Why is this study important?
Many people with Parkinson’s disease (PD) have unusually severe sleepiness during the day. This is called excessive daytime sleepiness or EDS. The underlying cause of the sleepiness is not known but is likely due to many factors. Sleepiness may lead to problems at work, decreased enjoyment of social activities, and an increased risk of having a motor vehicle accident. Two previous studies showed an improvement in EDS in patients with PD with the use of modafinil (Provigil^®), a drug that has been approved by the US Food and Drug Administration for the treatment of narcolepsy.
 
Who took part in the study and what did they do?
All patients who were seen at the Baylor College of Medicine movement disorders clinic were invited to participate in the study if they met all of the following criteria
·        Had a diagnosis of PD
·        Were between the ages of 35 and 80
·        Had a score of 10 or higher on the Epworth Sleepiness Scale
 
When first enrolled in the study, patients completed a variety of questionnaires, including a quality-of-life survey, a depression survey, a sleep survey, and the Epworth Sleepiness Scale. They also kept an on-off diary, which evaluated their motor symptoms of PD. In addition, they underwent a Multiple Sleep Latency Test.
 
Patients were randomly assigned to take either placebo or 100 mg of modafinil in the morning and at noon for one week and then placebo or 200 mg of modafinil in the morning and at noon for one more week. If, they had unbearable side effects, patients could choose to go back to the lower dose. Patients continued the treatment for two additional weeks and then returned to the clinic and repeated the assessments. 
 
Who were the researchers and what did they do?
Dr. William Ondo and his colleagues in the movement disorders clinic at the Baylor College of Medicine in Houston, Texas, examined each of the patients when the patients enrolled in the study and again at the end of the study. They assessed the severity of the PD and assigned a score based on the Unified Parkinson Disease Rating Scale. The researchers analyzed the patients’ Epworth Sleepiness Scale scores and Multiple Sleep Latency Tests after treatment with placebo or modafinil and compared them with the results before treatment (baseline) to see if there were any differences.   
 
What were the results?
Forty patients initially signed up to participate in the study, but two men in the placebo group dropped out for personal reasons and one woman in the modafinil group dropped out at the urging of her primary care doctor because she was experiencing back pain. The patients had a mean Epworth Sleepiness Scale score of 15.85 at baseline, indicating that they had severe daytime sleepiness. At the end of the study, the researchers found no meaningful difference in the change in the Epworth Sleepiness Scale scores of the patients who were taking modafinil, as compared with those taking placebo, but some individual patients did have some benefit. There were also no differences between any of the other measures, including the surveys, the Multiple Sleep Latency Test, or the scores on the Unified Parkinson Disease Rating Scale.
 
What was the authors’ conclusion?
“Our results do not support the efficacy of modafinil (400 mg/day in divided doses) for daytime somnolence in PD. The drug, however, was very well tolerated and had an immediate effect, and individual patients did benefit from taking it.”
 
This study was funded by Cephalon Pharmaceuticals, the manufacturer of Provigil.

Ondo WG, Fayle R, Atassi F, Jankovic J. Modafinil for daytime somnolence in Parkinson’s disease: double blind, placebo controlled parallel trial. J Neurol Neurosurg Psychiatry 2005;76:1636-1639.