Validation and attempts of revision of the MDS-recommended tests for the screening of Parkinson's disease dementia

Pathobiology of Cognitive Impairment in Parkinson Disease: Challenges and Outlooks

Cognitive impairment (CI) is a characteristic non-motor feature of Parkinson disease (PD) that poses a severe burden on the patients and caregivers, yet relatively little is known about its pathobiology. Cognitive deficits are evident throughout the course of PD, with around 25% of subtle cognitive decline and mild CI (MCI) at the time of diagnosis and up to 83% of patients developing dementia after 20 years. The heterogeneity of cognitive phenotypes suggests that a common neuropathological process, characterized by progressive degeneration of the dopaminergic striatonigral system and of many other neuronal systems, results not only in structural deficits but also extensive changes of functional neuronal network activities and neurotransmitter dysfunctions. Modern neuroimaging studies revealed multilocular cortical and subcortical atrophies and alterations in intrinsic neuronal connectivities. The decreased functional connectivity (FC) of the default mode network (DMN) in the bilateral prefrontal cortex is affected already before the development of clinical CI and in the absence of structural changes. Longitudinal cognitive decline is associated with frontostriatal and limbic affections, white matter microlesions and changes between multiple functional neuronal networks, including thalamo-insular, frontoparietal and attention networks, the cholinergic forebrain and the noradrenergic system. Superimposed Alzheimer-related (and other concomitant) pathologies due to interactions between α-synuclein, tau-protein and β-amyloid contribute to dementia pathogenesis in both PD and dementia with Lewy bodies (DLB). To further elucidate the interaction of the pathomechanisms responsible for CI in PD, well-designed longitudinal clinico-pathological studies are warranted that are supported by fluid and sophisticated imaging biomarkers as a basis for better early diagnosis and future disease-modifying therapies.

Cognitive evaluation in Parkinson's disease: applying the Movement Disorder Society recommendations in a population with a low level of formal education

BACKGROUND

 The diagnosis of cognitive disorders in Parkinson disease (PD) can be very challenging. Aiming at establishing uniform and reliable diagnostic procedures, the International Parkinson's Disease and Movement Disorder Society (MDS) commissioned task forces to delineate diagnostic criteria for mild cognitive impairment (MCI) and dementia in PD.

OBJECTIVES

 To investigate the applicability of the MDS recommendations for cognitive evaluation in a Brazilian sample of patients with PD with low levels of formal education.

METHODS

 A total of 41 patients with PD were subjected to a comprehensive neuropsychological evaluation based on tests proposed by the MDS, which included the Mini-Mental State Examination, the Mattis Dementia Rating Scale (MDRS), the Trail Making Test (TMT) parts A and B, in addition to language and memory skills assessment. Neuropsychiatric and daily functioning features were also evaluated. Spearman correlation analyses were used to evaluate the association between the scores obtained in the cognitive scales and demographic/clinical variables.

RESULTS

 Although none of the participants had a formal diagnosis of dementia, 50% presented some degree of cognitive impairment when considering the results of the MDRS. Of note, a noticeable number of patients was not able to complete the full neuropsychological assessment. The TMT part B was the most difficult task, being completed by only 22 participants (54%). As expected, the greater the educational level, the better the performance on the cognitive tests. Better motor function was also associated with better scores in cognition.

CONCLUSIONS

 Adopting strict inclusion/exclusion criteria and a comprehensive clinical evaluation, we found remarkable limitations for the MDS recommendations when individuals with low educational levels are considered. A revision of the current guidelines is necessary considering differences among populations, especially related to formal education.

Adherence to treatment in Parkinson's disease: A multicenter exploratory study with patients from six Latin American countries

BACKGROUND

Adherence to treatment in Parkinson's disease (PD) is compromised due to the need for multiple therapies, comorbidities related to aging, and the complexity of therapeutic schemes. In the present study, we aimed to explore adherence to treatment in groups of PD patients from six Latin-American (LA) countries and identify its associated demographic and clinical parameters.

METHODS

A multicenter, cross-sectional, exploratory study was conducted from September 2016 to March 2017. Treatment adherence was assessed using the simplified medication adherence questionnaire (SMAQ), applied to patients and caregivers. Sociodemographic and clinical variables (MDS-UPDRS Part III-IV, MMSE, Beck Depression Inventory-II (BDI-II)) were recorded.

RESULTS

Eight hundred patients from six LA countries were evaluated. Nonadherence was reported in 58.25% of the population, according to patients. The most frequent issues were forgetfulness and correct timing of doses. A high level of agreement in adherence prevalence and most SMAQ items were observed between patients and their caregivers. The nonadherent population had a significantly higher proportion of unemployment, free access to medication, troublesome dyskinesias and off-periods, lesser years of education, and worse motor, cognitive, and mood scores. In multiple logistic and linear regression analyses, MDS-UPDRS Part III, BDI-II, gender, free access to medication, treatment with dopamine agonists alone, years of education, excessive concerns about adverse effects, and beliefs about being well-treated remained significant contributors to adherence measures.

CONCLUSION

Educational strategies, greater involvement of PD patients in decision-making, and consideration of their beliefs and values might be of great need to improve medication adherence in this PD population.

Dementia in long-term Parkinson's disease patients: a multicentre retrospective study

While several studies have investigated the clinical progression of cognitive decline in Parkinson’s disease (PD) patients, there has been a paucity of data on specifically evaluating PD patients with a disease duration of over 20 years. This study retrospectively investigated the frequency of dementia in PD (PDD) patients with a disease duration of over 20 years assessed in research clinics across the UK and Australia. Data from 2327 PD patients meeting the United Kingdom Parkinson’s Disease Society Brain Bank Criteria was pooled. A diagnosis of probable PDD was made according to the Movement Disorder Society Level 1 criteria. Thirty-six participants had a disease duration of at least 20 years. Of the 36 patients, only 7 (19%) were classified as probable PDD. Compared to PD patients without dementia, those with dementia had lower levels of educational attainment and exhibited more severe motor features. Additionally, 34 out of the 36 patients (94%) exhibited a non-tremor dominant phenotype. No significant differences in age, age onset, disease duration, dopaminergic medication use, and sex distribution were observed between PD patients with and without dementia. Findings from the present study suggest that the prevalence of dementia in long-term PD patients may be lower than anticipated and suggest that the trajectory of cognitive decline in PD patients can be different. These findings highlight the need to investigate factors that might affect the outcome of cognitive decline in long-term PD patients, which may lead to the determination of potential modulating factors in the development of dementia in these patients.

Machine-Learning Algorithms Based on Screening Tests for Mild Cognitive Impairment

BACKGROUND

The mobile screening test system for mild cognitive impairment (mSTS-MCI) was developed and validated to address the low sensitivity and specificity of the Montreal Cognitive Assessment (MoCA) widely used clinically.

OBJECTIVE

This study was to evaluate the efficacy machine learning algorithms based on the mSTS-MCI and Korean version of MoCA.

METHOD

In total, 103 healthy individuals and 74 patients with MCI were randomly divided into training and test data sets, respectively. The algorithm using TensorFlow was trained based on the training data set, and then its accuracy was calculated based on the test data set. The cost was calculated via logistic regression in this case.

RESULT

Predictive power of the algorithms was higher than those of the original tests. In particular, the algorithm based on the mSTS-MCI showed the highest positive-predictive value.

CONCLUSION

The machine learning algorithms predicting MCI showed the comparable findings with the conventional screening tools.

Cerebrospinal fluid concentrations of inflammatory markers in Parkinson's disease and atypical parkinsonian disorders

Inflammation has been implicated in the pathogenesis of Parkinson’s disease (PD). We here investigate levels of inflammatory biomarkers in cerebrospinal fluid (CSF) in PD and atypical parkinsonian disorders (APD) compared with neurologically healthy controls. We included 131 patients with PD and 27 PD with dementia (PDD), 24 with multiple system atrophy (MSA), 14 with progressive supranuclear palsy (PSP) and 50 controls, all part of the Swedish BioFINDER study. CSF was analyzed for CRP, SAA, IL-6, IL-8, YKL-40 and MCP-1 (CCL2) as well as α-synuclein (α-syn), tau, tau phosphorylated at Thr181 (P-tau), Aβ₄₂ and NfL. In this exploratory study, we found higher levels of the inflammatory biomarker SAA in PDD and MSA compared with controls and PD and higher levels of CRP in PDD and MSA compared with PD. YKL-40 was lower in PD compared with controls. There were multiple positive correlations between the inflammatory markers, α-syn and markers of neuroaxonal injury (NfL and tau). In PD, higher levels of inflammatory biomarkers correlated with worse motor function and cognitive impairment. Thus, inflammatory biomarkers were increased in PDD and MSA. Furthermore, inflammatory biomarkers correlated with more severe disease regarding motor symptoms and cognitive impairment in PD, indicating an association between inflammation and more aggressive disease course. However, the results need confirmation in follow-up studies.

Detection of cognitive impairment using a machine-learning algorithm

PURPOSE

The Mini-Mental State Examination (MMSE) is one of the most frequently used bedside screening measures of cognition. However, the Korean Dementia Screening Questionnaire (KDSQ) is an easier and more reliable screening method. Instead, other clinical variables and raw data were used for this study without the consideration of a cutoff value. The objective of this study was to develop a machine-learning algorithm for the detection of cognitive impairment (CI) based on the KDSQ and the MMSE.

PATIENTS AND METHODS

The original dataset from the Clinical Research Center for Dementia of South Korea study was obtained. In total, 9,885 and 300 patients were randomly allocated to the training and test datasets, respectively. We selected up to 24 variables including sex, age, education duration, diabetes mellitus, and hypertension. We trained a machine-learning algorithm using TensorFlow based on the training dataset and then calculated its accuracy using the test dataset. The cost was calculated by conducting a logistic regression.

RESULTS

The accuracy of the model in predicting CI based on the KDSQ only, the MMSE only, and the combination of the KDSQ and MMSE was 84.3%, 88.3%, and 86.3%, respectively. For the KDSQ, the sensitivity for detecting CI was 91.50% and the specificity for detecting normal cognition (NL) was 59.60%. The sensitivity of the MMSE was 94.35%, and the specificity was 59.62%. When combining the KDSQ and the MMSE, the sensitivity for detecting CI was 91.5% and the specificity for detecting NL was 61.5%.

CONCLUSION

The algorithm predicting CI based on the MMSE is superior. However, the KDSQ can be administered more easily in clinical practice and the algorithm using KDSQ is a comparable screening tool.

Low Sensitivity of the Mini-Mental State Examination for Cognitive Assessment of Brazilian Patients With Parkinson Disease

INTRODUCTION

Recent publications have highlighted the low sensitivity of the Mini-Mental State Examination (MMSE) for the cognitive assessment of patients with Parkinson disease (PD). The Montreal Cognitive Assessment (MoCA), otherwise, has shown greater sensitivity when compared to the MMSE. Based on this, we have searched for the cognitive impairment measurable by the MoCA and the functional performance on activities of daily living in a sample of Brazilian patients with PD and normal MMSE. We hypothesized that the low sensitivity of the MMSE, already shown by other authors, could be replicated in a low-income country.

OBJECTIVE

To describe the performance on the MoCA and the dependence on third parties for activities of daily living in a sample of Brazilian patients with PD and normal MMSE.

METHODS

We evaluated 43 volunteers with PD and normal MMSE considering the Brazilian cutoffs. Cognitive performance was assessed through the MoCA and functional performance through a modified version of the Disability Assessment for Dementia Scale.

RESULTS

Despite normal score on the MMSE, considering the Brazilian cutoffs, 62.7% of the volunteers performed below the literature cutoff for the MoCA (26 points). Furthermore, 30.2% had dependence on third party for activities of daily living. By using a strict cutoff for the MMSE (26 points), 56.7% performed below the MoCA cutoff and 24.3% had dependence for activities of daily living.

CONCLUSIONS

Our findings confirm the limitations of the MMSE for the cognitive screening of patients with PD in a low-income country.

Validation of the Parkinson's Disease-Cognitive Rating Scale Applying the Movement Disorder Society Task Force Criteria for Dementia Associated with Parkinson's Disease

BACKGROUND

The authors studied the measurement properties of the Parkinson's Disease-Cognitive Rating Scale (PD-CRS) compared with Movement Disorders Society Task Force (MDS-TF) criteria for the diagnosis of dementia in patients with Parkinson's disease.

METHODS

The sample consisted of 223 patients who were diagnosed in accordance with the United Kingdom Parkinson's Disease Society Brain Bank who were assessed with both the MDS-TF and the PD-CRS criteria (in addition to other instruments) without the assessors' knowledge of previous results. Internal consistency was studied (homogeneity of the items and Guttmann's λ values were obtained) in addition to convergent, divergent, and discriminative validity. The receiver operating characteristic curve was obtained, and the cutoff point at which the PD-CRS had the greatest efficiency was analyzed.

RESULTS

The internal consistency was shown to be adequate, with a λ value of 0.821. A floor effect was observed in 4 of the items (Sustained Attention, Working Memory, Immediate Verbal Memory, and Alternating Verbal Fluency), and 1 item showed a ceiling effect (Clock Copying). The scale adequately discriminated patients with and without dementia (Kruskal-Wallis; P ≤ 0.000). The area under the curve was 0.899. With a cutoff score of 62 (from a possible score of 134), the scale achieved 94% sensitivity and 99% specificity.

CONCLUSIONS

The PD-CRS has adequate measurement properties and is a valid tool for studying the presence of dementia in patients with Parkinson's disease.

Clinical Epidemiology, Evaluation, and Management of Dementia in Parkinson Disease

The prevalence of neurodegenerative diseases such as Parkinson disease (PD) will increase substantially, due to the aging of the population and improved treatments leading to better disease-related outcomes. Dementia is the most common nonmotor symptom in PD, and most patients with PD will have cognitive dysfunction and cognitive decline in the course of their disease. The development of cognitive dysfunction in PD greatly limits the ability to participate in activities of daily living and can be a tipping point for nursing home placement or major caregiver stress. Understanding the different causes of dementia and how to reduce the incidence and impact of secondary cognitive dysfunction in PD are necessary skills for primary care physicians and neurologists. In this review, we discuss the clinical epidemiology of dementia in PD with an emphasis on preventable cognitive dysfunction, present tools for outpatient evaluation of cognitive dysfunction, and describe current pharmacological treatments for dementia in PD.

Validation of Neuropsychological Tests to Screen for Dementia in Chinese Patients With Parkinson's Disease

To compare the accuracy of different neuropsychological tests and their combinations for deriving reliable cognitive indices for dementia diagnosis in Parkinson's disease (PD). One hundred forty consecutive patients with PD were recruited and administrated an extensive battery of neuropsychological tests. Discriminant analysis and receiver-operator characteristic curve were used to evaluate their correct classifications and validity. Patients with PD having dementia (PDD; 23.5%) performed significantly worse in all tests than patients without dementia. Age of onset, disease duration, Hoehn-Yahr grade, Unified Parkinson's Disease Rating Scale part III scores, and education were associated with dementia in patients with PD. Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment, and Block Design (BD) showed better specificity and sensitivity when used alone, and combined use of MMSE and BD further increased the validity. Our results indicated that the accuracy of MMSE was better in dementia diagnosis of Chinese patients with PD, and combined use of MMSE and BD could further increase the validity of dementia diagnosis.

Longitudinal Measurements of Cerebrospinal Fluid Biomarkers in Parkinson's Disease

OBJECTIVE

The purpose of this study was to investigate whether cerebrospinal fluid (CSF) levels of tau, phosphorylated tau, β-amyloid42 , α-synuclein, neurofilament light, and YKL-40 change over time and if changes correlate with motor progression and/or cognitive decline in patients with PD and controls.

METHODS

We included 63 patients with PD (nondemented) and 21 neurologically healthy controls from the prospective and longitudinal Swedish BioFINDER study, all of whom had clinical assessments and lumbar punctures at baseline and after 2 years.

RESULTS

CSF tau levels correlated strongly with α-synuclein. The levels of CSF α-synuclein, tau, phosphorylated tau, neurofilament light, and YKL-40, but not β-amyloid42 , increased in CSF over 2 years in PD. No changes were seen in the control group. Studying patients with a short disease duration ( ≤ 5 years) and patients with a long disease duration ( > 5 years) separately, α-synuclein and tau only increased in the PD group with long disease duration. In the PD group, an increase in phosphorylated tau over 2 years correlated with faster motor progression and faster cognitive decline. An increase in YKL-40 over 2 years correlated with faster cognitive decline.

CONCLUSION

CSF biomarkers reflecting Lewy body pathology and neurodegeneration (α-synuclein), neuronal degeneration (tau, phosphorylated tau, and neurofilament light), and inflammation (YKL-40) increase significantly over 2 years in PD. CSF levels of α-synuclein and tau correlate and remain stable in the early symptomatic phase of PD but increase in the later phase. We hypothesize that CSF α-synuclein levels might increase as a result of more intense neurodegeneration in PD with long disease duration. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Parkinson's disease dementia: Diagnostic criteria and risk factor review

Cognitive impairment in Parkinson's disease (PD) greatly affects the morbidity and mortality rates of the disease and can be present as mild executive dysfunction even in the early stages. In advanced PD, the prevalence of dementia (PDD) reaches more than 80%. The Movement Disorders Society (MDS) has proposed diagnostic criteria for PDD and Mild Cognitive Impairment (MCI) in PD, raising the sensibility and specificity of those diagnoses compared with DSM IV, for example. Cognition impairment is an important issue to determine in PD because of therapeutic, epidemiologic, and prognostic factors. These guidelines should be applied to a diagnosis of PD-MCI and PDD as soon as possible in order to provide a correct diagnosis. Another important topic to discuss regarding cognition in PD is which patient would be more likely to develop PDD. There are some risk factors for cognitive impairment in PD with cumulative risk. Important risk factors related to PDD are age, time of diagnosis, rigid-akinetic phenotype, severe impairment, impairment of semantic fluency, genetic factors, low education level, and postural instability. Recognizing them is also important for early diagnosis. We discuss the diagnostic criteria of PD cognitive impairment and some aspects of risk factors related to it in this review.

People with Parkinson's disease and normal MMSE score have a broad range of cognitive performance

Cognitive impairment, including dementia, is common in Parkinson's disease (PD). The Mini-Mental State Examination (MMSE) has been recommended as a screening tool for Parkinson's disease dementia (PDD), with values below 26 indicative of possible dementia. Using a detailed neuropsychological battery, we examined the range of cognitive impairment in PD patients with an MMSE score of 26 or higher. In this multicenter, cross-sectional, observational study, we performed neuropsychological testing in a sample of 788 PD patients with MMSE scores of 26 or higher. Evaluation included tests of global cognition, executive function, language, memory, and visuospatial skills. A consensus panel reviewed results for 342 subjects and assigned a diagnosis of no cognitive impairment, mild cognitive impairment, or dementia. Sixty-seven percent of the 788 subjects performed 1.5 standard deviations below the normative mean on at least one test. On eight of the 15 tests, more than 20% of subjects scored 1.5 standard deviations or more below the normative mean. Greatest impairments were found on Hopkins Verbal Learning and Digit Symbol Coding tests. The sensitivity of the MMSE to detect dementia was 45% in a subset of participants who underwent clinical diagnostic procedures. A remarkably wide range of cognitive impairment can be found in PD patients with a relatively high score on the MMSE, including a level of cognitive impairment consistent with dementia. Given these findings, clinicians must be aware of the limitations of the MMSE in detecting cognitive impairment, including dementia, in PD.