The neuropsychological assessment battery categories test as a measure of executive dysfunction in patients with Parkinson's disease and essential tremor: an exploratory study

Comparison of core and process scores on the California Verbal Learning Test-3 for Parkinson's disease and essential tremor patients

INTRODUCTION

Parkinson's disease (PD) and essential tremor (ET) are two disorders known to lead to executive dysfunction, presumably through distinct pathways to the frontal lobes via the striatum or cerebellum, respectively. Memory functioning in PD and ET patients has been previously suggested to be adversely impacted by executive dysfunction. The aims of this exploratory study were to compare memory performance between and within groups on the California Verbal Learning Test - 3 (CVLT-3) through the analysis of core and process scores and to understand the relationship of these scores with measures of executive functioning.

METHOD

Seventy PD and 54 ET patients completed comprehensive neuropsychological testing. Independent sample t-tests or Mann-Whitney tests were used to compare between group core and process scores on the CVLT-3. Within-subjects analyses were conducted via Wilcoxon Signed Rank Test due to nonparametric data. Spearman's correlations were conducted to explore the relationship between memory process scores and measures of executive functioning.

RESULTS

The ET and PD samples were similar with regard to age, education, gender, and general cognitive functioning. PD patients made more repetition errors (U = 2391.50, p = .01) than ET patients and Normal Memory PD patients made more repetition errors than Low Memory PD patients (U= 711.00, p= .00). Correlational analyses revealed repetition errors were negatively associated with tests of inhibition, set shifting, and working memory (rs = -.293, -.232). ET patients demonstrated a preference for a serial cluster learning strategy (T = 861.00, p = .005), similar to PD patients (T= 1633.00, p = <.001).

CONCLUSIONS

The study revealed presence of higher repetition errors in the PD sample that was demonstrated to have a negative relationship with measures of executive functioning. Implications for investigating process ("qualitative") scores in memory performance to determine extent of executive involvement are discussed.

Clock-Drawing Tasks as Predictive Measurements for Disease Classification Among Patients With Parkinson's Disease and Essential Tremor

Background Nonmotor cognitive symptoms are widely being recognized in both Parkinson's Disease (PD) and Essential Tremor (ET), the two most common movement disorders. Clock-drawing (CD) test seems to be impaired early in the process of cognitive (executive) decline in PD. However, the optimal measures for detecting cognitive changes in ET patients have not been established. Examining whether the CD test is a quick test could identify frontal and visuospatial deficits in patients with Parkinson's disease (PD) and essential tremor (ET). Methods Visuospatial performance was assessed in 58 consecutive patients with ET and 75 with PD and 22 healthy controls (HC) who visited two neurological clinics of Athens in Greece. The CD and copy (CC) items of the PD-Cognitive Rating Scale were used as a test of visuospatial function. Results Both CD and CC scores were lower for ET compared to PD patients and HC (p=<0.001 for both comparisons). A binomial logistic regression showed that both CD and CC items predict if participants had ET or PD with high sensitivity 94.7% and specificity 87.9% and an area under the curve (AUC) 0.980 (95% confidence interval, 0.962-0.997). The model explained 86.1% (Nagelkerke R2) of the variance in the disease variable (ET/PD) and correctly classified 91.7% of the cases. Conclusion Patients with ET have more visuospatial deficits compared to PD and HC. CD task may be an easy, useful tool to track cognitive changes in nondemented patients with ET in clinical practice.

Cognition in non-demented Parkinson's disease vs essential tremor: A population-based study

OBJECTIVES

Patients with Parkinson's disease (PD) and essential tremor (ET) have a higher risk of cognitive impairment than age-matched controls. Only a few small studies (11-18 subjects per group) have directly compared the cognitive profile of these conditions. Our aim was to compare the cognitive profile of patients with these two conditions to each other and to healthy individuals in a population-based study of non-demented participants.

MATERIALS AND METHODS

This investigation was part of the NEDICES study, a survey of the elderly in which 2438 dementia-free participants underwent a short neuropsychological battery. We used nonparametric techniques to evaluate whether there are differences and/or a gradient of impairment across the groups (PD, ET, and controls). Also, we performed a head-to-head comparison of ET and PD, adjusting for age and education.

RESULTS

Patients with PD (N=46) and ET (N=180) had poorer cognition than controls (N=2212). An impaired gradient of performance was evident. PD scored lower than ET, and then each of these lower than controls, in memory (P<.05) and verbal fluency (P<.001) tasks. When we compared PD and ET, the former had lower scores in verbal fluency (P<.05), whereas the later had a poorer cognitive processing speed (P<.05).

CONCLUSIONS

This large population-based study demonstrates that both conditions influence cognitive performance, that a continuum exists from normal controls to ET to PD (most severe), and that although deficits are in many of the same cognitive domains, the affected cognitive domains do not overlap completely.

A Comparison Study of Cognitive and Neuropsychiatric Features of Essential Tremor and Parkinson's Disease

Background

Essential tremor (ET) and Parkinson’s disease (PD) are two of the most common movement disorders. Leaving aside their motor features, these two conditions share several non-motor features, including cognitive dysfunction and personality changes. However, there are few data comparing the cognitive and personality profiles of ET with PD. Here we compare the cognitive and personality profiles of the two diseases.

Methods

Thirty-two consecutive non-demented ET patients (13 females and 19 males) (67.7±9.8 years), 32 non-demented PD patients (13 females and 19 males) (67.7±9.5 years), and 32 healthy matched controls (14 females and 18 males) (67.9±10.1 years) underwent a neuropsychological test battery, including a global cognitive assessment and tests of attention, executive function, memory, language, and visuospatial function, as well as the Personality Assessment Inventory. Multivariable linear regression analyses were performed, adjusted for age, sex, years of education, medications that potentially affect cognitive function, number of medications, and the 17-item Hamilton Depression Rating Scale Total Score.

Results

Neuropsychological scores were similar in PD and ET patients, but patients with disease performed more poorly than control subjects in cognitive tasks such as attention, executive function, memory, and naming.

Discussion

ET and PD exhibited similar deficits in specific aspects of neuropsychological functioning, particularly those thought to rely on the integrity of the prefrontal cortex, and this suggests involvement of frontocerebellar circuits. These findings further challenge the traditional view of ET as a benign and monosymptomatic disorder.