Evidence to support early levodopa therapy in Parkinson disease

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.

Research in Parkinson's disease in India: A review

Parkinson's disease (PD) is a common neurodegenerative disorder affecting patients in large numbers throughout the world. In this article, we review all the published data on PD based on studies in Indian population. We have tried to consolidate the contribution of Indian studies in PD research. We found 95 articles, of which 92 were original research papers. This is a relatively less number, but in the last decade, there has been an increase in research on PD from this country. But most of them seem to be restricted to only a few research institutes. The nonmotor symptoms and genetics are the most commonly studied aspects. The systematic review of the articles reveals that the epidemiology in India may be different with relatively lesser incidence here. Most of the genetic mutations found to cause PD in other population are not found in India, revealing that other genetic factors may be involved. Further research needs to be encouraged to understand the disease in Indian patients better, as all the results cannot be extrapolated from the Western literature to this heterogeneous Indian population. There need to be more studies on therapeutic aspects of the disease.

Future Treatment of Parkinson’s Disease

New methods of drug delivery and slowing down the progression of Parkinson’s disease (PD) are the major goals of research. More steady drug levels in the blood are possible by means of controlled-release preparations of levodopa and long-acting dopamine agonists, as well as transcutaneous duodenal tubes and pumps for controlled subcutaneous infusion. Patches containing dopamine agonists absorbed through the skin may be developed. The role of D1 agonists as compared with D2 agonists remains to be elucidated. Agonists on autoreceptors of dopaminergic neurons may potentially reduce excessive stimulation of the intact neurons and this may slow down the rate of neuronal death in PD. Monoamine oxidase-B inhibitors may have a potentially protective action on neurons. Investigations are being carried out to evaluate this claim. Catechol-o-methyl-transferase inhibitors may be helpful in theory. There is also recent interest in inhibitors of excitatory amino acids, which may contribute to neuronal loss in PD.

Normal substantia nigra patients treated with levodopa - Clinical, therapeutic and pathological observations

BACKGROUND

Definite diagnosis of idiopathic Parkinson's disease is based on histological findings of marked substantia nigra neuronal loss and Lewy body inclusions. Almost all cases with clinical diagnosis of idiopathic Parkinson's disease are treated with levodopa. Because there is no biological marker for the diagnosis, erroneous clinical diagnosis and treatment of such cases with levodopa are well known. There is very limited literature on levodopa treated cases that had normal substantia nigra at autopsy.

METHODS

Patients seen at Movement Disorders Clinic Saskatchewan are offered autopsy at no cost to the family/estate of the patient. Autopsy studies are performed by certified neuropathologists. Notation on the status of substantia nigra is made in every autopsied case.

RESULTS

Between 1968 and 2014, 21 cases treated with levodopa had normal substantia nigra at autopsy. Eleven patients continued levodopa until death and 9 received the drug for four years or longer. No objective motor symptom benefit, dyskinesia or motor response fluctuations on levodopa were observed in any case. The most common final diagnosis was essential tremor.

CONCLUSION

Individuals with normal substantia nigra do not benefit from levodopa and do not manifest motor response fluctuations or dyskinesia. Long-term use of levodopa is not toxic to normal human substantia nigra.

Early-onset vs. Late-onset Parkinson's disease: A Clinical-pathological Study

BACKGROUND

Several studies have compared early-onset Parkinson disease (EOPD) and late-onset Parkinson disease (LOPD) but most are not based on autopsy confirmed cases.

METHODS

We compared clinical and pharmacological profiles, time to reach irreversible Hoehn and Yahr (H&Y) Stage 3 and levodopa motor complications in autopsy confirmed EOPD and LOPD cases.

RESULTS

At first clinic visit EOPD cases were younger but had longer disease duration and they died at a younger age (all p<0.0001). Anti-Parkinsonian drug use, including levodopa, was significantly delayed in EOPD. Lifetime use of amantadine (p<0.05) and dopamine agonists (p<0.01) were higher in EOPD. While lifetime use of levodopa was similar in the two groups, levodopa was used for a significantly longer period by EOPD (p< 0.0001). EOPD had a higher cumulative incidence of dyskinesias (p<0.01), wearing-off (p<0.01), and on-off (p<0.01). However, the time to dyskinesia onset was similar in the two groups. The threshold to wearing-off was much longer in EOPD (p<0.01). H&Y stage profile at first visit was similar in the two groups. The duration from disease onset to reach irreversible H&Y stage 3 was significantly longer in EOPD.

CONCLUSIONS

Our observations indicate that progression of PD is slower in EOPD and suggest that the pre-clinical interval in this group is longer. These findings can be used for case selection for drug trials and studies of the pathogenesis of PD.

Saskatchewan movement disorders program

We review the Saskatchewan Movement Disorders Program, which started in 1968 and has had the dual goals of patient care and research. The clinics are structured to collect research-worthy data including videos, longitudinal follow-up, and autopsy studies of patients seen in the clinics. At every clinic visit, the patient is evaluated by one or both authors. A total of 25% to 30% of the deceased come to autopsy. Frozen half-brain and formalin-fixed remnants from autopsy are preserved in our laboratories. Patients not seen in our clinic are not included in research, which makes it different from brain banks. So far, 515 cases have come to autopsy. So far, there have been 17 collaborating scientific teams from Canada, the United States, Europe, and Japan. The collaborators are not charged for access to our resources. This program offers a unique opportunity to study multiple aspects of movement disorder patients seen in clinical practice.

Progress in Clinical Neurosciences: A Forum on the Early Management of Parkinson's Disease

There are numerous concerns related to treatment choices involving early dopaminergic therapy in Parkinson's disease. These include the effect on the underlying progression of the neurodegenerative process as well as the development of motor complications such as fluctuations and dyskinesias. A number of recent basic and clinical studies have provided new insights but have also added confusion and controversy. This report summarizes presentations and discussion dealing with these issues from a one-day symposium involving Canadian Movement Disorders neurologists.

Neurobehavioral assessment of hydroalcoholic extract of Trigonella foenum-graecum seeds in rodent models of Parkinson's disease

CONTEXT

Neuroprotective therapy to rescue dopaminergic neurons is an important trait in the management of Parkinson's disease (PD).

OBJECTIVE

The present study identified and evaluated SFSE-T, a standardized hydroalcoholic extract of Trigonella foenum-graecum L. seeds (Fabaceae), in animal models of PD.

MATERIALS AND METHODS

The identification of SFSE-T was carried out by high-performance liquid chromatography for the marker compound trigonelline (TGN). The effects of single dose oral treatment of SFSE-T (10, 30 or 100 mg/kg) were studied using animal models of PD, namely, 6-hydroxydopamine (6-OHDA)-induced unilateral lesions in rats, and 4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurodegeneration in C57BL/6 mice. The effects of SFSE-T on monoamino oxidase (MAO) enzyme in vitro as well as possible side effects of SFSE-T in vivo were also evaluated.

RESULTS

The concentration of TGN in a test sample of SFSE-T was found to be 82%. SFSE-T (30 mg/kg, oral) showed a significant increase in the number of ipsilateral rotations (45.67 rotations in 30-min period) as compared with vehicle control group (no rotations) when tested in 6-OHDA-induced unilateral lesioned rats. SFSE-T (30 mg/kg, oral) showed significant reversal of motor dysfunction (spontaneous motor activity scores, speed, distance traveled and number of square crossed) caused by MPTP induced lesions in C57BL/6 mice in pretreatment (1 h) schedule but not in post-treatment (1 h) schedule. SFSE-T neither showed anticholinergic effects nor showed selective MAO-B enzyme inhibition in vitro.

DISCUSSION AND CONCLUSION

SFSE-T showed reversal of motor symptoms in an animal model of PD probably through neuroprotective properties.

Efficacy and safety of standardized extract of Trigonella foenum-graecum L seeds as an adjuvant to L-Dopa in the management of patients with Parkinson's disease

The objective of this study is to evaluate disease modifying efficacy and safety of a standardized extract of Trigonella foenum-graecum L, Fenugreek (IBHB) (family Fabaceae) as a nutritional adjuvant to Levo-dopa (L-Dopa) in Parkinson's disease (PD) patients. We conducted double-blind placebo-controlled proof of concept clinical study of IBHB capsules (300 mg, twice daily) with matching placebo for 6 months of period in 50 patients of PD stabilized on L-Dopa therapy. The efficacy outcome measures were the scores of Unified Parkinson's Disease Rating Scale (UPDRS - total and its subsections), and Hoehn and Yahr (H&Y) staging at baseline and end of 6-months treatment duration. Safety evaluation included haematology, biochemistry, urinalysis parameters and adverse event monitoring. Total UPDRS scores in IBHB treatment (0.098%) showed slower rise as opposed to steep rise (13.36%) shown by placebo. Further, Clinically Important Difference for total UPDRS scores and scores of motor subsection of UPDRS was found to be 5.3 and 4.8, respectively, in favour of IBHB treatment. Similar improvement was shown by IBHB in terms of H&Y staging as compared with placebo. IBHB was found to have excellent safety and tolerability profile. In conclusion, IBHB can be useful adjuvant treatment with L-Dopa in management of PD patients.

Molecular and clinical prodrome of Parkinson disease: implications for treatment

The development of interventions to slow or prevent progression represents an important aim for current research into Parkinson disease (PD). General agreement prevails that success in this endeavor will depend on a clearer understanding of etiology and pathogenesis, and several important advances have recently been made, particularly in defining the genetic causes of PD. Studies of the biochemical consequences of the mutations that cause familial PD, and postmortem brain studies of idiopathic, sporadic PD, have highlighted mitochondrial dysfunction, oxidative stress, and protein metabolism by the ubiquitin-proteasomal and autophagy systems as being central to pathogenesis. In parallel with advances in etiopathogenesis, a clearer perception has developed of the clinical prodrome of PD, offering an opportunity to identify individuals who are at risk of PD, as well as those in the earliest clinical phase of the disease that might even precede the onset of motor symptoms. These populations are potentially the most suitable in which to test new protective therapies, and to study potential peripheral markers of disease progression. The awareness of the early symptomatic period of PD also raises the possibility of providing treatments that not only improve motor function but might also favorably modify outcome.

Nerve cell death in degenerative diseases of the central nervous system: clinical aspects

The origin of degenerative diseases of the central nervous system lies in genetic and acquired disorders. Analysis of the clinical characteristics of diseases affecting specific neuronal systems may help us to understand their pathogenesis. The stereotyped symptomatology characteristic of most degenerative diseases results from neuronal death in specific pathways: pyramidal tract and motor neurons in amyotrophic lateral sclerosis, nigrostriatal dopamine system in Parkinson's disease, posterior and lateral columns of the spinal cord in Friedreich's ataxia, etc. This suggests that these neurons are sensitive to pathological processes that are still unknown. Progression of the disease, whether linear or not, is slow, but it is more rapid than similar effects due to ageing. This indicates either that the environmental cause of degeneration (if it exists) is continuously present or that a vital process has been once and for all disrupted, perhaps at the level of the genome, causing insufficient production of essential proteins, or accumulation of eventually toxic metabolites. Symptoms generally appear during adulthood, i.e. after normal differentiation has taken place, and after a considerable number of neurons have already been damaged. The initiation of neuronal death precedes the appearance of the first symptoms.

Disease Progression and Pharmacodynamics in Parkinson Disease – Evidence for Functional Protection with Levodopa and Other Treatments

We have modelled the Unified Parkinson's Disease Rating Scale (UPDRS) scores collected in 800 subjects followed for 8 years. Newly diagnosed and previously untreated subjects were initially randomized to treatment with placebo, deprenyl, tocopherol or both and, when clinical disability required, received one or more dopaminergic agents (levodopa (carbidopa/levodopa), bromocriptine, or pergolide). Using models for disease progression and pharmacodynamic models for drug effects we have characterized the changes in UPDRS over time to determine the influence of the various drug treatments. We have confirmed and quantitated the relative symptomatic benefits of the dopaminergic agents and provide model-based evidence for slowing of disease progression.

Postmortem brain fatty acid profile of levodopa-treated Parkinson disease patients and parkinsonian monkeys

Fatty acids play a critical role in brain function but their specific role in the pathophysiology of Parkinson disease (PD) and levodopa-induced motor complications is still unknown. From a therapeutic standpoint, it is important to determine the relation between brain fatty acids and PD because the brain fatty acid content depends on nutritional intake, a readily manipulable environmental factor. Here, we report a postmortem analysis of fatty acid profile by gas chromatography in the brain cortex of human patients (12 PD patients and nine Controls) as well as in the brain cortex of monkeys (four controls, five drug-naive MPTP monkeys and seven levodopa-treated MPTP monkeys). Brain fatty acid profile of cerebral cortex tissue was similar between PD patients and Controls and was not correlated with age of death, delay to autopsy or brain pH. Levodopa administration in MPTP monkeys increased arachidonic acid content (+7%; P < 0 .05) but decreased docosahexaenoic acid concentration (-15%; P < 0.05) and total n-3:n-6 polyunsaturated fatty acids ratio (-27%; P < 0.01) compared to drug-naive MPTP animals. Interestingly, PD patients who experienced motor complications to levodopa had higher arachidonic acid concentrations in the cortex compared to Controls (+13.6%; P < 0.05) and to levodopa-treated PD patients devoid of motor complications (+14.4%; P < 0.05). Furthermore, PD patients who took an above-median cumulative dose of levodopa had a higher relative amount of saturated fatty acids but lower monounsaturated fatty acids in their brain cortex (P < 0.01). These results suggest that changes in brain fatty acid relative concentrations are associated with levodopa treatment in PD patients and in a non-human primate model of parkinsonism.

Prognosis of Parkinson's disease: Time to stage III, IV, V, and to motor fluctuations

We report a long-term outcome on a large cohort of Japanese patients with Parkinson's disease (PD). A total of 1,768 (793 men, 975 women) consecutive patients visited our clinic from 1 January 1989 to 31 December 2002. Among them, 1,183 patients (531 men, 652 women) came to our clinic within 5 years from the onset of disease and at the Hoehn & Yahr Stage III or less at the first visit. Long-term outcome was evaluated in this subcohort of the patients. We examined the duration to reach Stage III, IV, and V, and the duration to develop wearing off and dyskinesia. Time to reach Stage III was slightly but significantly shorter in women, in that 23.8% of men and 35.3% of women reached Stage III by the end of the 5th year; 49.7% of men and 63.3% of women reached Stage III by the end of the 10th year, and 88.9% of men and 79.9% of women by the end of the 15th year (P < 0.001). Also, durations to develop wearing off and dyskinesia were shorter in women compared to men. These data suggest that the disease progression may be slightly faster for women. Young-onset patients showed significantly longer duration to reach Stage III, IV, and V but shorter duration to develop wearing off and dyskinesia. Not many studies are available in the literature on the long-term outcome of PD, and our data would be useful as a reference.

A new look at levodopa based on the ELLDOPA study

Levodopa has been the gold standard for Parkinson's disease (PD) therapy since it was successfully introduced in 1967. But in the years since then, after recognizing that levodopa often leads to the motor complications of wearing-off and dyskinesias, there have been debates among clinicians as to when levodopa therapy should be started. Delaying therapy was advocated for the purpose of delaying the development of these motor complications. This became more popular as the dopamine agonists became available. Although less potent than levodopa in ameliorating the symptoms of PD, they were much less likely to produce the unwanted motor complications, even though they had their own adverse effects. When it was recognized that dopamine, itself, might be a factor leading to the death of dopaminergic neurons through its contributing to the formation of oxyradicals, a new concern arose, namely that levodopa, through its conversion to brain dopamine, might add to the existing oxidative stress and possibly enhance neurodegeneration of dopaminergic neurons. Though widely debated and without definite evidence, this possibility was sufficient to make some clinicians have further reason to delay the start of levodopa therapy. The ELLDOPA study was created to test this hypothesis. The clinical component of the study failed to find an enhancement of PD symptoms after levodopa was withdrawn following 40 weeks of levodopa therapy. Rather, the clinical results indicated that the symptoms had progressed much less than placebo, and in a dose-response manner. This suggests that levodopa may actually have neuroprotective properties. The uncertainty that a 2-week withdrawal of levodopa may not have entirely eliminated its symptomatic benefit and the discordant results of the neuroimaging component of the ELLDOPA study have created even more uncertainty that levodopa is neuroprotective. A survey of neurologists who treat PD patients showed that the vast majority of these clinicians do not believe levodopa is neuroprotective, and they remain concerned about the drug's likelihood of inducing motor complications. Thus, the ELLDOPA study failed to change the treating pattern of PD, and the clinicians require more convincing evidence of either neuroprotection or neurotoxicity of levodopa before they would alter their treatment approach.

Pharmacokinetic and Pharmacodynamic Changes During the First Four Years of Levodopa Treatment in Parkinson’s Disease

The purpose of this analysis is to describe how levodopa pharmacokinetic and pharmacodynamic parameters change over the first 4 years of long-term levodopa treatment in patients with Parkinson's disease. Twenty previously untreated Parkinsonian patients were admitted to the general clinical research center (GCRC) for 4 days at the beginning of long-term levodopa therapy and 6, 12, 24 and 48 months later. On each GCRC admission, patients received a 2 hr IV infusion of levodopa on day 1 and day 4 with no oral levodopa between the infusions. After the first GCRC admission patients were treated with oral levodopa dosed for optimal control of Parkinsonism. Motor function was measured by finger tapping rate. A pharmacokinetic-pharmacodynamic model incorporating 3 effect compartments was used to fit the individual plasma levodopa concentrations and tapping rates. Motor function before the first levodopa infusion (E0(1)) improved over the first 20 months and subsequently returned to the initial baseline at the start of the study. A similar pattern was seen in motor function before the second infusion (E0(2)) after the 3 days levodopa withdrawal, with a decline predicted to fall below the initial baseline at the start of the study by 6 years. Eight patients showed an increase in maximum tapping rate with levodopa (E(max)) approaching a steady state after 16 months. Ten patients showed an increase in E(max) with a peak at 31 months. One patient showed a linear decrease and another patient did not change over the 48 months. Longitudinal progress models were used to describe the time course of pharmacokinetic and pharmacodynamic parameters over 4 years. Peak treatment benefit, defined as the difference between E(max) and E0(1) or E0(2) (D(max)1 or D(max)2), increased with time particularly after the 3-day levodopa withdrawal. Deterioration of pre-dose motor function (E0) as disease progresses coupled with a greater amplitude of response due to levodopa (D(max)) could be a key factor contributing to motor fluctuations associated with long-term levodopa treatment.

Neuroprotective effects of Bak Foong Pill in 1-methyl-4-phenyl-1,2,3,6-tetrahyrdropyridine (MPTP)-induced Parkinson's disease model mice

Neuroprotective effects of estrogen and estrogen-like chemicals on neurodegenerative diseases, especially Parkinson's disease, have been well established. In the present study, we compared the effects of Bak Foong Pill (BFP), a well-known gynaecological tonic in China, and 17beta-estradiol, on dopamine transporter (DAT) and tyrosine hydroxylase (TH) gene expression patterns in ovariectomized, 1-methyl-4-phenyl-1,2,3,6-tetrahyrdropyridine (MPTP)-induced Parkinson's disease (PD) model mice, using multiplex reverse transcription-polymerase chain reaction (RT-PCR). MPTP, a specific dopaminergic neurotoxin, significantly decreased DAT and TH mRNA levels in the striatum, midbrain and cerebellum, but not the cortex, of C57BL/6 mice. However, MPTP-challenge with BFP pretreatment demonstrated reduced neurotoxicity, with DAT and TH mRNA levels either not affected by MPTP or affected to a significantly lesser extent in the midbrain and striatum as compared to the MPTP treated controls. 17beta-estradiol treatment prevented MPTP-induced reduction of DAT expression in striatum and midbrain, but failed to alter TH expression. These results suggest that BFP is able to protect dopaminergic neurons against MPTP-induced neuronal damage in a mechanism that is different from the protective effect of estrogen.

Levodopa-induced motor complications are associated with alterations of glutamate receptors in Parkinson's disease

Glutamate receptors were studied in the brains of controls and Parkinson's disease (PD) patients, of which 10 of 14 developed motor complications (dyskinesias and/or wearing-off) following levodopa therapy. (125)I-RTI binding to the dopamine transporter and dopamine concentrations show comparable nigrostriatal denervation between the subgroups of PD patients. (3)H-Ro 25-6981 binding to the NR1/NR2B NMDA receptor was increased in the putamen of PD patients experiencing motor complications compared to those who did not (+53%) and compared to controls (+18%) whereas binding remained unchanged in the caudate nucleus. (3)H-AMPA binding was increased in the lateral putamen (+23%) of PD patients with motor complications compared to those without whereas it was decreased in the caudate nucleus of the PD patients (-16%) compared to controls. Caudate and putamen (3)H-CGP39653 binding to NR1/NR2A NMDA receptor and NR1 subunit mRNA levels measured by in situ hybridization were unchanged in subgroups of PD patients compared to controls. These findings suggest that glutamate receptor supersensitivity in the putamen plays a role in the development of motor complications (both wearing-Off and dyskinesias) following long-term levodopa therapy in PD.

Changes of GABA receptors and dopamine turnover in the postmortem brains of parkinsonians with levodopa-induced motor complications

Brain samples from 14 Parkinson's disease patients, 10 of whom developed motor complications (dyskinesias and/or wearing-off) on dopaminomimetic therapy, and 11 controls were analyzed. Striatal 3beta-(4-(125)I-iodophenyl)tropane-2beta-carboxylic acid isopropyl ester ([(125)I]RTI-121) -specific binding to dopamine transporter and concentration of dopamine were markedly decreased, but no association between level of denervation and development of motor complications was observed. The homovanillic acid/dopamine ratio of concentrations was higher in putamen of patients with wearing-off compared to those without. Striatal (35)S-labeled t-butylbicyclophosphorothionate ([(35)S]TBPS) and [(3)H]flunitrazepam binding to GABA(A) receptors were unchanged in patients with Parkinson's disease, whereas [(125)I]CGP 64213 -specific binding to GABA(B) receptors was decreased in the putamen and external segment of the globus pallidus of parkinsonian patients compared with controls. [(3)H]Flunitrazepam binding was increased in the putamen of patients with wearing-off compared to those without. [(35)S]TBPS-specific binding was increased in the ventral internal globus pallidus of dyskinetic subjects. These data suggest altered dopamine metabolism and increased GABA(A) receptors in the putamen related to the pathophysiology of wearing-off. The present results also suggest that an up-regulation of GABA(A) receptors in the internal globus pallidus is linked to the pathogenesis of levodopa-induced dyskinesias.

Clinical-pathological study of levodopa complications

We sought to determine the continued benefit and the pattern of motor complications of long-term levodopa treatment in Parkinson's disease. Patients were evaluated between 1968 and 1996. Only those who had an adequate levodopa trial and in whom autopsy revealed Lewy body Parkinson's disease were included. Total levodopa and mean daily dose were calculated in each case. Dyskinesia, wearing-off and on-off were collectively classified as motor adverse effects and reported as cumulative incidence. Forty-two patients (male, 30; female, 12) with mean 15.9 years of illness and 9.1 years follow-up received on average 500-mg levodopa daily over 9.8 years. Seventeen of 21 patients assessed during the last 18 months of life reported some motor benefit. Adverse effects were seen in 71.4% of patients. The most common was dyskinesia, in 61.9%; wearing-off in 35.7%; and on-off in 16.7% of patients. The earliest adverse effect was dyskinesia and the last to emerge was on-off. Isolated dyskinesia was seen in 35.7% and wearing-off in 7.1% of patients; 15.5% of patients developed dyskinesia after 2.6 years and 31% after 6.4 years on levodopa. We concluded that levodopa benefit declined and adverse effects increased with time. Dyskinesia was the earliest and the most common isolated adverse effect.

Increase of preproenkephalin mRNA levels in the putamen of Parkinson disease patients with levodopa-induced dyskinesias

The expression of preproenkephalin messenger RNA was studied in the brain of Parkinson disease (PD) patients using in situ hybridization. All these patients were treated with levodopa (LD) and the development of motor complications was recorded. Eleven normal controls and 14 PD patients were used, of which 4 developed dyskinesias, 3 developed wearing-off, 3 developed both dyskinesias and wearing-off, and 4 developed no adverse effect following dopaminomimetic therapy. Nigrostriatal denervation was similar between the subgroups of PD patients as assessed using 125I-RTI-specific binding to the dopamine transporter and measures of catecholamine concentrations by HPLC. A significant increase of preproenkephalin messenger RNA levels was observed in the lateral putamen of dyskinetic patients in comparison to controls (+210%; p < 0.01) and in comparison to nondyskinetic patients (+112%; p < 0.05). No change was observed in medial parts of the putamen or in the caudate nucleus. No relationship between preproenkephalin messenger RNA levels and other clinical variables such as development of wearing-off, age of death, duration of disease, or duration of LD therapy was found. These findings suggest that increase synthesis of preproenkephalin in the medium spiny output neurons of the striatopallidal pathway play a role in the development of dyskinesias following long-term LD therapy in Parkinson disease.

The effect of stage of Parkinson's disease at the onset of levodopa therapy on development of motor complications

The aim of this study was to ascertain whether the stage of Parkinson's disease (PD) (according to the Hoehn and Yahr staging system) would affect the length of time between the introduction of levodopa therapy and appearance of levodopa-associated motor complications. Forty patients with clinically definite PD were studied. In all, clinical and therapeutic data were collected from the time of diagnosis to the time of levodopa-associated motor complications (i.e. dyskinesia, motor fluctuations). In 17 patients, levodopa could be started in Hoehn and Yahr stage I (H & Y-I; 16.2 months after the onset of PD), whilst in 13 patients levodopa could be started in H & Y-II (19.6 months after the onset of the disease) and in 10 in H & Y-III (45.1 months after the onset of PD). Cox proportional hazard regression model shows that the PD patients in whom the initial levodopa treatment was introduced at stage III develop both dyskinesias and motor fluctuations significantly earlier than the patients whose levodopa started in stage I and II of PD. The median interval to develop dyskinesias was 66, 72 and 24 months for patients in whom levodopa was introduced in stage I, II and III, respectively. These values were 64, 55 and 14 months for motor fluctuations. These findings add to the clinical arguments that favour an essential role of severity of PD at levodopa initiation as a risk factor for the development of levodopa-associated motor complications.

Reliability of measurements of patient health status: a comparison of physician, patient, and caregiver ratings

The purpose of this preliminary study was to investigate the inter-rater reliability among physician, patient, and caregiver ratings on the Hoehn & Yahr (H & Y) and Schwab & England (S & E) rating instruments. We also examined differences in ratings between patients who attended clinic with and without caregivers (spouses and adult children). Patients and caregivers coming for an appointment at Colorado Neurological Institute were asked to independently complete the H & Y and S & E scales. Physicians rated the patients during the exam. In the group of patients who came to clinic with caregivers, there was significant agreement on both the H & Y and S & E (P<0.001). For patients not accompanied by caregivers, patients rated themselves as more debilitated on the S & E than physicians (P<0.001). Patients without caregivers rated themselves as more functional than patients with caregivers on both scales (P<0.001). Physicians also rated patients without caregivers as more functional on both scales (P<0.001). Results indicated there was consistency among ratings of physicians and patients accompanied by caregivers on both scales. Patients attending clinic alone rated themselves as worse on the S & E than physicians. Patients alone were rated as more functional than patients accompanied by caregivers on both scales regardless of rater.

Parkinson's Disease: Initial Treatment with Levodopa or Dopamine Agonists

The question of whether to use levodopa (LD) or dopamine agonists as initial therapy in Parkinson's disease has been a controversy for nearly 20 years. There are several issues relating to this treatment regimen that may effect ones decision. Review of them results in the following conclusions: LD does not cause the onset of motor fluctuations and dyskinesia; it probably relates to disease progression. Tolerance does not develop with long-term LD therapy. LD is not toxic. LD decreases mortality in Parkinson's disease. Motor fluctuations can occur with dopamine-agonist monotherapy, but the actual frequency is as yet unknown. Dopamine agonists are not neuroprotective. Clinical trials have indicated that LD remains the most potent symptomatic therapeutic agent available. Dopamine agonists do provide some symptomatic relief when used alone in early Parkinson's disease. Standard preparations of LD have the same effect on early disease as controlled release preparations. Dopamine agonists cause less dyskinesia and fluctuations. These conclusions indicate that both drugs are effective symptomatic agents with their own positive and negative aspects. There is no incorrect choice. It is reasonable to start young onset patients (younger than 50 years of age) with an agonist, because they seem to be more prone to develop motor fluctuations and dyskinesia. However, if employment is in jeopardy then LD may be needed. Because agonists cause more hallucinations, freezing, and somnolence, problems of particular relevance to the elderly (older than 70 years), then LD would be the best agent for older onset patients. In general, but particularly for those falling in between these age groups, treatment should be individualized. In this time of cost effectiveness, LD remains the least expensive of these agents.

Frequency of levodopa-related dyskinesias and motor fluctuations as estimated from the cumulative literature

There is no clear consensus regarding the frequency (and hence, the risk), of dyskinesias or motor fluctuations during chronic levodopa therapy for Parkinson's disease (PD). Multiple clinical series have tabulated these frequencies since the advent of levodopa over 30 years ago. We were interested in determining: (1) the aggregate frequency figures in the existing literature; and (2) how clinical series from the early levodopa era, which included patients with longer durations of parkinsonism, compare to more recent (modern era) series. We searched MEDLINE for all English language publications reporting the cumulative frequency of levodopa-induced dyskinesias or motor fluctuations during discrete intervals of treatment. This generated 2,478 publications spanning 1966 through September 2000. Papers with appropriate titles or abstracts were reviewed; reference lists from published clinical series were a source of additional papers for review. This ultimately yielded 74 publications with adequate data, relating to 112 intervals of levodopa treatment. Series that included patients with PD-onset well before levodopa availability (pre-levodopa era) were separately analyzed from all subsequent series. Series were grouped by duration of levodopa therapy and the median frequencies of dyskinesias and motor fluctuations were tabulated for each group. The data were analyzed both with and without adjustment for the number (N) in each series. Among series containing pre-levodopa era patients, the median dyskinesia frequency was already 50% by 5-6 months of treatment. This contrasts with the modern era series where dyskinesias were reported later in treatment. The median dyskinesia frequency was slightly less than 40% by 4-6 years of levodopa therapy among modern era patients. Motor fluctuations (wearing-off) were not tabulated in most of the early levodopa series. Among modern era reports, motor fluctuations were nil during the first year of levodopa therapy but were experienced by approximately 40% of patients by 4-6 years of treatment. Similar results were found when the analyses were restricted to only prospective studies where levodopa motor complications were targeted outcome measures. The conclusions reached were: (1) patients from the pre-levodopa era experienced dyskinesias much earlier during levodopa treatment than modern era patients, perhaps because of longer durations of pre-existing PD; (2) in the present era, patients treated with levodopa therapy for 4-6 years have approximately a 40% likelihood of experiencing motor fluctuations and a risk of dyskinesias just short of 40%; and (3) these findings represent incident data and the prevalence of clinically important morbidity may be substantially less.

Levodopa in Parkinson's disease: neurotoxicity issue laid to rest?

Orally administered levodopa remains the most effective symptomatic treatment for Parkinson's disease. The introduction of levodopa therapy is often delayed, however, because of the fear that it might be toxic for the remaining dopaminergic neurons, and thus accelerate the deterioration of the patient's condition. Evidence for levodopa toxicity comes mainly from in vitro studies which have demonstrated that levodopa can damage dopaminergic neurons by a mechanism that probably involves oxidative stress. It is widely accepted, however, that levodopa is not toxic for healthy animals and humans who do not have Parkinson's disease. It has been argued that the lesioned mesostriatal dopaminergic system could be more vulnerable to levodopa-induced toxicity, because the brain extracellular concentrations attained by levodopa are higher when the dopaminergic system is damaged, and remaining dopaminergic neurons experience a process of compensatory hyperactivity. Evidence for in vivo levodopa toxicity in animal models of Parkinson's disease is scarce and contradictory. A comprehensive recent study failed to find any evidence of levodopa toxicity in rats with either moderate or severe lesions of the mesostriatal dopaminergic system. Concerning the hypothesis of toxicity, some recent reports have shown that levodopa can have trophic effects on dopaminergic neurons in vitro, and our own work has shown that long term levodopa therapy promotes recovery of striatal dopaminergic markers in rats with moderate nigrostriatal lesions. Given that neither epidemiological nor clinical studies have ever provided evidence to support that long term levodopa administration can accelerate the progression of Parkinson's disease, we believe that levodopa therapy should not be delayed on the basis of an unconfirmed hypothesis.

Motor fluctuations in Parkinson's disease

OBJECTIVES

To assess patterns, prevalence, and risk factors of motor fluctuations in an unselected population of Parkinson's disease patients attending Movement Disorders Clinic of a tertiary hospital.

MATERIAL AND METHODS

Eighty patients with Parkinson's disease were interviewed and data about their clinical characteristics, motor fluctuations, i.e. dyskinesia, dystonia, motor blocks and details of drug therapy, were collected.

RESULTS

Forty patients had at least one type of motor fluctuation. Twenty three patients had motor blocks, 20 had dyskinesia and 11 had dystonia. Interval between onset of symptom and start of levodopa therapy and duration of levodopa therapy correlated with presence of motor fluctuations in general and to dyskinesia in particular. Patients with dyskinesia had younger age of onset of disease. Motor blocks showed a positive relationship to duration of disease.

CONCLUSIONS

Fifty percent of unselected patients of Parkinson's disease had motor fluctuations after a mean duration of 5 years of illness. Early initiation and longer duration of levodopa therapy were identified as risk factors for motor fluctuations. Younger patients had more risk of developing dyskinesias. Motor blocks were more common in patients with a longer duration of illness.

L-DOPA exacerbates amphetamine-induced dopamine depletion

Administration of L-DOPA to Parkinson patients has been suggested to exacerbate "functional denervation" of the nigrostriatal system. Therefore, experiments were conducted to determine if L-DOPA combined with the DOPA decarboxylase inhibitor, Ro4-4602 (benserazide hydrochloride) would potentiate amphetamine-induced neurotoxicity. Mice received two injections of saline or benserazide + L-DOPA (25.0 or 100.0 mg/kg) interspersed with four injections of amphetamine (15.0 mg/kg) at 2-h intervals. Significant depletion of striatal dopamine, DOPAC, and HVA was evident 1 wk following amphetamine administered with or without 25.0 mg/kg L-DOPA + benserazide, whereas 100.0 mg/kg L-DOPA + benserazide potentiated amphetamine-induced depletion of striatal dopamine (17 vs 28% of control values). This enhanced toxicity may be consequent to increased dopamine turnover following L-DOPA (360 vs 231%), a situation akin to that observed in compromised dopaminergic nigrostriatal systems of parkinsonian patients. Furthermore, striatal 5-HT was not altered by amphetamine alone, whereas concurrent administration of L-DOPA/ benserazide depleted 5-HT to 82% of control values. No changes were evident in the frontal cortex following amphetamine with or without concurrent L-DOPA/benserazide; however, L-DOPA/benserazide administered alone reduced 5-HT and 5-HT turnover to 58% of control values.

Parkinson's disease

Parkinson's disease is a common disabling disease of old age. The diagnosis of idiopathic Parkinson's disease is based on clinical signs and has poor sensitivity, with about 25% of patients confidently diagnosed as having the disease actually having other conditions such as multi-system atrophy and other parkinsonism-plus syndromes. Benign essential tremor and arteriosclerotic pseudo-parkinsonism can easily be confused with Parkinson's disease. The cause of Parkinson's disease remains unknown. Speculative research highlights the role of oxidative stress and free radical mediated damage to dopaminergic cells. Parkinson's disease is the one neurodegenerative disorder in which drugs have been demonstrated to be of value. There is now a wide variety of drugs and formulations available, including anticholinergics, amantidine, L-dopa, dopamine agonists including apomorphine, selegiline and soon to be available catechol-O-methyltransferase inhibitors. Disabling side-effects of treatment, fluctuations, dyskinesias and psychiatric problems require strategic use of the drugs available. There is an increasing potential for neurosurgical intervention.

Treatment of early Parkinson's disease: are complicated strategies justified?

A variety of medical treatment strategies have been proposed as a means of slowing the progression of Parkinson's disease. This includes administration of selegiline (deprenyl) therapy, early use of bromocriptine or pergolide, and delay of levodopa therapy or restriction of the dose. There is no compelling evidence supporting the use of any of these treatment strategies for this purpose. Carbidopa-levodopa remains the most potent medication for symptomatic treatment of Parkinson's disease. Although starting levodopa therapy with the controlled-release formulation is advocated, this does not appear to have any major advantages over standard carbidopa-levodopa. Further studies are needed to identify other means of halting the progression of Parkinson's disease.

Early diagnosis of Parkinson's disease

Early diagnosis of Parkinson's disease is often difficult. The insidious onset of the disease, its slow progression and the lack of laboratory tests to confirm the diagnosis contribute to this difficulty. Nevertheless, early diagnosis can be greatly facilitated by the systematic application of diagnostic clinical criteria and the selective use of radiological and laboratory tests.

Oxidative stress in Parkinson's disease

Oxidative damage and mitochondrial dysfunction are now considered to be important events in the cause of dopaminergic cell death in Parkinson's disease (PD). It is not known whether these biochemical abnormalities represent primary causes of PD or whether they are the end result of a series or reactions precipitated by environmental and genetic factors. Both oxidative damage and complex I deficiency are linked in a reciprocal manner and can potentially produce a toxic cellular environment capable of attacking a variety of biomolecules as well as inhibiting energy production. Defining the roles that these two biochemical defects play in nigral neuronal loss will provide important insights into the aetiology of PD.

Risk factors on the occurrence of response fluctuations and dyskinesias in Parkinson's disease

We studied the risk factors that influence the occurrence of response fluctuations and dyskinesias in 194 patients with Parkinson's disease (PD). These factors included age at onset, disease severity at levodopa initiation, duration of illness prior to levodopa therapy and the daily dose of levodopa at the end of study. The first three were fixed covariates and the last one was time-dependent. Patients with age onset before 50 years showed a higher risk of developing response fluctuations (RF) and dyskinesias in univariate analysis. We estimated the combined effects of these covariates through multivariate analysis and found that the age at onset was the sole factor related to the incidence of both complications. Additionally, it was the only variable that could enter the predictive model of stepwise regression. Our observation suggested that age at onset determined the occurrence of RF and dyskinesias. Patients with younger age at onset had higher risk of developing these adverse effects.

Value and appropriate use of rating scales and apparative measurements in quantification of disability in Parkinson's disease

Despite widespread use in pharmacotherapeutical trials, in the majority of rating scales used in Parkinson's disease (PD) validity, reliability and appropriate use have never been confirmed by statistical data. For this reason 350 unselected PD-pats. were investigated by an extensive standardized test-battery including registration of basis data, Columbia University Rating Scale (CURS), scale for assessment of functional disability (ADL), SCAG-scale, Hoehn & Jahr-scale (HY), mod. Webster step second-test (WSST), Purdue-pegboard, questionnaire for subjective complaints (SC), WDG, LPS1/2, 3/4, 6, 7, 10, clinical assessment of dementia, v. Zerssen-scale and orthostatic hypotension (60 degrees tilt up). For CURS, SCAG and ADL instrumental reliability was calculated by Cronbach's alpha. For CURS, SCAG, ADL and the total data of complete test battery (CTB) principal component analysis (PCA) was performed for data reduction. CURS, SCAG and ADL showed high internal consistency (alpha approximately > or = 0.9). For CURS 5 factors accounting for 66% total variance could be extracted by PCA. They represent gait, rigidity, tremor, right/left dexterity (eigenvalues > 1). For SCAG 3 factors (61% of total variance) representing dementia, depression and change of personality were extracted. For ADL 3 factors (67% of total variance) could be extracted, representing overall functional disability, handwriting and disability by pain. PCA of the CTB identified 8 interpretable factors (66% of total variance) characterizing at least partially the clinical profile of PD: 1. motor disability (assessment by rating-scales) 2. dementia, 3. motor-disability (assessment by apparative measurements), 4. depression, 5. orthostatic hypotension, 6. WDG, 7. tremor and 8. pain. Our data confirm the suitability of the investigated scales and give a rational base for their appropriate use in a sense of data reduction and economical evaluation.

The free radical hypothesis in idiopathic parkinsonism: evidence against it

The free radical hypothesis for the pathogenesis of idiopathic parkinsonism (Parkinson's disease) has many similarities to the argument invoking an autoimmune mechanism. In both cases, cellular and molecular machinery that might be involved in neuronal destruction have been demonstrated. In recent years, the free radical hypothesis has become particularly fashionable; several workers have reported observations which, they infer, support the notion that damage by free radicals is a major factor in the underlying disease process. There is, however, no conclusive evidence that free radicals play a prominent role in the causal chain of events that leads to idiopathic parkinsonism; several findings may be construed as evidence against such a contention.

Dopa and dopamine cause cultured neuronal death in the presence of iron

We examined the cytotoxicity of dopa and dopamine for cultured neurons by using a newly developed enzyme immunoassay for neurofilament protein to determine surviving neuronal numbers. Each of the two catechols caused neuronal death in the presence of iron with or without superoxide dismutase and catalase, while deferoxamine mesylate prevented neuronal loss. Lipid peroxidation of phospholipid liposomes was confirmed to be produced by the combination of the catechols and iron (Fe3(+)-ADP complex). Thus, it was strongly suggested that cultured neurons were killed via the peroxidative cleavage of cell membrane components provoked by the catechols and iron. This mechanism of neuronal loss may play an important role in the degeneration in the substantia nigra of Parkinson's disease, because the catechols and iron are abundant in this region.

Variation of therapeutic response in Parkinson's disease: a retrospective study

A retrospective study of variations of therapeutic response (dyskinesia and on-off phenomenon) in Parkinson's disease was conducted on 278 patients treated with levodopa for at least 6 months and hospitalized at National Neurological Institute "C. Besta" of Milan between 1974 and 1984. Variations of therapeutic response (TRV) were present in 105 of 278 patients; in this group, age at illness onset was significantly lower, while duration of levodopa treatment and also duration of illness were longer than in the group of patients without TRV. Multiple logistic regression analysis showed that the most important variables were age at illness onset and duration of treatment, but they were only modestly predictive. Other factors connected with progression of disease must also contribute to the TRV.

Dexamethasone suppression test in patients with Parkinson's disease

The Dexamethasone Suppression Test (DST), supposed to effectively distinguish between endogenous and nonendogenous depression, was performed in a group of 34 patients with Parkinson's disease. Abnormal DST results were observed in 50% of the patients. The patients were clinically divided into subgroups of depressed and nondepressed parkinsonians. Abnormal DST results were significantly more frequent in depressed (75%) than in nondepressed parkinsonians (27.7%).

Effect of deprenyl on the progression of disability in early Parkinson's disease

In a clinical trial that is still in progress, we studied the ability of deprenyl and tocopherol, antioxidative agents that act through complementary mechanisms, to delay the onset of disability necessitating levodopa therapy (the primary end point) in patients with early, untreated Parkinson's disease. Eight hundred subjects were randomly assigned in a two-by-two factorial design to receive deprenyl, tocopherol, a combination of both drugs, or placebo, and were followed up to determine the frequency of development of the end point. The interim results of independent monitoring prompted a preliminary comparison of the 401 subjects assigned to tocopherol or placebo with the 399 subjects assigned to deprenyl, alone or with tocopherol. Only 97 subjects who received deprenyl reached the end point during an average 12 months of follow-up, as compared with 176 subjects who did not receive deprenyl (P less than 10(-8). The risk of reaching the end point was reduced by 57 percent for the subjects who received deprenyl (Cox hazard ratio, 0.43; 95 percent confidence limits, 0.33 and 0.55; P less than 10(-10]. The subjects who received deprenyl also had a significant reduction in their risk of having to give up full-time employment (P = 0.01). We conclude from these preliminary results that the use of deprenyl (10 mg per day) delays the onset of disability associated with early, otherwise untreated cases of Parkinson's disease.