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A Good Nightís Sleep May Improve Working Memory Training in Parkinsonís Disease
- Sep 06 2012
New research has shown that some people with Parkinson’s disease (PD) can improve their working memory with specialized training, but only after a period of deep sleep at night. The study was published online August 20 in the journal Brain.
Working memory is the ability to actively store and manipulate information in the brain. Everyday tasks that require working memory include planning, problem solving, mental arithmetic and navigation. The mild cognitive impairment that can occur in Parkinson’s disease can affect working memory, leading to difficulty performing everyday activities, such as being able to remember who called just after hanging up the phone. Recent research has shown that people can improve their working memory with specific training tasks. Scientists do not know exactly how it works, but brain imaging studies have shown that training can actually change connections between brain cells (or neurons).
Michael Scullin, Ph.D., at Emory University School of Medicine wondered whether deep sleep along with training could improve working memory for people with Parkinson’s disease. To find out, Dr. Scullin and his colleagues studied 53 people with Parkinson’s disease and 10 people with dementia with Lewy bodies (DLB), a related disorder with more severe cognitive impairments than PD. Forty-two of the people with PD were taking one or more dopaminergic medications such as levodopa, whereas 11 were not taking any dopaminergic medication. The study volunteers stayed in a sleep laboratory for 48 consecutive hours. In the daytime, they completed eight training sessions for working memory. They also underwent tests – during which they were asked to remember numbers, and recite them forward and backward – to test working memory and short-term memory. During the two nights of the study, the volunteers were connected to a machine, called a polysonogram, which monitored aspects of their sleep such as sleep phase, breathing and leg movements.
- People with PD who were taking dopaminergic medication showed significant improvement in the working memory test, but not in the short-term memory test, from day one to day two. People with PD who were not taking dopaminergic medication and people with DLB showed no improvements in either the forward or backward test.
- The volunteers did not improve their scores from one test to another during the day. The improvement occurred in the test after which volunteers slept.
- Volunteers with the most improved working memory scores had more slow-wave deep sleep and higher oxygen levels as they slept.
What Does It Mean?
Cognitive complaints are common among people with PD and in the general population as well. Unfortunately, medications have only a limited role in improving cognitive function. This study suggests that the combination of dopaminergic medication, nighttime slow-wave sleep, and nighttime oxygen levels can all enhance working memory training in people with PD.
This finding is very encouraging, suggesting that people with PD could benefit from training to improve working memory. To maximize the benefit, doctors should correct existing sleep disturbances, the study’s authors say. For example, people with low oxygen levels as they sleep could use a device called a CPAP, or continuous positive airway pressure, to treat sleep apnea. This study assessed participants over 48 hours. Further research must be done to determine how long the effect of cognitive training could improve working memory in people with PD.
Reference: Scullin, M. K., Trotti, L. M., Wilson, A. G., Greer, S. A., Bliwise, D. L. (2012). Nocturnal sleep enhances working memory training in Parkinson’s disease but not Lewy body dementia. Brain, doi: 10.1093/brain/aws192.
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Source Date: Oct 11 2012