Body weight, levodopa pharmacokinetics and dyskinesia in Parkinson's disease

Weight and survival after deep brain stimulation for Parkinson's disease

BACKGROUND

Weight loss in Parkinson's disease (PD) is common and associated with increased mortality. The clinical significance of weight changes following deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) is unclear.

OBJECTIVES

To address (1) whether PD patients exhibit progressive weight loss, (2) whether staged DBS surgery is associated with weight changes, and (3) whether survival after DBS correlates with post-DBS weight.

METHODS

This is a single-center, longitudinal, retrospective cohort study of 1625 PD patients. We examined trends in weight over time and the relationship between weight and years survival after DBS using regression and mixed model analyses.

RESULTS

There was a decline in body weight predating motor symptom onset (n = 756, 0.70 ± 0.03% decrease per year, p < 0.001). Weight decline accelerated in the decade preceding death (n = 456, 2.18 ± 0.31% decrease per year, p < 0.001). DBS patients showed a weight increase of 2.0 ± 0.33% at 1 year following the first DBS lead implant (n = 455) and 2.68 ± 1.1% at 3 years if a contralateral DBS lead was placed (n = 249). The bilateral STN DBS group gained the most weight after surgery during 6 years of follow up (vs bilateral GPi, 3.03 ± 0.45% vs 1.89 ± 0.31%, p < 0.01). An analysis of the DBS cohort with date of death available (n = 72) revealed that post-DBS weight (0-12 months after the first or 0-36 months after the second surgery) was positively associated with survival (R2 = 0.14, p < 0.001).

DISCUSSION

Though PD is associated with significant weight loss, DBS patients gained weight following surgery. Higher post-operative weight was associated with increased survival. These results should be replicated in other cohorts.

To restrict or not to restrict? Practical considerations for optimizing dietary protein interactions on levodopa absorption in Parkinson's disease

Administration of levodopa for Parkinson's disease (PD) has remained the most effective therapy for symptom management despite being in use for over 50 years. Advancing disease and age, changing tolerability and gastrointestinal (GI) dysfunction may result in change in dietary habits and body weight, as well as unpredictable motor fluctuations and dyskinesias. Dietary proteins which convert into amino acids after digestion are implicated as major factors that inhibit levodopa absorption. For people living with PD (PwP) who experience motor fluctuations, low protein diets (LPD) and protein redistribution diets (PRD) may be effective and are often recommended as a non-pharmacologic approach for improving levodopa bioavailability. However, there is a lack of consensus on a standard definition of these diets and appropriate treatment algorithms for usage. This may be due to the paucity of high-level evidence of LPD and PRD in PwP and whether all or specific subgroups of patients would benefit from these strategies. Managing diet and protein intake with proper education and monitoring may reduce complications associated with these diets such as dyskinesias and unintentional weight loss. Additionally, alterations to medications and GI function may alter levodopa pharmacokinetics. In this narrative review we focus on 1) mechanisms of dietary protein and levodopa absorption in the intestine and blood brain barrier, 2) dietetic approaches to manage protein and levodopa interactions and 3) practical issues for treating PwP as well as future directions to be considered.

Sex Is the Main Determinant of Levodopa Clinical Pharmacokinetics: Evidence from a Large Series of Levodopa Therapeutic Monitoring

BACKGROUND

Different studies, mostly with limited cohorts, have suggested the effects of patients' characteristics on levodopa (LD) pharmacokinetics.

OBJECTIVE

We primarily aimed at investigating in a large population the relationship between patients' features and LD kinetic variables, to assess the main demographic and clinical predictors of LD clinical pharmacokinetics.

METHODS

The study was retrospective, based on data collected from subjects with parkinsonism on chronic LD undergoing LD therapeutic monitoring (TM). LD TM includes serial quantitative motor tests and blood samples to measure plasma drug concentrations after each subject's chronically taken first-morning LD dose intake.

RESULTS

Five hundred patients, 308 males (61.6%), mean (SD) age of 65 (10.1) years were included. Parkinsonian symptoms and LD therapy lasted 5.5 (4.5) and 3.4 (3.9) years, respectively. MDS-UPDRS part III "off" score was 28.8 (15.2). LD dose was 348.2 (187.1) mg/day. From multiple linear regression analysis, test dose, sex, type of LD decarboxylase inhibitor, weight and MDS-UPDRS part III score were linear predictors of both LD peak plasma concentration (Cmax) (R2 = 0.52) and area under the 3-h plasma concentration-time curve (AUC) (R2 = 0.71), while age was a further predictor only for AUC. Besides test dose, sex was the strongest independent contributing variable to LD AUC, which resulted 27% higher in females compared to males.

CONCLUSION

This is the largest collection of data on the relationship between demographic and clinical-therapeutic variables and LD kinetics in patients with parkinsonian symptoms. As a main clinically practical finding, women might require a 25% reduced weight-normalized LD dose compared with men to achieve the same LD bioavailability.

Sex and gender differences in movement disorders: Parkinson's disease, essential tremor, dystonia and chorea

Sex and gender-based differences in epidemiology, clinical features and therapeutical responses are emerging in several movement disorders, even though they are still not widely recognized. In this chapter, we summarize the most relevant evidence concerning these differences in Parkinson's disease, essential tremor, dystonia and chorea. Indeed, both sex-related biological (hormonal levels fluctuations) and gender-related variables (socio-cultural and environmental factors) may differently impact symptoms manifestation and severity, phenotype and disease progression of movement disorders on men and women. Moreover, sex differences in treatment responses should be taken into account in any therapeutical planning. Physicians need to be aware of these major differences between men and women that will eventually have a major impact on better tailoring prevention, treatment, or even delaying progression of the most common movement disorders.

Parkinson's disease: the nutrition perspective

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease and affects about 1% of the population over the age of 60 years in industrialised countries. The aim of this review is to examine nutrition in PD across three domains: dietary intake and the development of PD; whole body metabolism in PD and the effects of PD symptoms and treatment on nutritional status. In most cases, PD is believed to be caused by a combination of genetic and environmental factors and although there has been much research in the area, evidence suggests that poor dietary intake is not a risk factor for the development of PD. The evidence about body weight changes in both the prodromal and symptomatic phases of PD is inconclusive and is confounded by many factors. Malnutrition in PD has been documented as has sarcopaenia, although the prevalence of the latter remains uncertain due to a lack of consensus in the definition of sarcopaenia. PD symptoms, including those which are gastrointestinal and non-gastrointestinal, are known to adversely affect nutritional status. Similarly, PD treatments can cause nausea, vomiting and constipation, all of which can adversely affect nutritional status. Given that the prevalence of PD will increase as the population ages, it is important to understand the interplay between PD, comorbidities and nutritional status. Further research may contribute to the development of interventional strategies to improve symptoms, augment care and importantly, enhance the quality of life for patients living with this complex neurodegenerative disease.

Plasticity, genetics, and epigenetics in l-dopa-induced dyskinesias

l-Dopa-induced dyskinesias (LIDs) are a frequent complication in l-dopa-treated patients affected by Parkinson's disease (PD). In the last years, several progresses in the knowledge of LIDs mechanisms have led to the identification of several molecular and electrophysiologic events. A complex cascade of intracellular events underlies the pathophysiology of LIDs, and, among these, aberrant plasticity in the cortico-basal ganglia system, at striatal and cortical level, plays a key role. Furthermore, several recent studies have investigated genetic susceptibility and epigenetic modifications in LIDs pathophysiology that might have future relevance in clinical practice and pharmacologic research. These progresses might lead to the development of specific strategies not only to treat, but also to prevent or delay the development of LIDs in PD.

New insights into pathogenesis of l-DOPA-induced dyskinesia

Parkinson's disease (PD) is a progressive and self-propelling neurodegenerative disorder, which is characterized by motor symptoms, such as rigidity, tremor, slowness of movement and problems with gait. These symptoms become worse over time. To date, Dopamine (DA) replacement therapy with 3, 4-dihydroxy-l-phenylalanine (L-DOPA) is still the most effective pharmacotherapy for motor symptoms of PD. Unfortunately, motor fluctuations consisting of wearing-off effect actions and dyskinesia tend to occur in a few years of starting l-DOPA. Currently, l-DOPA-induced dyskinesia (LID) is troublesome and the pathogenesis of LID requires further investigation. Importantly, a new intervention for LID is imminent. Thus, this review mainly summarized the clinical features, risk factors and pathogenesis of LID to provide updatefor the development of therapeutic targets and new approaches for the treatment of LID.

Mavoglurant (AFQ056) for the treatment of levodopa-induced dyskinesia in patients with Parkinson's disease: a meta-analysis

Background

Mavoglurant (AFQ056), a selective metabotropic glutamate receptor 5 (mGluR5) inhibitor, was tested for t levodopa-induced dyskinesia (LID) in patients with Parkinson’s Disease (PD). However, clinical trials showed inconsistent results regarding the efficacy of mavoglurant in treating LID in patients with Parkinson's disease (PD).

Methods

A computer literature search of PubMed, Scopus, Web of science, and Cochrane CENTRAL was conducted until March 2021. We selected relevant randomized controlled trials comparing mavoglurant to placebo. Study data were extracted and pooled as mean difference (MD) in the meta-analysis model.

Results

Six RCTs were included in this meta-analysis with a total of 485 patients. Mavoglurant was not significantly superior to placebo in terms of the “off-time” (MD −0.27 h, 95% CI −0.65 to 0.11), “on time” (MD 0.29 h, 95% CI −0.09 to 0.66), Lang-Fahn activities of daily living dyskinesia scale (MD −0.95, 95% CI −1.98 to 0.07), UPDRS-III (MD −0.51, 95% CI −1.66 to 0.65), or UPDRS-IV (MD −0.41, 95% CI −0.85 to 0.03). However, the pooled modified abnormal involuntary movement scale favored the mavoglurant group than the placebo group (MD −2.53, 95% CI −4.23 to −0.82).

Conclusions

This meta-analysis provides level one evidence that mavoglurant is not effective in treating the LID in patients with PD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05319-7.

Analysis of Genetic and Non-genetic Predictors of Levodopa Induced Dyskinesia in Parkinson's Disease

Background: Levodopa (L-Dopa), representing the therapeutic gold standard for the treatment of Parkinson disease (PD), is associated with side effects like L-Dopa induced dyskinesia (LID). Although several non-genetic and genetic factors have been investigated for association with LID risk, contrasting results were reported and its genetic basis remain largely unexplored.

Methods: In an Italian PD cohort (N = 460), we first performed stepwise multivariable Cox Proportional Hazard regressions modeling LID risk as a function of gender, PD familiarity, clinical subtype, weight, age-at-onset (AAO) and years-of-disease (YOD), L-Dopa dosage, severity scores, and scales assessing motor (UPDRS-III), cognitive (MoCA), and non-motor symptoms (NMS). Then we enriched the resulting model testing two variants—rs356219 and D4S3481—increasing the expression of the SNCA gene, previously suggested as a potential mechanism of LID onset. To account for more complex (non-linear) relations of these variables with LID risk, we built a survival random forest (SRF) algorithm including all the covariates mentioned above.

Results: Among tested variables (N = 460 case-complete, 211 LID events; total follow-up 31,361 person-months, median 61 months), disease duration showed significant association (p < 0.005), with 6 (3–8)% decrease of LID risk per additional YOD. Other nominally significant associations were observed for gender—with women showing a 39 (5–82)% higher risk of LID—and AAO, with 2 (0.3–3)% decrease of risk for each year increase of PD onset. The SRF algorithm confirmed YOD as the most prominent feature influencing LID risk, with a variable importance of about 8% in the model. In genetic models, no statistically significant effects on incident LID risk was observed.

Conclusions: This evidence supports a protective effect of late PD onset and gender (men) against LID risk and suggests a new independent protective factor, YOD. Moreover, it underlines the importance of personalized therapeutic protocols for PD patients in the future.

Female, aging, difference formulations of DCI, or lower body weight increases AUC4hr of levodopa in patients with Parkinson's disease

INTRODUCTION

There is considerable intra- and inter-individual variability in the pharmacokinetics (PK) of levodopa after oral administration. Inter-individual variability in levodopa PK has also been demonstrated in fasting single-dose studies. We examined the factors that affect levodopa PK in patients with Parkinson's disease (PD) and quantified the intensity of their respective effects.

METHODS

We studied 220 patients who underwent PK assessment after administration of 1 tablet of levodopa/DOPA decarboxylase inhibitor (DCI) combination, which contained 10 mg carbidopa/100 mg levodopa or 25 mg benserazide/100 mg levodopa. PK was evaluated using non-compartmental analysis.

RESULTS

In total, 220 PD patients (including 112 men) were studied. The mean age (±standard deviation) and mean disease duration was 68.1 ± 8.9 and 7.7 ± 5.8 years, respectively. The Cmax of levodopa was 9.0 ± 4.0 ng/mL, Tmax was 41.4 ± 40.2 min, and area under the blood concentration-time curve up to 4 h (AUC_4hr) was 12.3 ± 3.7 ng/mL*4hr. Factors affecting AUC_4hr were analyzed using multiple linear regression models. Age (1.1 ± 0.23 per +10 years, p = 3.1E-8), sex (2.2 ± 0.5 for female, p = 1.9E-5), DCI (1.4 ± 0.4 for benserazide, p = 0.0028), and body weight (-0.77 ± 0.22 per +10 kg, p = 5.4E-4) were significantly related to AUC_4hr, while disease duration, dyskinesia status, and eGFR were not related to AUC_4hr and Cmax.

CONCLUSION

Female, aging, difference formulations of DCI, or lower body weight independently contributes to increased AUC_4hr of levodopa in Japanese patients with PD in this study.

Analysis of factors associated with brittle response in patients with Parkinson's disease

Introduction

The brittle response (BR) in patients with Parkinson’s disease (PD) refers to a special type of levodopa‐induced dyskinesia (LID). This study aimed to describe the clinical characteristics of BR patients and to analyze the associated risk factors.

Methods

A retrospective study was conducted to analyze the data of 97 patients with PD. Patients were divided into a BR group and a non‐brittle response (NBR) group. Demographic and clinical data, motor symptoms, and non‐motor symptoms of the two groups were assessed.

Results

Among 97 PD patients, 11 were in the BR group and 86 were in the NBR group. The proportion of female patients was 72.7% and 38.3%, respectively, in the BR and NBR groups (P < 0.05). Compared to NBR patients, BR patients had relatively low body weight, low BMI, long disease duration, high levodopa equivalent daily dosage (LEDD), and high levodopa dose per weight (P < 0.05). The BR group had significantly higher scores of UPDRS (II, III, and IV) (P < 0.05). But no difference was found in the UPDRS I, emotional state, cognitive status, and accompanied by REM sleep behavior disorder (RBD) (P> 0.05). Multivariate logistic regression analysis showed that BR patients had lower body weight and higher levodopa dose per weight.

Conclusion

BR is associated with being female, low body weight, low BMI, long disease duration, high LEDD, and high levodopa dose per weight. Body weight and levodopa dose per body weight are independent risk factors for BR.

Sex differences in movement disorders

In a range of neurological conditions, including movement disorders, sex-related differences are emerging not only in brain anatomy and function, but also in pathogenesis, clinical features and response to treatment. In Parkinson disease (PD), for example, oestrogens can influence the severity of motor symptoms, whereas elevation of androgens can exacerbate tic disorders. Nevertheless, the real impact of sex differences in movement disorders remains under-recognized. In this article, we provide an up-to-date review of sex-related differences in PD and the most common hyperkinetic movement disorders, namely, essential tremor, dystonia, Huntington disease and other chorea syndromes, and Tourette syndrome and other chronic tic disorders. We highlight the most relevant clinical aspects of movement disorders that differ between men and women. Increased recognition of these differences and their impact on patient care could aid the development of tailored approaches to the management of movement disorders and enable the optimization of preclinical research and clinical studies.

Sex differences in Parkinson's disease: A transcranial magnetic stimulation study

BACKGROUND

Demographic and clinical studies imply that female sex may be protective for PD, but pathophysiological evidence to support these observations is missing. In early PD, functional changes may be detected in primary motor cortex using transcranial magnetic stimulation.

OBJECTIVE

We hypothesised that if pathophysiology differs between sexes in PD, this will be reflected in differences of motor cortex measurements.

METHODS

Forty-one newly diagnosed PD patients (22 males, 19 females) were clinically assessed using MDS-UPDRS part III, and various measures of cortical excitability and sensorimotor cortex plasticity were measured over both hemispheres, corresponding to the less and more affected side, using transcranial magnetic stimulation. Twenty-three healthy (10 men, 13 women) participants were studied for comparison.

RESULTS

Among patients, no significant differences between sexes were found in age, age of diagnosis, symptom duration, and total or lateralized motor score. However, male patients had disturbed interhemispheric balance of motor thresholds, caused by decreased resting and active motor thresholds in the more affected hemisphere. Short interval intracortical inhibition was more effective in female compared to male patients in both hemispheres. Female patients had a preserved physiological focal response to sensorimotor plasticity protocol, whereas male patients showed an abnormal spread of the protocol effect.

CONCLUSION

The study provides one of the first neurophysiological evidences of sex differences in early PD. Female patients have a more favorable profile of transcranial magnetic stimulation measures, possibly reflecting a more successful cortical compensation or delayed maladaptive changes in the sensorimotor cortex. © 2019 International Parkinson and Movement Disorder Society.

Bound, free, and total L-dopa measurement in plasma of Parkinson's disease patients

Peaks and troughs of levodopa in plasma contribute to pulsatile postsynaptic dopamine receptor stimulation in patients with Parkinson's disease. Measurement of levodopa plasma levels mostly only considers the total levodopa plasma concentration. Objectives were to determine bound, free, and total plasma levodopa and to investigate their correlations to each other. We employed reversed-phase high-performance liquid chromatography combined with electrochemical detection. Bound levodopa was computed as difference between total and free L-dopa values. Close correlations between free and total (R = 0.93, p < 0.0001), bound and total (R = 0.91, p < 0.0001) plasma levodopa appeared. A considerable variability of levodopa concentrations occurred. The ratio between bound and free levodopa did not differ in patients with a higher and lower oral daily levodopa dosing. Free, bound, and total levodopa plasma levels are closely related. Estimation of the total levodopa level only seems to be meaningful.

Sex-related pattern of intrinsic brain connectivity in drug-naïve Parkinson's disease patients

BACKGROUND

Sex difference is related to specific clinical features in PD patients over the disease course.

OBJECTIVES

To investigate the potential sex-difference effect on the spontaneous neuronal activity within the most reported resting-state networks in early untreated PD patients and its correlation with baseline and longitudinal clinical features.

METHODS

Fifty-six drug-naïve PD patients (30/26 male/female) and 30 (15/15 male/female) matched controls were enrolled in the study. Topological and spectral resting-state functional MRI features of the sensorimotor, dorsal and ventral attention, frontoparietal, and default-mode networks were analyzed for possible sex-difference effects in both PD patients and controls groups. Additionally, a region-of-interest analysis was performed to test for a sex effect on basal ganglia connectivity. Multivariate ordinal regression was used to investigate whether connectivity findings at baseline were predictors of motor impairment over a 2-year follow-up period.

RESULTS

Compared to female PD patients and controls, male PD patients showed an abnormal spectral composition of the sensorimotor and dorsal attention networks in the slow-5 band. The region-of-interest analysis showed an increased connectivity within the basal ganglia in female PD patients compared to males. Functional sensorimotor connectivity changes at baseline showed to be an independent predictor of disease severity at 2-year follow-up.

CONCLUSIONS

Our findings revealed the presence of a disease-related, sex-specific cortical and subcortical connectivity pattern within the sensorimotor network, in the early stage of PD. We hypothesize that these findings may be related to the presence of different sex-specific nigrostriatal dopaminergic pathways and might predict PD progression. © 2019 International Parkinson and Movement Disorder Society.

Risk factors of levodopa-induced dyskinesia in Parkinson's disease: results from the PPMI cohort

Levodopa-induced dyskinesias (LID) negatively impact on the quality of life of patients with Parkinson's disease (PD). We assessed the risk factors for LID in a cohort of de-novo PD patients enrolled in the Parkinson's Progression Markers Initiative (PPMI). This retrospective cohort study included all PD patients enrolled in the PPMI cohort. Main outcome was the incidence rate of dyskinesia, defined as the first time the patient reported a non-zero score in the item "Time spent with dyskinesia" of the MDS-UPDRS part IV. Predictive value for LID development was assessed for clinical and demographical features, dopamine transporter imaging (DaTscan) pattern, cerebrospinal fluid (CSF) biomarkers (Aβ42, total tau, phosphorylated tau, total α synuclein) and genetic risk score for PD. Overall, data from 423 PD patients were analyzed. The cumulative incidence rate of LID was 27.4% (95% CI = 23.2-32.0%), with a mean onset time of 5.81 years from PD diagnosis. Multivariate Cox regression analysis showed several factors predicting LID development, including female gender (HR = 1.61, 95% CI = 1.05-2.47), being not completely functional independent as measured by the modified Schwab & England ADL scale (HR = 1.81, 95% CI = 0.98-3.38), higher MDS-UPDRS part III score (HR = 1.03, 95% CI = 1.00-1.05), postural instability gait disturbances or intermediate phenotypes (HR = 1.95, 95% CI = 1.28-2.96), higher DaTscan caudate asymmetry index (HR = 1.02, 95% CI = 1.00-1.03), higher polygenic genetic risk score (HR = 1.39, 95% CI = 1.08-1.78), and an anxiety trait (HR = 1.02, 95% CI = 1.00-1.04). In PD patients, cumulative levodopa exposure, female gender, severity of motor and functional impairment, non-tremor dominant clinical phenotype, genetic risk score, anxiety, and marked caudate asymmetric pattern at DaTscan at baseline represent independent risk factors for developing LID.

DAT gene polymorphisms (rs28363170, rs393795) and levodopa-induced dyskinesias in Parkinson's disease

L-dopa-induced dyskinesias (LID) is a common motor side effect of levodopa therapy of Parkinson's disease (PD). The identified predictors may only partially account for the risk of developing LID and genetic factors may contribute to this variability. The present study is aimed to investigate whether polymorphisms in the dopamine transporter gene (DAT) are associated with the risk of developing LID. Genotyping of the 40-bp VNTR (rs28363170) and rs393795 (A/C) polymorphisms of the DAT gene was performed in a well-characterized cohort of 181 Italian PD patients in treatment with L-DOPA for 3 years or more. The results of our study show that there is no difference in dyskinesias prevalence among carriers of the two DAT gene polymorphisms. However, the combination of the two genotypes 10R/10R (rs28363170) and A carrier (rs393795) of the DAT gene reduces the risk of LID occurrence during long-term therapy with l-DOPA with respect to the PD subjects who did not carry these alleles (OR = 0.31; 95% CI, 0.09-0.88). Also based on a logistic regression analysis, the 10R/10R and the A carrier allele of the rs393795 polymorphisms of the DAT gene, could reduce the susceptibility to develop LID during levodopa therapy adjusted by demographical and clinical variables (OR = 0.19; 95% CI, 0.05-0.69). Additional studies further investigating the rs28363170 and rs393795 polymorphisms with LID in PD are needed to clarify their role in different ethnicities.

Pharmacokinetics of Rytary®, An Extended-Release Capsule Formulation of Carbidopa-Levodopa

Parkinson's disease (PD) is a chronic progressive neurological disorder characterized by resting tremor, rigidity, bradykinesia, gait disturbance, and postural instability. Levodopa, the precursor to dopamine, coadministered with carbidopa or benserazide, aromatic amino acid decarboxylase inhibitors, is the most effective and widely used therapeutic agent in the treatment of PD. With continued levodopa treatment, a majority of patients develop motor complications such as dyskinesia and motor 'on-off' fluctuations, which are, in part, related to the fluctuations in plasma concentrations of levodopa. A new extended-release (ER) carbidopa-levodopa capsule product (also referred to as IPX066) was developed and approved in the US as Rytary^® and in the EU as Numient^®. The capsule formulation is designed to provide an initial rapid absorption of levodopa comparable to immediate-release (IR) carbidopa-levodopa, and to subsequently provide stable levodopa concentrations with reduced peak-to-trough excursions in plasma concentrations in order to reduce motor fluctuations associated with pulsatile stimulation of dopamine receptors and to minimize dyskinesia. Phase III studies of this ER carbidopa-levodopa capsule formulation in patients with PD have shown a significant reduction in 'off' time compared with IR carbidopa-levodopa and carbidopa-levodopa-entacapone. We present a review of the clinical pharmacokinetics and pharmacodynamics of this ER product of carbidopa-levodopa in healthy subjects and in patients with PD.

Levodopa-induced dyskinesia: clinical features, incidence, and risk factors

Symptoms of Parkinson's disease have been controlled with levodopa for many years; however, motor complications consisting of wearing off of medication effect and dyskinesias tend to occur within a few years of starting levodopa. Motor complications can begin a few months after taking levodopa, with the average time to onset estimated to be 6.5 years. Dyskinesias can be troublesome and require intervention. Levodopa-induced dyskinesia can be composed of a variety of movement disorders including chorea, dystonia, ballism, myoclonus, and akathisia. Based on the clinical pattern, the most common dyskinesia is chorea and choreoathetosis. The clinical manifestations can be divided into three main categories based on their clinical movement patterns and the temporal correlation between the occurrence of dyskinesia and the levodopa dosing: on or peak-dose dyskinesias, biphasic dyskinesias, and Off dyskinesias. Severe cases of dyskinesia have been reported, with the extreme being dyskinesia-hyperpyrexia syndrome. The prevalence of LID has been reported in many studies, but the reported incidence varies. The rate of LID development is from 3 to 94%. The prevalence of LID mainly depends on age at onset, disease duration, and severity, and duration of levodopa therapy. Some of the risk factors for the development of dyskinesia are modifiable. Modifiable risk factors include levodopa dose and body weight. Non-modifiable risk factors include age, gender, duration of disease, clinical subtype, disease progression, disease severity, and genetic factors.

Dyskinesias and levodopa therapy: why wait?

Throughout the years there has been a longstanding discussion on whether levodopa therapy in Parkinson's disease should be started in early vs. later stages, in order to prevent or delay motor complications such as fluctuations and dyskinesias. This controversial topic has been extensively debated for decades, and the prevailing view today is that levodopa should not be postponed. However, there is still fear associated with its use in early stages, especially in younger patients, who are more prone to develop dyskinesias. Even though dyskinesias are linked to levodopa use in Parkinson's disease, it has been shown that starting with a different medication (such as dopamine agonists) will not significantly delay their onset once levodopa is introduced. Since levodopa provides better symptomatic control, and other drugs may be associated with notable side effects, it is our view that there is insufficient evidence to justify levodopa-sparing strategies. The physician should try to assess each patient individually, taking into account motor and non-motor demands, as well as risk factors for potential complications, finding the optimum treatment strategy for each one. The following article provides an historical narrative perspective, as well as a literature review of those intrinsic and modifiable risk factors that have been associated with levodopa-induced dyskinesias, which should be taken into consideration when choosing the therapeutic strategy in individual Parkinson's disease patients.

Management of Parkinson's disease in older women

Elderly women with Parkinson's disease (PD) represent a specific patient population that may benefit from individualized treatment strategies. PD has been shown to occur approximately twice as often in men than in women, resulting in theories regarding estrogen being protective against the disease and as a potential treatment strategy. Given women's longer life expectancy they are more likely to reach an age where antiparkinsonian medications are associated with side-effects. This paper will review medical and surgical treatments as well as the relationship of gender and age with respect to the management of PD.

Dose-Response Analysis of the Effect of Carbidopa-Levodopa Extended-Release Capsules (IPX066) in Levodopa-Naive Patients With Parkinson Disease

Parkinson disease is an age-related disorder of the central nervous system principally due to loss of dopamine-producing cells in the midbrain. Levodopa, in combination with carbidopa, is widely regarded as an effective treatment for the symptoms of Parkinson disease. A dose-response relationship is established for carbidopa-levodopa extended-release capsules (IPX066) in levodopa-naive Parkinson disease patients using a disease progression model. Unified Parkinson Disease Rating Scale (UPDRS) part II plus part III scores from 171 North American patients treated with placebo or IPX066 for approximately 30 weeks from a double-blind, parallel-group, dose-ranging study were used to develop the pharmacodynamic model. The model comprised 3 components: a linear function describing disease progression, a component describing placebo (or nonlevodopa) effects, and a component to describe the effect of levodopa. Natural disease progression in early Parkinson disease as measured by UPDRS was 11.6 units/year and faster in patients with more severe disease (Hoehn-Yahr stage 3). Maximum placebo/nonlevodopa response was 23.0% of baseline UPDRS. Maximum levodopa effect from IPX066 was 76.7% of baseline UPDRS, and the ED50 was 450 mg levodopa. Equilibration half-life for the effect compartment was 62.8 days. Increasing age increased and being female decreased equilibration half-life. The quantitative model allowed description of the entire time course of response to clinical trial intervention.

Influence of genetic, biological and pharmacological factors on levodopa dose in Parkinson's disease

AIM

Levodopa is first-line treatment of Parkinson's disease motor symptoms but, dose response is highly variable. Therefore, the aim of this study was to determine how much levodopa dose could be explained by biological, pharmacological and genetic factors.

PATIENTS & METHODS

A total of 224 Parkinson's disease patients were genotyped for SV2C and SLC6A3 polymorphisms by allelic discrimination assays. Comedication, demographic and clinical data were also assessed.

RESULTS

All variables with p < 0.20 were included in a multiple regression analysis for dose prediction. The final model explained 23% of dose variation (F = 11.54; p < 0.000001).

CONCLUSION

Although a good prediction model was obtained, it still needs to be tested in an independent sample to be validated.

Effects of long-term treatment with rotigotine transdermal system on dyskinesia in patients with early-stage Parkinson's disease

PURPOSE

In two 6-month, double-blind, placebo-controlled studies, rotigotine transdermal system was well-tolerated and efficacious monotherapy in early-stage PD. This post hoc analysis of the long-term open-label extensions (NCT00594165; NCT00599196) of these studies assessed incidence and severity of dyskinesia in participants treated with rotigotine, with or without concomitant levodopa, for up to 6 years.

METHODS

Open-label rotigotine was titrated to optimal dose (≤16 mg/24 h). Concomitant levodopa was permitted. Dyskinesia data, recorded using the Unified Parkinson's Disease Rating Scale Part IV, were pooled from the two open-label studies.

RESULTS

Of 596 participants who received open-label rotigotine, 299 (50%) remained at trial closure; no patient discontinued due to dyskinesia. In the two studies, median exposure to rotigotine was 1910 days (∼5 years, 3 months), and 1564.5 days (∼4 years, 3 months). During up to 6 years of open-label rotigotine, 423/596 (71%) received levodopa. Dyskinesias were reported in 115/596 (19%) participants, 90/115 (78%) of who developed dyskinesia after levodopa was added; 25 reported dyskinesia in the absence of levodopa (includes patients who never received open-label levodopa, and those who reported dyskinesia before starting concomitant levodopa). Dyskinesia severity data were available for 107 of the 115 participants. In 56/107 (52%) participants, dyskinesia was considered 'not disabling' for all occurrences; the worst-case severity was 'mildly disabling' for 33/107 (31%), and 'moderately' or 'severely disabling' for 18/107 (17%; 3% of total participants).

CONCLUSION

During treatment with rotigotine in patients with PD for up to 6 years the incidence of dyskinesia was low, and the dyskinesia was generally 'not disabling' or 'mildly disabling'.

Dopamine dysregulation syndrome in Parkinson's disease: from clinical and neuropsychological characterisation to management and long-term outcome

OBJECTIVE

Dopamine dysregulation syndrome (DDS) refers to a compulsive pattern of dopaminergic drug misuse complicating Parkinson's disease (PD). To date, few data are available on DDS risk factors, cognitive profile and long-term outcome.

METHODS

In this retrospective case-control study, consecutive PD outpatients fulfilling criteria for DDS were assessed over a 6-year period (2005-2011). They were compared with 70 PD cases matched for age at onset, gender and disease duration, and with 1281 subjects with motor fluctuations and dyskinesias. DDS patients and matched controls underwent extensive neuropsychological assessment. Strategies for DDS patients management and the outcome at the last follow-up visit were recorded.

RESULTS

Thirty-five patients with DDS were identified, reporting history of depression, family history of PD and drug abuse, greater difference between 'Off' versus 'On' motor symptoms compared to age-matched controls. They had younger age at onset (but not any gender difference) compared to general PD population. Cognitive profile of DDS did not show major abnormalities, including executive functions. DDS patients have been followed up for 3.2±2.1 years and remission was recorded in 40% of cases. Negative DDS outcome was significantly associated with poor caregiver supervision. Sustained remission occurred more commonly on clozapine and on duodenal levodopa infusion and subthalamic nucleus deep brain stimulation (STN-DBS) than on apomorphine pump treatment.

CONCLUSIONS

Clinicians should be aware of risk factors predisposing to DDS. Duodenal levodopa infusion and, less consistently, STN-DBS were more commonly associated with DDS remission. Effective caregiving plays a key role in long-term behavioural outcome.

Characteristics, pathophysiology and clinical management of weight loss in Huntington’s disease

SUMMARY Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion in the HTT gene. Clinically, the disease is characterized by motor impairment, cognitive deterioration and behavioral disturbances. Unintended weight loss is also a hallmark of the disease and frequently leads to general weakening and a decline in the quality of life of HD patients. Moreover, a higher BMI has been associated with a slower rate of disease progression. In this review, the authors first delineate the characteristics of weight loss in both HD patients and genetic models of the disease. Subsequently, they discuss the pathophysiological processes underlying weight loss in HD and highlight the implications for management and care of HD patients with, or at risk of, unintended weight loss.

Markers of disease severity are associated with malnutrition in Parkinson's disease

OBJECTIVE

In Parkinson's disease (PD), commonly reported risk factors for malnutrition in other populations commonly occur. Few studies have explored which of these factors are of particular importance in malnutrition in PD. The aim was to identify the determinants of nutritional status in people with Parkinson's disease (PWP).

METHODS

Community-dwelling PWP (>18 years) were recruited (n = 125; 73M/52F; Mdn 70 years). Self-report assessments included Beck's Depression Inventory (BDI), Spielberger Trait Anxiety Inventory (STAI), Scales for Outcomes in Parkinson's disease-Autonomic (SCOPA-AUT), Modified Constipation Assessment Scale (MCAS) and Freezing of Gait Questionnaire (FOG-Q). Information about age, PD duration, medications, co-morbid conditions and living situation was obtained. Addenbrooke's Cognitive Examination (ACE-R), Unified Parkinson's Disease Rating Scale (UPDRS) II and UPDRS III were performed. Nutritional status was assessed using the Subjective Global Assessment (SGA) as part of the scored Patient-Generated Subjective Global Assessment (PG-SGA).

RESULTS

Nineteen (15%) were malnourished (SGA-B). Median PG-SGA score was 3. More of the malnourished were elderly (84% vs. 71%) and had more severe disease (H&Y: 21% vs. 5%). UPDRS II and UPDRS III scores and levodopa equivalent daily dose (LEDD)/body weight (mg/kg) were significantly higher in the malnourished (Mdn 18 vs. 15; 20 vs. 15; 10.1 vs. 7.6 respectively). Regression analyses revealed older age at diagnosis, higher LEDD/body weight (mg/kg), greater UPDRS III score, lower STAI score and higher BDI score as significant predictors of malnutrition (SGA-B). Living alone and higher BDI and UPDRS III scores were significant predictors of a higher log-adjusted PG-SGA score.

CONCLUSIONS

In this sample of PWP, the rate of malnutrition was higher than that previously reported in the general community. Nutrition screening should occur regularly in those with more severe disease and depression. Community support should be provided to PWP living alone. Dopaminergic medication should be reviewed with body weight changes.

Risk factors for hallucinations in Parkinson's disease: results from a large prospective cohort study

The aim of this study was to identify risk factors for the development of hallucinations in patients with Parkinson's disease (PD). A broad range of motor and nonmotor features was assessed at baseline and during the following 5 years in 386 PD patients. Cross-sectional analyses of baseline data and longitudinal analyses of follow-up data were performed to identify risk factors for hallucinations in PD. Twenty-one percent of the patients had hallucinations at baseline, whereas 46% of the patients without hallucinations at baseline developed this feature during follow-up. Univariate survival analysis showed that older age, female sex, less education, higher age at onset, and more severe motor and cognitive impairment, depression, daytimes sleepiness, autonomic dysfunction, and motor fluctuations and dyskinesias, as well as higher daily levodopa dose, were associated with the risk of developing hallucinations. This largely corresponds with the features that were associated with the presence of hallucinations at baseline. In a stepwise regression model, older age at onset, female sex, excessive daytime sleepiness, autonomic dysfunction, and dyskinesias emerged as independent risk factors for developing hallucinations. Female sex, autonomic dysfunction, motor fluctuations, and dyskinesias have not been reported as risk factors in previous studies. These findings lend support to the notion that hallucinations in PD are caused by a combination of risk factors that are associated with (the interaction between) older age and more advanced disease. The identification of female sex as a risk factor for developing of hallucinations in PD is a new finding and should be verified in future studies.

Genetic variability in estrogen disposition: Potential clinical implications for neuropsychiatric disorders

Variability in the physiological levels of neuroactive estrogens is widely believed to play a role in predisposition to several disorders of the central nervous system. Local biosynthesis of estrogens in the brain as well as their circulating serum levels are known to contribute to this pool of neuroactive steroids. It has been well accepted that estrogens modulate neuronal functions by affecting genesis, differentiation, excitability, and degeneration of nerve cells. These actions of estrogens appear to be more prominent in females with higher concentrations and marked variability of circulating serum levels occurring over a woman's lifetime. However, our knowledge regarding the variability of neuroactive steroid levels is very limited. Furthermore, several studies have recently reported differences in the synchronization of circulating and neuronal levels of estradiol. In the absence of reliable circulating steroid levels, knowledge of genetic variability in estrogen disposition may play a determining factor in predicting altered susceptibility or severity of neuropsychiatric disorders in women. Over the past decade, several genetic variants have been linked to both differential serum estrogen levels and predisposition to diverse types of neuropsychiatric disorders in women. Polymorphisms in genes encoding estrogen-metabolizing enzymes as well as estrogen receptors may account for this phenotypic variability. In this review, we attempt to show the contribution of genetics in determining estrogenicity in females with a particular emphasis on the central nervous system. This knowledge will further provide a driving force for unearthing the novel field of "Estrogen Pharmacogenomics." © 2010 Wiley-Liss, Inc.

Classifying risk factors for dyskinesia in Parkinson's disease

BACKGROUND

Currently there is no classification of risk factors applicable to an individual patient with Parkinson's disease for the development of dyskinesia.

METHODS

We conducted literature search to identify and classifying risk factors into groups - (a) intrinsic vs extrinsic and (b) modifiable vs non-modifiable.

RESULTS

Younger age, young age of onset and severity of PD are major intrinsic non-modifiable risk factors for dyskinesia, female gender is another factor but not independent of other factors. Genetic expression and plasticity may determine pre-disposition to age of onset of PD and dyskinesia, these are currently non-modifiable factors arising due to an interaction of intrinsic and extrinsic factors. Lower initial body weight and weight loss during the course of the disease increase the risk of dyskinesia. Levodopa dose per kilogram body weight is a more significant risk factor than absolute levodopa dose. Early use of longer acting non-levodopa (i.e. dopamine agonists) medications delays the onset of dyskinesia. Interaction between body weight, levodopa dose and mode and duration of drug delivery is a significant modifiable factor.

CONCLUSION

Dyskinesia in PD arises as a consequence of the interaction of intrinsic versus extrinsic and modifiable versus non-modifiable factors. Identification and manipulation of modifiable factors for an individual patient may reduce the risk and burden of dyskinesia. Adjustment of levodopa dose according to body weight during the course of the disease seems to be a significant modifiable risk factor for dyskinesia.

Parkinson's disease as a disconnection syndrome

Parkinson's disease (PD) is a major neurodegenerative disorder that is usually considered in terms of midbrain and basal ganglia dysfunction. Regarding PD instead as a disconnection syndrome may prove beneficial to understanding aspects of cognition, perception, and other neuropsychological domains in the disease. PD is usually of unilateral onset, providing evidence of intrahemispheric dissociations and an imbalance in the usual relative strengths of the right and left hemispheres. Hence, in order to appreciate the neuropsychology of PD, it is important to apply to this disease our understanding of hemispheric lateralization effects and within-hemisphere circuitry from brainstem to higher-order association cortex. The focus of this review is on the relevance of PD-related disconnections among subcortical and cortical structures to cognition, perception, emotion, and associated brainstem-based domains such as sleep and mood disturbance. Besides providing information on disease characteristics, regarding PD as a disconnection syndrome allows us to more completely understand normal brain-behavior relations in general.

Weight loss in neurodegenerative disorders

Unintended weight loss frequently complicates the course of many neurodegenerative disorders and can contribute substantially to both morbidity and mortality. This will be illustrated here by reviewing the characteristics of unintended weight loss in the three major neurodegenerative disorders: Alzheimer's disease, Parkinson's disease and Huntington's disease. A common denominator of weight loss in these neurodegenerative disorders is its typically complex pathophysiology. Timely recognition of the underlying pathophysiological process is of crucial importance, since a tailored treatment of weight loss can considerably improve the quality of life. This treatment is, primarily, comprised of a number of methods of increasing energy intake. Moreover, there are indications for defects in the systemic energy homeostasis and gastrointestinal function, which may also serve as therapeutic targets. However, the clinical merits of such interventions have yet to be demonstrated.

Neurotrophic and neuroprotective actions of estrogen: basic mechanisms and clinical implications

Estrogen is an important hormone signal that regulates multiple tissues and functions in the body. This review focuses on the neurotrophic and neuroprotective actions of estrogen in the brain, with particular emphasis on estrogen actions in the hippocampus, cerebral cortex and striatum. Sex differences in the risk, onset and severity of neurodegenerative disease such as Alzheimer's disease, Parkinson's disease and stroke are well known, and the potential role of estrogen as a neuroprotective factor is discussed in this context. The review assimilates a complex literature that spans research in humans, non-human primates and rodent animal models and attempts to contrast and compare the findings across species where possible. Current controversies regarding the Women's Health Initiative (WHI) study, its ramifications, concerns and the new studies needed to address these concerns are also addressed. Signaling mechanisms underlying estrogen-induced neuroprotection and synaptic plasticity are reviewed, including the important concepts of genomic versus nongenomic mechanisms, types of estrogen receptor involved and their subcellular targeting, and implicated downstream signaling pathways and mediators. Finally, a multicellular mode of estrogen action in the regulation of neuronal survival and neurotrophism is discussed, as are potential future directions for the field.

Body weight in patients with Parkinson's disease

There is some evidence suggesting that Parkinson's disease (PD) patients exhibit lower body weight when compared to age-matched healthy subjects. Low body mass index (BMI) is correlated with low bone mineral density, both of which are major risk factors for hip fractures. Possible determinants of weight loss in PD patients include hyposmia, impaired hand-mouth coordination, difficulty chewing, dysphagia, intestinal hypomotility, depression, decreased reward processing of dopaminergic mesolimbic regions, nausea, and anorexia as the side effects of medication, and increased energy requirements due to muscular rigidity and involuntary movements. It is unclear whether PD patients in general, or only a subgroup of those affected, definitely show lower BMI in the advanced stages of the disease. We therefore recommend that the body weight of PD patients be monitored monthly as the disease progresses, and that a patient's nutrition should be supplemented with sufficient amounts of vitamin D and calcium to reduce the risk of hip fractures and strengthen bone density. Because meal times may coincide with unpredictable off periods associated with akinesia and impaired hand-mouth coordination, PD patients also need flexible food schedules that accommodate the associated symptoms of this disease.

Levodopa availability improves with progression of Parkinson’s disease

BACKGROUND

Previous pharmacokinetic trials with standard levodopa formulations showed a different behaviour of levodopa degradation in plasma of patients with Parkinson's disease (PD) in various stages.

OBJECTIVES

To investigate associations between levodopa plasma levels in relation to the scored intensity of PD.

SUBJECTS AND METHODS

We administered water soluble 100 mg levodopa and 25 mg benserazide to 50 PD patients, taken off medication for at least 12 hours, and assessed the levodopa plasma concentrations during an 180 minutes period under standardised conditions.

RESULTS

The computed area under the curve (AUC) values of levodopa plasma levels were significant higher in advanced PD patients. PD rating scores significantly correlated to the AUC outcomes and the maximum levodopa plasma concentration.

CONCLUSIONS

Levodopa availability improves with progression of PD. This may result from deteriorated peripheral activity of levodopa metabolising enzymes or an increasing enteric dysfunction with subsequent better duodenal levodopa absorption or both.

Chronic levodopa intake increases levodopa plasma bioavailability in patients with Parkinson's disease

Previous pharmacokinetic trials with standard levodopa formulations showed a different behavior of levodopa degradation in plasma of patients with Parkinson's disease (PD) in various advanced stages. The objective of this trial was to compare levodopa plasma metabolism in PD patients with and without previous long-term levodopa intake after oral intake of a dispensable levodopa/benserazide formulation (DLB). The over a 150 min interval computed area under the curve values of levodopa plasma levels after DLB administration were significantly (ANCOVA: F(1,19) = 7.88, P = 0.01) higher in PD patients with chronic levodopa treatment compared to patients without prior levodopa treatment. The maximum plasma levodopa concentration did not differ (ANCOVA: F(1.19) = 1.17, P = 0.29). Long-term levodopa administration results in an increased levodopa plasma bioavailability in PD patients.