Effect of dopamine agonists on fatigue and somnolence in Parkinson's disease

Istradefylline for OFF Episodes in Parkinson’s Disease: A US Perspective of Common Clinical Scenarios

The effective management of OFF episodes remains an important unmet need for patients with Parkinson’s disease (PD) who develop motor complications with long-term levodopa therapy. Istradefylline is a selective adenosine A_2A receptor antagonist for the treatment of patients with PD experiencing OFF episodes while on levodopa/decarboxylase inhibitor. Originally approved in Japan, istradefylline was recently approved in the USA. In this article, we provide a specific review of the four clinical studies that the FDA included in the approval of istradefylline in the USA, and discuss common clinical scenarios, based on our experience, where treatment with istradefylline may benefit patients experiencing motor fluctuations.

A systematic review of the literature on disorders of sleep and wakefulness in Parkinson's disease from 2005 to 2015

Sleep disorders are among the most common non-motor manifestations in Parkinson's disease (PD) and have a significant negative impact on quality of life. While sleep disorders in PD share most characteristics with those that occur in the general population, there are several considerations specific to this patient population regarding diagnosis, management, and implications. The available research on these disorders is expanding rapidly, but many questions remain unanswered. We thus conducted a systematic review of the literature published from 2005 to 2015 on the following disorders of sleep and wakefulness in PD: REM sleep behavior disorder, insomnia, nocturia, restless legs syndrome and periodic limb movements, sleep disordered breathing, excessive daytime sleepiness, and circadian rhythm disorders. We discuss the epidemiology, etiology, clinical implications, associated features, evaluation measures, and management of these disorders. The influence on sleep of medications used in the treatment of motor and non-motor symptoms of PD is detailed. Additionally, we suggest areas in need of further research.

Nonmotor Effects of Conventional and Transdermal Dopaminergic Therapies in Parkinson's Disease

Nonmotor symptoms (NMS) are an integral component of Parkinson's disease (PD). Because the burden and range of NMS are key determinants of quality of life for patients and caregivers, their management is a crucial issue in clinical practice. Although a range of NMS have a dopaminergic pathophysiological basis, this fact is underrecognized, and thus, they are often regarded as dopamine unresponsive symptoms. However, substantial evidence indicates that many NMS respond to oral and transdermal dopaminergic therapies. In contrast, certain NMS are exacerbated or even precipitated by dopaminergic drugs and these unwanted effects may be seriously dangerous. Therefore, a dopaminergic strategy for NMS should be based on a consideration of the benefits vs the risks in individual patients with PD.

The Pathophysiology of Fatigue in Parkinson's Disease and its Pragmatic Management

BACKGROUND

Fatigue is 1 of the most common and most disabling symptoms among patients with Parkinson's disease (PD) and has a significant impact on their quality of life. Yet the pathophysiology of fatigue is poorly understood, while its treatment is "limited to an empirical approach based on plausible hypotheses."

METHODS

PubMed was searched for articles with the key words "Parkinson's disease" or "parkinsonism" and "fatigue" that were published by or before August 2015. The analysis of articles, which were selected on subjective grounds, was used to review the current knowledge of pathophysiology and treatment outcomes in studies focused on fatigue in PD.

CONCLUSIONS

Clinical and experimental findings support the view that fatigue is a primary manifestation of PD. The main hypothesized pathophysiological mechanisms include abnormal basal ganglia (BG)-cortical mechanisms, particularly frontal loops, and an imbalance between neurotransmitters (e.g., dopamine [DA] and serotonin), along with an altered hypothalamus-pituitary-adrenal axis, neuroinflammation, cardiac sympathetic denervation, etc. Pragmatic treatment of fatigue in patients with PD includes various pharmacological (dopaminergic and psychostimulant drugs, antidepressants) and nonpharmacological strategies, although current knowledge suffers from insufficient evidence to support the use of any drug or nondrug therapy.

Interventions for fatigue in Parkinson's disease

BACKGROUND

Factors contributing to subjective fatigue in people with idiopathic Parkinson's disease (PD) are not well known. This makes it difficult to manage fatigue effectively in PD.

OBJECTIVES

To evaluate the effects of pharmacological and non-pharmacological interventions, compared to an inactive control intervention, on subjective fatigue in people with PD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); MEDLINE (via PubMed); Ovid EMBASE; EBSCO CINAHL; Ovid PsycINFO; PEDro; and the WHO International Clinical Trials Registry Platform Search Portal up to April 2015. References of included studies and identified review articles were screened for additional studies. There were no restrictions based on language, date of publication or study setting.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that report on subjective fatigue in people with PD.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, data collection and risk of bias assessments.

MAIN RESULTS

Eleven studies were eligible for this systematic review, with a total of 1817 people. Three studies included only people who experienced clinically relevant fatigue (Fatigue Severity Scale score ≥ 4 out of 7 or Multidimensional Fatigue Inventory total score > 48 out of 100), whereas all other studies did not select participants on the basis of experienced fatigue. Nine studies investigated the effects of medication (i.e. levodopa-carbidopa, memantine, rasagiline, caffeine, methylphenidate, modafinil or doxepin) on subjective fatigue. All studies were placebo controlled. There was insufficient evidence to determine the effect of doxepin on the impact of fatigue on activities in daily life (ADL) or fatigue severity (one study, N = 12, standardised mean difference (SMD) = -1.50, 95% confidence interval (CI) -2.84 to -0.15; low quality evidence). We found high quality evidence that rasagiline reduced or slowed down the progression of physical aspects of fatigue (one study, N = 1176, SMD = -0.27, 95% CI -0.39 to -0.16, I(2) = 0%). None of the other pharmacological interventions affected subjective fatigue in PD. With regard to adverse effects, only levodopa-carbidopa showed an increase for the risk of nausea (one study, N = 361, risk ratio (RR) = 1.85, 95% CI 1.05 to 3.27; high quality evidence). Two studies investigated the effect of exercise on fatigue compared with usual care. We found low quality evidence for the effect of exercise on reducing the impact of fatigue on ADL or fatigue severity (two studies, N = 57, SMD = -0.45, 95% CI -1.21 to 0.32, I(2) = 44%).

AUTHORS' CONCLUSIONS

Based on the current evidence, no clear recommendations for the treatment of subjective fatigue in PD can be provided. Doxepin may reduce the impact of fatigue on ADL and fatigue severity; however, this finding has to be confirmed in high quality studies. Rasagiline may be effective in reducing levels of physical fatigue in PD. No evidence was found for the effectiveness of levodopa-carbidopa, memantine, caffeine, methylphenidate, modafinil or exercise. Studies are needed to investigate the effect of exercise intensity on exercise capacity and subjective fatigue. Future studies should focus on interventions that address the maladaptive behavioural or cognitive aspects of fatigue in people with PD. Characteristics, such as severity and nature of perceived fatigue and underlying mood disorders should be considered to identify responders and non-responders when studying interventions for fatigue. The development of a core-set of self-report fatigue questionnaires with established responsiveness and known minimal important difference values will facilitate the interpretation of change in fatigue scores.

Fatigue rating scales critique and recommendations by the Movement Disorders Society task force on rating scales for Parkinson's disease

Fatigue has been shown to be a consistent and common problem in Parkinson's disease (PD) in multiple countries and cultures. It is one of the most disabling of all symptoms, including motor dysfunction, and appears early, often predating the onset of motor symptoms. Several studies of the epidemiology of fatigue have been published, often using different scales, but few on treatment. The Movement Disorder Society (MDS) commissioned a task force to assess available clinical rating scales, critique their psychometric properties, summarize their clinical properties, and evaluate the evidence in support of their use in clinical studies in PD. Six clinical researchers reviewed all studies published in peer reviewed journals of fatigue in PD, evaluated the scales' previous use, performance parameters, and quality of validation data, if available. Scales were rated according to criteria provided by the MDS. A scale was "recommended" if it has been used in clinical studies beyond the group that developed it, has been used in PD and psychometric studies have established that it is a valid, reliable and sensitive to change in people with PD. Requiring a scale to have demonstrated sensitivity to change in PD specifically rather than in other areas in order to attain a rating of "recommended" differs from the use of this term in previous MDS task force scale reviews. "Suggested" scales failed to meet all the criteria of a "recommended" scale, usually the criterion of sensitivity to change in a study of PD. Scales were "listed" if they had been used in PD studies but had little or no psychometric data to assess. Some scales could be used both to screen for fatigue as well as to assess fatigue severity, but some were only used to assess severity. The Fatigue Severity Scale was "recommended" for both screening and severity rating. The Fatigue Assessment Inventory, an expanded version of the Fatigue severity Scale, is "suggested" for both screening and severity. The Functional Assessment of Chronic Illness Therapy-Fatigue was "recommended" for screening and "suggested" for severity. The Multidimensional Fatigue Inventory was "suggested" for screening and "recommended" for severity. The Parkinson Fatigue Scale was "recommended" for screening and "suggested" for severity rating. The Fatigue Severity Inventory was "listed" for both screening and severity. The Fatigue Impact Scale for Daily Use, an adaptation of the Fatigue Impact Scale was "listed" for screening and "suggested" for severity. Visual Analogue and Global Impression Scales are both "listed" for screening and severity. The committee concluded that current scales are adequate for fatigue studies in PD but that studies on sensitivity and specificity of the scales are still needed.

Fatigue in Parkinson disease, stroke, and traumatic brain injury

Fatigue is a serious, QoL-limiting symptom of many neurologic conditions. Physicians should be thorough and consistent in their assessment for this problem and not let motor symptoms monopolize an office visit. Although the use of pharmacology to treat this problem has predominantly only anecdotal evidence of efficacy, several nonpharmacologic interventions may prove helpful. The directions of future research should aim to create clear treatment guidelines using the pharmacologic agents available.

Physical and mental fatigue in Parkinson's disease: epidemiology, pathophysiology and treatment

Fatigue is one of the most common non-motor complaints of Parkinson's disease (PD) patients and is associated with reduced activity and poorer quality of life. Fatigue can be experienced as a state of being tired or weary (subjective fatigue) or as a process of becoming tired or fatigued (fatigability). Subjective mental and physical fatigue are evaluated using self-report questionnaires such as the Multidimensional Fatigue Inventory. Physical fatigability is studied in a laboratory setting using physical exercise protocols and transcranial magnetic stimulation. Mental fatigability is evaluated by measuring attention over time using a reaction-time paradigm called the Attention Network Test (ANT). PD patients report more subjective physical and mental fatigue than controls on a variety of fatigue questionnaires. PD patients have increased physical fatigability in force generation and finger tapping. Levodopa and modafinil improve physical fatigability in PD subjects. Methylphenidate is useful for treating subjective physical fatigue. PD subjects have greater mental fatigability than control subjects and display abnormal performance in all three attention networks in the ANT. Therapies targeting the neurotransmitter systems involved in attention may be helpful for treating mental fatigability. Future fatigue research should focus on developing gold standards for fatigue measurement and developing treatments for fatigue and fatigability in PD.