scholarly journals Effects of levodopa on cognition in healthy volunteers: implications for Parkinson’s disease

2015 ◽  
Vol 42 (S1) ◽  
pp. S17-S17
Author(s):  
A Vo ◽  
KN Seergobin ◽  
S Jiang ◽  
PA MacDonald
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Treatment Strategies ◽  
Critical Factor ◽  
Learning Task ◽  
Brain Regions ◽  
Healthy Adults ◽  
Learning Performance ◽  
Task Completion ◽  
Endogenous Dopamine

Background: Cognitive impairments are now recognized in Parkinson’s disease. Some of these deficits owe to disease pathology itself whereas others are due to paradoxical effects of dopaminergic medications, such as levodopa. The dopamine overdose hypothesis proposes that dissimilar effects of medication on cognition depend on baseline endogenous dopamine levels in underlying brain regions. We sought to directly test this prevalent theory. Methods: We tested healthy adults, who presumably have optimal endogenous dopamine levels, in two sessions. Participants received 100/25 mg of levodopa/carbidopa in one session and an equal volume of placebo in the other. During each session, participants completed a probabilistic reversal learning task. The number of trials to task completion was used as a behavioural proxy of learning performance. Results: A paired t-test covaried with drug-placebo order revealed that healthy adults learned more poorly on levodopa compared to placebo. Conclusions: Our findings suggest that baseline endogenous dopamine levels are a critical factor determining the effects of dopaminergic medications on cognition, independent of Parkinson’s disease pathology. Partitioning which cognitive functions are helped versus hindered by medication and improving our understanding of the underlying psychopharmacology of these effects is important for improving treatment strategies in Parkinson’s disease.

scholarly journals Attention and reinforcement learning in Parkinson’s disease

2020 ◽  
Author(s):  
Brónagh McCoy ◽  
Rebecca P. Lawson ◽  
Jan Theeuwes
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Reinforcement Learning ◽  
Interactive Effect ◽  
Learning Task ◽  
Brain Regions ◽  
Learning Performance ◽  
Activation Patterns ◽  
Probabilistic Classification ◽  
Dorsolateral Prefrontal

ABSTRACTDopamine is known to be involved in several important cognitive processes, most notably in learning from rewards and in the ability to attend to task-relevant aspects of the environment. Both of these features of dopaminergic signalling have been studied separately in research involving Parkinson’s disease (PD) patients, who exhibit diminished levels of dopamine. Here, we tie together some of the commonalities in the effects of dopamine on these aspects of cognition by having PD patients (ON and OFF dopaminergic medication) and healthy controls (HCs) perform two tasks that probe these processes. Within-patient behavioural measures of distractibility, from an attentional capture task, and learning performance, from a probabilistic classification reinforcement learning task, were included in one model to assess the role of distractibility during learning. Dopamine medication state and distractibility level were found to have an interactive effect on learning performance; less distractibility in PD ON was associated with higher accuracy during learning, and this was altered in PD OFF. Functional magnetic resonance imaging (fMRI) data acquired during the learning task furthermore allowed us to assess multivariate patterns of positive and negative outcomes in fronto-striatal and visual brain regions involved in both learning processes and the executive control of attention. Here, we demonstrate that while PD ON show a clearer distinction between outcomes than OFF in dorsolateral prefrontal cortex (DLPFC) and putamen, PD OFF show better distinction of activation patterns in visual regions that respond to the stimuli presented during the task. These results demonstrate that dopamine plays a key role in modulating the interaction between attention and learning at the level of both behaviour and activation patterns in the brain.

Introduction: The Impact of Continuous Levodopa Infusion in the Treatment of Parkinson's Disease

CNS Spectrums ◽  
2008 ◽  
Vol 13 (S7) ◽  
pp. 3-3 ◽  
Author(s):  
Erik Wolters
Keyword(s):  
Quality Of Life ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Treatment Strategies ◽  
Resting Tremor ◽  
Endogenous Dopamine ◽  
Dopamine Signaling ◽  
The Impact ◽  
Dopaminergic Stimulation

Parkinson's disease was first described in 1817 by James Parkinson. Based on his observation of only six individuals, Parkinson accurately described the resting tremor and festinate gait, bradykinesia, and postural instability associated with the disease today. Parkinson's disease primarily affects people >50 years of age and causes progressive neurological degeneration, physical disability, and worsening quality of life.Consequently, most currently available drugs aim to restore striatal dopamine signaling. This can be best reached by increasing the supply of dopamine with oral levodopa (L-dopa), but also by stimulating dopamine receptors directly using dopamine agonists, or by inhibiting the reuptake of endogenous dopamine. Unfortunately, mainly due to the short half-life of L-dopa and the erratic absorption of oral L-dopa (causing pulsatile dopaminergic stimulation) these treatment strategies become increasingly ineffective in the course of this disease, and motor complications may further reduce the quality of life in these patients.

Background

2013 ◽  
Author(s):  
J. Eric Ahlskog
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Treatment Strategies ◽  
Lewy Bodies ◽  
Psychometric Testing ◽  
Brain Regions ◽  
Memory Problems ◽  
Neurodegenerative Dementia ◽  
Short Test ◽  
Doctor's Office

This book has a combined focus on two neurodegenerative conditions: dementia with Lewy bodies and Parkinson’s disease with dementia. While patients with either disorder experience quite variable problems, these two disorders have striking similarities when viewed in the aggregate. Thus, the symptoms of these two conditions are much the same, and so are the treatment strategies. Before addressing treatment, it is crucial to define the relevant terms, broaden our understanding, and discuss how these diagnoses are made. We will start with some basics. These disorders typically start in middle age and later, where selected brain circuits deteriorate for unknown reasons. Common neurodegenerative conditions include Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis (ALS; Lou Gehrig’s disease). Such conditions involve limited regions of the brain or spinal cord, slowly progressing and leading to disability. Each is clinically identified by the specific neurologic deficits unique to that condition. Why each affects certain brain regions, sparing others, is a crucial but unanswered question. Although much has been learned about degenerative syndromes, we do not know the causes of any of them. Dementia implies a loss of intellectual abilities sufficient to compromise activities of daily living. Most often the term dementia is used in the context of neurodegenerative disorders. Mild thinking and memory problems that do not substantially interfere with daily routines fall into the category of mild cognitive impairment (MCI; see below). Doctors diagnosing dementia rely on the history from the patient and family, plus cognitive tests. Short tests assessing memory, attention, and calculation, among other things, can be done in the doctor’s office. Such tests include the so-called Mini-Mental State Examination and the Short Test of Mental Status. More refined and informative tests, termed psychometric testing, are done under the auspices of psychologists; these typically require 2 to 4 hours. Clinicians addressing dementia must also look for treatable causes before concluding that the problem is a neurodegenerative dementia. This assessment typically includes a brain scan, blood tests, and a review of the patient’s medical history and medication list, which may indicate the need for additional testing.

Parkinson’s puzzle

2012 ◽  
Vol 153 (52) ◽  
pp. 2060-2069 ◽  
Author(s):  
András Guseo
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Clinical Symptoms ◽  
Critical Factor ◽  
Unknown Origin ◽  
Symptomatic Improvement ◽  
Blue Green Algae ◽  
Clinical Observations ◽  
Degenerative Disorders ◽  
Local Cell

Parkinson’s disease is one of the most frequent progressive degenerative disorders with unknown origin of the nervous system. The commutation of the disease on Guam led to the discovery of a neurotoxin which was also found in other continents. This neurotoxin was identified in the common cyanobacteria (blue-green algae). Early clinical observations suggested some loose correlations with gastric and duodenal ulcer and Parkinson’s disease, while recent studies revealed a toxin, almost identical to that found in cyanobacteria in one strain of Helicobacter pylori, which proved to cause Parkinson like symptoms in animals. Therefore, it cannot be ruled out that there is a slowly progressive poisoning in Parkinson’s disease. The disease specific alpha-sinuclein inclusions can be found in nerve cells of the intestinal mucosa far before the appearance of clinical symptoms indicating that the disease may start in the intestines. These results are strengthened by the results of Borody’s fecal transplants, after which in Parkinson patients showed a symptomatic improvement. Based on these observations the Parkinson puzzle is getting complete. Although these observations are not evidence based, they may indicate a new way for basic clinical research, as well as a new way of thinking for clinicians. These new observations in psycho-neuro-immunology strengthen the fact that immunological factors may also play a critical factor facilitating local cell necrosis which may be influenced easily. Orv. Hetil., 2012, 153, 2060–2069.

scholarly journals Neuroinflammation and protein pathology in Parkinson’s disease dementia

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Antonina Kouli ◽  
Marta Camacho ◽  
Kieren Allinson ◽  
Caroline H. Williams-Gray
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
T Lymphocytes ◽  
Substantia Nigra ◽  
Amyloid Β ◽  
Brain Regions ◽  
Parkinson’S Disease Dementia ◽  
Activated Microglia ◽  
Cell Counts ◽  
The Brain

AbstractParkinson’s disease dementia is neuropathologically characterized by aggregates of α-synuclein (Lewy bodies) in limbic and neocortical areas of the brain with additional involvement of Alzheimer’s disease-type pathology. Whilst immune activation is well-described in Parkinson’s disease (PD), how it links to protein aggregation and its role in PD dementia has not been explored. We hypothesized that neuroinflammatory processes are a critical contributor to the pathology of PDD. To address this hypothesis, we examined 7 brain regions at postmortem from 17 PD patients with no dementia (PDND), 11 patients with PD dementia (PDD), and 14 age and sex-matched neurologically healthy controls. Digital quantification after immunohistochemical staining showed a significant increase in the severity of α-synuclein pathology in the hippocampus, entorhinal and occipitotemporal cortex of PDD compared to PDND cases. In contrast, there was no difference in either tau or amyloid-β pathology between the groups in any of the examined regions. Importantly, we found an increase in activated microglia in the amygdala of demented PD brains compared to controls which correlated significantly with the extent of α-synuclein pathology in this region. Significant infiltration of CD4+ T lymphocytes into the brain parenchyma was commonly observed in PDND and PDD cases compared to controls, in both the substantia nigra and the amygdala. Amongst PDND/PDD cases, CD4+ T cell counts in the amygdala correlated with activated microglia, α-synuclein and tau pathology. Upregulation of the pro-inflammatory cytokine interleukin 1β was also evident in the substantia nigra as well as the frontal cortex in PDND/PDD versus controls with a concomitant upregulation in Toll-like receptor 4 (TLR4) in these regions, as well as the amygdala. The evidence presented in this study show an increased immune response in limbic and cortical brain regions, including increased microglial activation, infiltration of T lymphocytes, upregulation of pro-inflammatory cytokines and TLR gene expression, which has not been previously reported in the postmortem PDD brain.

scholarly journals Growth Factor Therapy for Parkinson’s Disease: Alternative Delivery Systems

2021 ◽  
pp. 1-7
Author(s):  
Sarah Jarrin ◽  
Abrar Hakami ◽  
Ben Newland ◽  
Eilís Dowd
Keyword(s):  
Parkinson’S Disease ◽  
Gene Therapy ◽  
Parkinson's Disease ◽  
Growth Factors ◽  
Growth Factor ◽  
Ex Vivo ◽  
Brain Regions ◽  
Delivery Systems ◽  
Alternative Delivery

Despite decades of research and billions in global investment, there remains no preventative or curative treatment for any neurodegenerative condition, including Parkinson’s disease (PD). Arguably, the most promising approach for neuroprotection and neurorestoration in PD is using growth factors which can promote the growth and survival of degenerating neurons. However, although neurotrophin therapy may seem like the ideal approach for neurodegenerative disease, the use of growth factors as drugs presents major challenges because of their protein structure which creates serious hurdles related to accessing the brain and specific targeting of affected brain regions. To address these challenges, several different delivery systems have been developed, and two major approaches—direct infusion of the growth factor protein into the target brain region and in vivo gene therapy—have progressed to clinical trials in patients with PD. In addition to these clinically evaluated approaches, a range of other delivery methods are in various degrees of development, each with their own unique potential. This review will give a short overview of some of these alternative delivery systems, with a focus on ex vivo gene therapy and biomaterial-aided protein and gene delivery, and will provide some perspectives on their potential for clinical development and translation.

scholarly journals A Guide to the Generation of a 6-Hydroxydopamine Mouse Model of Parkinson’s Disease for the Study of Non-Motor Symptoms

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 598
Author(s):  
Débora Masini ◽  
Carina Plewnia ◽  
Maëlle Bertho ◽  
Nicolas Scalbert ◽  
Vittorio Caggiano ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Mouse Model ◽  
Survival Rates ◽  
Dorsal Striatum ◽  
Brain Regions ◽  
Motor Symptoms ◽  
Operative Care ◽  
6 Hydroxydopamine ◽  
Non Motor Symptoms

In Parkinson’s disease (PD), a large number of symptoms affecting the peripheral and central nervous system precede, develop in parallel to, the cardinal motor symptoms of the disease. The study of these conditions, which are often refractory to and may even be exacerbated by standard dopamine replacement therapies, relies on the availability of appropriate animal models. Previous work in rodents showed that injection of the neurotoxin 6-hydroxydopamine (6-OHDA) in discrete brain regions reproduces several non-motor comorbidities commonly associated with PD, including cognitive deficits, depression, anxiety, as well as disruption of olfactory discrimination and circadian rhythm. However, the use of 6-OHDA is frequently associated with significant post-surgical mortality. Here, we describe the generation of a mouse model of PD based on bilateral injection of 6-OHDA in the dorsal striatum. We show that the survival rates of males and females subjected to this lesion differ significantly, with a much higher mortality among males, and provide a protocol of enhanced pre- and post-operative care, which nearly eliminates animal loss. We also briefly discuss the utility of this model for the study of non-motor comorbidities of PD.

scholarly journals Intrinsic motivation in patients with Parkinson’s disease: a neuropsychological investigation of curiosity using dopamine transporter imaging

2021 ◽  
Author(s):  
Yayoi Shigemune ◽  
Iori Kawasaki ◽  
Akira Midorikawa ◽  
Toru Baba ◽  
Atsushi Takeda ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Intrinsic Motivation ◽  
Extrinsic Motivation ◽  
Brain Regions ◽  
Word Recall ◽  
Negative Consequences ◽  
Dopamine Transporters ◽  
Trail Making ◽  
Neuropsychological Investigation

AbstractBoth intrinsic and extrinsic motivation are believed to involve brain regions that are innervated by the dopaminergic pathway. Although dopaminergic neurons in the midbrain deteriorate in Parkinson’s disease (PD), it remains unclear whether intrinsic motivation is impaired in PD patients. To address this issue, we investigated intrinsic motivation in PD patients using a task designed to assess the “Pandora effect,” which constitutes a curiosity for resolving uncertainty, even if this curiosity is likely to result in negative consequences. Twenty-seven PD patients and 27 age-matched healthy controls (HCs) completed a curiosity task in which they were required to decide either to view or skip negative pictures (e.g., snakes, spiders) and an examination battery that included the Mini-Mental State Examination, a verbal fluency test, the Trail Making Test, 10-word recall tests, and questionnaires for behavioral inhibition/activation and depression. DaTSCAN images to assess the distribution of dopamine transporters in the striatum were acquired only from PD patients. The results revealed that PD patients, relative to the HCs, viewed the pictures less frequently under both the certain and uncertain conditions. However, both the PD patients and HCs viewed the pictures at a higher frequency under the uncertain condition than under the certain condition. In the PD patients, the proportion of pictures viewed under the certain condition was positively correlated with the distribution of dopamine transporters in the striatum. These results suggest that despite the overall decreasing level of interest in viewing negative pictures, the motivation to resolve uncertainty is relatively intact in PD patients.

Inflammatory Mechanisms in Parkinson’s Disease: From Pathogenesis to Targeted Therapies

2021 ◽  
pp. 107385842199226
Author(s):  
Stellina Y. H. Lee ◽  
Nathanael J. Yates ◽  
Susannah J. Tye
Keyword(s):  
Parkinson’S Disease ◽  
Central Nervous System ◽  
Parkinson's Disease ◽  
Nervous System ◽  
Immune Cells ◽  
Critical Factor ◽  
Neurodegenerative Process ◽  
Inflammatory Processes ◽  
The Central Nervous System ◽  
Novel Target

Inflammation is a critical factor contributing to the progressive neurodegenerative process observed in Parkinson’s disease (PD). Microglia, the immune cells of the central nervous system, are activated early in PD pathogenesis and can both trigger and propagate early disease processes via innate and adaptive immune mechanisms such as upregulated immune cells and antibody-mediated inflammation. Downstream cytokines and gene regulators such as microRNA (miRNA) coordinate later disease course and mediate disease progression. Biomarkers signifying the inflammatory and neurodegenerative processes at play within the central nervous system are of increasing interest to clinical teams. To be effective, such biomarkers must achieve the highest sensitivity and specificity for predicting PD risk, confirming diagnosis, or monitoring disease severity. The aim of this review was to summarize the current preclinical and clinical evidence that suggests that inflammatory processes contribute to the initiation and progression of neurodegenerative processes in PD. In this article, we further summarize the data about main inflammatory biomarkers described in PD to date and their potential for regulation as a novel target for disease-modifying pharmacological strategies.

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