Excessive daytime sleepiness in Parkinson disease: is it the drugs or the disease?

Effect of chronic kidney disease on excessive daytime sleepiness in Parkinson disease

BACKGROUND AND PURPOSES

Excessive daytime sleepiness (EDS) is a common sleep disorder in patients with Parkinson disease (PD). Non-ergot dopamine agonists increase the risk of unanticipated sleep episodes.

OBJECTIVE

  We aimed to assess the influence of renal function on EDS in patients with PD.

METHODS

Sixty-two patients treated with ropinirole or pramipexole were recruited for this study. We evaluated the historical and clinical characteristics including the motor symptom rating scales, Epworth Sleepiness Scale (ESS), and estimated glomerular filtration rate (eGFR). An ESS score of 10 or greater was defined as EDS. Participants with eGFR < 60 ml/min/1.73 m(2) were determined to have chronic kidney disease (CKD). Multiple logistic regression analysis was performed to determine the predictive factors of EDS.

RESULTS

Chronic kidney disease was found to be a significant predictive factor for EDS in all patients (P = 0.014). We observed a negative correlation between the severity of daytime sleepiness and renal function in patients treated with pramipexole alone (r(s) = -0.637, P < 0.001).

CONCLUSIONS

Chronic kidney disease may be a risk factor for EDS, especially in patients treated with pramipexole, which is directly excreted in the urine.

Anxiety and depression severity are related to right but not left onset Parkinson's disease duration

Depression and anxiety have both been associated with relative left frontal hypoactivation and the motor symptoms of Parkinson's disease typically begin in a lateral or asymmetrical fashion. Hence, PD patients with right hemibody onset may experience heightened depression and anxiety. However, research is mixed regarding whether right or left hemibody onset PD is associated with elevated levels of depression and anxiety. This literature, though, has not considered the potential moderating variable of disease duration. We hypothesized that disease duration would be positively correlated with measures of depression and anxiety in right but not left hemibody onset PD patients. The results indicated that scores on the Geriatric Depression Scale, Beck Depression Inventory-II, and the State Trait Anxiety Scale - State correlated positively with disease duration, but only in the right hemibody onset group of PD patients. Thus, right hemibody onset PD is associated with more severe depressive and anxiety symptoms, but only when disease duration is considered.

How well do we recognise non-motor symptoms in a British Parkinson's disease population?

Although awareness of non-motor symptoms in Parkinson's disease (PD) has recently increased, little is known about their recognition and treatment in routine clinical practice. We therefore applied non-motor rating scales for dementia, depression, anxiety and excessive daytime sleepiness to a community-ascertained cohort of 202 PD patients. Hospital case notes were reviewed for evidence that the non-motor problems had been recognized and whether any action had been taken to ameliorate or assess these symptoms. The prevalence of each non-motor problem was as follows: dementia 25.3% (95% CI 19.0, 32.4), depression 37.3% (95% CI 30.6, 44.4), anxiety 31.3% (95% CI 25.0, 38.2), excessive daytime sleepiness 59.4% (95% CI 52.2, 66.3). However, these features were only recognised in 27.2, 38.7, 9.5, and 12.8%, respectively. We did not identify any specific factor that predicted under-recognition. Our study shows that when rating scales are applied to formally assess for non-motor symptoms a large clinical 'iceberg effect' emerges with the majority of symptoms going unrecognised and untreated.

Excessive daytime sleepiness in patients with Parkinson's disease

Excessive daytime sleepiness (EDS) is described as inappropriate and undesirable sleepiness during waking hours and is a common non-motor symptom in Parkinson's disease, affecting up to 50% of patients. EDS has a large impact on the quality of life of Parkinson's disease patients as well as of their caregivers, in some cases even more than the motor symptoms of the disease. Drug-induced EDS is a particular problem as many dopamine agonists used for the treatment of Parkinson's disease have EDS as an adverse effect. Dopaminergic treatment may also render a subset of Parkinson's disease patients at risk for sudden-onset sleep attacks that occur without warning and can be particularly hazardous if the patient is driving. This demonstrates the need for early recognition and management not only to increase health-related quality of life but also to ensure patient safety. There are many assessment tools for EDS, including the Epworth Sleepiness Scale (ESS) and the Multiple Sleep Latency Test (MSLT), although only the Parkinson's Disease Sleep Scale (PDSS) and the SCales for Outcomes in PArkinson's Disease-Sleep (SCOPA-S) are specifically validated for Parkinson's disease. Polysomnography can be used when necessary. Management comprises non-pharmacological and pharmacological approaches. Non-pharmacological approaches can be the mainstay of treatment for mild to moderate EDS. Advice on good sleep hygiene is instrumental, as pharmacological approaches have yet to provide consistent and reliable results without significant adverse effects. The efficacy of pharmacological treatment of EDS in Parkinson's disease using wakefulness-promoting drugs such as modafinil remains controversial. Further areas of research are now also focusing on adenosine A(2A) receptor antagonists, sodium oxybate and caffeine to promote wakefulness. A definitive treatment for the highly prevalent drug-induced EDS has not yet been found.

Evaluation and management of the non-motor features of Parkinson's disease

Parkinson's disease (PD) is traditionally viewed as a motor disorder with a characteristic triad of tremor, rigidity and bradykinesia. There is now increasing awareness that PD is a complex systemic disorder with many nonmotor symptoms (NMS) which include autonomic dysfunction, sleep disorders, sensory and neuropsychiatric features. NMS become more common in severity and frequency with advancing disease when neuropsychiatric features such as cognitive impairment and psychosis dominate the clinical picture. NMS are strongly correlated with quality of life for patients and their families as well as institutional care placement. Despite their importance, NMS are poorly recognized by clinicians and often undeclared by patients. Use of a validated screening tool NMSQuest followed by specific symptom assessment instruments strengthens the recognition and holistic management of NMS in PD. Some NMS such as mood disturbance, anxiety, pain and insomnia may be improved by optimization of dopaminergic therapy. Conversely, psychosis, excess daytime somnolence or impulse control disorder (ICD) may be triggered by dopaminergic drugs. Other NMS such as dementia and severe depression may be unresponsive to dopaminergic treatment and may reflect perturbations in cholinergic, serotonergic or noradrenergic neurotransmitter function. These symptoms are more challenging to manage but may be ameliorated to some extent by agents such as acetylcholinesterase inhibitor or antidepressant drugs. This contribution reviews the evidence for the evaluation and management of key NMS in PD (apathy, anxiety, depression, psychosis, dementia, ICD, sleep disturbance, autonomic dysfunction, pain) and highlights the urgent need for both novel therapies and more controlled trials for current therapeutic strategies.

Exercise alleviates Parkinsonism: clinical and laboratory evidence

The present review examines the putative benefits for individuals afflicted with Parkinsonism, whether in the clinical setting or in the animal laboratory, accruing from different exercise regimes. The tendency for patients with Parkinson's disease (PD) to express either normal or reduced exercise capacity appears regulated by factors such as fatigue, quality-of-life and disorder severity. The associations between physical exercise and risk for PD, the effects of exercise on idiopathic Parkinsonism and quality-of-life, the effects of exercise on animal laboratory models of Parkinsonism and dopamine (DA) loss following neurotoxic insults, and the effects of exercise on the DA precursor, L-Dopa, efficacy are examined. It would appear to be case that in view of the particular responsiveness of the dopaminergic neurons to exercise, the principle of 'use it or lose' may be of special applicability among PD patients.

Scales to assess sleep impairment in Parkinson's disease: critique and recommendations

There is a broad spectrum of sleep disturbances observed in Parkinson's disease (PD). A variety of scales have been applied to the evaluation of PD sleep and wakefulness, but only a small number have been assessed specifically for clinimetric properties in the PD population. The movement disorder society has commissioned this task force to examine these scales and to assess their use in PD. A systematic literature review was conducted to explore the use of sleep scales in PD and to determine which scales qualified for a detailed critique. The task force members, all of whom have extensive experience in assessing sleep in PD reviewed each of the scales using a structured proforma. Scales were categorized into recommended, suggested and listed according to predefined criteria. A total of 48 potential scales were identified from the search and reviewed. Twenty-nine were excluded because they did not meet review criteria or were variations of scales already included, leaving 19 scales that were critiqued and rated by the task force based on the rating criteria. Only six were found to meet criteria for recommendation or suggestion by the task force: the PD sleep scale (PDSS) and the Pittsburgh sleep quality index (PSQI) are recommended for rating overall sleep problems to screen and to measure severity, the SCOPA-sleep (SCOPA) is recommended for rating overall sleep problems both to screen and to measure severity, and for rating daytime sleepiness; the Epworth sleepiness scale (ESS) is recommended for rating daytime sleepiness to screen and to measure severity; the inappropriate sleep composite score (ISCS) is suggested for rating severe daytime sleepiness or sleep attacks to screen and to measure severity; and the Stanford sleepiness scale (SSS) is suggested for rating sleepiness and to measure severity at a specific moment. The task force does not recommend the development of new scales, but emphasizes the need for educational efforts to train physicians in sleep interview techniques and polysomnography.

Role of dopamine receptor agonists in the treatment of early Parkinson's disease

In the last two decades, the usefulness of dopamine receptor agonists in the symptomatic treatment of Parkinson' disease (PD) has been demonstrated in many randomized controlled clinical trials. The initial role of such compounds as an adjunctive therapy to L-dopa to improve motor fluctuations has now expanded to the treatment of early PD as initial monotherapy. The rationale for the use of dopamine receptor agonists in early disease is to delay or reduce the incidence of motor complications resulting from long-term L-dopa therapy, probably by virtue of less pulsatile stimulation of postsynaptic dopamine receptors. Indeed, controlled trials with both ergot and non-ergot dopamine receptor agonists, such as cabergoline, pergolide, pramipexole and ropinirole, have shown lower risk of motor fluctuations and dyskinesias than with L-dopa, when used as monotherapy in early PD patients. The benefit of agonists in preventing motor complications is, however, balanced by a smaller effect on motor symptoms compared with L-dopa. Moreover, a greater incidence of side-effects, particularly somnolence, hallucinations and leg oedema, occurs with dopamine receptor agonists. Because of the risk of fibrotic reactions, ergot derivatives (bromocriptine, cabergoline, and pergolide) are not recommended as first-line antiparkinsonian medication. In younger patients, who are usually more prone to developing L-dopa-induced motor complications, the initial treatment with dopamine receptor agonists can be recommended. Further pharmacological refinement of PD management with these drugs may result from new formulations of old drugs, such as once-daily prolonged-release ropinirole, or new agonists, such as the rotigotine patch, that can allow more continuous dopaminergic stimulation and improve patient compliance with the drug treatment. Theoretically, another advantage of dopamine receptor agonists is the potential for a neuroprotective effect, through many different mechanisms of actions. Preliminary controlled trials with pramipexole and ropinirole, although encouraging, did not provide conclusive proof of the disease-modifying effect of dopamine receptor agonists; large controlled clinical trials are now underway and results are expected soon.

Cerebrospinal hypocretin, daytime sleepiness and sleep architecture in Parkinson's disease dementia

Excessive daytime sleepiness is common in Parkinson's disease and has been associated with Parkinson's disease-related dementia. Narcoleptic features have been observed in Parkinson's disease patients with excessive daytime sleepiness and hypocretin cell loss has been found in the hypothalamus of Parkinson's disease patients, in association with advanced disease. However, studies on cerebrospinal fluid levels of hypocretin-1 (orexin A) in Parkinson's disease have been inconclusive. Reports of sleep studies in Parkinson's disease patients with and without excessive daytime sleepiness have also been disparate, pointing towards a variety of causes underlying excessive daytime sleepiness. In this study, we aimed to measure cerebrospinal fluid hypocretin-1 levels in Parkinson's disease patients with and without dementia and to study their relationship to dementia and clinical excessive daytime sleepiness, as well as to describe potentially related sleep architecture changes. Twenty-one Parkinson's disease patients without dementia and 20 Parkinson's disease patients with dementia, along with 22 control subjects without sleep complaints, were included. Both Epworth sleepiness scale, obtained with the help of the caregivers, and mini-mental state examination were recorded. Lumbar cerebrospinal fluid hypocretin-1 levels were measured in all individuals using a radio-immunoassay technique. Additionally, eight Parkinson's disease patients without dementia and seven Parkinson's disease patients with dementia underwent video-polysomnogram and multiple sleep latencies test. Epworth sleepiness scale scores were higher in Parkinson's disease patients without dementia and Parkinson's disease patients with dementia than controls (P < 0.01) and scores >10 were more frequent in Parkinson's disease patients with dementia than in Parkinson's disease patients without dementia (P = 0.04). Cerebrospinal fluid hypocretin-1 levels were similar among groups (controls = 321.15 +/- 47.15 pg/ml; without dementia = 300.99 +/- 58.68 pg/ml; with dementia = 309.94 +/- 65.95 pg/ml; P = 0.67), and unrelated to either epworth sleepiness scale or mini-mental state examination. Dominant occipital frequency awake was slower in Parkinson's disease patients with dementia than Parkinson's disease patients without dementia (P = 0.05). Presence of slow dominant occipital frequency and/or loss of normal non-rapid eye movement sleep architecture was more frequent among Parkinson's disease patients with dementia (P = 0.029). Thus, excessive daytime sleepiness is more frequent in Parkinson's disease patients with dementia than Parkinson's disease patients without dementia, but lumbar cerebrospinal fluid hypocretin-1 levels are normal and unrelated to severity of sleepiness or the cognitive status. Lumbar cerebrospinal fluid does not accurately reflect the hypocretin cell loss known to occur in the hypothalamus of advanced Parkinson's disease. Alternatively, mechanisms other than hypocretin cells dysfunction may be responsible for excessive daytime sleepiness and the sleep architecture alterations seen in these patients.

Sharpening the boundaries of Parkinson-associated dementia: recommendation for a neuropsychological diagnostic procedure

Older adults suffering from Parkinson's disease (PD) frequently present with an additional form of severe neurodegenerative and/or vascular pathology. Findings of differential clinical manifestations of cognitive impairment, depending on presence and nature of such coexisting brain pathology, raise the question for neuropsychological procedures that are capable not only of distinguishing between non-demented PD patients and patients with Parkinson-associated dementia (PDD), but also of detecting other types of cognitive decline, most likely Alzheimer's disease (AD) or vascular dementia (VD), superimposing PD. The aim of this article is to review the literature on neuropsychological processes at risk in developing PDD, to introduce comorbid causes of cognitive decline in the presence of PD, to discuss the scope of the "cortical versus subcortical dementia"-concept in view of its capability of differentiating dementias, and to scrutinize existing diagnostic criteria concerning the toleration of comorbidity. Additionally, we derive an evidence-based neuropsychological diagnostic procedure for assessing PDD under special consideration of these comorbid aspects.

TNF-NF-kappaB signaling mediates excessive somnolence in hemiparkinsonian rats

Daytime somnolence is common in patients with Parkinson's disease (PD); however there is a lack of understanding of the cellular mechanisms involved in mediating these effects. It has been hypothesized that microglial activation and the subsequent increase of pro-inflammatory cytokines play an important role in the pathogenesis of PD. Because some cytokines are involved in the regulation of sleep, this study was designed to determine if tumor necrosis factor (TNF) and interleukin-1beta (IL-1beta), mediate daytime somnolence in the proteasome inhibitor (MG-132)-induced hemiparkinsonian rat model. Our results indicated that microglial activation caused the loss of dopaminergic neurons in the substantia nigra, and the expression of TNF-alpha, but not IL-1beta, increased in the midbrain and hypothalamus in MG-132-induced hemiparkinsonian rats. Slow-wave sleep (SWS) increased after the induction of hemiparkinsonism, but rapid eye movement (REM) sleep was not consistently altered. Application of the TNF receptor fragment (TNFRF) blocked hemiparkinsonism-induced SWS alteration, whereas the IL-1 receptor antagonist (IL-1ra) exhibited no effect. Increased nuclear translocation of NF-kappaB in the midbrain, and the blockade of SWS enhancement in MG-132-induced hemiparkinsonian rats by an inhibitor of NF-kappaB activation indicate that the TNF-NF-kappaB cascade is a critical mediator of MG-132 hemiparkinsonian-induced sleep alteration. This observation suggests potential therapeutic interventions to target the excessive daytime somnolence in patients with PD.

Sleep disturbances in Malaysian patients with Parkinson's disease using polysomnography and PDSS

BACKGROUND

Sleep disturbances such as sleep fragmentation, sleep disordered breathing (SDB), periodic limb movements (PLM), excessive daytime somnolence (EDS) and insomnia are prevalent in Parkinson's disease (PD). However, studies in the Asian population are limited.

METHODS

This was a cross-sectional study involving 46 Malaysians with PD using polysomnography (PSG) and standardized translated Parkinson's disease sleep scale (PDSS). Overnight PSG recordings, UPDRS and PDSS scores, and baseline demographic data were obtained.

RESULTS

Data from 44 patients were analysed. Thirty-six patients (81.8%) had PSG-quantified sleep disorders. Twenty-three (52.3%) had sleep fragmentation, 24 (54.6%) had SDB and 14 (32%) had PLM. EDS was present in 9.1%. Insomnia was reported by 31.8%. Patients with sleep fragmentation had significantly higher UPDRS scores and lower PDSS insomnia sub-scores. The UPDRS scores correlated negatively with the TST and sleep efficiency. All patients with EDS had SDB (p=0.056). The PDSS insomnia sub-items correlated with sleep fragmentation on PSG.

CONCLUSION

: The prevalence of sleep disorders based on PSG and PDSS in our PD patients was high, the commonest being sleep fragmentation and SDB, while EDS was the least prevalent. Problem specific sub-items of the PDSS were more accurate in predicting the relevant PSG-related changes compared to the PDSS as a whole.

Mild cognitive impairment is common in Parkinson's disease patients with normal Mini-Mental State Examination (MMSE) scores

PURPOSE

Cognitive impairment occurs in the majority of Parkinson's disease (PD) patients, but little is known about detection of mild cognitive impairment (MCI) in this population. We report on the frequency and characteristics of cognitive deficits in PD patients with intact global cognition based on Mini-Mental State Examination (MMSE) performance.

METHODS

One hundred and six PD patients with normal age- and education-adjusted MMSE scores (mean [SD] score=29.1 [1.1]) were administered standardized neuropsychological tests assessing memory, executive function, and attention. Impairment on a cognitive domain was a low score (i.e., >or=1.5 SD below the published normative mean) on at least two measures or tests (for memory and executive abilities) or a single measure (for attention).

RESULTS

Mild cognitive impairment was found in 29.2% of PD patients, with 17.9% demonstrating single domain and 11.3% multiple domain impairment. Memory and attention impairment were most common (15.1% and 17.0%, respectively), followed by executive impairment (8.5%). Depending on the measure of disease severity chosen, increasing age and disease severity, anti-anxiety medication use, and a suggestion for increasing severity of daytime sleepiness were independent predictors of cognitive impairment.

CONCLUSIONS

Cognitive deficits are common in PD patients with "normal" cognition based on MMSE performance, suggesting that MCI is under-recognized in clinical practice due to routine use of insensitive screening instruments. In contrast with some previous reports, early memory impairment may be as common as either executive or attentional deficits in PD. In addition, psychiatric medication use and daytime sleepiness may be reversible or treatable contributors to cognitive impairment.

Fatigue in Parkinson's disease is not related to excessive sleepiness or quality of sleep

OBJECTIVES

Many patients with Parkinson's disease (PD) suffer from non-motor symptoms like sleep disturbances, excessive daytime sleepiness and fatigue. The aim of our research was to explore whether fatigue is related to sleepiness and sleep problems, depression and functional status, controlled for age, gender and disease duration.

METHODS

The sample consisted of 78 PD patients from Eastern Slovakia (52% males, mean age 68.8+/-8.7, mean disease duration 7.2+/-6.8). The Multidimensional Fatigue Inventory (5 dimensions), the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, Hospital Anxiety and Depression Scale and the Unified Parkinson's Disease Rating Scale were used. Demographic data were obtained in a structured interview. Multiple linear regression was used to analyse the data.

RESULTS

Sleepiness did not show significant association with fatigue in any of the fatigue domains; neither did quality of sleep. Depression was significantly associated with all domains of fatigue, the strongest being the relationship with general fatigue (beta .42), reduced motivation (beta .39), mental fatigue (beta .35) (p<.001), and physical fatigue (beta .31) (p<.01), while the relationship with reduced activity was less strong (beta .22) (p<.05). Worse functional status was significantly related to reduced activity (beta .50), general fatigue (beta .35), physical fatigue (beta .35), and mental fatigue (beta .35) (p<.001).

CONCLUSION

Fatigue is not related to daytime sleepiness or night-time sleep dysfunction. Fatigue is more strongly influenced by the presence of depression and worse functional status.

Sleep disorders associated with Parkinson's disease: role of dopamine, epidemiology, and clinical scales of assessment

Sleep dysfunction is common among patients with Parkinson's disease and occurs in approximately two thirds of patients. The problems range from nocturnal issues such as difficulty with sleep initiation, sleep fragmentation, disturbance of circadian rhythm, and rapid eye movement sleep behavior disorder, to daytime problems such as excessive daytime sleepiness. Frequent nighttime awakening and sleep disruption are the most common sleep problems in Parkinson's disease. Dopamine plays an important role in maintaining wakefulness. To improve sleep in Parkinson's disease, it is important to achieve the critical balance of adequate dopaminergic therapy and control of symptoms. Increased dopaminergic agents can cause dyskinesias and painful dystonia, and undertreatment can cause nighttime akinesia, rigidity, and worse quality of sleep. Other nondopaminergic drugs commonly used in Parkinson's disease can also affect sleep. In patients with advanced Parkinson's disease, deep brain stimulation of the subthalamic nucleus has a favorable impact on sleep quality and sleep architecture.

Restless Legs Syndrome

Restless legs syndrome is a symptomatic urge to move the legs, usually accompanied or caused by uncomfortable/ unpleasant sensations deep within the legs that begin or are worsened during periods of rest or inactivity in the evening or night and are partially or totally relieved by movement. It can occur intermittently or daily. Nonpharmacologic treatments include moderate exercise; good sleep hygiene; elimination of alcohol, caffeine, and nicotine; and hot baths, massage, and stretching. Activities promoting mental alertness may improve symptoms. Moderate exercise and use of nasal continuous positive airway pressure are the only nonpharmacologic treatments with proven benefit. For intermittent restless legs syndrome, carbidopa/levodopa and nonpharmacologic therapy are recommended as primary treatments. For daily restless legs syndrome, dopamine agonists, particularly ropinirole and pramipexole, are suggested as the drugs of choice. Carbidopa/levodopa could be considered for daily restless legs syndrome, but augmentation is a significant drawback to its use. Carbamazepine and gabapentin have limited data to support their use.

Intervening in the neuropsychiatric features of Parkinson's disease

Although Parkinson's disease is considered a movement disorder, it has a wide range and high prevalence of affective, psychotic, cognitive, behavioral and sleep-related features. To treat such features, agents including antidepressants, anxiolytics, antipsychotics and cognition-enhancing agents are commonly prescribed, although the targeted syndromes are often incompletely understood and controlled studies demonstrating a treatment's efficacy and tolerability in Parkinson's disease patients are often lacking. Nevertheless, the available information does suggest the outlines of management methods, pending expanded research to identify optimal strategies specific to Parkinson's disease.

Management of the behavioral aspects of Parkinson's disease

Parkinson's disease is a progressive and debilitating movement disorder that is diagnosed by its motor signs. The behavioral manifestations of Parkinson's disease are prevalent and frequently complicate the course of the disease. These may be due to the illness itself or its treatment and are often more disabling than the motor symptoms. This review focuses on the management of the most common behavioral symptoms of Parkinson's disease, including depression, anxiety, psychosis, dementia, delirium, sleep disorders, fatigue, apathy, emotionalism and compulsive behaviors.

Non-motor dysfunction in Parkinson's disease

In the field of neurology, Parkinson's disease (PD) is commonly perceived to be a disorder affecting only the (extrapyramidal) motor system, characteristically manifesting as bradykinesia, rigidity, tremor and postural instability. Although non-motor symptoms such as behavioural abnormalities, dysautonomia, sleep disturbances and sensory dysfunctions are also common and quite disabling manifestations of the disease, they are often not formally assessed and thus are frequently misdiagnosed and/or under diagnosed. For this reason, in this review we have concentrated on the pathophysiological and clinical basis of non-motor involvement such as olfactory dysfunction, depression, dementia, dysautonomia and sleep disorders in PD. The early recognition of these symptoms may well perhaps lead to an earlier diagnosis of PD, but in any case should lead to more prompt and effective treatment of the relatively unrecognized non-motor problems associated with PD.

A nationwide survey of excessive daytime sleepiness in Parkinson's disease in France

To determine the prevalence of excessive daytime sleepiness (EDS) and that of dozing and sudden onset of sleep episodes (SOS) while driving in ambulatory patients with Parkinson's disease (PD) in France, a national sample of private and public neurologists was asked to recruit the first 10 consecutive nondemented PD patients. Each patient completed a questionnaire including the Epworth Sleepiness Scale (ESS) and the likelihood of dozing off and experiencing SOS episodes behind the wheel. Clinical and demographic data were collected. One thousand six hundred and twenty-five patients with PD were included in the survey. Twenty-nine percent of the patients suffered from EDS (ESS score>or=10) but only 0.8% declared a high chance of dozing while driving and 0.5% reported totally unpredictable SOS episodes while driving. Risk factors for EDS were male gender, reduced activity of daily living, and a high daily levodopa equivalent dosage. Risk factors for SOS episodes while driving were an ESS score>or=10, male gender, and low Hoehn and Yahr staging. EDS is common in ambulatory patients with PD and is a major risk factor for dozing and for SOS episodes behind the wheel in patients who drive.