Frontal functions in depressed and nondepressed Parkinson's disease patients: impact of severity stages

Mild Behavioral Impairment in Parkinson's Disease: An Updated Review on the Clinical, Genetic, Neuroanatomical, and Pathophysiological Aspects

Neuropsychiatric symptoms (NPS), including depression, anxiety, apathy, visual hallucinations, and impulse control disorders, are very common during the course of Parkinson's disease (PD), occurring even at the prodromal and premotor stages. Mild behavioral impairment (MBI) represents a recently described neurobehavioral syndrome, characterized by the emergence of persistent and impactful NPS in later life, reflecting arisk of dementia. Accumulating evidence suggests that MBI is highly prevalent in non-demented patients with PD, also being associated with an advanced disease stage, more severe motor deficits, as well as global and multiple-domain cognitive impairment. Neuroimaging studies have revealed that MBI in patients with PD may be related todistinct patterns of brain atrophy, altered neuronal connectivity, and distribution of dopamine transporter (DAT) depletion, shedding more light on its pathophysiological background. Genetic studies in PD patients have also shown that specific single-nucleotide polymorphisms (SNPs) may be associated with MBI, paving the way for future research in this field. In this review, we summarize and critically discuss the emerging evidence on the frequency, associated clinical and genetic factors, as well as neuroanatomical and neurophysiological correlates of MBI in PD, aiming to elucidate the underlying pathophysiology and its potential role as an early "marker" of cognitive decline, particularly in this population. In addition, we aim to identify research gaps, and propose novel relative areas of interest that could aid in our better understanding of the relationship of this newly defined diagnostic entity with PD.

Mild cognitive impairment, psychiatric symptoms, and executive functioning in patients with Parkinson's disease

OBJECTIVE

Mild cognitive impairment (MCI) and psychiatric symptoms (anxiety, depression, and apathy) are common in Parkinson's disease (PD). While studies have supported the association between psychiatric symptoms and cognitive performance in PD, it is unclear if the magnitude of link between psychiatric symptoms and cognitive health is stronger by MCI status. The purpose of this study was to examine the association between cognitive performance and psychiatric symptoms in PD and whether MCI status moderates this association.

METHODS/DESIGN

Participants (N = 187) completed a comprehensive neuropsychological assessment that included measures of attention, language, executive function (EF), visuospatial ability, episodic memory, and psychiatric symptoms. Participants were classified as PD-MCI (N = 73) or PD-normal cognition (NC; N = 114). Linear regression analyses were conducted to examine the association between psychiatric symptoms and cognitive performance and the moderating effect of PD-MCI status.

RESULTS

There were no differences in mean psychiatric symptoms between PD-MCI and PD-NC. Psychiatric symptoms were predominantly associated with worse EF. The magnitude of the association between anxiety and worse EF was larger in participants with PD-MCI compared with PD-NC. A multivariable regression analysis examining the independent contributions of each symptom demonstrated the most robust association between EF and anxiety.

CONCLUSIONS

Symptoms of anxiety, depression, and apathy are associated with worse executive functioning in individuals with PD. PD-MCI may be important in moderating the association between cognitive performance, specifically anxiety, and EF. Factors that promote cognitive resilience may serve as key therapeutic modalities in managing neuropsychiatric symptoms in PD.

Mild behavioral impairment is linked to worse cognition and brain atrophy in Parkinson disease

OBJECTIVE

To evaluate the associations of mild behavioral impairment (MBI) with cognitive deficits and patterns of gray matter changes in Parkinson disease (PD).

METHODS

Sixty patients with PD without dementia and 29 healthy controls underwent a cognitive neuropsychological evaluation and structural MRI scan. MBI was evaluated with the MBI Checklist (MBI-C), a rating scale designed to elicit emergent neuropsychiatric symptoms in accordance with MBI criteria. We divided the patients with PD into 2 groups: 1 group with high MBI-C scores (PD-MBI) and the other with low MBI-C scores (PD-noMBI).

RESULTS

Among 60 patients with PD, 20 were categorized as having PD-MBI (33.33%). In healthy controls, no participants met the MBI cut-point threshold. The PD-MBI group had significantly lower Montreal Cognitive Assessment and z scores in all 5 domains and the global score compared to healthy controls and those with PD-noMBI. In addition, all cognitive domains except language and global cognition negatively correlated with the MBI-C total score in all patients with PD. For cortical structures, the PD-MBI group revealed middle temporal cortex thinning and decreased volume compared with the PD-noMBI group, and decreased volume in this area negatively correlated with the MBI-C total score.

CONCLUSIONS

The impaired cognitive function over all domains and atrophy in the temporal area in the PD-MBI group are in line with posterior cortical circuit deficits in PD, which have been associated with a faster rate of progression to dementia. These initial results suggest that MBI might be an early and important marker for incident cognitive decline and dementia in patients with PD.

Cost-effectiveness analysis of the treatment of mild and moderate Alzheimer's disease in Brazil

OBJECTIVE

To perform a cost-effectiveness analysis of donepezil and rivastigmine therapy for mild and moderate Alzheimer's disease (AD) from the perspective of the Brazilian Unified Health System.

METHOD

A hypothetical cohort of 1,000 individuals of both sexes, aged >65 years, and diagnosed with AD was simulated using a Markov model. The time horizon was 10 years, with 1-year cycles. A deterministic and probabilistic sensitivity analysis was performed.

RESULTS

For mild AD, the study showed an increase in quality-adjusted life years (QALYs) of 0.61 QALY/21,907.38 Brazilian reais (BRL) for patients treated with donepezil and 0.58 QALY/BRL 24,683.33 for patients treated with rivastigmine. In the moderate AD group, QALY increases of 0.05/BRL 27,414.96 were observed for patients treated with donepezil and 0.06/BRL 34,222.96 for patients treated with rivastigmine.

CONCLUSIONS

The findings of this study contradict the standard of care for mild and moderate AD in Brazil, which is based on rivastigmine. A pharmacological treatment option based on current Brazilian clinical practice guidelines for AD suggests that rivastigmine is less cost-effective (0.39 QALY/BRL 32,685.77) than donepezil. Probabilistic analysis indicates that donepezil is the most cost-effective treatment for mild and moderate AD.

The impact of depression on survival of Parkinson's disease patients: a five-year study

OBJECTIVE: The aim of this study is to evaluate the survival rate in a cohort of Parkinson's disease patients with and without depression. METHODS: A total of 53 Parkinson's disease subjects were followed up from 2003-2008 and 21 were diagnosed as depressed. Mean time of follow up was 3.8 (SD 95% = 1.5) years for all the sample and there was no significant difference in mean time of follow up between depressed and nondepressed Parkinson's disease patients. Survival curves rates were fitted using the Kaplan-Meier method. In order to compare survival probabilities according to the selected covariables the Log-Rank test was used. Multivariate analysis with Cox regression was performed aiming at estimating the effect of predictive covariables on the survival. RESULTS: The cumulative global survival of this sample was 83% with nine deaths at the end of the study - five in the depressed and four in the nondepressed group, and 55.6% died in the first year of observation, and none died at the fourth and fifth year of follow up. CONCLUSION: Our finding point toward incremental death risk in depressed Parkinson's disease patients.

Acute exercise improves cognition in the depressed elderly: the effect of dual-tasks

OBJECTIVE

The goal of this study was to assess the acute effect of physical exercise on the cognitive function of depressed elderly patients in a dual-task experiment.

INTRODUCTION

Physical exercise has a positive effect on the brain and may even act as a treatment for major depressive disorder. However, the effects of acute cardiovascular exercise on cognitive function during and after one session of aerobic training in elderly depressive patients are not known.

METHODS

Ten elderly subjects diagnosed with major depressive disorder performed neuropsychological tests during and after a moderate physical exercise session (65-75%HR(max)). A Digit Span Test (Forward and Backward) and a Stroop Color-Word Test were used to assess cognitive function. The elderly participants walked on an electric treadmill for 30 minutes and underwent the same cognitive testing before, during, immediately after, and 15 minutes after the exercise session. In the control session, the same cognitive testing was conducted, but without exercise training.

RESULTS

The results of the Digit Span Test did not change between the control and the exercise sessions. The results of the Stroop Color-Word Test improved after physical exercise, indicating a positive effect of exercise on cognition.

CONCLUSIONS

These data suggest that the cognitive functions of depressed elderly persons, especially attention and inhibitory control, are not impaired during and after an acute session of physical exercise. In contrast, the effect of dual-tasks showed beneficial results for these subjects, mainly after exercise. The dual-task may be a safe and useful tool for assessing cognitive function.

Cognitive and personality features in Parkinson disease: 2 sides of the same coin?

OBJECTIVE

This study seeks to identify the possible relationship between certain executive functions and the main personality traits in 25 nondemented Parkinson disease (PD) patients.

BACKGROUND

Both the presence of cognitive changes-mainly concerning executive functions-and peculiar personality traits, such as low novelty seeking, moral rigidity, industriousness, or introversion, were fully documented in PD patients.

METHODS

Patients underwent the Tower of London test and Alternating Fluency tasks for planning abilities and cognitive flexibility to be assessed. Personality features were evaluated using the Big Five Adjectives checklist.

RESULTS

The study provided evidence of a significant correlation between the Tower of London and the Emotional Stability factor and between Alternating Fluencies and the Openness to Experience factor.

CONCLUSIONS

The Tower of London test and the Emotional Stability factor may require filtering of irrelevant information, activation of inhibition mechanisms, and use of negative feedback. The Alternating Fluency tasks and the Openness to Experience factor may require the ability to switch set and to express flexible thoughts or opinions in daily life. These results indicate that cognitive and personality changes in PD may be different expressions of a common psychologic mechanism related to the dysfunction of the frontostriatal system.

Relationship between depression and cognitive dysfunctions in Parkinson's disease without dementia

To explore the relationship between depression and cognitive impairment in non-demented PD patients, we evaluated neurological and neuropsychological asset in 65 patients with a diagnosis of major depressive disorder (dPD) according to DSM-IV criteria and 60 patients without depression (nPD). Compared with nPD patients, dPD patients had significantly higher scores on behavioral rating scales and performed worse on the Frontal Assessment Battery (FAB), Semantic Fluency Task, Copying Task (CT), and Stroop Test. Three dPD subgroups were identified based on the first two DSM-IV criteria: patients fulfilling criterion 1 (depressed mood; group 1); patients fulfilling criterion 2 (apathy/anhedonia; group 2); patients fulfilling criteria 1 and 2 (group 3). Patients of group 2 scored significantly lower than patients of group 1 on the CT, FAB and phonological fluency task. Patients of groups 2 and 3 scored significantly lower than nPD patients on visuoconstructional and frontal tasks. Similar results were obtained in dPD patients stratified in four subgroups based on cut-off scores of the Apathy Evaluation Scale and the Snaith Hamilton Pleasure Scale. In summary, PD patients with concomitant apathy and anhedonia may show more severe cognitive impairments. Since such patients are diagnosed to be affected by depression according to clinical DSM-IV criteria, we suggest that DSM-IV criteria may not distinguish an affective from a cognitive disorder in PD.

Increased oxidation of certain glycolysis and energy metabolism enzymes in the frontal cortex in Lewy body diseases

Lipoxidative damage of aldolase A, enolase 1, and glyceraldehyde dehydrogenase (GAPDH) was found in the frontal cortex in a percentage of aged controls by bidimensional gel electrophoresis, Western blot test, in-gel digestion, and mass spectrometry. Aldolase A and enolase 1 were altered in 12 of 19 cases, whereas oxidation of GAPDH was found in 6 of 19 controls. The three enzymes were oxidized in the frontal cortex in the majority of cases of incidental Parkinson's disease (iPD), PD, and dementia with Lewy bodies (DLB). Differences were statistically significant (chi(2) test) for GAPDH in PD and DLB. Densitometric studies have shown that the ratio of oxidized protein per spot is higher in iPD, PD, and DLB compared with controls. These findings show oxidation of three enzymes linked with glycolysis and energy metabolism in the adult human brain as well as increased oxidation of aldolase A, enolase 1, and GAPDH in the frontal cortex in Lewy body diseases. Modifications of these enzymes may result in decreased activity and may partly account for impaired metabolism and function of the frontal lobe in PD.

Cognitive and motor components of response speed in the stroop test in Parkinson's disease patients

This study assessed the performance of patients with Parkinson's disease (PD) in the Stroop test. Twenty-seven patients with PD (17 men, 10 women; mean age, 63.3 +/- 10.5 years) and 27 age-matched controls (14 men, 13 women; mean age, 63.5 +/- 9.2 years) were administered the color-naming, word-reading, and incongruent color-word-naming tasks in the Stroop test. Compared with the normal control group, the PD group had slower speeds for all three tasks and greater Stroop interference, indicating a response inhibition deficit in PD patients. Further analysis indicated that slowness during color naming might be due to motor slowness, rather than a central cognitive processing problem in color discrimination. In conclusion, the performance of the PD group on the three tasks of the Stroop test suggests that the PD patients were deficient in motor responses and cognitive inhibitory abilities.