Cognitive impairment in Parkinson's disease

Mild cognitive impairment in Parkinson's disease: subtypes and motor characteristics

The aims of this project were to determine the risk factors for and clinical characteristics of mild cognitive impairment (MCI) in Parkinson's disease (PD). We performed a retrospective record review of 72 non-demented PD patients (age: 57.79 +/- 10.57, duration of PD: 7.32 +/- 4.97) who completed a standardized neurological assessment, including a full neuropsychological battery, as part of their diagnostic work-up. Of these participants, 47.2% were cognitively normal and 52.8% met criteria for MCI. The majority of MCI patients had single domain MCI (23/38), the affected domains being memory (n = 9), executive function (n = 6), visuospatial skills (n = 6), and language (n = 2). The MCI group had longer duration of disease and higher postural instability and gait disorder subscale scores than the cognitively normal group. This report provides further support for use of the concept of MCI in PD research. There may be certain disease characteristics that could alert practitioners to the emergence of cognitive changes in patients. Future studies should focus on additional risk factors for MCI subtypes and their possible progression to frank dementia.

Motor phenotype of LRRK2 G2019S carriers in early-onset Parkinson disease

OBJECTIVE

To determine the motor phenotype of LRRK2 G2019S mutation carriers. LRRK2 mutation carriers were previously reported to manifest the tremor dominant motor phenotype, which has been associated with slower motor progression and less cognitive impairment compared with the postural instability and gait difficulty (PIGD) phenotype.

DESIGN

Cross-sectional observational study.

SETTING

Thirteen movement disorders centers.

PARTICIPANTS

Nine hundred twenty-five early-onset Parkinson disease cases defined as age at onset younger than 51 years.

MAIN OUTCOME MEASURES

LRRK2 mutation status and Parkinson disease motor phenotype: tremor dominant or PIGD. Demographic information, family history of Parkinson disease, and the Unified Parkinson's Disease Rating Scale score were collected on all participants. DNA samples were genotyped for LRRK2 mutations (G2019S, I2020T, R1441C, and Y1699C). Logistic regression was used to examine associations of G2019S mutation status with motor phenotype adjusting for disease duration, Ashkenazi Jewish ancestry, levodopa dose, and family history of Parkinson disease.

RESULTS

Thirty-four cases (3.7%) (14 previously reported) were G2019S carriers. No other mutations were found. Carriers were more likely to be Ashkenazi Jewish (55.9% vs 11.9%; P < .001) but did not significantly differ in any other demographic or disease characteristics. Carriers had a lower tremor score (P = .03) and were more likely to have a PIGD phenotype (92.3% vs 58.9%; P = .003). The association of the G2019S mutation with PIGD phenotype remained after controlling for disease duration and Ashkenazi Jewish ancestry (odds ratio, 17.7; P < .001).

CONCLUSION

Early-onset Parkinson disease G2019S LRRK2 carriers are more likely to manifest the PIGD phenotype, which may have implications for disease course.

Impaired verbal memory in Parkinson disease: relationship to prefrontal dysfunction and somatosensory discrimination

Objective

To study the neurocognitive profile and its relationship to prefrontal dysfunction in non-demented Parkinson's disease (PD) with deficient haptic perception.

Methods

Twelve right-handed patients with PD and 12 healthy control subjects underwent thorough neuropsychological testing including Rey complex figure, Rey auditory verbal and figural learning test, figural and verbal fluency, and Stroop test. Test scores reflecting significant differences between patients and healthy subjects were correlated with the individual expression coefficients of one principal component, obtained in a principal component analysis of an oxygen-15-labeled water PET study exploring somatosensory discrimination that differentiated between the two groups and involved prefrontal cortices.

Results

We found significantly decreased total scores for the verbal learning trials and verbal delayed free recall in PD patients compared with normal volunteers. Further analysis of these parameters using Spearman's ranking correlation showed a significantly negative correlation of deficient verbal recall with expression coefficients of the principal component whose image showed a subcortical-cortical network, including right dorsolateral-prefrontal cortex, in PD patients.

Conclusion

PD patients with disrupted right dorsolateral prefrontal cortex function and associated diminished somatosensory discrimination are impaired also in verbal memory functions. A negative correlation between delayed verbal free recall and PET activation in a network including the prefrontal cortices suggests that verbal cues and accordingly declarative memory processes may be operative in PD during activities that demand sustained attention such as somatosensory discrimination. Verbal cues may be compensatory in nature and help to non-specifically enhance focused attention in the presence of a functionally disrupted prefrontal cortex.

Cognitive impairment in Parkinson's disease: tools for diagnosis and assessment

Cognitive impairment (CI) and dementia are frequent and debilitating features associated with Parkinson's disease (PD). Formal neuropsychological examination is required to ascertain the degree and pattern of CI over the course of the disease. The use of different tools may explain heterogeneous data obtained from studies to date. Normative data for extensively used scales [Mattis Dementia Rating Scale (MDRS), Mini-Mental State Examination (MMSE)] is incomplete in PD populations. According to sample characteristics, statistical analyses, and methodological quality, 33 studies using scales not specific to PD (MDRS, MMSE, Cambridge Cognitive Assessment, FAB) or PD-specific scales (Mini-Mental Parkinson, Scales for Outcomes of Parkinson's disease-Cognition, Parkinson's Disease-Cognitive Rating Scale, and Parkinson Neuropsychometric Dementia Assessment) were eligible for the critical analysis of their appropriateness to assess cognition in PD. Of the four scales specifically designed for PD, the SCOPA-COG and the PD-CRS have undergone extensive and rigorous validation processes. While the SCOPA-COG mainly assesses "frontal-subcortical" cognitive defects, the PD-CRS also assesses "instrumental-cortical" functions, allowing better characterization of the different patterns of CI that may be present in PD from the earliest stages. The MMP and PANDA scales were designed as brief screening tests for CI and have not yet been subjected to extensive clinimetric evaluations. Further research on PD-specific tools seems mandatory to help establish accurate cut-off scores for the diagnosis of mild PDD, detect cognitive profiles more prone to the future development of dementia, and allow comparisons between different descriptive or interventional studies.

Motor patterns in Parkinson's disease: a data-driven approach

To identify patterns of motor disturbances in Parkinson's disease (PD) and evaluate their relation with other PD domains. A cohort of 399 PD patients was randomly divided into two samples. Factors within the motor section of the SPES/SCOPA were identified by exploratory factor analysis on data from the first sample and next tested by confirmatory factor analysis in the second sample. Relations with other PD domains were evaluated by regression analyses. A four factor model was found to be valid. This included a tremor, a bradykinetic-rigid, and two axial factors. One axial factor ("rise", "gait", "postural instability") was associated with age and cognition, while the other axial factor ("freezing", "speech", "swallowing") was related to dopaminergic medication and complications of therapy. Both other factors showed no relevant associations with demographic and clinical characteristics. The identification of motor factors and their relation with other domains of the disease may help to elucidate the mechanisms responsible for these associations and provide an objective base for further research on subtypes in PD.

Distinct patterns of regional cerebral glucose metabolism in Parkinson's disease with and without mild cognitive impairment

There is no consensus with regard to the clinical and neuroimaging characteristics of prodromal dementia in Parkinson's disease (PD). To delineate functional neuroimaging features of PD with mild cognitive impairment (PDMCI) and with no cognitive impairment (PDNC), we compared regional cerebral glucose metabolism (CMRglc) amongst 13 patients with PDMCI, 27 with PDNC, and 13 healthy controls. The PDNC patients had limited areas of hypometabolism in the frontal and occipital cortices. In the PDMCI patients, there were extensive areas of hypometabolism in the posterior cortical regions, including the temporo-parieto-occipital junction, medial parietal, and inferior temporal cortices. The present results suggest that posterior cortical dysfunction is the primary neuroimaging feature of PD patients at risk for dementia.

Dementia and mild cognitive impairment in patients with Parkinson's disease

The objective of this research was to assess the occurrence of cognitive impairment in 32 individuals (average age: 67.2 years old) with Parkinson' disease (PD). Procedures: clinical-neurological assessment; modified Hoehn and Yahr staging scale (HYS); standard neuropsychological battery of CERAD (Consortium to Establish a Registry for Alzheimer' Disease); Pfeffer questionnaire; and Clinical Dementia Rating. A comparison was made with a control group (CG), consisting of 26 individuals with similar age and educational level but without cognitive impairment. The PD patients showed an inferior performance in the CERAD battery when compared to the CG. Three PD sub-groups were characterised according to cognition: no cognitive impairment - 15 cases; mild cognitive impairment - 10; dementia - 7 cases. There was a significant association between motor disability (HYS) and the occurrence of dementia. Dementia and mild cognitive impairment frequently occur in PD patients and should be investigated in a routine way.

Cross-cultural validation of the Scales for Outcomes in Parkinson's Disease-Psychosocial questionnaire (SCOPA-PS) in four Latin American countries

OBJECTIVE

To conduct a cross-national validation of the Scales for Outcomes in Parkinson's Disease-PsychoSocial questionnaire (SCOPA-PS) in four Latin American Countries.

METHODS

Data quality (missing items), scale assumptions (item-test correlation), internal consistency (Cronbach's alpha, item homogeneity), factor structure, content validity, and precision (standard error of measurement, SEM) of the scale were explored, as was convergent validity with motor symptoms (Clinical Impression of Severity Index [CISI-PD], Scales for Outcomes in Parkinson's Disease-Motor Scale), emotional status (Hospital Anxiety and Depression Scale) and health-related quality of life (Parkinson Disease Questionnaire-39). Known-groups validity was studied by category of severity, based on Hoehn and Yahr staging (HY), CISI-PD, and disease duration.

RESULTS

Three hundred thirty-one Parkinson's disease (PD) patients with usable data participated (mean age 64.7 years; 42.3% female; mean PD duration 8.5 years; HY, 1 to 5). Data quality (missing items <10%), scale assumptions (item-total correlation = 0.43 - 0.71) and internal consistency of SCOPA-PS (Cronbach's alpha = 0.87; item homogeneity = 0.38) were satisfactory. Factor analysis suggested a unifactorial structure. High convergent validity was found for depression (r(S) = 0.61), anxiety (r(S) = 0.62), and health-related quality of life (r(S) = 0.82). Known-groups validity analyses indicated a gradual influence of severity category and disease duration on SCOPA-PS scores (P < 0.0001). SEM value was 8.24 (7 to 12 in previous studies). These magnitudes may be indicative of the threshold for a real change and a minimum important difference.

CONCLUSIONS

The Latin American versions of the SCOPA-PS displayed appropriate psychometric attributes.

Montreal cognitive assessment performance in patients with Parkinson's disease with "normal" global cognition according to mini-mental state examination score

OBJECTIVES

To examine Montreal Cognitive Assessment (MoCA) performance in patients with Parkinson's disease (PD) with "normal" global cognition according to Mini-Mental State Examination (MMSE) score.

DESIGN

A cross-sectional comparison of the MoCA and the MMSE.

SETTING

Two movement disorders centers at the University of Pennsylvania and the Philadelphia Veterans Affairs Medical Center.

PARTICIPANTS

A convenience sample of 131 patients with idiopathic PD who were screened for cognitive and psychiatric complications.

MEASUREMENTS

Subjects were administered the MoCA and MMSE, and only subjects defined as having a normal age- and education-adjusted MMSE score were included in the analyses (N=100). As previously recommended in patients without PD, a MoCA score less than 26 was used to indicate the presence of at least mild cognitive impairment (MCI).

RESULTS

Mean MMSE and MoCA scores+/-standard deviation were 28.8+/-1.1 and 24.9+/-3.1, respectively. More than half (52.0%) of subjects with normal MMSE scores had cognitive impairment according to their MoCA score. Impairments were seen in numerous cognitive domains, including memory, visuospatial and executive abilities, attention, and language. Predictors of cognitive impairment on the MoCA using univariate analyses were male sex, older age, lower educational level, and greater disease severity; older age was the only predictor in a multivariate model.

CONCLUSION

Approximately half of patients with PD with a normal MMSE score have cognitive impairment based on the recommended MoCA cutoff score. These results suggest that MCI is common in PD and that the MoCA is a more sensitive instrument than the MMSE for its detection.

Addenbrooke's Cognitive Examination validation in Parkinson's disease

BACKGROUND

There is a clear need for brief, sensitive and specific cognitive screening instruments in Parkinson's disease (PD).

OBJECTIVES

To study Addenbrooke's Cognitive Examination (ACE) validity for cognitive assessment of PD patient's using the Mattis Dementia Rating Scale (MDRS) as reference method. A specific scale for cognitive evaluation in PD, in this instance the Scales for Outcomes of Parkinson's disease-Cognition (SCOPA-COG), as well as a general use scale the Mini-mental state examination (MMSE) were also studied for further correlation.

METHODS

Forty-four PD patients were studied, of these 27 were males (61%), with a mean (SD) age of 69.5 (11.8) years, mean (SD) disease duration of 7.6 (6.4) years (range 1-25), mean (SD) total Unified Parkinson's Disease Rating Scale (UPDRS) score 37 (24) points, UPDRS III 16.5 (11.3) points. MDRS, ACE and SCOPA-COG scales were administered in random order. All patients remained in on-state during the study.

RESULTS

Addenbrooke's Cognitive Examination correlated with SCOPA-COG (r = 0.93, P < 0.0001), and MDRS (r = 0.91 P < 0.0001) and also with MMSE (r = 0.84, P < 0.001). Area under the receiver-operating curve, taking MDRS as the reference test, was 0.97 [95% confidence interval (CI): 0.92-1.00] for ACE, 0.92 (95% CI: 0.83-1.00) for SCOPA-COG and 0.91 (95% CI: 0.83-1.00) for MMSE. Best cut-off value for ACE was 83 points [Sensitivity (Se) = 92%; Specificity (Sp) = 91%; Kappa concordance (K) = 0.79], 20 points for the SCOPA-COG (Se = 92%; Sp = 87%; K = 0.74) and 26 points for MMSE (Se = 61%; Sp = 100%; K = 0.69).

CONCLUSION

Addenbrooke's Cognitive Examination appears to be a valid tool for dementia evaluation in PD, with a cut-off point which should probably be set at 83 points, displaying good correlation with both the scale specifically designed for cognitive deficits in PD namely SCOPA-COG, as well as with less specific tests such as MMSE.

A comprehensive model of health-related quality of life in Parkinson's disease

BACKGROUND

Insight in how impairments and disabilities related to Parkinson's disease (PD) influence health-related quality of life (HRQoL) is required to review adequacy of current management strategies.

METHODS

The Scales for Outcomes in Parkinson's disease (SCOPA) evaluation was used to assess impairments and disabilities. HRQoL was assessed with the EuroQol-5D Visual Analogue Scale. 378 patients with PD who participated in the SCOPA/PROPARK cohort were assessed while on their usual treatment. Multiple linear regression analysis and structural equation modelling were used to construct a model of factors that influence HRQoL.

RESULTS

A model with good fit was constructed that identified various impairments and disabilities as important contributors to HRQoL in PD. Of the disabilities, psychosocial well-being had a larger impact on HRQoL than physical functioning. Of the impairments, depression had the largest contribution to HRQoL, followed by axial motor symptoms, gastrointestinal symptoms, and urinary symptoms. In addition, pain, psychiatric and motor complications, and daytime sleepiness had small but significant influences on HRQoL.

CONCLUSION

Multiple factors, including disabilities, nonmotor symptoms and axial motor symptoms, affect HRQoL in patients with PD. In patients who are on symptomatic treatment aiming to alleviate mainly motor symptoms, there is a large impact on HRQoL of nonmotor and nondopaminergic symptoms. Research is warranted to develop and evaluate management strategies for the aspects that currently impact on HRQoL as psychosocial well-being, depressive symptoms, axial motor symptoms, gastrointestinal symptoms, and urinary symptoms. These findings call for a multidisciplinary approach in the care of these features.

Features associated with the development of non-motor manifestations in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder, predominantly characterized by the presence of motor symptoms. However, the non motor manifestations (NMM) are a frequent complaint in the PD patients. There is a lack of information about the risk factors associated with the NMM in these patients. The aim of this study is to evaluate the prevalence of the more common NMM in a population of PD patients and to determine the features associated with its development. We studied 124 ambulatory PD patients. NMM were defined by the presence of neuropsychiatric manifestations, cognitive disorder, autonomic dysfunction or sleep related problems. In a multivariate analysis we found that the years of evolution of the PD and the presence of cognitive dysfunction are the risk factors for the neuropsychiatric and autonomic manifestations, whereas axial impairment is a risk factor for cognitive disorders and dyskinesias is for sleep related problems. In conclusion, this study shows that the features related to the PD progression appear as the main risk factors associated with NMM.