Posted on 09/26/2011 1:36:55 PM PDT by decimon
Up-and-down cycle flattens as age disrupts pattern
A marker for Alzheimer's disease rises and falls in the spinal fluid in a daily pattern that echoes the sleep cycle, researchers at Washington University School of Medicine in St. Louis have found.
The pattern is strongest in healthy young people and reinforces a link between increased Alzheimer's risk and inadequate sleep that had been discovered in animal models. The brain's relative inactivity during sleep may provide an opportunity to finish clearing away the Alzheimer's marker, a byproduct of brain activity called amyloid beta. The body clears amyloid beta from the brain through the spinal fluid and other mechanisms.
In the new study, scientists report that the normal highs and lows of amyloid beta levels in the fluid that surrounds the brain and spinal cord begin to flatten in older adults, whose sleep periods are often shorter and more prone to disruption. In older adults with brain plaques linked to Alzheimer's disease, the ebb and flow is eradicated, and amyloid beta levels are close to constant.
The study is now online in Archives of Neurology.
"In healthy people, levels of amyloid beta drop to their lowest point about six hours after sleep, and return to their highest point six hours after maximum wakefulness," says Randall Bateman, MD, associate professor of neurology. "We looked at many different behaviors, and the transitions between sleep and wakefulness were the only phenomena that strongly correlated with the rise and fall of amyloid beta in the spinal fluid."
Bateman's laboratory conducted the study in partnership with Washington University's Sleep Medicine Center.
"We've known for some time that significant sleep deprivation has negative effects on cognitive function comparable to that of alcohol intoxication," says Stephen Duntley, MD, professor of neurology and director of the center. "But it's recently become apparent that prolonged sleep disruption and deprivation can actually play an important role in pathological processes that underlie diseases. This connection to Alzheimer's disease isn't confirmed yet in humans, but it could be very important."
Duntley notes that older adults often sleep less and have fewer periods of deep slumber. A number of factors linked to aging, such as reduced exercise levels, can disrupt the normal daily patterns of sleep and waking. These disruptions often become more pronounced as individuals age. The risk of Alzheimer's disease also increases with age.
Scientists studied three sets of subjects: a group age 60 and older who tested positive for the presence of amyloid beta plaques in the brain; a group in the same age range who did not have plaques; and a group of healthy persons age 18-60.
Researchers used a spinal tap to monitor amyloid beta in the spinal fluid hourly for 24 to 36 hours, and videotaped patients' activities and monitored their brain activity during that period.
In the group with brain plaques, amyloid beta levels were close to constant. But in the other two groups, the levels regularly rose and fell in a snakelike, sinusoidal pattern. The highs and lows of this pattern were much more pronounced in younger subjects.
Lead author Yafei Huang, PhD, statistical data analyst, reviewed the subjects' activities during the monitoring period at 30-second intervals. She grouped them into categories such as eating or drinking, watching television, using the bathroom, and using a computer or text messaging.
None of these activities could be closely correlated with changes in amyloid beta levels. But peaks in sleep and wakefulness, assessed both by videotape and by records of patients' brain activity levels, consistently occurred before the peaks and valleys of amyloid beta levels.
Researchers are currently testing if deliberate interruption of sleep in young healthy subjects disrupts the normal daily decrease in spinal amyloid beta.Scientists may follow these studies with tests of whether sleeping pills and other interventions that improve sleep help maintain the rise and fall of amyloid beta in the spinal fluid.
"It's still speculation, but there are tantalizing hints that better sleep may be helpful in reducing Alzheimer's disease risk," says Duntley. "We know from a number of studies that exercise enhances sleep, and research also has shown that exercise is associated with decreased risk of Alzheimer's. Sleep might be one link through which that effect occurs."
###
Huang Y, Potter R, Sigurdson W, Santacruz A, Shih S, Ju Y-E, Kasten T, Morris JC, Mintun M, Duntley S, Bateman RJ. Effects of age and amyloid deposition on amyloid beta dynamics in the human central nervous system. Archives of Neurology, online September 12, 2011.
Funding from the National Institutes of Health, the Washington University Clinical and Translational Science Award, an anonymous foundation, Betty and Steve Schmid, the Knight Initiative for Alzheimer Research, the James and Elizabeth McDonnell Fund for Alzheimer Research and Eli Lilly supported this study.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Ping
This has me wondering if melatonin helps.
I agree with this. A family friend has onset and he is great in the morning and fades in the afternoon. He was at our Parish BBQ yesterday and around 2:30 he knew it was time to go home. He was my Jr. High School History teacher and a great influence on me over the years.
Sundowning?
OR...Vitamin D3???
?
Alzheimers research can give us some hope of countering this terrible disease.
This looks particularly interesting to me. Could enhancing sleep prevent or even cure Alzheimer's?
Sundowners “syndrome” is the falloff in a dementia patient’s ability to function as the day progresses.
My husband’s great aunt Olive had Alzheimer’s. Toward the end, at dusk, she would leave the house that she shared with her elder sister Elsie and start walking back to the house where she grew up. I believe that she was around 93 at the time, with her sister being about 95. Elsie would get into her old Cadillac and drive out to find her. She was usually just a few blocks away, a dutiful daughter trudging home to make dinner for her mother.
The last paragraph of the article talking about the importance of exercise and sleep is great. We already know that quality sleep (REM sleep) is very important to health.
The health articles I most like are those involving what people can do for themselves.
You wrote: “I would be interested in knowing if untreated sleep apnea could then be a cause at some level of Alzheimers. My dad succumbed to Alzheimers and was a pretty good snorer.”
_______________________________________________________
Sorry I’m late to this discussion. Just discovered it now.
Below are some articles that might be of interest.
If anyone knows of easier treatments (for sleep apnea) that avoid the use of C-PAP machines, please let me know. If possible, pass on this info to others who might be more knowledgeable than I am and might have good suggestions. If so, please report back. Thanks.
_______
Sleep Apnea Linked to Cognitive Difficulties and Deficits in Gray Matter
ScienceDaily (Nov. 14, 2010) — Patients with obstructive sleep apnea (OSA) may blame their daytime difficulties on simple sleepiness, but new research suggests that their brains may be to blame. Specifically, their cognitive challenges may be caused by structural deficits in gray matter, brought on by the intermittent oxygen deprivation that comes with OSA. The good news is that these deficits may be partially or fully reversible with early detection and treatment, according to Italian researchers...
Full article here: http://www.sciencedaily.com/releases/2010/11/101112141119.htm
_______
Sleep apnea may raise dementia risk, study finds
San Francisco Chronicle
August 10, 2011
… Sleep disorders, and sleep apnea in particular, have long been associated with memory loss and dementia in particular, but the study is among the first to strongly suggest that the sleep problems may be a cause - not an effect - of the cognitive impairment...
... “What we’re seeing is a nearly twofold increase of having cognitive problems five years later.”...
... Some animal studies have found a connection between hypoxia and buildup of beta amyloid, the material that collects like plaque in the brains of Alzheimer’s patients. Other studies have tied low oxygen levels to increased brain inflammation...
Full article here: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2011/08/10/MNJK1KLC2V.DTL
_______
Obstructive sleep apnea: brain structural changes and neurocognitive function before and after treatment
“... After treatment, we observed significant improvements involving memory, attention, and executive-functioning that paralleled gray-matter volume increases in hippocampal and frontal structures...”
http://www.ncbi.nlm.nih.gov/pubmed/21037021
_______
Sleep-Disordered Breathing, Hypoxia, and Risk of Mild Cognitive Impairment and Dementia in Older Women
http://jama.ama-assn.org/content/306/6/613.short
_______
Sleep-Disordered Breathing and Cognitive Decline in Older Adults
http://jama.ama-assn.org/content/306/6/654.short
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.