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News in Brief
A recent study makes the observation that REM sleep behavior disorder can be the first sign of Parkinson’s disease (PD) for some people, and can actually precede the onset of the classic motor symptoms — such as tremor, stiffness or slowness of movement — by more than a decade. The research appears in the July 28, 2010 online edition of the journal Neurology.
REM is the abbreviation for the “Rapid Eye Movement” phase of sleep when dreaming occurs. REM sleep behavior disorder, or RBD, is a sleep disturbance in which violent dreams or nightmares are acted out by the sleeper. The dreamer may scream or yell in his or her sleep, or engage in violent movements as if enacting a fight or attempting to run from an assailant. In most cases, the sleeper has no recollection later of the nocturnal violence; but for the bed partner, the experience can be frightening. RBD has been linked to Parkinson’s disease and other Parkinson syndromes, especially diffuse Lewy body disease.
Researcher Bradley F. Boeve, M.D., at the Mayo Clinic in Rochester, MN, was prompted to study the long-term course of REM behavior disorder after learning of people living with Parkinson’s who mentioned experiencing their RBD symptoms for decades. In a retrospective study using the clinic’s extensive medical records, the investigators sought to find persons with Parkinson’s who reported vivid dreams many years before they developed the disease.
- In reviewing 550 medical records of people with REM behavior disorder and Parkinson’s and related disorders:
- 27 individuals, or nearly five percent, had vivid dream enactment that preceded any diagnosis of Parkinson’s by 15 years or more.
- Most of these individuals were men.
- Most developed a form of dementia related to Parkinson’s.
What Does it Mean?
These results indicate that the processes that lead to PD may begin decades before motor or cognitive symptoms develop, much longer than previously believed. Knowing this may help doctors in the future to identify people in the early stages of Parkinson’s and to develop therapies that could slow down or stop the progression of the disease before symptoms appear. The study does not mean that all persons with RBD will develop Parkinson’s because the study population was pre-selected on the basis of already having PD. If REM behavior disorder is the first sign of Parkinson’s in some individuals, the implication is that the biological changes of the disease begin earlier than expected.
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A new study links relatively high blood levels of vitamin D with a reduced risk of developing Parkinson’s disease (PD). The research was published in the July 2010 issue of Archives of Neurology.
Vitamin D helps the body to absorb calcium and to keep bones strong. Sources of vitamin D include sunlight and certain foods. Studies have suggested that low levels of vitamin D increase the risk of PD as well as other chronic diseases. In fact, people diagnosed with PD tend to exhibit low vitamin D levels.
In this new study, Paul Kneckt, D.P.H., and colleagues at the National Institute for Health and Welfare in Helsinki, Finland, performed the first long-term investigation into the relationship between vitamin D levels and the incidence of PD. They studied blood samples drawn from nearly 3,200 healthy men and women in Finland between 1978 and 1980 as part of a national health survey.
At that time, participants were between ages 50 and 79. By 2007, 50 of the participants had developed Parkinson’s. Researchers thawed the blood samples, analyzed vitamin D levels, and assessed any relationship to PD.
- People with the highest levels of vitamin D had a 65 percent lower risk of developing Parkinson’s than those with the lowest levels.
What Does it Mean?
The authors offer the hypothesis that low levels of vitamin D may be directly or indirectly associated with a greater risk of developing PD. More study is needed to understand the role of vitamin D in PD. This study and others cannot prove that exposure to a vitamin can protect against PD. Vitamin D requires sunlight for its production but the participants of the current study in Finland had much less exposure to sunlight than do most people in the United States. This study highlights the importance of maintaining adequate levels of vitamin D; people with PD are advised to talk to their doctors about the necessity of supplementation and appropriate dosages.
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A multicenter, randomized and blinded clinical trial reported in the June 3, 2010, issue of the New England Journal of Medicine, has found only a minimal difference between two alternative brain targets in the effectiveness of deep brain stimulation (DBS), which is a surgical intervention for Parkinson’s disease (PD).
The study is the largest to date to examine the two targets in the brain — the subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi). The research team, led by Kenneth Follet, M.D., Ph.D., of the Iowa City Veteran Affairs Administration, arranged for half of the 299 participants to undergo surgery at each of the two targets. Neurologists assessed PD symptoms of all participants every three months for two years.
- Participants who underwent STN stimulation and those who underwent GPi stimulation experienced equal benefit, as measured by the motor component of the widely-used United Parkinson’s Disease Rating Scale.
- People in both groups experienced improvements in quality of life measures and both were able to reduce their medication intake during the 24 months following surgery.
- Those in the STN group experienced a larger reduction in medication use than the GPi group (about 1.5 tablets of standard Sinemet 25/100 per day).
- In cognitive performance, both groups experienced a slight deterioration, but those in the STN group showed a greater decline in one aspect of visual processing.
- The STN group also showed a slight increase in depression, while the GPi group showed a slight decrease.
What Does it Mean?
One of the central questions about DBS since the procedure was approved more than a decade ago has been where to place the electrodes: the STN or the GPi. From this large and well-controlled study, the verdict is a tie: the two target sites appear to be equally effective overall in terms of motor function, individual satisfaction and adverse effects.
This said, people with Parkinson’s should be aware that the doctor’s choice of target may be based on factors unique to the situation of a particular person — including cognitive status, medication usage, medical and psychiatric health.