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

Rapid Cognitive Deterioration in Progressive Supranuclear Palsy: A 1-Year Follow-Up Study

BACKGROUND

Nowadays, cognitive impairment has been characterized as one of the most vital clinical symptoms in progressive supranuclear palsy (PSP).

OBJECTIVES

Based on a relatively large cohort, we aimed to show the cognitive deterioration in different PSP subtypes during 1-year follow-up and investigate potential contributors for disease prognosis.

METHODS

One hundred seventeen patients from Progressive Supranuclear Palsy Neuroimage Initiative (PSPNI) cohort underwent neuropsychological tests and 1-year follow-up, with 73 diagnosed as PSP-Richardson syndrome (PSP-RS) and 44 as PSP-non-RS. Patients were divided into normal cognition (PSP-NC), mild cognitive impairment (PSP-MCI), and PSP-dementia. Cognitive impairment and progression rates were compared between PSP-RS and PSP-non-RS, and determinants for MCI conversion to dementia were calculated by multiple cox regression.

RESULTS

At baseline, 30.8% of PSP patients were diagnosed as dementia, 53.0% as MCI, and only 16.2% as NC. Compared to PSP-non-RS, PSP-RS suffered more from motor symptoms and cognitive impairment. During follow-up, PSP-RS also exhibited faster disease progression in Mini-Mental State Examination and visuospatial function, with cognitive deterioration in attention and executive function, but retained in language and memory subdomains. Twenty-seven of 62 PSP-MCI patients converted to dementia during follow-up, with the diagnosis of RS subtype as the most significant contributor to conversion (hazard ration = 2.993, 95% confidence interval = 1.451, 5.232, P = 0.009).

CONCLUSIONS

Patients with PSP-RS showed more severe cognitive impairment and faster decline longitudinally than patients with PSP-non-RS. Additionally, the diagnosis of RS subtype appears to be the most contributed factor for MCI conversion to dementia within just 1-year follow-up period.

Differential diagnosis of multiple system atrophy with predominant parkinsonism and Parkinson's disease using neural networks (part II)

Neural networks (NNs) possess the capability to learn complex data relationships, recognize inherent patterns by emulating human brain functions, and generate predictions based on novel data. We conducted deep learning utilizing an NN to differentiate between Parkinson's disease (PD) and the parkinsonian variant (MSA-P) of multiple system atrophy (MSA). The distinction between PD and MSA-P in the early stages presents significant challenges. Considering the recently reported heterogeneity and random distribution of lesions in MSA, we performed an analysis employing an NN with voxel-based morphometry data from the entire brain as input variables. The NN's accuracy in distinguishing MSA-P from PD demonstrates sufficient practicality for clinical application.

Cognition in cerebellar disorders: What's in the profile? A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aim to examine the profile and extent of cognitive deficits in patients with cerebellar disorders, and to provide a complete overview of the cognitive domains that might be affected in the Cerebellar Cognitive Affective Syndrome (CCAS).

METHODS

MEDLINE, Embase, PsycINFO, and Web of Science were systematically searched to 17-07-2024. Studies were considered if the participants were adult patients with a clinical diagnosis of cerebellar disorder and were neuropsychological assessed. Outcomes were grouped into the domains of processing speed, language, social cognition, executive function, visuospatial skills, episodic memory, verbal intelligence, attention, and working memory. All aetiologies were included for first evaluation and patients were assigned to one of two groups (focal vs. degenerative) for secondary evaluation. Random-effects models were employed for the meta-analyses.

RESULTS

129 studies with a total of 3140 patients with cerebellar disorders were included. Patients performed significantly worse compared to control/standardized data in all domains. Deficits were most pronounced in processing speed, ES [95% CI] = - 0.83 [- 1.04, - 0.63], language, ES [95% CI] = - 0.81 [- 0.94, - 0.67], and social cognition, ES [95% CI] = - 0.81 [- 1.19, - 0.42]. Cognitive impairment varied between patients with focal cerebellar lesions and degenerative cerebellar disorders, but was overall worse in the degenerative group.

DISCUSSION

Cerebellar disorders can impact many cognitive domains, extending beyond executive functioning, visuospatial skills, and language. These outcomes contribute to a broader understanding of the cerebellum's role in cognition and sheds light on the cognitive deficits associated with cerebellar disorders.

Characteristics of cerebral glucose metabolism in patients with cognitive impairment in multiple system atrophy

Objective

We aimed to conduct 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) to investigate the metabolic changes in brain regions associated with cognitive decline in patients with multiple system atrophy (MSA) and to assess the diagnostic efficacy of 18F-FDG PET imaging for evaluating the cognitive status of MSA patients.

Methods

This study included 44 MSA patients (MSA group) and 30 healthy controls (HC group) who underwent brain 18F-FDG PET imaging. All patients were subjected to the Mini-Mental State Examination and categorized into the MSA with normal cognition (MSA-NC) and MSA with cognitive impairment (MSA-CI) groups. Statistical parametric mapping (version 12) was used to analyze PET images and compare the differences in brain metabolism between the MSA and HC groups. The PET images of MSA-CI and MSA-NC patients were compared to analyze the metabolic characteristics, and the regional cerebral metabolic rate of glucose (rCMRglc) was calculated for different brain regions. Receiver operating characteristic (ROC) curves were used to analyze the ability of the rCMRglc of different brain regions to assess the cognitive status of MSA patients.

Results

Compared with the HC group, the MSA group showed diffuse reductions in glucose metabolism in the cerebellar regions, decreased metabolism in specific areas of the left inferior parietal lobule, right putamen, and left middle temporal gyrus, and increased metabolism in the left postcentral gyrus, right postcentral gyrus, left precuneus. Compared with the MSA-NC group, the MSA-CI group exhibited decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus (Montreal Neurological Institute coordinates: 18, -6, 70) showed better diagnostic efficacy for identifying MSA-CI, with an area under the ROC curve of 0.829 (95%CI = 0.696-0.963), sensitivity of 84.6% (95%CI = 66.5-93.9%), and specificity of 83.3% (95%CI = 60.8-94.2%).

Conclusion

Compared with MSA-NC patients, the MSA-CI patients show decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus may be a potential molecular imaging biomarker for diagnosing MSA-CI.

Cognitive impairment in Parkinson's disease and other parkinsonian syndromes

In this narrative review, we address mild cognitive impairment, a frequent complication of Parkinson's disease (PD) and atypical parkinsonian disorders (APDs). Recent diagnostic criteria have blurred the lines between PD and dementia with Lewy bodies (DLB), particularly in the cognitive domain. Additionally, atypical parkinsonian syndromes like progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) often present with significant cognitive decline. Even multiple system atrophy (MSA) can be associated with cognitive impairment in some cases. Several biomarkers, including imaging techniques, such brain magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET), as well as pathological proteins either of the cerebrospinal fluid (CSF), such as Tau, amyloid beta, and synuclein, or of the serum, such as neurofilament light chain (Nfl) are more and more often utilized in the early differential diagnosis of APDs. The complex interplay between these conditions and the evolving understanding of their underlying pathologies highlight the need for further research to refine diagnostic criteria, possibly incorporate the new findings from the biomarker's field into the diagnostic criteria and develop targeted therapeutic strategies.

Positron emission tomography molecular imaging for pathological visualization in multiple system atrophy

Multiple system atrophy (MSA) is a complex, heterogeneous neurodegenerative disorder characterized by a multifaceted pathogenesis. Its key pathological hallmark is the abnormal aggregation of α-synuclein, which triggers neuroinflammation, disrupts both dopaminergic and non-dopaminergic systems, and results in metabolic abnormalities in the brain. Positron emission tomography (PET) is a non-invasive technique that enables the visualization, characterization, and quantification of these pathological processes from diverse perspectives using radiolabeled agents. PET imaging of molecular events provides valuable insights into the underlying pathomechanisms of MSA and holds significant promise for the development of imaging biomarkers, which could greatly improve disease assessment and management. In this review, we focused on the pathological mechanisms of MSA, summarized relevant targets and radiopharmaceuticals, and discussed the clinical applications and future perspectives of PET molecular imaging in MSA.

Locus coeruleus neuromelanin, cognitive dysfunction, and brain metabolism in multiple system atrophy

BACKGROUND

Cognitive dysfunction is increasingly recognized in multiple system atrophy (MSA). Locus coeruleus (LC) integrity is associated with cognitive performance both in healthy controls (HC) and neurodegenerative conditions such as Parkinson's disease (PD). Furthermore, cortical glucose hypometabolism is associated with impaired cognitive performance in MSA. However, knowledge about LC sub-regional degeneration and its association with cognitive dysfunction and cortical glucose metabolism is lacking.

OBJECTIVE

To investigate LC sub-regional involvement and its association with cognitive impairment and brain metabolism in MSA.

METHODS

Eleven MSA, eighteen PD, and eighteen HC participants were included in the study. Neuromelanin-sensitive MRI was used to determine rostral, middle and caudal LC neuromelanin signals. Brain glucose metabolism was investigated with [18F]Fluorodeoxyglucose PET (FDG-PET). The Montreal Cognitive Assessment (MoCA) was used as a measure of global cognition.

RESULTS

Middle LC neuromelanin signal was significantly reduced in MSA [t(43) = 3.70, corrected-p = 0.004] and PD [t(43) = 2.63, corrected-p = 0.041] compared to HC, while caudal LC was only reduced in MSA [t(43) = 2.82, corrected-p = 0.030]. In MSA, decreased rostral LC neuromelanin was associated with lower MoCA scores (ρ = 0.760, p = 0.006) which, in turn, were associated with lower frontal cortex glucose metabolism. An association between rostral LC neuromelanin signal and frontal cortex glucose metabolism was found in exploratory analyses.

CONCLUSION

Loss of LC neuromelanin signal was found in MSA, the middle and caudal parts being targeted. Rostral LC neuromelanin signal loss was associated with both frontal cortex hypometabolism and lower MoCA scores. This pathophysiological link should be further investigated as the noradrenergic system transmission is amenable to pharmacological manipulation.

The Spectrum of Cognitive Impairment in Atypical Parkinsonism Syndromes: A Comprehensive Review of Current Understanding and Research

Multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) are the most common atypical parkinsonism (AP) syndromes. They are clinically characterized by varying combinations of levodopa-poorly responsive parkinsonism, motor, cerebellar, and other signs. They are associated with a wide spectrum of non-motor symptoms, including prominent cognitive impairment such as global cognitive deficits, memory, executive, attentional, visuospatial, language, and non-verbal reasoning dysfunctions. Within the APs, their cognitive functioning is distributed along a continuum from MSA with the least impaired cognitive profile (similar to Parkinson's disease) to PSP and CBD with the greatest decline in global cognitive and executive domains. Although their pathological hallmarks are different-MSA α-synucleinopathy, CBD, and PSP 4-repeat tauopathies-cognitive dysfunctions in APs show both overlaps and dissimilarities. They are often preceding and anticipate motor dysfunctions, finally contributing to reduced quality of life of patients and caregivers. The present paper will review the current evidence of the prevalence and type of cognitive impairment in these AP syndromes, their neuroimaging, pathogenic backgrounds, and current management options based on extensive literature research. Cognitive dysfunctions in APs are due to disruption of prefronto-subcortical and striato-thalamo-cortical circuitries and multiple essential brain networks. This supports the concept that they are brain network disorders due to complex pathogenic mechanisms related to the basic proteinopathies that are still poorly understood. Therefore, the pathophysiology and pathogenesis of cognitive impairment in APs deserve further elucidation as a basis for early diagnosis and adequate treatment of these debilitating comorbidities.

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.

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.

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.

Molecular Imaging in Parkinsonian Disorders—What’s New and Hot?

Highlights

Abstract

Neurodegenerative parkinsonian disorders are characterized by a great diversity of clinical symptoms and underlying neuropathology, yet differential diagnosis during lifetime remains probabilistic. Molecular imaging is a powerful method to detect pathological changes in vivo on a cellular and molecular level with high specificity. Thereby, molecular imaging enables to investigate functional changes and pathological hallmarks in neurodegenerative disorders, thus allowing to better differentiate between different forms of degenerative parkinsonism, improve the accuracy of the clinical diagnosis and disentangle the pathophysiology of disease-related symptoms. The past decade led to significant progress in the field of molecular imaging, including the development of multiple new and promising radioactive tracers for single photon emission computed tomography (SPECT) and positron emission tomography (PET) as well as novel analytical methods. Here, we review the most recent advances in molecular imaging for the diagnosis, prognosis, and mechanistic understanding of parkinsonian disorders. First, advances in imaging of neurotransmission abnormalities, metabolism, synaptic density, inflammation, and pathological protein aggregation are reviewed, highlighting our renewed understanding regarding the multiplicity of neurodegenerative processes involved in parkinsonian disorders. Consequently, we review the role of molecular imaging in the context of disease-modifying interventions to follow neurodegeneration, ensure stratification, and target engagement in clinical trials.

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.