Only few studies have addressed driving ability in Parkinson's disease (PD) to date. However, studies investigating accident proneness of PD patients are urgently needed in the light of motor disability in PD and--particularly--the report of "sleep attacks" at the wheel. We sent a questionnaire about sudden onset of sleep (SOS) and driving behavior to 12,000 PD patients. Subsequently, of 6,620 complete data sets, 361 patients were interviewed by phone. A total of 82% of those 6,620 patients held a driving license, and 60% of them still participated in traffic. Of the patients holding a driving license, 15% had been involved in and 11% had caused at least one accident during the past 5 years. The risk of causing accidents was significantly increased for patients who felt moderately impaired by PD, had an increased Epworth Sleepiness Scale (ESS) score, and had experienced SOS while driving. Sleep attacks at the wheel usually occurred in easy driving situations and resulted in typical fatigue-related accidents. Those having retired from driving had a more advanced (subjective) disease severity, higher age, more frequently female gender, an increased ESS score, and a longer disease duration. The study revealed SOS and daytime sleepiness as critical factors for traffic safety in addition to motor disabilities of PD patients. The results suggest that real sleep attacks without any prior sleepiness are rare. However, our data underline the importance of mobility for patients and the need for further studies addressing the ability to drive in PD.

With respect to the ongoing discussion of "sleep attacks" in Parkinson's disease (PD), we sought to estimate the prevalence of sudden onset of sleep (SOS) with and without preceding sleepiness in PD, to identify associated factors, and to define the role of antiparkinsonian medication in SOS. We sent a questionnaire about SOS, sleep behaviour, and medication to 12,000 PD patients. The response rate was 63%, from which 6,620 complete data sets could be analysed. A total of 42.9% of our population reported SOS, 10% of whom never experienced sleepiness before the appearance of SOS (4.3% of all), and we identified the administration of all dopaminergic drugs as a risk factor for SOS. However, SOS occurred earlier after introduction of nonergoline dopamine agonists (DA) and was more strongly associated with nonergoline DA in younger patients (below 70 years) with a shorter disease duration (up to 7 years) but, actually, medication was less efficient in predicting SOS than most other factors considered such as higher age, male sex, longer disease duration, and the report of sleep disturbances. This survey strongly suggests that SOS is a multifactorial phenomenon. Some subgroups are at particular risk of experiencing SOS under nonergoline DA, especially at the beginning of this therapy. Our results support the current notion that SOS, in part, can be attributed to PD-specific pathology because disease duration and subjective disease severity have been shown to be predictors of SOS. We recommend the development of a standardised question to recognise SOS and to facilitate the comparison of prevalence estimates.

Genes encoding proteins involved in dopaminergic transmission are potential candidate genes for the induction of somnolence in Parkinson's disease (PD) because dopaminergic agents have been shown to be associated with sudden onset of sleep (SOS) in PD. We conducted an association study on dopamine D2, D3, and D4 receptor gene polymorphisms comparing 137 PD patients with SOS and 137 PD patients without SOS matched according to drug therapy, disease duration, sex, and age. Our results show a significant association between the dopamine D2 receptor gene polymorphism Taq IA and SOS in PD. No significant association between two other investigated polymorphisms and the phenomenon of "sleep attacks" in PD was observed.

Treatment standards or guidelines have been developed for most features of Parkinson's disease (PD). However, data on the actual treatment that is put into practice are scarce. In 2000, a nationwide survey on the topic of sudden onset of sleep (SOS) in PD was initiated among the members of the German patient support group (deutsche Parkinson-Vereinigung, dPV). A part of this mailed questionnaire survey covering the antiparkinsonian and concomitant medication of the participants is presented here. This study analyses data sets from more than 6,500 PD patients. The mean dopaminergic dose was equivalent to 599 +/- 387 mg levodopa/die. The most frequently administered drugs were levodopa (94.2 %), dopamine agonists (DA) (71.7 %), amantadine (40.1 %), selegiline (27.6 %), entacapone (20.4 %), budipine (12.3 %), and anticholinergics (11.8 %). Costs of pharmacotherapy were estimated to be approximately 399 million/year in Germany. PD drug therapy in general strongly depended on age, disease duration, and the level of care. The treatment guidelines were apparently not consistently followed underlining the need for their continuous propagation throughout the medical community. In addition our data suggest that non-motor symptoms in PD are not adequately treated and that concomitant sedative medication contributes to the occurrence of SOS.

Our results show a significant association between the (-909T/C) preprohypocretin polymorphism and sudden onset of sleep in Parkinson disease. However, we could not demonstrate any interaction between the Taq IA and (-909T/C) polymorphisms with respect to the occurrence of sudden onset of sleep, suggesting that multiple genetic factors may contribute to the pathogenesis of this phenomenon.