Mild Cognitive Impairment and Progression to Dementia in Progressive Supranuclear Palsy

Subjective cognitive complaints in patients with progressive supranuclear palsy

Introduction

Subjective cognitive complaints (SCC) refer to self-reported cognitive decline that may or may not be reflected in objective neuropsychological evaluations. Such SCC are prevalent in neurodegenerative diseases, including Parkinson's disease (PD), but the prevalence and clinical features in patients with progressive supranuclear palsy (PSP) have not been investigated.

Methods

We recruited 83 PSP patients without dementia and investigated their SCC using a semi-structured interview. Comprehensive neuropsychological test results and patient clinical features were compared according to presence of SCC and underlying cognitive state.

Results

Among the 83 patients, 16 had normal cognition (NC), 67 had mild cognitive impairment (MCI), and 36 (43.4%) reported SCC. Among NC patients, 37.5% (6/16) had SCC, while 44.8% (30/67) of MCI patients reported SCC. There were no differences between the neuropsychological test results or demographic and clinical characteristics of PSP patients with or without SCC in the NC group. The demographic and clinical characteristics of the MCI+SCC (MCI with SCC)and MCI-SCC (MCI without SCC) groups were comparable, but the MCI+SCC group had significantly worse neuropsychological scores than the MCI-SCC group, particularly in tests assessing attention, language, visual memory, and fronto-executive function domains.

Discussion

While SCC are commonly reported by PSP patients, patients with PSP and MCI+SCC had worse cognitive function than those who did not report SCC. These findings suggest that SCC in PSP patients with MCI could be a worsening sign of cognitive function. Therefore, it is crucial for physicians to assess SCC in PSP patients and to provide timely diagnosis and management of cognitive decline.

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.

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.

Clinical Spectrum of Tauopathies

Tauopathies are both clinical and pathological heterogeneous disorders characterized by neuronal and/or glial accumulation of misfolded tau protein. It is now well understood that every pathologic tauopathy may present with various clinical phenotypes based on the primary site of involvement and the spread and distribution of the pathology in the nervous system making clinicopathological correlation more and more challenging. The clinical spectrum of tauopathies includes syndromes with a strong association with an underlying primary tauopathy, including Richardson syndrome (RS), corticobasal syndrome (CBS), non-fluent agrammatic primary progressive aphasia (nfaPPA)/apraxia of speech, pure akinesia with gait freezing (PAGF), and behavioral variant frontotemporal dementia (bvFTD), or weak association with an underlying primary tauopathy, including Parkinsonian syndrome, late-onset cerebellar ataxia, primary lateral sclerosis, semantic variant PPA (svPPA), and amnestic syndrome. Here, we discuss clinical syndromes associated with various primary tauopathies and their distinguishing clinical features and new biomarkers becoming available to improve in vivo diagnosis. Although the typical phenotypic clinical presentations lead us to suspect specific underlying pathologies, it is still challenging to differentiate pathology accurately based on clinical findings due to large phenotypic overlaps. Larger pathology-confirmed studies to validate the use of different biomarkers and prospective longitudinal cohorts evaluating detailed clinical, biofluid, and imaging protocols in subjects presenting with heterogenous phenotypes reflecting a variety of suspected underlying pathologies are fundamental for a better understanding of the clinicopathological correlations.

NREM Sleep EEG Characteristics Correlate to the Mild Cognitive Impairment in Patients with Parkinsonism

Early identification and diagnosis of mild cognitive impairment (MCI) in patients with parkinsonism (PDS) are critical. The aim of this study was to identify biomarkers of MCI in PDS using conventional electroencephalogram (EEG) power spectral analysis and detrended fluctuation analysis (DFA). In this retrospective study, patients with PDS who underwent an overnight polysomnography (PSG) study in our hospital from 2019 to 2020 were enrolled. Patients with PDS assessed by clinical examination and questionnaires were divided into two groups: the PDS with normal cognitive function (PDS-NC) group and the PDS with MCI (PDS-MCI) group. Sleep EEG signals were extracted and purified from the PSG and subjected to a conventional power spectral analysis, as well as detrended fluctuation analysis (DFA) during wakefulness, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep. Forty patients with PDS were enrolled, including 25 with PDS-NC and 15 with PDS-MCI. Results revealed that compared with PDS-NC patients, patients with PDS-MCI had a reduced fast ratio ((alpha + beta)/(delta + theta)) and increased DFA during NREM sleep. DFA during NREM was diagnostic of PDS-MCI, with an area under the receiver operating characteristic curve of 0.753 (95% CI: 0.592-0.914) (p < 0.05). Mild cognitive dysfunction was positively correlated with NREM-DFA (r = 0.426, p = 0.007) and negatively correlated with an NREM-fast ratio (r = -0.524, p = 0.001). This suggested that altered EEG activity during NREM sleep is associated with MCI in patients with PDS. NREM sleep EEG characteristics of the power spectral analysis and DFA correlate to MCI. Slowing of EEG activity during NREM sleep may reflect contribution to the decline in NREM physiological function and is therefore a marker in patients with PDS-MCI.

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.

Cerebellar rTMS in PSP: a Double-Blind Sham-Controlled Study Using Mobile Health Technology

There are no effective treatments in progressive supranuclear palsy (PSP). The aim of this study was to test the efficacy of theta burst repetitive transcranial magnetic stimulation (rTMS) on postural instability in PSP. Twenty PSP patients underwent a session of sham or real cerebellar rTMS in a crossover design. Before and after stimulation, static balance was evaluated with instrumented (lower back accelerometer, Rehagait®, Hasomed, Germany) 30-s trials in semitandem and tandem positions. In tandem and semitandem tasks, active stimulation was associated with increase in time without falls (both p=0.04). In the same tasks, device-extracted parameters revealed significant improvement in area (p=0.007), velocity (p=0.005), acceleration and jerkiness of sway (p=0.008) in real versus sham stimulation. Cerebellar rTMS showed a significant effect on stability in PSP patients, when assessed with mobile digital technology, in a double-blind design. These results should motivate larger and longer trials using non-invasive brain stimulation for PSP patients.

Evaluating the Real-World Representativeness of Participants with Mild Cognitive Impairment in Canadian Research Protocols: a Comparison of the Characteristics of a Memory Clinic Patients and Research Samples

Background

Studies of mild cognitive impairment (MCI) employ rigorous eligibility criteria, resulting in sampling that may not be representative of the broader clinical population.

Objective

To compare the characteristics of MCI patients in a Calgary memory clinic to those of MCI participants in published Canadian studies.

Methods

Clinic participants included 555 MCI patients from the PROspective Registry of Persons with Memory SyMPToms (PROMPT) registry in Calgary. Research participants included 4,981 individuals with MCI pooled from a systematic literature review of 112 original, English-language peer-reviewed Canadian studies. Both samples were compared on baseline sociodemographic variables, medical and psychiatric comorbidities, and cognitive performance for MCI due to Alzheimer’s disease and Parkinson’s disease.

Results

Overall, clinic patients tended to be younger, more often male, and more educated than research participants. Psychiatric disorders, traumatic brain injury, and sensory impairment were commonplace in PROMPT (up to 83% affected) but > 80% studies in the systematic review excluded these conditions. PROMPT patients also performed worse on global cognition measures than did research participants.

Conclusion

Stringent eligibility criteria in Canadian research studies excluded a considerable subset of MCI patients with comorbid medical or psychiatric conditions. This exclusion may contribute to differences in cognitive performance and outcomes compared to real-world clinical samples.

Motor, cognitive and behavioral differences in MDS PSP phenotypes

INTRODUCTION

Movement Disorder Society (MDS) new diagnostic criteria for Progressive Supranuclear palsy (PSP) identifying different disease phenotypes were recently released. The aim of the present study is to report on the cognitive and behavioral features of the different phenotypes diagnosed according to the MDS criteria.

METHODS

Forty-nine PSP patients underwent an extensive battery of clinical assessments. Differences between PSP subtypes were computed with χ² or ANOVA tests. Using the z scores, subjects were classified as having normal cognition, mild cognitive impairment, single or multiple domain, and dementia. A logistic regression model was implemented to investigate the major determinants of PSP non-Richardson's syndrome phenotype.

RESULTS

Half of the cohort presented Richardson's syndrome (46.9%), followed by PSP with parkinsonism and corticobasal syndrome (22.4% and 14.2%, respectively). Richardson's syndrome and PSP with corticobasal syndrome presented a similar burden of disease. The only cognitive testing differentiating the phenotypes were semantic fluency and ideomotor apraxia. The majority of our cohort was either affected by dementia or presented normal cognition. Richardson's syndrome presented the highest rate of dementia. The only marker of PSP non-Richardson's syndrome phenotype was better performance in visuo-spatial testing, implying worse visuo-spatial abilities in PSP Richardson's syndrome.

CONCLUSION

Available clinical assessments hardly capture differences between PSP phenotypes. The cognitive testing differentiating the PSP phenotypes were semantic fluency and ideomotor apraxia. In PSP, mild cognitive impairment likely represents an intermediate step from normal cognition to dementia. The only marker of PSP non-Richardson's syndrome phenotype was better performance in visuo-spatial testing.

Stereotypic behaviours in frontotemporal dementia and progressive supranuclear palsy

INTRODUCTION

The behavioural variant of frontotemporal dementia (bvFTD), and the Richardson variant of progressive supranuclear palsy (PSP-RS) share several clinical signs and symptoms. Since stereotypic behaviours are fairly common in bvFTD, and are also described in other degenerative dementias including Alzheimer's disease, and parkinsonisms with dementia, we aimed to examine the extent to which stereotypies also characterise PSP-RS.

METHODS

We compared 53 bvFTD patients with 40 demented PSP-RS patients, seen consecutively as outpatients at four Italian Hospitals. Patients were assessed by the Neuropsychiatric Inventory (NPI); Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) for cognitive functions; Stereotypy Rating Inventory (SRI) for stereotypies; Unified Parkinson's Disease Rating Scale (UPDRS) for motor function; and Activities of Daily Living (ADL) to assess autonomy in daily life.

RESULTS

The groups did not differ for age, illness duration, cognitive functions or total NPI score; PSP-RS had significantly more depressive symptoms and greater motor and autonomy compromise than bvFTD. The groups did not differ significantly on total SRI score, but bvFTD had significantly more cooking and eating stereotypies. Twenty-three (57.5%) PSP-RS and 43 (81%) bvFTD patients had at least one stereotypy; 16/23 (69.5%) PSP-RS and 9/43 (20.9%) bvFTD patients appeared aware of their stereotypies.

CONCLUSION

Stereotypies were common in our demented PSP-RS patients. Further studies on earlier stage non-demented PSP patients are required to ascertain whether stereotypies are characteristic of PSP in general or are confined to PSP-RS, and whether they may be used to suggest a PSP diagnosis early in disease course.