Brief Cognitive Assessment in the Early Stages of Parkinson Disease

In vivo Illustration of Altered Dopaminergic and GABAergic Systems in Early Parkinson's Disease

Background

Changes in γ-aminobutyric acid (GABA) function are noted in patients with Parkinson's disease (PD) who have some non-motor impairments. However, dopamine-related GABA function and GABA-related cognitive changes are still unclear.

Methods

Thirteen drug-naive early-stage PD patients underwent a series of PET scans with [¹¹C]flumazenil(FMZ) and [¹¹C]CFT. The [¹¹C]FMZ binding potential (BP_ND) derived from a Logan plot analysis was compared between PD patients and age-matched controls. The [¹¹C]CFT radioactivity relative to the cerebellar counterpart was estimated as a semiquantitative value [¹¹C]CFT SUVR. Correlations between [¹¹C]FMZ BP_ND and [¹¹C]CFT SUVR in the same region of interest were also examined.

Results

In patients in the PD group, [¹¹C]CFT SUVR was significantly lower in the putamen. The levels of [¹¹C]FMZ BP_ND in the cerebral cortex (frontal lobe dominancy) and the affected-side putamen were also reduced. In addition, [¹¹C]CFT SUVR was negatively correlated with the [¹¹C]FMZ BP_ND level in the affected-side putamen. In patients in the PD group, the total frontal assessment battery (FAB) score was positively correlated with the [¹¹C]FMZ BP_ND in the frontal region.

Conclusion

GABAergic dysfunction coexists with dopaminergic loss not only in the putamen but also over the extrastriatal region in patients with early PD and is related to frontal dysfunction. The negative correlation of [¹¹C]CFT SUVR with [¹¹C]FMZ BP_ND in the affected putamen suggests that a greater dopaminergic demise would decelerate GABA release (or an increase in tracer binding), resulting in persistent failure of the GABAergic system in PD patients.

Path analysis of biomarkers for cognitive decline in early Parkinson’s disease

Clinical and biochemical diversity of Parkinson’s disease (PD) and numerous demographic, clinical, and pathological measures influencing cognitive function and its decline in PD create problems with the determination of effects of individual measures on cognition in PD. This is particularly the case where these measures significantly interrelate with each other producing intricate networks of direct and indirect effects on cognition. Here, we use generalized structural equation modelling (GSEM) to identify and characterize significant paths for direct and indirect effects of 14 baseline measures on global cognition in PD at baseline and at 4 years later. We consider 269 drug-naïve participants from the Parkinson’s Progression Marker Initiative database, diagnosed with idiopathic PD and observed for at least 4 years after baseline. Two GSEM networks are derived, highlighting the possibility of at least two different molecular pathways or two different PD sub-types, with either CSF p-tau181 or amyloid beta (1–42) being the primary protein variables potentially driving progression of cognitive decline. The models provide insights into the interrelations between the 14 baseline variables, and determined their total effects on cognition in early PD. High CSF amyloid concentrations (> 500 pg/ml) are associated with nearly full protection against cognitive decline in early PD in the whole range of baseline age between 40 and 80 years, and irrespectively of whether p-tau181 or amyloid beta (1–42) are considered as the primary protein variables. The total effect of depression on cognition is shown to be strongly amplified by PD, but not at the time of diagnosis or at prodromal stages. CSF p-tau181 protein could not be a reliable indicator of cognitive decline because of its significantly heterogeneous effects on cognition. The outcomes will enable better understanding of the roles of the clinical and pathological measures and their mutual effects on cognition in early PD.

The correlation of non-motor symptoms and sleep on balance in Parkinson's disease patients with normal cognition and mild cognitive impairment

BACKGROUND

Parkinson's disease (PD) is characterized by non-motor symptoms (NMS) as well as by motor symptoms. Together with the impairment of cognitive functions, NMS and sleep also affect motor symptoms negatively. The aim of our study is to examine the correlation of NMS and sleep on balance in PD patients with normal cognition (PD-NC) and with mild cognitive impairment (PD-MCI).

METHODS

A total of 69 patients were included in our study. Using the Standardized Mini-Mental State Examination, participants were divided into 2 groups, PD-NC and PD-MCI. Patients were assessed with the Unified Parkinson's Disease Rating Scale (UPDRS), the Berg Balance Scale (BBS), the Tinetti Balance Assessment Tool (TBAT), the Non-Motor Symptoms Questionnaire (NMSQ), and the Parkinson's Disease Questionnaire (PDQ-39).

RESULTS

PD-MCI patients had statistically significant worse motor symptoms and more balance disorder compared to PD-NC (UPDRS: p = 0.009; BBS: p = 0.010; TBAT: p = 0.004). PD-MCI patients had greater severity of non-motor symptoms and worse sleep quality than the PD-NC group (NMSQ-total: p = 0.02; NMSQ-sleep total: p = 0.01). The evaluation has shown that with a diagnosis of MCI, NMS, and sleeping problems were correlated, and the correlation was associated with impairment of the balance function. While being more pronounced in the PD-MCI group, quality of life was affected in both groups (p < 0.05).

CONCLUSION

Our data demonstrate a negative effect on the balance function in patients with cognitive impairment suffering increased NMS and sleeping disorders. Treatment of these patients needs to concentrate on NMS and cognitive functions as much as on motor symptoms.

Measuring executive dysfunction in Parkinson's disease: Reliability and validity of the Spanish version of Frontal Assessment Battery (FAB-E)

Background

Deficits in executive functions (EFs) are frequently detected in patients with Parkinson’s disease (PD). The Frontal Assessment Battery (FAB) is a screening test for assessing EFs although it has not been so far adapted and validated in Spain. We evaluated the reliability and validity of the Spanish version of the FAB (FAB-E) in PD patients.

Materials and methods

Our study included 54 healthy subjects and 67 PD patients. Cognitive assessment of participants was conducted using the FAB-E, Mini-Mental State Examination (MMSE), Trail Making Test (TMT), Revised-Barcelona Test (RBT) and Executive Interview (EXIT-25). Internal consistency, intra- and test-retest reliabilities, concurrent and discriminant validity of the FAB-E were examined. To evaluate the influence of cognitive dysfunction in PD on the performance of the FAB-E, we also classified the PD patients into groups according to their cognitive status as measured by the MMSE using published criteria to identify cognitive deficits in PD.

Results

The FAB-E showed good internal consistency (α = 0.751). The intraclass correlation coefficients (ranging from 0.559 to 0.891) and Spearman correlations (from 0.494 to 0.864) of the FAB-E subtests indicated a good-strong reliability. The total and subtest scores generally showed a good concurrent validity, except for the prehension behaviour item of the FAB-E and the Interference and Go/no-go tasks of the EXIT-25 that presented low estimates. Excluding the prehension behaviour subtest, the performance of the FAB-E was higher in the control group than in PD patients. Cognitive dysfunction in PD patients also indicated significant poorer FAB-E scores excepting the motor and prehension behaviour subtests. Discriminant analysis determined a cut-off of 14.5 was optimal to differentiate healthy subjects from PD patients. Moreover, a cut-off <12.5 allocated satisfactorily those PD patients with cognitive impairment (MMSE<26) and scores <11.5 classified suitably those PD patients with dementia (MMSE<24).

Conclusion

The FAB-E is an accurate tool for evaluating EFs in patients with PD and can provide useful information for distinguishing PD patients with and without cognitive dysfunction at a bedside assessment.

Cognitive profile of non-demented Parkinson's disease: Meta-analysis of domain and sex-specific deficits

INTRODUCTION

Better awareness of the cognitive domains affected in non-demented Parkinson's Disease (PD) should improve understanding of cognitive disease mechanisms. A complete understanding of the cognitive areas impaired in non-demented PD is hindered because most studies use small clinical samples without comparison to healthy controls. This meta-analysis examined cumulative evidence across studies to determine if there were impairments in non-demented PD in the three cognitive domains thought to be most widely affected in PD: frontal executive, visuospatial, and verbal memory. Because there are well-documented sex differences in PD, a second objective was to explore sex differences in these findings.

METHODS

MEDLINE, EMBASE and PsycINFO databases were searched (1988-March 2017). Random effects models were used to compute and compare effect sizes of differences between PD patients and controls within cognitive domains. Sex differences in effect sizes were also examined in these comparisons. Moderating factors including age, disease duration, motor symptom severity, levodopa dosage, and depression were examined through meta-regression.

RESULTS

PD patients showed deficits of moderate effect sizes in all three cognitive domains relative to controls. Significant sex differences were observed only for frontal executive abilities, with male PD patients showing greater deficits than female PD patients relative to controls. No moderators of effect sizes were identified in the domain specific overall or sex-segregated meta-analyses.

CONCLUSIONS

Results indicate that non-demented PD patients have deficits of moderate magnitude in frontal executive, verbal memory, and visuospatial abilities. Our findings of greater frontal executive deficits in males warrant further confirmation.

Screening for Mild Cognitive Impairment in Parkinson's Disease: Comparison of the Italian Versions of Three Neuropsychological Tests

Mild cognitive impairment (MCI) is frequent in Parkinson's disease (PD). Recently proposed criteria for MCI in PD (PD-MCI) indicate level I diagnosis based on abbreviated assessment and level II based on comprehensive neuropsychological evaluation. The study explored the sensitivity and specificity of the Italian versions of three neuropsychological tests for level I diagnosis of PD-MCI. We recruited 100 consecutive PD patients. After screening for inclusion criteria, 43 patients were included. The sensitivity and specificity of the Mini Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), and the Addenbrooke's Cognitive Examination Revised (ACE-R) in comparison to level II diagnosis of PD-MCI were examined. PD-MCI was diagnosed (level II) in 51% of patients. Disease duration was significantly longer and PD motor scales were more severely impaired in MCI group. The receiver-operator characteristics curve documented nonsignificant difference in the performance of the three tests, with slight advantage of MMSE (corrected data). The time of administration favored MMSE. In Italian-speaking PD patients, MMSE might represent a good screening tool for PD-MCI, because of the shorter time of administration and the performance comparable to those of MoCA and ACE-R. Further studies are needed to validate the new PD-MCI criteria across different languages and cultures.

Low FAB score as a predictor of future falling in patients with Parkinson's disease: a 2.5-year prospective study

Falling is one of the most disabling features of Parkinson's disease (PD). Many cross-sectional studies, case-control studies, and prospective studies have attempted to identify risk factors or predictors of falls, but consistent results are yet to be obtained because of the various factors involved. We prospectively studied patients with various severities of PD to identify risk factors for future falls during 2.5 years of follow-up. We registered 95 patients with PD, and 83 patients were included in data analysis. A total of 23 variables were evaluated by multivariate logistic regression analysis. Thirty-one patients (37%) had a previous history of falling, and 26 patients (30%) experienced their first fall. The prevalence of falls at 2.5 years was 62% (52 of 83 patients). Frontal Assessment Battery (FAB) score (OR 1.393, p = 0.005, 95% CI 1.104-1.759) and history of fall present (OR 0.142, p = 0.002, 95% CI 0.042-0.48) were related to falling on multiple logistic regression analysis. The following variables differed significantly between patients with first falls and those without falling: levodopa equivalent dose (p = 0.023), UPDRS part I (p = 0.006), SF-8 (p = 0.017), and FAB (p = 0.026). Calculation of the FAB score may be useful for predicting the risk of future falls in patients with various severities of PD. Our results suggest that a low FAB score combined with a history of falling within the past 6 months carries an increased risk of future falls.

Intracerebroventricular transplanted bone marrow stem cells survive and migrate into the brain of rats with Parkinson's disease

In this study, 6-hydroxydopamine was stereotaxically injected into the right substantia nigra compact and ventral tegmental area of rats to establish Parkinson's disease models. The rats then received a transplantation of bone marrow stromal cells that were previously isolated, cultured and labeled with 5-bromo-2'-deoxyuridine in vitro. Transplantation of the bone marrow stromal cells significantly decreased apomorphine-induced rotation time and the escape latency in the Morris water maze test as compared with rats with untreated Parkinson's disease. Immunohistochemical staining showed that, 5-bromo-2'-deoxyuridine-immunoreactive cells were present in the lateral ventricular wall and the choroid plexus 1 day after transplantation. These immunoreactive cells migrated to the surrounding areas of the lateral cerebral ventricle along the corpus callosum. The results indicated that bone marrow stromal cells could migrate to tissues surround the cerebral ventricle via the cerebrospinal fluid circulation and fuse with cells in the brain, thus altering the phenotype of cells or forming neuron-like cells or astrocytes capable of expressing neuron-specific proteins. Taken together, the present findings indicate that bone marrow stromal cells transplanted intracerebroventricularly could survive, migrate and significantly improve the rotational behavior and cognitive function of rats with experimentally induced Parkinson's disease.

Cognitive Status Correlates with CXCL10/IP-10 Levels in Parkinson's Disease

Cognitive impairment and depressive symptoms are of great interest in Parkinson's disease (PD), since they are very common and lead to increased disability with poor quality of life. Inflammatory mechanisms have been implicated in PD and its nonmotor symptoms. In the current pilot study, we aimed to evaluate plasma levels of chemokines in PD patients and to analyze the putative association of chemokines with depressive symptoms and cognitive performance. We hypothesized that higher chemokines levels are associated with worse cognitive performance and increased depressive symptoms in PD. For this purpose, 40 PD patients and 25 age- and gender-matched controls were subjected to a clinical evaluation including cognitive and mood tests. Peripheral blood was drawn and plasma levels of CCL2/MCP-1, CCL11/eotaxin, CCL24/eotaxin-2, and CXCL10/IP-10 were measured by enzyme-linked immunosorbent assay. PD patients and control individuals presented comparable plasma concentrations of all the evaluated chemokines. In PD patients, CXCL10/IP-10 plasma levels correlated positively with Hoehn and Yahr staging scale. In addition, the higher CXCL10/IP-10 levels, the worse performance on cognitive tests. Although there was no significant difference between PD patients and control individuals regarding chemokines levels, our preliminary results showed that CXCL10/IP-10 may be associated with cognitive status in PD.

Executive dysfunction in Parkinson's disease: a review

Executive dysfunction can be present from the early stages of Parkinson's disease (PD). It is characterized by deficits in internal control of attention, set shifting, planning, inhibitory control, dual task performance, and on a range of decision-making and social cognition tasks. Treatment with dopaminergic medication has variable effects on executive deficits, improving some, leaving some unchanged, and worsening others. In this review, we start by defining the specific nature of executive dysfunction in PD and describe suitable neuropsychological tests. We then discuss how executive deficits relate to pathology in specific territories of the basal ganglia, consider the impact of dopaminergic treatment on executive function (EF) in this context, and review the changes in EFs with disease progression. In later sections, we summarize correlates of executive dysfunction in PD with motor performance (e.g., postural instability, freezing of gait) and a variety of psychiatric (e.g., depression, apathy) and other clinical symptoms, and finally discuss the implications of these for the patients' daily life.

Perceived and performance-based executive dysfunction in Parkinson's disease

Executive dysfunction is common in early stage Parkinson's disease (PD). We evaluated the relationship between self- and informant-report measurement of real-world executive functions as well as performance-based neuropsychological measures in mildly cognitively impaired individuals with PD and healthy controls. The PD group reported more difficulty with initiation of complex tasks compared to caregiver ratings, and processing speed was a strong predictor of self-reported executive dysfunction for the PD group, followed by depression. Processing speed and semantic verbal fluency predicted informant-reported executive dysfunction in PD. These findings highlight the contribution of speeded processing for performance of everyday executive tasks in PD.

Plasma levels of soluble tumor necrosis factor receptors are associated with cognitive performance in Parkinson's disease

Inflammatory mechanisms have been implicated in a series of neuropsychiatric conditions, including behavioral disturbances, cognitive dysfunction, and affective disorders. Accumulating evidence also strongly suggests their involvement in the pathophysiology of Parkinson's disease (PD). This study aimed to evaluate plasma levels of inflammatory biomarkers, and their association with cognitive performance and other non-motor symptoms of PD. PD patients and control individuals were subjected to various psychometric tests, including the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and Beck's Depression Inventory (BDI). Biomarker plasma levels were measured by enzyme-linked immunosorbent assay (ELISA). PD patients exhibited worse performance on MMSE and the programming task of FAB, and presented higher soluble tumor necrosis factor receptor (sTNFR) plasma levels than control individuals. Among PD patients, increased sTNFR1 and sTNFR2 concentrations were associated with poorer cognitive test scores. After multiple linear regression, sTNFR1 and education remained a significant predictor for FAB scores. Our data suggest that PD is associated with a proinflammatory profile, and sTNFRs are putative biomarkers of cognitive performance, with elevated sTNFR1 levels predicting poorer executive functioning in PD patients.

Predictors of cognitive decline in the early stages of Parkinson's disease: a brief cognitive assessment longitudinal study

Our objectives were to perform a longitudinal assessment of mental status in early stage Parkinson's disease (PD) patients, with brief neuropsychological tests, in order to find predictive factors for cognitive decline. Sixty-one, early stage, and nondemented patients were assessed twice, over a 2-year interval, with a global cognitive test (mini-mental state examination (MMSE)) and a frontal function test (frontal assessment battery (FAB)) and motor function scales. Dementia and hallucinations were diagnosed according to the DSM-IV criteria. Cognitive function scores did not decrease significantly, except for FAB lexical fluency score. Four patients presented with dementia at followup. The MMSE score below cut-off, worse gait dysfunction, the nontremor motor subtype, and hallucinations were significantly related to dementia. Rigidity and speech dysfunction were related to dementia and a decrease in FAB scores. We can conclude that decline in the MMSE and FAB scores is small and heterogeneous in the early stages of PD. Scores below cut-off in the MMSE could be helpful to predict dementia. Nontremor motor deficits could be predictive factors for frontal cognitive decline and dementia.

The heterogeneity of cognitive symptoms in Parkinson's disease: a meta-analysis

Several studies have reported heterogeneity in cognitive symptoms associated with specific characteristics of patients with Parkinson's disease (PD). Indeed, researchers have characterised subtypes of patients suffering from PD according to various criteria. Those most frequently used are the type of predominant motor symptoms (tremors or non-tremor symptoms), age at onset and presence of depression. Some characteristics, like the predominant motor subtypes, as well as the presence of depression, are more widely used to categorise cognitive differences between patients. The goal of this study was to analyse the impact of the type of predominant motor symptoms and depression on cognition in PD. A meta-analysis of 27 studies (from 1989 to 2012) was carried out to calculate the average effect size of these factors on the most often used cognitive test during those past years to evaluate cognitive skills, the Mini-Mental State Examination. The studies analysed showed significant mean weighted effect sizes on cognition for the type of motor symptoms (d=0.42; 95% CI 0.30 to 0.54) and for depression (d=0.52; 95% CI 0.38 to 0.66). These results suggested that PD participants with non-tremor predominant motor symptoms or with depression had more or more severe cognitive impairments. Identification of different subtypes in PD is important for a better understanding of the cognitive symptoms associated with this disease. Better knowing the impact of different features of PD subgroups could help to design more appropriate treatments for patients with PD.

Acute treatment with bis selenide, an organic compound containing the trace element selenium, prevents memory deficits induced by reserpine in rats

Taking into account the promising pharmacological actions of (Z)-2,3-bis(4-chlorophenylselanyl) prop-2-en-1-ol) (bis selenide), an organic compound containing the trace element selenium, and the constant search for drugs that improve the cognitive performance, the objective of the present study was to investigate whether bis selenide treatment ameliorates memory deficits induced by reserpine in rats. For this aim, male adult rats received a single subcutaneous injection of reserpine (1 mg/kg), a biogenic amine-depleting agent used to induce memory deficit. After 24 h, bis selenide at doses of 25 and 50 mg/kg was administered to rats by intragastric route, and 1 h later, the animals were submitted to behavior tasks. The effects of acute administration of bis selenide on memory were evaluated by social recognition, step-down passive avoidance, and object recognition paradigms. Exploratory and locomotor activities of rats were determined using the open-field test. Analysis of data revealed that the social memory disruption caused by reserpine was reversed by bis selenide at both doses. In addition, bis selenide, at the highest dose, prevented the memory deficit resulting from reserpine administration to rats in step-down passive avoidance and object recognition tasks. No significant alterations in locomotor and exploratory behaviors were found in animals treated with reserpine and/or bis selenide. Results obtained from distinct memory behavioral paradigms revealed that an acute treatment with bis selenide attenuated memory deficits induced by reserpine in rats.