (including quantity, frequency and error rates) in patients with PSP, PD and focal frontal or subcortical lesions, and age- and education-matched healthy controls. We then compared these characteristics with performance on extensive neuropsychological testing. We found that PSP patients generated significantly fewer words than patients with PD and patients with right frontal focal lesions, and healthy controls. Phonemic fluency was also significantly reduced in patients with left frontal and subcortical focal lesions. However, there were no significant group differences in word frequency or error rates. Phonemic fluency was best predicted by performance on the Vocabulary and Hayling neuropsychological tests. We argue that these findings provide important evidence that reduced phonemic fluency is a hallmark of PSP and argue that the specificity of this impairment betrays an underlying impairment in energization, reflecting dysfunction of left frontal and subcortical networks.

Spatial attention and spatial short term memory in PSP and Parkinson's disease

Progressive Supranuclear Palsy (PSP) is a neurodegenerative disorder characterised by deterioration in motor, oculomotor and cognitive function. A key clinical feature of PSP is the progressive paralysis of eye movements, most notably for vertical saccades. These oculomotor signs can be subtle, however, and PSP is often misdiagnosed as Parkinson's disease (PD), in its early stages. Although some of the clinical features of PD and PSP overlap, they are distinct disorders with differing underlying pathological processes, responses to treatment and prognoses. One key difference lies in the effects the diseases have on cognition. The oculomotor system is tightly linked to cognitive processes such as spatial attention and spatial short-term memory (sSTM), and previous studies have suggested that PSP and PD experience different deficits in these domains. We therefore hypothesised that people with PSP (N = 15) would experience problems with attention (assessed with feature and conjunction visual search tasks) and sSTM (assessed with the Corsi blocks task) compared to people with PD (N = 16) and Age Matched Controls (N = 15). As predicted, feature and conjunction search were sgnificantly slower in the PSP group compared to the other groups, and this deficit was significantly worse for feature compared to conjunction search. The PD group did not differ from AMC on feature search but were significantly impaired on the conjunction search. The PSP group also had a pronounced vertical sSTM impairment that was not present in PD or AMC groups. It is argued that PSP is associated with specific impairment of visuospatial cognition which is caused by degeneration of the oculomotor structures that support exogenous spatial attention, consistent with oculomotor theories of spatial attention and memory.

Past, Present, and Future of Non-invasive Brain Stimulation Approaches to Treat Cognitive Impairment in Neurodegenerative Diseases: Time for a Comprehensive Critical Review

Low birth rates and increasing life expectancy experienced by developed societies have placed an unprecedented pressure on governments and the health system to deal effectively with the human, social and financial burden associated to aging-related diseases. At present, ∼24 million people worldwide suffer from cognitive neurodegenerative diseases, a prevalence that doubles every five years. Pharmacological therapies and cognitive training/rehabilitation have generated temporary hope and, occasionally, proof of mild relief. Nonetheless, these approaches are yet to demonstrate a meaningful therapeutic impact and changes in prognosis. We here review evidence gathered for nearly a decade on non-invasive brain stimulation (NIBS), a less known therapeutic strategy aiming to limit cognitive decline associated with neurodegenerative conditions. Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation, two of the most popular NIBS technologies, use electrical fields generated non-invasively in the brain to long-lastingly enhance the excitability/activity of key brain regions contributing to relevant cognitive processes. The current comprehensive critical review presents proof-of-concept evidence and meaningful cognitive outcomes of NIBS in eight of the most prevalent neurodegenerative pathologies affecting cognition: Alzheimer's Disease, Parkinson's Disease, Dementia with Lewy Bodies, Primary Progressive Aphasias (PPA), behavioral variant of Frontotemporal Dementia, Corticobasal Syndrome, Progressive Supranuclear Palsy, and Posterior Cortical Atrophy. We analyzed a total of 70 internationally published studies: 33 focusing on Alzheimer's disease, 19 on PPA and 18 on the remaining neurodegenerative pathologies. The therapeutic benefit and clinical significance of NIBS remains inconclusive, in particular given the lack of a sufficient number of double-blind placebo-controlled randomized clinical trials using multiday stimulation regimes, the heterogeneity of the protocols, and adequate behavioral and neuroimaging response biomarkers, able to show lasting effects and an impact on prognosis. The field remains promising but, to make further progress, research efforts need to take in account the latest evidence of the anatomical and neurophysiological features underlying cognitive deficits in these patient populations. Moreover, as the development of in vivo biomarkers are ongoing, allowing for an early diagnosis of these neuro-cognitive conditions, one could consider a scenario in which NIBS treatment will be personalized and made part of a cognitive rehabilitation program, or useful as a potential adjunct to drug therapies since the earliest stages of suh diseases. Research should also integrate novel knowledge on the mechanisms and constraints guiding the impact of electrical and magnetic fields on cerebral tissues and brain activity, and incorporate the principles of information-based neurostimulation.