News ArchivesRead News
Sleep improves working memory in people with Parkinson's disease
Monday August 20, 2012
Emory news center - People with Parkinson's disease performed markedly better on a test of working memory after a night's sleep, and sleep disorders can interfere with that benefit, researchers have shown.
While the classic symptoms of Parkinson's disease include tremors and slow movements, Parkinson's can also affect someone's memory, including "working memory." Working memory is defined as the ability to temporarily store and manipulate information, rather than simply repeat it. The use of working memory is important in planning, problem solving and independent living.
The findings underline the importance of addressing sleep disorders in the care of patients with Parkinson's, and indicate that working memory capacity in patients with Parkinson's potentially can be improved with training. The results also have implications for the biology of sleep and memory.
The results were published this week in the journal Brain.
"It was known already that sleep is beneficial for memory, but here, we've been able to analyze what aspects of sleep are required for the improvements in working memory performance," says postdoctoral fellow Michael Scullin, PhD, who is the first author of the paper. The senior author is Donald Bliwise, PhD, professor of neurology at Emory University School of Medicine.
The performance boost from sleep was linked with the amount of slow wave sleep, or the deepest stage of sleep. Several research groups have reported that slow wave sleep is important for synaptic plasticity, the ability of brain cells to reorganize and make new connections.
Sleep apnea, the disruption of sleep caused by obstruction of the airway, interfered with sleep's effects on memory. Study participants who showed signs of sleep apnea, if it was severe enough to lower their blood oxygen levels for more than five minutes, did not see a working memory test boost.
In this study, participants took a "digit span test," in which they had to repeat a list of numbers forward and backward. The test was conducted in an escalating fashion: the list grows incrementally until someone makes a mistake. Participants took the digit span test eight times during a 48-hour period, four during the first day and four during the second. In between, they slept.
Repeating numbers in the original order is a test of short-term memory, while repeating the numbers in reverse order is a test of working memory.
"Repeating the list in reverse order requires some effort to manipulate the numbers, not just spit them back out again," Scullin says. "It's also a purely verbal test, which is important when working with a population that may have motor impairments."
54 study participants had Parkinson's disease, and 10 had dementia with Lewy bodies: a more advanced condition, where patients may have hallucinations or fluctuating cognition as well as motor symptoms. Those who had dementia with Lewy bodies saw no working memory boost from the night's rest. As expected, their baseline level of performance was lower than the Parkinson's group.
Participants with Parkinson's who were taking dopamine-enhancing medications saw their performance on the digit span test jump up between the fourth and fifth test. On average, they could remember one more number backwards. The ability to repeat numbers backward improved, even though the ability to repeat numbers forward did not.
Patients needed to be taking dopamine-enhancing medications to see the most performance benefit from sleep. Patients not taking dopamine medications, even though they had generally had Parkinson's for less time, did not experience as much of a performance benefit. This may reflect a role for dopamine, an important neurotransmitter, in memory.
Scullin and Bliwise are planning an expanded study of sleep and working memory, in healthy elderly people as well as patients with neurodegenerative diseases.
"Many elderly people go through a decline in how much slow wave sleep they experience, and this may be a significant contributor to working memory difficulties," Scullin says.
The research was supported by the National Institute of Neurological Disorders and Stroke (R01 NS050595) and the National Institute of Aging (F32 AG041543).
M.K. Scullin, L.M. Trotti, A.G. Wilson, S.A. Greer and D.L. Bliwise. Nocturnal sleep enhances working memory training in Parkinson's disease but not Lewy body dementia. Brain (2012) doi: 10.1093/brain/aws192
Recent NewsNov 17 - 'Moving Day' participant is not letting young-onset Parkinson's disease stop him
Nov 17 - Focused ultrasound shows promise for treating Parkinson's tremor
Nov 17 - New research to target air pollution as a potential trigger for Parkinson’s
Nov 17 - This device will let you feel what it's like to suffer from Parkinson's
Nov 10 - How does Parkinson's disease influence depression?
Nov 10 - House votes to repeal ObamaCare's Medicare cost-cutting board
Nov 10 - Microsoft shows off watch that quiets Parkinson's tremors
Nov 3 - Utah group battling Parkinson's disease with boxing
Nov 3 - UVA-LED STUDY EXAMINES POTENTIAL OF SOUND WAVES TO MANAGE PARKINSON’S DISEASE
Oct 27 - Herbicide's link to Parkinson's disease
Oct 27 - NTU Singapore, KAIST scientists discover new mechanism that causes Parkinsonian symptoms
Oct 27 - 70,000 Washingtonians face higher insurance costs after Trump order, officials say
Oct 18 - Brain disconnections may contribute to Parkinson's hallucinations
Oct 18 - Fighting Parkinson's disease through dance
Oct 17 - Scientists Identify Structure of PINK1, Key Parkinson’s-protective Protein
Oct 17 - Diabetes drug cuts Parkinson's risk by 28 percent, study finds
Oct 10 - Advances in Brain Pacemaker Reduces Tremors, Helps Parkinson's Sufferers Live a More Normal Life
Oct 10 - Medical History Could Help Predict Parkinson's Disease Risk Long Before Diagnosis
Oct 3 - Changes in Olfactory Bulb Explain Loss of Smell in Early Stages of Parkinson’s Disease, Study Finds
Oct 3 - Sleep Disturbances May Worsen Motor Symptoms in Parkinson’s Disease, Study Suggests