Three studies released today present possible positive news for people with Parkinson's disease. The studies, which will be presented at the American Academy of Neurology's 65th Annual Meeting in San Diego, March 16 to 23, 2013, report on treatments for blood pressure problems, the wearing-off that can occur when people have taken the main drug for Parkinson's for a long time, and for people early in the disease whose symptoms are not well-controlled by their main drugs.
"All of these treatments are promising news for people with Parkinson's disease, which is the second most common neurodegenerative disease after Alzheimer's disease," said Robert A. Hauser, MD, MBA, of the University of South Florida in Tampa and a Fellow of the American Academy of Neurology, who was an author of all three studies.
The first study dealt with the rapid drop in blood pressure that people with Parkinson's can experience when standing up, which can lead to dizziness, fainting and falls. The problem, which affects about 18 percent of people with the disease, occurs because the autonomic nervous system fails to respond to changes in posture by releasing enough of the chemical norepinephrine.
In the study, 225 people were randomized to receive either eight weeks of stable dose treatment with a placebo or the drug droxidopa, which converts to norepinephrine. After one week of stable treatment, those who received the drug had a clinically meaningful, two-fold decrease in the symptoms of dizziness and lightheadedness, when compared to placebo. They also had fewer falls, or 0.38 falls per patient per week, compared to 1.73 for those receiving a placebo on average over the entire 10-week study duration.
The second study looked at treatment with a new drug for "wearing-off" that occurs with people who have been taking levodopa for several years. As each dose wears off, people experience longer periods of time where the motor symptoms do not respond to levodopa. For the study, 420 people who were experiencing an average of six hours of "off" time per day received a placebo or one of four dosages of the drug tozadenant in addition to their levodopa for 12 weeks. People receiving two of the dosages of the drug had slightly more than an hour less off time per day at the end of 12 weeks than they had at the start of the study. They also did not have more troublesome involuntary movements during their "on" time, called dyskinesia, that can occur.
The third study looked at 321 people with early Parkinson's disease whose symptoms were not well-controlled by a dopamine agonist drug. For the 18-week study, the participants took either the drug rasagiline or a placebo in addition to their dopamine agonist. At the end of the study, those taking rasagiline had improved by 2.4 points on a Parkinson's disease rating scale. In addition, rasagiline was well tolerated with adverse events similar to placebo.
Explore further: Investigational drug may reduce involuntary movements