Assessment of sleepiness and unintended sleep in Parkinson's disease patients taking dopamine agonists.

OBJECTIVE: We sought to determine if patients with Parkinson's disease (PD), taking dopamine agonists (DAs) and reporting unintended sleep episodes (SEs), exhibit physiologically defined daytime sleepiness and can thus be differentiated from those taking DAs but not reporting SEs. METHODS: Twenty-four patients with abnormal Epworth Sleepiness Scale scores of >10 who were taking DAs were enrolled into one of two groups: those with SEs (SE+, n=16) and those without (SE-, n=8). Three consecutive days of testing included two nights of polysomnography followed by the Multiple Sleep Latency Test (MSLT). RESULTS: Overall frequency of pathological sleepiness (MSLT <5 min) was 42% (10/24). Mean levels of sleepiness, frequencies of pathological sleepiness, and naps with stage 2 or REM-sleep were similar between SE+ and SE- groups. Sleep tendency was similar in patients prescribed pergolide, ropinirole, and pramipexole combined with levodopa. Polysomnography testing revealed no significant differences between the groups in total sleep time, sleep efficiency, sleep architecture, or presence of restless legs syndrome or periodic leg movements. There was no relation between degree of nocturnal sleep disturbance and level of daytime sleepiness. CONCLUSIONS: The results of this study suggest SEs in PD patients occur upon a background of excessive daytime sleepiness and are unrelated to nocturnal sleep or use of a specific DA.

Multiple risk factors for Parkinson's disease.

OBJECTIVE: To determine the relative contribution of various risk factors to the development of Parkinson's disease (PD). METHODS: Ten variables that were independently associated with PD in a health system population-based case-control study of epidemiological risk factors for the disease were jointly assessed. Stepwise logistic regression, adjusted for sex, race and age was used to develop a multiple variate model that best predicted the presence of PD. The population attributable risk was estimated for each variable in the final model, as well as for all factors together. RESULTS: The 10 initial variables included >20 years occupational exposure to manganese or to copper, individually; >20 years joint occupational exposure to either lead and copper, copper and iron, or lead and iron; a positive family history of PD in first- or second-degree relatives; occupational exposure to insecticides or herbicides; occupational exposure to farming; and smoking. Logistic regression resulted in a final model that included >20 years joint occupational exposure to lead and copper (p=0.009; population attributable risk [PAR]=3.9%), occupational exposure to insecticides (p=0.002; PAR=8.1%), a positive family history of PD in first- and second-degree relatives (p=0.001; PAR=12.4%), and smoking

Effects of task structure on category priming in patients with Parkinson's disease and in healthy individuals.

Lexical decision tasks have been used to study both shifts of attention and semantic processing in Parkinson's Disease (PD). Whereas other laboratories have reported normal levels of semantic priming among PD patients, our laboratory has reported abnormally large levels. In this study, two experiments were performed to determine the influence of task structure on the extent of semantic priming during lexical decision-making and pronunciation tasks among PD patients and neurologically healthy controls. In Experiment 1, the effect of Prime Dominance (the ratio of category to neutral trials) on lexical decision-making was studied. Although equal numbers of word and nonword trials were presented, half of the PD patients and controls were studied under Category Prime Dominance (category : neutral prime ratio of 2:1) and half were studied under Neutral Prime Dominance (category : neutral prime ratio of 1:2). In Experiment 2, PD and control participants were studied on lexical decision-making and pronunciation tasks where twice as many words as nonword trials were presented, consistent with other studies from our laboratory. In Experiment 1, we found no group differences in the magnitude of priming and no effect of Prime Dominance. Moreover, the findings were similar in pattern and magnitude to results published by Neely (1977). In Experiment 2, we observed larger priming effects among PD patients than among controls, but only on the lexical decision (LD) task. These results support the hypothesis that abnormally large category-priming effects appear in LD studies of PD patients when the number of word trials exceeds the number of nonword trials. Furthermore, increased lexical priming in PD appears to be due to processes operating during the decision-making period that follows presentation of the lexical target.