Sharpening the boundaries of Parkinson-associated dementia: recommendation for a neuropsychological diagnostic procedure

Cognitive testing in late-stage Parkinson's disease: A critical appraisal of available instruments

OBJECTIVE

For patients with Parkinson's disease (PD), cognitive impairment is one of the most disabling non-motor symptoms, particularly in the late disease stages (LSPD). Without a common cognitive assessment battery, it is difficult to estimate its prevalence and limits comparisons across studies. In addition, some instruments traditionally used in PD may not be adequate for use in LSPD. We sought to identify instruments used to assess cognition in LSPD and to investigate their global characteristics and psychometric properties to recommend a cognitive battery for the LSPD population.

METHOD

We conducted a literature search of EMBASE and MEDLINE for articles reporting the use of cognitive tests in LSPD. The global characteristics and psychometric properties of the four most used cognitive tests in each cognitive domain were verified to recommend a cognitive assessment battery.

RESULTS

Of 60 included studies, 71.7% used screening scales to assess cognition. Of the 53 reported instruments, the Montreal Cognitive Assessment, the Digit Span, the Trail Making Test, the Semantic Fluency test, the Rey Auditory Verbal Learning Test, the Brief Visuospatial Memory Test-Revised, the Boston Naming Test, the Judgment of Line Orientation, and the Clock Drawing Test corresponded best overall to the requirements considered important for selecting instruments in LSPD.

CONCLUSION

Screening scales are frequently used to assess cognition in LSPD. We recommend a cognitive assessment battery that considers the special characteristics of the LSPD population, including being quick and easy to use, with minimized motor demands, and covering all relevant cognitive domains.

Profile of cognitive impairment in late-stage Parkinson's disease

INTRODUCTION

The profile of cognitive impairment associated with the late stages of Parkinson's disease (LSPD) is rarely reported. Its characterization is necessary to better understand the cognitive changes that occur as the disease progresses and to better contribute to its management.

METHODS

In this cross-sectional study, we characterized the cognitive profile of LSPD patients using the comprehensive assessment methodology proposed by the International Parkinson and Movement Disorders Society Task Force. The association of clinical and demographic variables with dementia diagnosis was also investigated using binary logistic regression analysis.

RESULTS

Eighty-four LSPD patients were included (age 75.4 ± 6.9; disease duration 16.9 ± 7.5). Fifty-four (64.3%) were classified as demented and presented a global impairment cognitive profile. In the nondemented group (N = 30), 25 (83.3%) LSPD patients met the diagnostic criteria for mild cognitive impairment, mostly with multiple domain impairment (96.0%) and a heterogeneous profile. Memory was the most frequent and severely impaired cognitive domain in both groups. Disease disability, orientation, complex order comprehension, verbal learning, and visuoconstructive abilities were significantly associated with dementia diagnosis (p < .05).

CONCLUSIONS

Cognitive impairment in multiple domains was common in LSPD patients. The most frequent and prominent deficits were in the memory domain, with a strong interference from attention impairment. Disease disability, orientation, complex order comprehension, verbal learning, and visuoconstructive abilities proved to be important determinants for dementia diagnosis.

Neuropsychological spectrum in early PD: Insights from controlled and automatic behavioural regulation

Initial changes in Parkinson's disease (PD) are marked by loss of automatic movements and decline of some cognitive functions. Yet, the exact profile and extent of cognitive impairments in early stages of PD as well as their mechanisms related to automatic motor dysfunction remain unclear. Our objective was to examine the neuropsychological changes in early PD and their association to automatic and controlled modes of behavioural control. Significant relationships between early PD and cognitive dysfunction in set-shifting, abstraction ability/concept formation, processing speed, visuospatial/constructional abilities and verbal-visual memory was found. We also noted that tests with a strong effortful and controlled component were similarly affected as automatic tests by early PD, particularly those testing verbal memory, processing speed and visuospatial/constructional functions. Our findings indicate that initial stages of PD sets constraints over most of the cognitive domains normally assessed and are not easily explained in terms of either automatic or controlled mechanisms, as both appear similarly altered in early PD.

Towards Consensus on Essential Components of Physical Examination in Primary Care-based Memory Clinics

Background

Primary care-based memory clinics were established to meet the needs of persons with memory concerns. We aimed to identify: 1) physical examination maneuvers required to assess persons with possible dementia in specialist-supported primary care-based memory clinics, and 2) the best-suited clinicians to perform these maneuvers in this setting.

Methods

We distributed in-person and online surveys of clinicians in a network of 67 primary care-based memory clinics in Ontario, Canada.

Results

90 surveys were completed for an overall response rate of 66.7%. Assessments of vital signs, gait, and for features of Parkinsonism were identified as essential by most respondents. There was little consensus on which clinician should be responsible for specific physical examination maneuvers.

Conclusions

While we identified specific physical examination maneuvers deemed by providers to be both necessary and feasible to perform in the context of primary care-based memory clinics, further research is needed to clarify interprofessional roles related to the examination.

Differential sialylation of serpin A1 in the early diagnosis of Parkinson's disease dementia

The prevalence of Parkinson’s disease (PD) increases with age. Up to 50% of PD show cognitive decline in terms of a mild cognitive impairment already in early stages that predict the development of dementia, which can occur in up to 80% of PD patients over the long term, called Parkinson’s disease dementia (PDD). So far, diagnosis of PD/PDD is made according to clinical and neuropsychological examinations while laboratory data is only used for exclusion of other diseases. The aim of this study was the identification of possible biomarkers in cerebrospinal fluid (CSF) of PD, PDD and controls (CON) which predict the development of dementia in PD. For this, a proteomic approach optimized for CSF was performed using 18 clinically well characterized patients in a first step with subsequent validation using 84 patients. Here, we detected differentially sialylated isoforms of Serpin A1 as marker for differentiation of PD versus PDD in CSF. Performing 2D-immunoblots, all PDD patients could be identified correctly (sensitivity 100%). Ten out of 24 PD patients showed Serpin A1 isoforms in a similar pattern like PDD, indicating a specificity of 58% for the test-procedure. In control samples, no additional isoform was detected. On the basis of these results, we conclude that differentially sialylated products of Serpin A1 are an interesting biomarker to indicate the development of a dementia during the course of PD.

Diagnostic criteria for mild cognitive impairment in Parkinson's disease: Movement Disorder Society Task Force guidelines

Mild cognitive impairment is common in nondemented Parkinson's disease (PD) patients and may be a harbinger of dementia. In view of its importance, the Movement Disorder Society commissioned a task force to delineate diagnostic criteria for mild cognitive impairment in PD. The proposed diagnostic criteria are based on a literature review and expert consensus. This article provides guidelines to characterize the clinical syndrome and methods for its diagnosis. The criteria will require validation, and possibly refinement, as additional research improves our understanding of the epidemiology, presentation, neurobiology, assessment, and long-term course of this clinical syndrome. These diagnostic criteria will support future research efforts to identify at the earliest stage those PD patients at increased risk of progressive cognitive decline and dementia who may benefit from clinical interventions at a predementia stage.

Parkinson's disease dementia and potential therapeutic strategies

Dementia in Parkinson's disease (PD-D) has only been acknowledged in the recent three decades, but research in this field has accelerated. The purpose of this review was to discuss advances in PD-D regarding biomarker correlates and potential therapeutic targets. Attention and executive dysfunction, memory deficits that improve with cueing, and visual hallucinations are characteristic in PD-D. PD-D dramatically increases the disability and misery of the disease. Current treatment for PD-D is symptomatic, modest, and only transiently effective. There is wide agreement that more effective treatment is needed, but this will require more knowledge about PD-D pathophysiology. Advances in the pathogenesis of PD have focused on the substantia nigra, which is the location from where the pathophysiology of motor symptoms primarily arises in initial stages. In contradistinction, pathology studies have suggested that cognitive decline correlates with cortical and subcortical-cortical projection pathway abnormalities. There is evidence that substantia nigra mechanisms, including protein aggregation of α-synuclein (e.g., Lewy bodies) may also play a role in cortical neuron degeneration. Other different mechanisms, such as Alzheimer's disease pathology (e.g., Aβ aggregation) may be operant for PD-D. Biomarkers of various types are being proposed for the study of PD-D as well as for objective measures of PD-D prediction and progression. Therapeutic targets are currently derived mostly from general PD neurodegeneration research rather than cortical PD neurodegeneration per se. Protein aggregation, genes that are associated with PD, oxidative stress, inflammation, and trophic factors constitute the major classes of therapeutic targets for PD-D. More research is needed on the specific aspects of cortical dysfunction and degeneration that create PD-D.