Selegiline diminishes cardiovascular autonomic responses in Parkinson's disease

Neurodegenerative diseases and blood pressure variability: A comprehensive review from HOPE Asia

Asia has an enormous number of older people and is the primary contributor to the rise in neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The therapy of many neurodegenerative diseases has not yet progressed to the point where it is possible to alter the course of the disease. Mid-life hypertension is an important predictor of later-life cognitive impairment and brain neurodegenerative conditions. These findings highlight the pivotal role of preventing and managing hypertension as a risk factor for neurodegenerative disease. Autonomic dysfunction, neuropsychiatric and sleep disturbances can arise in neurodegenerative diseases, resulting in blood pressure variability (BPV). The BPV itself can worsen the progression of the disease. In older people with neurodegenerative disease and hypertension, it is critical to consider 24-h blood pressure monitoring and personalized blood pressure therapy.

Effects of MAO-B inhibitors on non-motor symptoms and quality of life in Parkinson's disease: A systematic review

Non-motor symptoms (NMS) are common among patients with Parkinson's disease and reduce patients' quality of life (QOL). However, there remain considerable unmet needs for NMS management. Three monoamine oxidase B inhibitors (MAO-BIs), selegiline, rasagiline, and safinamide, have become commercially available in many countries. Although an increasing number of studies have reported potential beneficial effects of MAO-BIs on QOL and NMS, there has been no consensus. Thus, the primary objective of this study was to provide an up-to-date systematic review of the QOL and NMS outcomes from the available clinical studies of MAO-BIs. We conducted a literature search using the PubMed, Scopus, and Cochrane Library databases in November 2021. We identified 60 publications relevant to this topic. Overall, rasagiline and safinamide had more published evidence on QOL and NMS changes compared with selegiline. This was likely impacted by selegiline being introduced many years prior to the field embarking on the study of NMS. The impact of MAO-BIs on QOL was inconsistent across studies, and this was unlikely to be clinically meaningful. MAO-BIs may potentially improve depression, sleep disturbances, and pain. In contrast, cognitive and olfactory dysfunctions are likely unresponsive to MAO-BIs. Given the paucity of evidence and controlled, long-term studies, the effects of MAO-BIs on fatigue, autonomic dysfunctions, apathy, and ICD remain unclear. The effects of MAO-BIs on static and fluctuating NMS have never been investigated systematically. More high-quality studies will be needed and should enable clinicians to provide personalized medicine based on a non-motor symptom profile.

Rasagiline does not exacerbate autonomic blood pressure dysregulation in early or mild Parkinson’s disease

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Blood pressure dysregulation is important in Parkinson’s disease.

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Anti-Parkinsonian drugs that have less effect on blood pressure should be used.

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Some monoamine oxidase B inhibitor may cause orthostatic hypotension.

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Rasagiline does not exacerbate orthostatic hypotension and nocturnal blood pressure.

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Rasagiline is a suitable medication for early or mild Parkinson's disease.

Introduction

Orthostatic hypotension (OH) and abnormal blood pressure (BP) fluctuations occur mainly due to noradrenergic dysfunction and are clinically important in patients with Parkinson’s disease (PD). They lead to impairments of cognition function, daily activities, and quality of life. Some monoamine oxidase (MAO)-B inhibitors have a sympathomimetic amine, which can be attributed to OH. Therefore, we determined whether rasagiline, a common MAO-B inhibitor used in PD treatment, can contribute to cardiovascular autonomic BP dysregulation in patients with early or mild PD.

Methods

Nineteen patients with early or mild PD were recruited, and tilt test and 24-h ambulatory BP monitoring (ABPM) were performed before and after rasagiline administration. Early or mild PD was defined as patients with de novo (n = 4), levodopa (n = 10), dopamine agonist (n = 1), levodopa and one dopamine agonist (n = 2), levodopa and droxidopa (n = 1), and levodopa and istradefylline (n = 1). Furthermore, patients with motor fluctuation and multiple dopamine agonists were excluded from our study.

Results

OH and BP frequency were not significantly exacerbated before or after rasagiline administration. No significant differences of type in BP fluctuation on ABPM and the degree of nocturnal BP falls were found before and after rasagiline administration. The Unified Parkinson’s Disease Rating Scale motor score in patients (post-rasagiline administration) was significantly improved compared with before.

Conclusion

Rasagiline seems to be a suitable medication for Parkinsonian symptoms in patients with early and mild PD. It does not exacerbate cardiovascular autonomic responses, circadian rhythm of BP, or both.

Altered cardiorespiratory regulation during exercise in patients with Parkinson's disease: A challenging non-motor feature

The incidence of Parkinson’s disease is increasing worldwide. The motor dysfunctions are the hallmark of the disease, but patients also experience non-motor impairments, and over 40% of the patients experience coexistent abnormalities, such as orthostatic hypotension. Exercise training has been suggested as a coping resource to alleviate Parkinson’s disease symptoms and delay disease progression. However, the body of knowledge is showing that the cardiovascular response to exercise in patients with Parkinson’s disease is altered. Adequate cardiovascular and hemodynamic adjustments to exercise are necessary to meet the metabolic demands of working skeletal muscle properly. Therefore, since Parkinson’s disease affects parasympathetic and sympathetic branches of the autonomic nervous system and the latter are crucial in ensuring these adjustments are adequately made, the understanding of these responses during exercise in this population is necessary. Several neural control mechanisms are responsible for the autonomic changes in the cardiovascular and hemodynamic systems seen during exercise. In this sense, the purpose of the present work is to review the current knowledge regarding the cardiovascular responses to dynamic and isometric/resistance exercise as well as the mechanisms by which the body maintains appropriate perfusion pressure to all organs during exercise in patients with Parkinson’s disease. Results from patients with Parkinson’s disease and animal models of Parkinson’s disease provide the reader with a well-rounded knowledge base. Through this, we will highlight what is known and not known about how the neural control of circulation is responding during exercise and the adaptations that occur when individuals exercise regularly.

Evaluation of Cardiac Autonomic Functions in Older Parkinson's Disease Patients: a Cross-Sectional Study

In Parkinson's disease (PD), non-motor symptoms may occur such as autonomic dysfunction. We aimed to evaluate both parasympathetic and sympathetic cardiovascular autonomic dysfunction in older PD cases. 84 PD cases and 58 controls, for a total of 142, participated in the study. Parasympathetic tests were performed using electrocardiography. Sympathetic tests were assessed by blood pressure measurement and 24-hour ambulatory blood pressure measurement. The prevalence of orthostatic hypotension in PD patients was 40.5% in PD patients and 24.1% in the control group (p> 0.05). The prevalence of postprandial hypotension was 47.9% in the PD group and 27.5% in the controls (p <0.05). The prevalence of impairment in heart rate response to deep breathing was 26.2% in the PD group and 6.9% in the control group (p <0.05). The prevalence of postprandial hypotension in PD with orthostatic hypotension was 94% and 16% in PD patients without orthostatic hypotension (p <0.05). The prevalence of impairment in heart rate response to deep breathing was 52.9% in PD patients with orthostatic hypotension and 8% in PD cases without orthostatic hypotension (p<0.05). The prevalence of impairment in heart rate response to postural change was 41% in PD cases with orthostatic hypotension and 12% in PD cases without orthostatic hypotension (p <0.05).Although there are tests for assessing cardiovascular autonomic function that are more reliable, they are more complicated, and evaluation of orthostatic hypotension by blood pressure measurement and cardiac autonomic tests by electrocardiography are recommended since these tests are cheap and easy.

Recent advances in Parkinson’s disease therapy: use of monoamine oxidase inhibitors

Monoamine oxidase inhibitors inhibit dopamine metabolism and are therefore effective in treating Parkinson's disease, a condition associated with progressive striatal dopamine deficiency secondary to degeneration of dopaminergic neurons in the substantia nigra. Selegiline is currently the most widely used monoamine oxidase-B inhibitor for Parkinson's disease, but has a low and variable bioavailability, and is metabolized to L-methamphetamine and L-amphetamine that carry a risk for potential neurotoxicity. There are two new approaches that circumvent these potential disadvantages. First, selegiline orally disintegrating tablets provide a novel delivery form of selegiline, avoiding first pass metabolism by rapid absorption through the oral mucosa, thus leading to significantly lower plasma concentrations of L-metamphetamine and L-amphetamine. Selegiline orally disintegrating tablets prove to be clinically effective and safe in patients with moderately advanced Parkinson's disease. Second, rasagiline is a new monoamine oxidase inhibitor, without known neurotoxic metabolites. In large clinical trials, rasagiline proves effective as monotherapy in early Parkinson's disease, as well as adjunctive therapy to levodopa in advanced disease. Clinical data suggest, in addition, a disease-modifying effect of rasagiline that may correlate with neuroprotective activity of monoamine oxidase-B inhibitors in animal models of Parkinson's disease.

The management of orthostatic hypotension in Parkinson's disease

Orthostatic hypotension (OH) is a common and disabling symptom affecting Parkinson's disease (PD) patients. We present the effect of the different therapies commonly used to manage PD on this clinical manifestation. For this purpose, we describe the relationship between OH and the current treatments employed in PD, such as L-DOPA, dopaminergic agonists, and continuous dopaminergic stimulation therapies. Additionally, we review the therapeutic measures that could be used to ameliorate OH. There are different approaches to deal with this manifestation, including pharmacological and non-pharmacological treatments, although none of them is specifically aimed for treating OH in PD.

MAO-B inhibitors: multiple roles in the therapy of neurodegenerative disorders?

Monoamine oxidases play a central role in catecholamine catabolism in the central nervous system. The biochemical and pharmacological properties of inhibitors of the monoamine oxidase type B are reviewed. The evidence for biochemical activities distinct from their ability to inhibit MAO-B is discussed, including possible antioxidative and antiapoptotic activities of these agents. The significance of these properties for the pharmacological management of Parkinson's disease and the evidence for a neuroprotective effect of one such agent (selegiline) is also discussed.

Disease progress and response to treatment as predictors of survival, disability, cognitive impairment and depression in Parkinson's disease

AIM

To describe the time to clinical events (death, disability, cognitive impairment and depression) in Parkinson's disease using the time course of disease status and treatment as explanatory variables.

METHODS

Disease status based on the Unified Parkinson's Disease Rating Scale (UPDRS) and the time to clinical outcome events were obtained from 800 patients who initially had early Parkinson's disease. Parametric hazard models were used to describe the time to the events of interest.

RESULTS

Time course of disease status (severity) was an important predictor of clinical outcome events. There was an increased hazard ratio for death 1.4 (95% CI 1.31, 149), disability 2.75 (95% CI 2.30, 3.28), cognitive impairment 4.35 (95% CI 1.94, 9.74), and depressive state 1.43 (95% CI 1.26, 1.63) with each 10 unit increase of UPDRS. Age at study entry increased the hazard with hazard ratios of 49.1 (95% CI 8.7, 278) for death, 4.76 (95% CI 1.10, 20.6) for disability and 90.0 (95% CI 63.3-128) for cognitive impairment at age 60 years. Selegiline treatment had independent effects as a predictor of death at 8 year follow-up with a hazard ratio of 2.54 (95% CI 1.51, 4.25) but had beneficial effects on disability with a hazard ratio of 0.363 (95% CI 0.132, 0.533) and depression with a hazard ratio of 0.372 (95% CI 0.12, 0.552).

CONCLUSIONS

Our findings show that the time course of disease status based on UPDRS is a much better predictor of future clinical events than any baseline disease characteristic. Continued selegiline treatment appears to increase the hazard of death.

Cardiovascular baroreceptor activity and selective inhibition of monoamine oxidase

Cardiovascular baroreceptor responsiveness of conscious rats treated with selective inhibitors of monoamine oxidase (MAO) types A and B was determined by measurement of blood pressure (BP) and heart rate (HR) responses to intravenous injection of phenylephrine and sodium nitroprusside. Treatment with selegiline (1 or 5 mg/kg p.o. daily for 7 days) did not significantly modify resting levels of BP and HR, lower or upper HR plateau levels, or HR/BP gain. Treatment with clorgyline (2 mg/kg p.o. daily for 7 days) increased HR/BP gain but also did not modify resting BP or HR, or lower and upper plateau levels of HR. The results are compatible with an effect of MAO-A inhibition to modify monoamine levels in medullary areas participating in CNS control of blood pressure.

Serotonin and blood pressure regulation

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension.

Association of heart rate variability with clinical outcome in parkinsonian patients after subthalamic deep brain stimulation: a retrospective cohort study

BACKGROUND/PURPOSE

Lower sympathetic and parasympathetic function increases the morbidity in Parkinsonian patients. We conducted this retrospective study to elucidate the effect of subthalamic deep brain stimulation (STN-DBS) on autonomic cardiovascular regulation of patients with Parkinson's disease.

METHODS

Twelve men and four women with advanced Parkinson's disease (mean age: 63 years) who underwent bilateral STN-DBS were followed up for 9-32 months. Daytime electrocardiography for 5 minutes and rating scores were recorded before and after surgery. Good response was defined as improvement >50% in the Unified Parkinson's Disease Rating Scale (UPDRS), and a fair response as improvement between 10% and 50% after surgery. Digitalized electrocardiography signals such as high-frequency power [HF; 0.15-0.45 Hz, to reflect vagal (parasympathetic) regulation], low-frequency power (LF; 0.04-0.15 Hz, contributed from mixed sympathetic and parasympathetic divisions), and the fraction of LF/(HF + LF) in normalized units (LF%, to reflect sympathetic regulation) were transformed with fast Fourier transformation to power spectrum and heart rate variables.

RESULTS

Six male and two female patients were good responders and the others were fair responders. There were no significant differences in height, weight, duration of disease, levadopa equivalent daily dose, preoperative and postoperative UPDRS, and DBS-off and levodopa-off UPDRS between the good and fair response groups. There were no significant differences between the good and fair response groups for preoperative heart rate interval, LF values, LF% values, and HF values. Compared with preoperative values, the good response group showed a significant increase in LF but not in heart rate, LF%, and HF after surgery. In contrast, the fair response group showed no significant change in all heart rate variables postoperatively.

CONCLUSION

Our study showed an improvement in autonomic cardiovascular regulation in Parkinsonian patients with >50% improvement in rating scale after STN-DBS, which implied morbidity reduction in nonmotor symptoms among such patients.

Antipsychotic pharmacotherapy and orthostatic hypotension: identification and management

Orthostatic hypotension is a common adverse effect of antipsychotics that may delay or prevent titration to a dose necessary to control psychotic symptoms. Complications of orthostatic hypotension include syncope, transient ischaemic attack, stroke, myocardial infarction and death. The risk of orthostatic hypotension associated with antipsychotic therapy is increased in patients with disorders of the autonomic nervous system, fluid imbalance and those taking concomitant drug therapy that affects haemodynamic tone. Prospective monitoring for changes in postural blood pressure is important because patients with psychotic disorders often do not articulate symptoms of orthostasis and the subjective report of dizziness does not correlate well with orthostatic blood pressure changes. Nonpharmacological strategies and patient education, most notably, slowly rising from the supine position, are crucial first steps in the prevention and treatment of both symptomatic and asymptomatic orthostatic hypotension. Pharmacological treatment is only recommended when symptomatic orthostatic hypotension persists despite proper nonpharmacological therapy and there is a compelling indication for antipsychotic treatment. Fludrocortisone is a reasonable first choice for symptomatic orthostatic hypotension. Other agents including desmopressin and midodrine may be considered in patients who do not respond favourably to a trial of fludrocortisone, but safety concerns and lack of evidence limit the utility of these agents.

Neurogenic orthostatic hypotension of Parkinson's disease: what exploration for what treatment?

The aim of this short review is to illustrate, using orthostatic hypotension as an example, the clinical problems related to autonomic features in Parkinson's disease. Orthostatic hypotension is frequently encountered in Parkinson's disease and its diagnosis remains manometric (a fall of at least 20 and/or 10 mmHg in standing blood pressure). It is often associated with supine hypertension to be taken into account before prescribing. To distinguish between the role of disease and of drugs (not only antiparkinsonian drugs), a simple clinical test of autonomic nervous system activity (deep breathing test and standing test with measurement of 30/15 ratio) can be used. When diagnosis with multisystem atrophy is discussed, cardiac [¹²³I]-metaiodobenzylguanidine (MIBG) scintigraphy is of value showing in Parkinson's disease a decreased uptake of the radiopharmaceutical indicating postganglionic sympathetic denervation. Concerning treatment, nonpharmacological methods have to be systematically used since no drug has been specifically evaluated for the treatment of orthostatic hypotension of Parkinson's disease.

Treatment of dysautonomia in extrapyramidal disorders

Although extrapyramidal diseases are commonly thought to solely affect the extrapyramidal motor system, nonmotor symptoms such as behavioural abnormalities, dysautonomia, sleep disturbances and sensory dysfunctions are also frequently observed. Autonomic dysfunction as an important clinical component of extrapyramidal disease (idiopathic Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, dementia with Lewy bodies) is often not formally assessed and thus frequently misdiagnosed. Symptoms of autonomic dysfunction in general impact more on quality of life than motor symptoms. Appropriate symptom-oriented diagnosis and symptomatic treatment as part of an interdisciplinary approach can greatly benefit the patient. Unfortunately, double-blind, randomized, controlled studies are scarce with the consequence that most recommendations are not based on the highest level of evidence. This review elaborates a limited overview on the treatment of cardiovascular, gastrointestinal, urogenital and sudomotor autonomic dysfunction in various extrapyramidal syndromes.

Cardiovascular autonomic dysfunction in Parkinson's disease

Symptoms of cardiovascular dysautonomia are a common occurrence in Parkinson's disease (PD). In addition to this dysautonomia as part of PD itself, dysfunction of the autonomic nervous system (ANS) can be triggered as a side-effect of drug treatment interacting with the ANS or - if prominent and early - an indication of a different disease such as multiple system atrophy (MSA). Various diagnostic tests are available to demonstrate autonomic failure. While autonomic function tests can differentiate parasympathetic from sympathetic dysfunction, cardiac imaging can define the pathophysiologically involved site of a lesion. Standard tests such as 24-h ambulatory blood pressure measurements can identify significant autonomic failure which needs treatment. The most frequent and disturbing symptom of cardiovascular autonomic dysfunction is orthostatic hypotension. Symptoms include generalized weakness, light-headiness, mental "clouding" up to syncope. Factors like heat, food, alcohol, exercise, activities which increase intrathoraric pressure (e.g. defecation, coughing) and certain drugs (e.g. vasodilators) can worsen a probably asymptomatic orthostatic hypotension. Non-medical and medical therapies can help the patient to cope with a disabling symptomatic orthostatic hypotension. Supine hypertension is often associated with orthostatic hypotension. The prognostic role of cardiovagal and baroreflex dysfunction is still not yet known.

Hypertension, hypercholesterolemia, diabetes, and risk of Parkinson disease

OBJECTIVE

To determine whether history of hypertension, hypercholesterolemia, or diabetes is associated with risk of Parkinson disease (PD).

METHODS

Prospective study among participants in two large cohorts: the Nurses' Health Study (121,046 women) and the Health Professionals Follow-up Study (50,833 men). Mean duration of follow-up was 22.9 years in women, aged 30 to 55 years at baseline, and 12.6 years in men, aged 40 to 75 years at baseline. Relative risks (RRs) of PD were estimated from a Cox proportional hazards model adjusting for potential confounders.

RESULTS

We identified a total of 530 incident cases of PD during the follow-up. Risk of PD was not associated with self-reported history of hypertension (RR = 0.96, 95% CI = 0.80 to 1.15), high cholesterol (RR = 0.98, 95% CI = 0.82 to 1.19), or diabetes (RR = 1.04, 95% CI = 0.74 to 1.46), after adjusting for age and smoking in pack-years. Risk of PD decreased modestly with increasing levels of self-reported total cholesterol (RR for a 50-mg/dL increase in total cholesterol = 0.86, 95% CI = 0.78 to 0.95, p for trend = 0.02), but use of cholesterol-lowering drugs was not associated with PD risk (RR comparing users with nonusers = 0.85, 95% CI = 0.59 to 1.23). Among individuals with PD, systolic blood pressure was similar to noncases up to the time of diagnosis but declined afterward.

CONCLUSIONS

Results of this large prospective study suggest that Parkinson disease risk is not significantly related to history of hypertension, hypercholesterolemia, or diabetes but may modestly decline with increasing blood cholesterol levels.

Selegiline and blood pressure in patients with Parkinson's disease

OBJECTIVES

Parkinson's disease (PD) frequently affects both the extrapyramidal system and the autonomic nervous system (ANS), the latter also being sometimes disturbed by PD medications. Specifically selegiline is known to disturb cardiovascular ANS functions and may cause or enhance orthostatic hypotension.

METHODS

In order to study the effect of the withdrawal of selegiline on the regulation of blood pressure (BP) in advanced PD, an orthostatic test was performed in 14 PD patients with wearing-off before the morning levodopa dose and thereafter repetitively at 1-h intervals for up to 4 h. A Unified Parkinson's Disease Rating Scale motor score evaluation was also carried out hourly. The tests were repeated after a 4-week selegiline washout period.

RESULTS

Selegiline withdrawal decreased systolic BP significantly during the on-stage in a supine position as well as during the orthostatic test. The initial drop of BP in the orthostatic test was significantly smaller after selegiline withdrawal. The heart rate remained unaffected.

Cardiovascular responses to combined treatment with selective monoamine oxidase type B inhibitors and L-DOPA in the rat

BACKGROUND AND PURPOSE

Postural hypotension is a common side-effect of L-DOPA treatment of Parkinson's disease, and may be potentiated when L-DOPA is combined with selegiline, a selective inhibitor of monoamine oxidase B (MAO-B). Rasagiline is a new, potent and selective MAO-B inhibitor, which does not possess the sympathomimetic effects of selegiline. We have studied the effects of these selective MAO inhibitors, L-DOPA and dopamine on the cardiovascular system of the rat.

EXPERIMENTAL APPROACH

Blood pressure and heart rate was measured in conscious rats following acute or chronic administration of rasagiline, selegiline and L-DOPA, by comparison with the selective MAO-A inhibitor clorgyline, or the MAO-A/B inhibitor tranylcypromine. Cardiovascular responses, catecholamine release, and modification of pressor response to dopamine were studied in pithed rats.

KEY RESULTS

In conscious rats neither rasagiline nor selegiline caused significant potentiation of the effects of L-DOPA (50, 100, 150 mg.kg(-1)) on blood pressure or heart rate at doses which selectively inhibited MAO-B, but L-DOPA responses were potentiated by clorgyline and tranylcypromine. In rats treated twice daily for 8 days with L-DOPA and carbidopa, selegiline (5 mg.kg(-1)) but not rasagiline (0.2 mg.kg(-1)) caused a significant hypotensive response to L-DOPA and carbidopa, although both drugs caused similar inhibition of MAO-A and MAO-B. In pithed rats, selegiline but not rasagiline increased catecholamine release and heart rate, and potentiated dopamine pressor response at MAO-B selective dose.

CONCLUSIONS AND IMPLICATIONS

The different responses to the two MAO-B inhibitors may be explained by the amine releasing effect of amphetamine metabolites formed from selegiline.

Skin biopsy for assessment of autonomic denervation in Parkinson's disease

Autonomic dysfunction in Parkinson's disease (PD) is considered a late complication of the disease or an adverse effect of anti-parkinsonian medications. Morphological changes are demonstrated only by postmortem examination. The study objective was to evaluate peripheral autonomic neural involvement in PD using punch skin biopsy. The study sample included 22 patients (mean age 50 +/- 7.7 years, mean disease duration 5.3 +/- 3.8 years) and 19 controls. Four-millimeter skin biopsies were immunohistochemically stained with anti-PGP 9.5 antibody. Autonomic innervation of the blood vessels, sweat glands, and erector pili muscles was assessed and rated from 0 (normal) to 2 (severe). Cutaneous autonomic innervation was decreased in patients compared to controls. Semi quantitative analysis demonstrated reduced autonomic innervation of the blood vessels (1.0 +/- 0.8 vs. 0.42 +/- 0.8 in controls; p < 0.02), of sweat glands (0.95 +/- 0.67 vs. 0.47 +/- 0.61; p < 0.02) and of the erector pili muscles (1.06 +/- 0.55 vs 0.21 +/- 0.42; p < 0.001). This method demonstrates that the peripheral autonomic system is affected in PD at early stage of the disease and that autonomic involvement in PD may be more prevalent than previously thought.

Assessment of P wave duration and dispersion in Parkinson's disease

Cardiovascular disorders such as decreased heart rate variability, orthostatic hypotension, and arrhythmias have been frequently observed in Parkinson's disease (PD) patients. In this study, authors measured P wave duration and dispersion in PD patients and controls. Twenty-three consecutive patients with idiopathic PD and sex-age matched 23 control subjects were included to the study. A 12-lead surface ECG was obtained from each participant. Maximum-minimum P wave duration and P wave dispersion (PWD) were measured in both groups. Maximum P wave duration was found to be higher in PD patients than controls (117+/-12 vs. 105+/-9 ms p=0.001). Minimum P wave duration was similar in PD patients and controls (64+/-11 vs. 63+/-11 ms p=0.7). PWD in PD patients was also found to be higher than those of controls (53+/-11 vs. 43+/-10 ms p=0.0001). P wave duration and PWD did not significantly differ between PD patients taking anti-parkinsonian agents from those who were not (119+/-13 vs. 116+/-13 ms p=0.4 and 55+/-11 vs. 52+/-11 ms p=0.5, respectively). Moreover, when the PD patients taking anti-parkinsonian agents were excluded from the study, PD patients had still higher P wave duration and PWD compared to controls (119+/-11 vs. 105+/-9 ms p=0.004, 52+/-10 vs. 43+/-10 ms p=0.009, respectively). In conclusion, we found that P wave duration and PWD were greater in PD patients compared to control subjects.

Orthostatic hypotension as an early finding in Parkinson's disease

Patients with Parkinson's disease (PD) commonly have clinically significant orthostatic hypotension (OH). In such patients PD+OH might be confused with multiple system atrophy (MSA), in which OH is a frequent finding, or with pure autonomic failure (PAF), if OH preceded clinical manifestations of the movement disorder. This study addressed whether OH can occur as an early finding in PD+OH. Historical data were analyzed from 35 patients with PD+OH evaluated at the NIH. OH was considered early if the patient had OH before, concurrent with, or starting within 1 year after onset of a symptomatic movement disorder. MSA was excluded by myocardial 6-[(18)F]fluorodopamine-derived radioactivity more than 2 standard deviations below the normal mean. Among the 35 PD+OH patients, 21 (60 %) had documentation of OH as an early finding. In 4 such patients, OH had preceded parkinsonism, and in 4 others, OH had dominated the early clinical picture, even after cessation of levodopa treatment for the movement disorder. In PD, OH can occur early in the disease, occasionally preceding or overshadowing the movement disorder.

Orthostatic heart rate variability analysis in idiopathic Parkinson's disease

OBJECTIVES

We evaluated time and spectral analyses of 24-h heart rate variability (HRV) and the heart rate responses to passive tilt in patients with idiopathic Parkinson's disease (IPD) in order to investigate cardiovascular autonomic functions.

MATERIAL AND METHODS

Twenty-three subjects with IPD without autonomic symptoms and 15 age-matched healthy controls were enrolled. Frequency- and time-domain HRV parameters were studied during resting and passive head-up tilt (HUT) test.

RESULTS

All time-domain parameters were found to be low in patients with IPD. In patients with IPD, both low frequency (LF) and high frequency (HF) decreased during HUT period and no significant change in LF to HF ratio was noted. Both time- and frequency-domain HRV indices showed no correlation with age, disease severity and duration, and with l-dopa medication.

CONCLUSION

The results indicate that impairment of autonomic nervous system function in IPD without autonomic symptoms is frequent, and does not show clear association with clinical stage and the age of the patients.

Monoamine oxidase B inhibitors for early Parkinson's disease

BACKGROUND

It has been postulated that monoamine oxidase B (MAO-B) inhibitors alter disease progression in Parkinson's disease (PD). Clinical trials have produced conflicting results.

OBJECTIVES

To assess the evidence from randomized controlled trials for the effectiveness and safety of long-term use of MAO-B inhibitors in early PD.

SEARCH STRATEGY

We searched the following electronic databases: Cochrane Central Register of Controlled trials (CENTRAL) (The Cochrane Library Issue 2, 2004), MEDLINE (last searched 18th August 2004) and EMBASE (last searched 18th August 2004). We also handsearched neurology and movement disorders conference proceedings, checked reference lists of relevant studies and contacted other researchers.

SELECTION CRITERIA

We sought to include all unconfounded randomized controlled trials that compared a MAO-B inhibitor with control, in the presence or absence of levodopa or dopamine agonists, in patients with early PD and where treatment and follow up lasted at least one year.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion, assessed the methodological quality, and extracted the data. A small amount of additional data was provided by the original authors. Random-effects models were used to analyse results, where appropriate.

MAIN RESULTS

Ten trials were included (a total of 2422 patients), nine using selegiline, one using lazabemide. The methodological quality was reasonable although concealment of allocation was definitely adequate in only four trials. The mean follow up was for 5.8 years. MAO-B inhibitors were not associated with a significant increase in deaths (odds ratio (OR) 1.15; 95% confidence interval (CI) 0.92 to 1.44). They provided small benefits over control in impairment (weighted mean difference (WMD) for change in motor UPDRS score was 3.81 points less with MAO-B inhibitors; 95% CI 2.27 to 5.36) and disability (WMD for change in UPDRS ADL score was 1.50 less; 95% CI 0.48 to 2.53) at one year which, although statistically significant, were not clinically significant. There was a marked levodopa-sparing effect with MAO-B inhibitors which was associated with a significant reduction in motor fluctuations (OR 0.75; 95% CI 0.59 to 0.94) but not dyskinesia (OR 0.97; 95% CI 0.76 to 1.25). The reduction in motor fluctuations was, however, not robust in sensitivity analyses. Although adverse events were generally mild and infrequent, withdrawals due to side-effects were higher (OR 2.36; 95% CI 1.32 to 4.20) with MAO-B inhibitors.

AUTHORS' CONCLUSIONS

MAO-B inhibitors do not appear to delay disease progression but may have a beneficial effect on motor fluctuations. There was no statistically significant effect on deaths although the confidence interval does not exclude a small increase with MAO-B inhibitors. At present we do not feel these drugs can be recommended for routine use in the treatment of early Parkinson's disease but further randomized controlled trials should be carried out to clarify, in particular, their effect on deaths and motor complications.

Pharmacology of orthostatic hypotension in Parkinson's disease: from pathophysiology to management

Orthostatic hypotension is highly prevalent in the elderly, and affects up to 20% of patients with Parkinson's disease. Pharmacological approaches help to demonstrate that Parkinson's disease is a primary autonomic failure with involvement of the peripheral autonomic nervous system as shown by decreased [(123)I] meta-iodobenzylguanidine cardiac uptake and preserved growth hormone response to clonidine. No specific clinical trial has evaluated efficacy of antihypotensive drugs in Parkinson's disease. End point of treatment should be a reduction in postural symptoms. Midodrine (Proamatin), Roberts Pharmaceutical), a vasoconstrictor and fludrocortisone (Florinef), Bristol-Myers Squibb), a volume expander are first choice drugs. No data are available on their effects on orthostatic hypotension-related morbidity. The usefulness of other drugs remains to be demonstrated. This review will highlight the importance of nonpharmacological measures in the management of orthostatic hypotension in Parkinson's disease.

Cardiovascular autonomic dysfunction correlates with brain MRI lesion load in MS

OBJECTIVE

The aim of the present study was to investigate the cardiovascular autonomic control in clinically definite multiple sclerosis (MS) patients with a standardised battery of cardiovascular tests and to correlate these findings with the brain magnetic resonance imaging (MRI) lesion load.

METHODS

Fifty-one patients with MS and 50 healthy controls were studied. Brain MRI was performed in all patients showing typical MS lesions. The cardiovascular tests were carried out using a standardised battery.

RESULTS

Heart rate (HR) responses to deep breathing (P < 0.05) and tilt table testing (P < 0.001) were significantly decreased in MS patients when compared to those of the controls. Blood pressure (BP) responses in the tilt table test were also impaired in MS patients (diastolic P < 0.001, systolic P < 0.05). Of the different brain areas investigated the total volume of the midbrain MRI lesions (P < 0.05) was the one most clearly associated with the impaired BP responses.

CONCLUSIONS

MS results in both reduced HR variation and decreased BP reactions indicating disturbed cardiovascular regulation. In particular, the midbrain lesions found in MS are associated with cardiovascular dysfunction.

Differential effects of various treatment combinations on cardiovascular dysfunction in patients with Parkinson's disease

OBJECTIVES

Patients with Parkinson's disease (PD) frequently suffer from cardiovascular dysfunction, which may be enhanced to various extents by different antiparkinsonian drugs.

MATERIALS AND METHODS

We analysed electrocardiogram (ECG) abnormalities, cardiovascular reflexes (CVR) and orthostatic hypotension (OH) in 148 patients with idiopathic PD assigned to five different combination therapies of levodopa (LD) plus either bromocriptine (BRO), ropinirole (ROP), selegiline (SEL), anticholinergic (ACH) or amantadine (AMA) or to LD monotherapy before and after a 1-week washout of the add-on drug. Patients were matched for age and disease severity (Hoehn and Yahr stage 2-3). Rater-blinded cardiovascular testing was performed at baseline, and following a 1-week washout period of the add-on drugs.

RESULTS

We found that the incidence of cardiovascular dysfunction was generally higher in patients receiving a combination therapy compared with patients on LD monotherapy. ECG abnormalities were found in 40-52% of patients in combination therapy, but in only 20% of the patients receiving LD monotherapy. After discontinuation of BRO and SEL, there were significant improvements in ECG, OH and CVR. After washout of ACH and AMA, a significant improvement was found only in the CVR score. AMA and ROP were the add-on drugs with the least adverse cardiovascular effects.

CONCLUSION

We conclude that pre-existing cardiovascular autonomic dysfunction should be investigated and taken into account when deciding which combination therapy to choose in the treatment of parkinsonian patients.

Age and duration related changes in muscle sympathetic nerve activity in Parkinson's disease

OBJECTIVE

To clarify the characteristics of sympathetic vasomotor function in Parkinson's disease by sympathetic neurographic analysis.

METHODS

Muscle sympathetic nerve activity (MSNA) was recorded using a microneurographic technique at rest and during head up tilt in 18 patients with idiopathic Parkinson's disease and 21 healthy controls.

RESULTS

Heart rate and blood pressure at rest did not differ between index and control subjects. The increase in these variables and MSNA in response to tilting was slightly blunted in the Parkinson's group. Resting MSNA showed a negative correlation with age in patients with Parkinson's disease (p<0.05) and a positive correlation with age in controls (p<0.01). There was a negative correlation between duration of disease or disability levels and MSNA (p<0.01).

CONCLUSIONS

Sympathetic vasomotor function may be related to age and disease duration in Parkinson's disease.

Low monoamine oxidase B in peripheral organs in smokers

One of the major mechanisms for terminating the actions of catecholamines and vasoactive dietary amines is oxidation by monoamine oxidase (MAO). Smokers have been shown to have reduced levels of brain MAO, leading to speculation that MAO inhibition by tobacco smoke may underlie some of the behavioral and epidemiological features of smoking. Because smoking exposes peripheral organs as well as the brain to MAO-inhibitory compounds, we questioned whether smokers would also have reduced MAO levels in peripheral organs. Here we compared MAO B in peripheral organs in nonsmokers and smokers by using positron emission tomography and serial scans with the MAO B-specific radiotracers,l-[11C]deprenyl and deuterium-substituted l-[11C]deprenyl (l-[11C]deprenyl-D2). Binding specificity was assessed by using the deuterium isotope effect. We found that smokers have significantly reduced MAO B in peripheral organs, particularly in the heart, lungs, and kidneys, when compared with nonsmokers. Reductions ranged from 33% to 46%. Because MAO B breaks down catecholamines and other physiologically active amines, including those released by nicotine, its inhibition may alter sympathetic tone as well as central neurotransmitter activity, which could contribute to the medical consequences of smoking. In addition, although most of the emphases on the carcinogenic properties of smoke have been placed on the lungs and the upper airways, this finding highlights the fact that multiple organs in the body are also exposed to pharmacologically significant quantities of chemical compounds in tobacco smoke.

Autonomic Nervous System Dysfunction in Parkinson's Disease

Autonomic nervous system (ANS) dysfunction is common in Parkinson's disease (PD), affects 70% to 80% of patients, and causes significant morbidity and discomfort. Autonomic nervous system dysfunction symptoms in PD include sexual dysfunction, swallowing and gastrointestinal disorders, bowel and bladder abnormalities, sleep disturbances, and derangements of cardiovascular regulation, particularly, orthostatic hypotension. Autonomic nervous system dysfunction in PD may be caused by an underlying degenerative process that affects the autonomic ganglia, brainstem nuclei, and hypothalamic nuclei. Anti-parkinsonian medications can cause or worsen symptoms of ANS dysfunction. The care of a PD patient with ANS dysfunction relies on its recognition and directed treatment, including coordinated care between the neurologist and appropriate subspecialist. Pharmacotherapy may be useful to treat orthostasis, gastrointestinal, urinary, and sexual dysfunction.

Selegiline in the treatment of Parkinson's disease: its impact on orthostatic hypotension

Less than a consensus exists as to whether chronic treatment with selegiline in combination with levodopa/carbidopa in patients with Parkinson's disease, is associated with more pronounced orthostatic hypotension than treatment with levodopa/carbidopa alone. To resolve this issue, we compared orthostatic tolerance and autonomic reflexes in 95 patients with Parkinson's disease treated chronically with either selegiline alone (n = 10), levodopa/carbidopa alone (n = 49) or both agents combined (n = 36). Supine heart rate and blood pressure, autonomic cardiovascular reflexes and the frequency and magnitude of orthostatic hypotension were similar in all three treatment groups.

Selegiline attenuates cardiac oxidative stress and apoptosis in heart failure: association with improvement of cardiac function

We have shown recently that selegiline exerts a cardiac neuroprotective effect in chronic heart failure. Since selegiline has an antioxidant antiapoptotic effect, we proposed to determine whether selegiline attenuates cardiac oxidative stress and myocyte apoptosis in chronic heart failure by modulating Bcl-2 and Bax protein expression, and whether the effects are associated with the improvement of cardiac function. Rabbits with rapid cardiac pacing (360 beats/min) and sham operation without pacing were randomized to receive oral selegiline (1 mg/day) or placebo for 8 weeks. Echocardiography was used to measure left ventricular fractional shortening. After 8 weeks of treatment, animals were studied for arterial norepinephrine and left ventricular systolic function (fractional shortening and dP/dt), and were then sacrificed for measuring the stable oxidative product of myocardial mitochondrial DNA (mtDNA) 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), myocyte apoptosis by monoclonal antibody to single stranded DNA, and Bcl-2 and Bax protein expression by Western blot and immunohistochemistry. Rapid cardiac pacing increased plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, reduced Bcl-2 and the Bcl-2 to Bax ratio. These changes were associated with decreased left ventricular fractional shortening and dP/dt. Selegiline treatment in chronic heart failure animals reduced plasma norepinephrine, cardiac oxidative stress and myocyte apoptosis, prevented the changes of Bcl-2 and Bcl-2 to Bax ratio, and improved left ventricular fractional shortening and dP/dt. The findings suggest that the reduction by selegiline of myocyte apoptosis is related to the decrease of cardiac oxidative stress and the modulation of apoptotic and antiapoptotic proteins. The antioxidant antiapoptotic effects of selegiline are potentially beneficial in the improvement of cardiac function in chronic heart failure.

Cardiovascular autonomic reactivity is decreased in adolescents with Type 1 diabetes

AIMS

To characterize autonomic nervous system function by means of the heart rate and blood pressure responses to various stimuli in relation to pubertal maturation in patients with Type 1 diabetes mellitus (DM).

METHODS

One hundred out of 138 eligible patients at the Out-patient Diabetes Clinic and 100 healthy control subjects were examined in terms of cardiovascular parameters at rest, during deep breathing and when standing. Heart rate variability was analysed with time domain,frequency domain and fractal dimension parameters. Tanner pubertal staging was performed before the examinations.

RESULTS

The time domain parameters of heart rate variability at rest or during standing did not significantly differ between the patients and controls in total or at pubertal stages. In the spectral analysis of heart rate variability the very low frequency band was decreased in the patients during standing (P = 0.023).The increase in the very low frequency (P = 0.013)and low frequency (P = 0.031) spectral powers upon changing from a supine position to standing was attenuated in the patients in total, while no significant differences were observed within the Tanner pubertal stages between patients and controls. Heart rate variability during deep breathing was decreased in the patients with distal polyneuropathy (P = 0.006).

CONCLUSIONS

Although cardiovascular integrity is in the main well preserved in adolescent patients with Type 1 DM, these patients are prone to attenuated autonomic nervous system reactivity.

Comparison of heart rate variability analysis methods in patients with Parkinson's disease

The aim of the present study was to evaluate different analysis methods for revealing heart rate variability (HRV) differences between untreated patients with Parkinson's disease and healthy controls. HRV in standard cardiovascular reflex tests and during a 10 min rest period were measured by time- and frequency-domain and geometrical and non-linear analysis methods. Both frequency- and time-domain measures revealed abnormal HRV in the patients, whereas non-linear and geometrical measures did not. The absolute high-frequency spectral power of HRV was the strongest independent predictor to separate the patients from the controls (p = 0.001), when the main time-domain and absolute frequency-domain measures were compared with each other. When the corresponding normalised spectral units, instead of the absolute units, were used in the comparison, the two best single measures for separating the groups were the 30/15 ratio of the tilting test (p = 0.003) and the max/min ratio during deep breathing (p = 0.024). When the correlations between the different measures were estimated, the time-domain measures, fractal dimension and absolute spectral powers correlated with each other. The frequency- and time-domain analysis techniques of stationary short-term HRV recordings revealed significant differences in cardiovascular regulation between untreated patients with Parkinson's disease and the controls. This confirms cardiovascular regulation failure before treatment in the early stages of Parkinson's disease. The HRV spectral powers, in absolute units, were the most effective single parameters in segregating the two groups, emphasising the role of spectral analysis in the evaluation of HRV in Parkinson's disease.

Modulation of neuroendocrine--immune signaling by L-deprenyl and L-desmethyldeprenyl in aging and mammary cancer

The aging process is characterized by a decline in cellular functions of diverse systems of the body, including the neuroendocrine-immune network. One neuroendocrinological theory of aging is based on findings that the loss of hypothalamic neurotransmitter functions and an imbalance in hormonal secretion contribute to the cessation of reproductive cycles and the development of mammary and pituitary tumors. One potential cause of immunosenescence is an age-related decline in the regulatory functions of sympathetic noradrenergic nerve fibers whose neurotransmitters signal lymphoid cells in the bone marrow, thymus, spleen, and lymph nodes. In addition to impairment caused by the generation of free radicals during numerous biochemical processes, there is a shift in the pro-oxidant/anti-oxidant balance resulting in cellular oxidative stress and hastening the aging process. Altered interactions between the neuroendocrine system and the immune system are associated with increased incidence, development, and growth of breast cancer and other neoplastic diseases. We have demonstrated that the disruption in the neuroendocrine-immune interactions in old rats, and in female rats with mammary tumors, can be reversed by deprenyl, a monoamine oxidase inhibitor. Deprenyl treatment leads to enhanced central and peripheral catecholaminergic activity and a readjustment of immunological responses. In this brief review, the nature and changes in the bi-directional communication between the neuroendocrine system and immune system and the possible mechanism(s) of actions of deprenyl in restoring these interactions during aging and mammary cancer are discussed.

Orthostatic hypotension in patients with Parkinson's disease: pathophysiology and management

Orthostatic hypotension is common in elderly patients, and is now considered to be an important prognostic factor for cognitive decline and mortality. In patients with Parkinson's disease, the prevalence of symptomatic orthostatic hypotension may be as high as 20%. Two factors could explain this high prevalence. First, dopaminergic drugs may induce or worsen orthostatic hypotension. Secondly, Parkinson's disease is a cause of primary autonomic failure with an involvement of the peripheral autonomic system as shown by the ubiquitous distribution of Lewy bodies and reduced iobenguane [metaiodobenzylguanidine (MIBG)] cardiac uptake. These pathological and pharmacological characteristics clearly differentiate autonomic failure of Parkinson's disease from multiple system atrophy. If autonomic abnormalities appear to be present from the first stage of the disease, early onset (within the first year) of symptomatic orthostatic hypotension in the course of parkinsonism can be considered as an exclusion criteria for idiopathic Parkinson's disease. No specific clinical trials have evaluated the effects of antihypotensive drugs in patients with Parkinson's disease and thus no specific therapeutic strategy can be recommended. The management of orthostatic hypotension in patients with Parkinson's disease should always start with patient education and nonpharmacological treatment. Drug therapy should be reserved for symptomatic patients who do not get benefit from nonpharmacological management. Among the available drugs, alpha1-adrenergic agonists (mainly midodrine) or plasma volume expanders (mainly fludrocortisone) are the most frequently used. There are also some drugs that are currently investigational such as yohimbine and droxidopa. Other drugs such as desmopressin or octreotide may be of interest in some situations. Domperidone is widely used in patients with parkinsonism with no proven effect on orthostatic hypotension.

Effect of levodopa on orthostatic and postprandial hypotension in elderly Parkinsonian patients

BACKGROUND

This study describes orthostatic and postprandial hypotension in elderly Parkinsonian patients and evaluates the effect of levodopa therapy on orthostatic and postprandial hypotension in these patients.

METHODS

Seventeen elderly patients with a clinical diagnosis of Parkinson's disease or Parkinsonism based on the U.K. Parkinson's Disease Society Brain Bank criteria (age range, 66-84 years) participated in the study. Blood pressure was continuously monitored during standardized standing and meal tests, after starting 125-mg b.i.d. doses of levodopa/benserazide (Madopar) or placebo, in a double-blind, randomized, cross-over design. Seventeen age- and sex-matched healthy subjects served as controls.

RESULTS

Orthostatic hypotension was infrequently found in Parkinsonian patients (13%) and healthy subjects (6%; p =.58, between groups), whereas postprandial hypotension was more frequent in Parkinsonian patients (82%) than in healthy subjects (41%; p <.05, between groups). Doses of levodopa/benserazide, administered 2 times per day, did not result in significantly larger blood pressure decreases after standing or eating, or in higher frequencies of orthostatic or postprandial hypotension in the Parkinsonian group. Postprandial hypotension was related to disease severity (r = -.56, p <.05).

CONCLUSIONS

Postprandial hypotension, but not orthostatic hypotension, was more common in elderly Parkinsonian patients than in healthy subjects. Therapy with 125-mg b.i.d. doses of levodopa/benserazide did not significantly aggravate orthostatic or postprandial hypotension.

Abnormal skin wrinkling in the less affected side in hemiparkinsonism-a possible test for sympathetic dysfunction in Parkinson's disease

Some patients with Parkinson's disease (PD) suffer from autonomic dysfunction, even in the early stage of the disease. We examined the skin wrinkling response following immersion of the hands in warm water in 18 patients with hemiparkinsonism. This test evaluates the function of the sympathetic autonomic system. Mean age of the patients was 61 +/- 10 and mean disease duration 5.5 +/- 3.5 years. Both hands of each patient were immersed in warm water for 30 minutes and the number of skin ridges of the fingertip of each finger was counted. The results of each hand were compared to those of nine healthy controls. The mean number of the ridges of the less affected hand was significantly decreased as compared to the affected hand and controls (6.1 +/- 6.8 vs 13.1 +/- 6.8 and 15.3 +/- 8.5, respectively; P < 0.01). These results suggest that autonomic dysfunction is prevalent in the less affected side of patients with PD and can be simply tested by the skin response test.

Changes in vascular alpha 1- and alpha 2-adrenoceptor responsiveness by selegiline treatment

Pharmacoepidemiological studies have reported an excess of mortality with selegiline, a MAO B inhibitor used in the treatment of Parkinson's disease. The mechanism of this putative adverse effect remains unknown but an interaction with the sympathetic nervous system was suggested. The aim of the present study was to investigate the influence of selegiline (10 mg/daily, orally during one week) on vascular alpha1- and alpha2-adrenoceptor responsiveness in conscious unrestrained dogs. Selegiline significantly increased resting values of both systolic and diastolic blood pressures and noradrenaline plasma levels (HPLC) without changing heart rate. Moreover, spectral analysis of systolic blood pressure (Fast Fourier Transformation) showed that selegiline increased the relative energy of a low frequency band without modifying the total spectrum. ED 50 calculated from dose-pressor response curves with phenylephrine (after beta-blockade by propranolol), an index of alpha1-adrenoceptor response or with noradrenaline (after alpha1- and beta blockade by prazosin plus propranolol), an index of alpha2-adrenoceptor response, were significantly higher after selegiline. Selegiline failed to modify the number of platelet alpha2-adrenoceptors measured by [(3)H] RX 821002 binding. Yohimbine-induced increase in noradrenaline release was significantly more marked after selegiline. These results support the evidence that selegiline induces a vascular alpha1- and alpha2-adrenoceptor-hyposensitivity that can be explained by the increase in noradrenaline release elicited by the drug.

Ambulatory ECG and analysis of heart rate variability in Parkinson's disease

OBJECTIVES

Cardiovascular reflex tests have shown both sympathetic and parasympathetic failure in Parkinson's disease. These tests, however, describe the autonomic responses during a restricted time period and have great individual variability, providing a limited view of the autonomic cardiac control mechanisms. Thus, they do not reflect tonic autonomic regulation. The aim was to examine tonic autonomic cardiovascular regulation in untreated patients with Parkinson's disease.

METHODS

24 Hour ambulatory ECG was recorded in 54 untreated patients with Parkinson's disease and 47 age matched healthy subjects. In addition to the traditional spectral (very low frequency, VLF; low frequency, LF; high frequency, HF) and non-spectral components of heart rate variability, instantaneous beat to beat variability (SD1) and long term continuous variability (SD2) derived from Poincaré plots, and the slope of the power law relation were analysed.

RESULTS

All spectral components (p<0.01) and the slope of the power-law relation (p<0.01) were lower in the patients with Parkinson's disease than in the control subjects. The Unified Parkinson's disease rating scale total and motor scores had a negative correlation with VLF and LF power spectrum values and the power law relation slopes. Patients with mild hypokinesia had higher HF values than patients with more severe hypokinesia. Tremor and rigidity were not associated with the HR variability parameters.

CONCLUSIONS

Parkinson's disease causes dysfunction of the diurnal autonomic cardiovascular regulation as demonstrated by the spectral measures of heart rate variability and the slope of the power law relation. This dysfunction seems to be more profound in patients with more severe Parkinson's disease.

Cardiovascular reflex testing contributes to clinical evaluation and differential diagnosis of Parkinsonian syndromes

The differentiation between Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA) may be difficult but is important for prognostic and therapeutic purposes. Varying degrees of autonomic failure have been described in PD and MSA, whereas its involvement in PSP remains controversial. The aim of this study was to investigate autonomic function in patients fulfilling strict clinical diagnostic criteria for the disorders above, to evaluate the diagnostic capacity of laboratory autonomic tests. The study group was consecutively recruited among patients referred to a movement disorder unit. Thirty-four patients with PD, 15 patients with PSP, and 47 patients with MSA were compared with 18 healthy age-matched controls. Autonomic tests included analysis of heart rate variability (HRV) in temporal domain, at rest and during forced respiration, as well as blood pressure (BP) changes during 75 degrees head-up tilt. HRV did not differ between groups during quiet breathing but was significantly reduced during forced respiration in MSA (P < 0.01), while PD and PSP groups did not differ from controls. Hypotensive responses during orthostatic provocation were seen in PD (P < 0.01) and MSA (P < 0.001), whereas BP remained stable in most PSP patients, not differing from the healthy control group. On an individual basis, decreased HRV and severe hypotensive responses were seen in MSA patients regardless of age and disease duration, whereas PD patients showed this combination only at high age and long duration. In PSP, only a few cases with decreased HRV and limited hypotensive responses were found. We conclude that cardiovascular reflex tests can supplement the clinical differentiation of Parkinsonian syndromes.

The effect of catechol-O-methyltransferase inhibition with entacapone on cardiovascular autonomic responses in L-Dopa-treated patients with Parkinson's disease

We have compared the effects of entacapone, a peripherally acting catechol-O-methyltransferase (COMT) inhibitor, and placebo on cardiovascular autonomic responses in L-Dopa/dopa decarboxylase inhibitor-treated patients with Parkinson's disease (PD). In a double-blind, randomized, crossover study with two consecutive 1-week treatment periods, a battery of cardiovascular reflex tests (orthostatic, Valsalva, deep breathing, and isometric hand grip tests) was performed in a group of 15 patients with idiopathic PD. The first set of tests was performed after withholding L-Dopa overnight (control, "off" stage). The second and third sets of tests were performed in "on" stage after 1-week treatment with either entacapone 200 mg or placebo administered with each dose of L-Dopa/dopa decarboxylase (DDC) inhibitor. Valsalva, deep breathing, and orthostatic tests demonstrated no statistically significant differences in the ratio of the longest and shortest electrocardiographic R-to-R wave (R-R) intervals between entacapone and placebo or between study treatments and control. Blood pressure responses to both orthostatic challenge and prolonged isometric work (hand grip test) were similar between treatments. Systolic orthostatic hypotension was observed in only one patient during the control test, but it occurred more frequently after L-Dopa/DDC inhibitor, regardless of concomitant administration of either entacapone (n = 3) or placebo (n = 4). Peripheral COMT inhibition with entacapone does not significantly alter cardiovascular autonomic responses in L-Dopa-treated patients with PD.

Heart rate variability in patients with untreated Parkinson's disease

The aim of this study was to evaluate cardiovascular responses as a marker of autonomic nervous system (ANS) disturbances in patients with untreated Parkinson's disease (PD) and to assess the relationship between them and the clinical characteristics of PD. The ANS functions were investigated in 50 patients with PD and 55 healthy subjects by measuring standard cardiovascular autonomic reflexes and heart rate variability (HRV) at rest using spectral analysis (the autoregressive model and the fast Fourier transformation), the percentage of the counts of beat-to-beat variation greater than 50 ms and the fractal dimension. Significantly attenuated HRV and deficient blood pressure reaction to tilting were found in the PD patient group. The patients with hypokinesia/rigidity as the initial symptom of PD had a more pronounced HRV deficit than those with tremor onset. Untreated PD patients suffer significant failure in cardiovascular nervous system regulation, and in patients with hypokinesia/rigidity as their initial disease manifestation the risk of this ANS dysfunction is high. However, in the early stages of PD these changes did not reach significance at individual level.

Selegiline improves cardiac sympathetic terminal function and beta-adrenergic responsiveness in heart failure

Selegiline is a centrally acting sympatholytic agent with neuroprotective properties. It also has been shown to promote sympathetic reinnervation after sympathectomy. These actions of selegiline may be beneficial in heart failure that is characterized by increased sympathetic nervous activity and functional sympathetic denervation. Twenty-seven rabbits with rapid cardiac pacing (360 beats/min, 8 wk) and twenty-three rabbits without pacing were randomly assigned to receive selegiline (1 mg/day, 8 wk) or placebo. Rapid pacing increased plasma norepinephrine (NE) and decreased left ventricular fractional shortening, baroreflex sensitivity, cardiac sympathetic nerve terminal profiles, cardiac NE uptake activity, and myocardial beta-adrenoceptor density. Selegiline administration to animals with rapid ventricular pacing attenuated the increase in plasma NE and decreases in fractional shortening, baroreflex sensitivity, sympathetic nerve profiles, NE uptake activity and beta-adrenoceptor density. Thus selegiline appears to exert a sympatholytic and cardiac neuroprotective effect in pacing-induced cardiomyopathy. The effects are potentially beneficial because selegiline not only improves cardiac function but also increases baroreflex sensitivity in heart failure.

Selegiline-induced postural hypotension in Parkinson's disease: a longitudinal study on the effects of drug withdrawal

OBJECTIVES

The United Kingdom Parkinson's Disease Research Group (UKPDRG) trial found an increased mortality in patients with Parkinson's disease (PD) randomized to receive 10 mg selegiline per day and L-dopa compared with those taking L-dopa alone. Recently, we found that therapy with selegiline and L-dopa was associated with selective systolic orthostatic hypotension which was abolished by withdrawal of selegiline. This unwanted effect on postural blood pressure was not the result of underlying autonomic failure. The aims of this study were to confirm our previous findings in a separate cohort of patients and to determine the time course of the cardiovascular consequences of stopping selegiline in the expectation that this might shed light on the mechanisms by which the drug causes orthostatic hypotension.

METHODS

The cardiovascular responses to standing and head-up tilt were studied repeatedly in PD patients receiving selegiline and as the drug was withdrawn.

RESULTS

Head-up tilt caused systolic orthostatic hypotension which was marked in six of 20 PD patients on selegiline, one of whom lost consciousness with unrecordable blood pressures. A lesser degree of orthostatic hypotension occurred with standing. Orthostatic hypotension was ameliorated 4 days after withdrawal of selegiline and totally abolished 7 days after discontinuation of the drug. Stopping selegiline also significantly reduced the supine systolic and diastolic blood pressures consistent with a previously undescribed supine pressor action.

CONCLUSION

This study confirms our previous finding that selegiline in combination with L-dopa is associated with selective orthostatic hypotension. The possibilities that these cardiovascular findings might be the result of non-selective inhibition of monoamine oxidase or of amphetamine and metamphetamine are discussed.