Probing the Secrets of Sharp Memory in Old Age
March 24, 2010
Science Daily/American Chemical Society
A study of the brains of people who stayed mentally sharp into their 80s and beyond challenges the notion that brain changes linked to mental decline and Alzheimer's disease are a normal, inevitable part of aging.
In a presentation given at the 239th National Meeting of the American Chemical Society (ACS) in San Fransisco March 23, Changiz Geula, Ph.D. and colleagues described their discovery of elderly people with super-sharp memory -- so-called "super-aged" individuals -- who somehow escaped formation of brain "tangles."
The tangles consist of an abnormal form of a protein called "tau" that damages and eventually kills nerve cells. Named for their snarled, knotted appearance under a microscope, tangles increase with advancing age and peak in people with Alzheimer's disease.
"This discovery is very exciting," said Geula, principal investigator of the Northwestern University Super Aging Project and a professor of neuroscience at the Cognitive Neurology and Alzheimer's Disease Center. "It is the first study of its kind and its implications are vast.
We always assumed that the accumulation of tangles is a progressive phenomenon throughout the normal aging process. Healthy people develop moderate numbers of tangles, with the most severe cases linked to Alzheimer's disease. But now we have evidence that some individuals are immune to tangle formation.
The evidence also supports the notion that the presence of tangles may influence cognitive performance. Individuals with the fewest tangles perform at superior levels. Those with more appear to be normal for their age."’
The scientists found that super-aged people appear to fall into two subgroups: Those who are almost immune to tangle formation and those that have few tangles.
"One group of super-aged seems to dodge tangle formation," Geula explained. "Their brains are virtually clean, which doesn't happen in normal-aged individuals. The other group seems to get tangles but it's less than or equal to the amount in the normal elderly. But for some reason, they seem to be protected against its effects."
http://www.sciencedaily.com/releases/2010/03/100323212139.htm
Healthy Adults May Need Less Sleep as They Age
February 2, 2010
Science Daily/American Academy of Sleep Medicine
A study in the Feb. 1 issue of the journal Sleep suggests that healthy older adults without sleep disorders can expect to have a reduced "sleep need" and to be less sleepy during the day than healthy young adults.
Results show that during a night of eight hours in bed, total sleep time decreased significantly and progressively with age. Older adults slept about 20 minutes less than middle-aged adults, who slept 23 minutes less than young adults. The number of awakenings and the amount of time spent awake after initial sleep onset increased significantly with age, and the amount of time spent in deep, slow-wave sleep decreased across age groups. Yet even with these decreases in sleep time, intensity and continuity, older adults displayed less subjective and objective daytime sleep propensity than younger adults.
Furthermore, two additional nights involving experimental disruption of slow-wave sleep led to a similar response in all age groups. Daytime sleep propensity increased, and slow-wave sleep rebounded during a night of recovery sleep. According to the authors, this suggests that the lack of increased daytime sleepiness in the presence of an age-related deterioration in sleep quality cannot be attributed to unresponsiveness to variations in homeostatic sleep pressure. Instead, healthy aging appears to be associated with reductions in the sleep duration and depth required to maintain daytime alertness.
"Our findings reaffirm the theory that it is not normal for older people to be sleepy during the daytime," said principal investigator Derk-Jan Dijk, PhD, professor of sleep and physiology at the University of Surrey in the U.K. "Whether you are young or old, if you are sleepy during the day you either don't get enough sleep or you may suffer from a sleep disorder."
The study was conducted at the Clinical Research Centre of the University of Surrey and involved 110 healthy adults without sleep disorders or sleep complaints; 44 were young (20 to 30 years), 35 were middle-aged (40 to 55 years) and 31 were older adults (66 to 83 years). After an eight-hour baseline sleep test, subjects were randomized to two nights with or without selective slow-wave sleep disruption by acoustic stimuli, followed by one recovery night. Nighttime sleep was evaluated by polysomnography, while sleep propensity was assessed using the Multiple Sleep Latency Test (MSLT) and the Karolinska Sleepiness Scale.
During the baseline night, mean objective total sleep time decreased from 433.5 minutes for young adults to 409.9 minutes for middle-aged adults and 390.4 minutes for older adults. Average minutes of slow-wave sleep decreased from 118.4 minutes for young adults to 85.3 minutes for middle-aged adults and 84.2 minutes for older adults. Mean number of minutes spent awake after initial sleep onset increased from 21 for young adults to 49.9 for middle-aged adults and 70.7 for older adults.
Objective daytime sleepiness measured by the MSLT decreased with age. When asked to lie in a comfortable position on the bed and try to fall asleep, young adults fell asleep in an average of 8.7 minutes, compared with 11.7 minutes for middle-aged adults and 14.2 minutes for older adults.
The authors noted that the cause of the age-related reductions in slow-wave sleep and sleep need still must be established. Related factors could include alterations in reproductive hormones or changes in the brain. They added that the study did not address sleep propensity during the evening hours, when it is possible that older adults may be sleepier than young adults.
According to the authors, the study also has implications for the treatment of insomnia in older adults, who may be unaware of their reduced sleep need. Therefore, sleep restriction, which leads to increased homeostatic sleep pressure, may be a successful behavioral therapy for insomnia in healthy older adults.
http://www.sciencedaily.com/releases/2010/02/100201091632.htm
Sleep Disturbances Improve After Retirement
November 2, 2009
Science Daily/American Academy of Sleep Medicine
A new study in the journal Sleep shows that retirement is followed by a sharp decrease in the prevalence of sleep disturbances. Findings suggest that this general improvement in sleep is likely to result from the removal of work-related demands and stress rather than from actual health benefits of retirement.
Results show that the odds of having disturbed sleep in the seven years after retirement were 26 percent lower (adjusted odds ratio of 0.74) than in the seven years before retiring. Sleep disturbance prevalence rates among 14,714 participants fell from 24.2 percent in the last year before retirement to 17.8 percent in the first year after retiring.
The greatest reduction in sleep disturbances was reported by participants with depression or mental fatigue prior to retirement. The postretirement improvement in sleep also was more pronounced in men, management-level workers, employees who reported high psychological job demands, and people who occasionally or consistently worked night shifts.
Results also show that there is a slowly increasing prevalence of sleep disturbances with increasing age, which can be observed both before and after retirement. From the first to the seventh year after retirement, the prevalence of sleep disturbances increased from 17.8 percent to 19.7 percent but remained significantly lower than at any time point prior to retirement.
"We believe these findings are largely applicable in situations where financial incentives not to retire are relatively weak," said Vahtera. "In countries and positions where there is no proper pension level to guarantee financial security beyond working age, however, retirement may be followed by severe stress disturbing sleep even more than before retirement."
http://www.sciencedaily.com/releases/2009/11/091101132537.htm
Light-Treatment Device to Improve Sleep Quality in the Elderly
June 1, 2009
Science Daily/Rensselaer Polytechnic Institute
Sleep disturbances increase as we age. Some studies report more than half of seniors 65 years of age or older suffer from chronic sleep disturbances. Researchers have long believed that the sleep disturbances common among the elderly often result from a disruption of the body’s circadian rhythms — biological cycles that repeat approximately every 24 hours.
In recent years, scientists at Rensselaer Polytechnic Institute’s Lighting Research Center and elsewhere have demonstrated that blue light is the most effective at stimulating the circadian system when combined with the appropriate light intensity, spatial distribution, timing, and duration. A team at the Lighting Research Center (LRC) has tested a goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults.
“Light and dark patterns are the major synchronizer of circadian rhythms to the 24-hour solar day,” said Mariana Figueiro, Ph.D., Lighting Research Center Light and Health Program director and principal investigator on the project. “Light stimulus travels through the retina, the light-sensitive nerve tissue lining the back wall of the eye, to reach the master clock in the brain. However, a combination of age-related changes in the eye and a more sedentary lifestyle may reduce the amount of light stimulus reaching an older person’s retina, therefore reducing the amount of light for the circadian system.”
As we age, the lens in the eye thickens and the pupil shrinks, reducing the amount of light passing through to the retina. Making matters worse, in some cases, such as with persons with Alzheimer’s disease, the circadian system may require a stronger light stimulus due to deteriorating neural processes in the brain. These physical and neural changes can lead to muted signals to the circadian system. Factor in environmental influences, such as an indoor lifestyle with less access to daylight, and you have a perfect scenario for the development of irregular sleep-activity patterns, according to Figueiro.
The research team explains that a marked increase in daytime lighting levels can counteract the age-dependent losses in retinal light exposure by providing a stronger signal to the circadian system. However, the color and intensity of commercially available lighting systems, like those used in senior residences, assisted-living facilities, and nursing homes, are designed for visual effectiveness and minimal energy use and not necessarily efficacious for generating light to stimulate the older circadian system.
Commercially-available “white” light sources advertised to treat circadian-related sleep disorders are usually very bright light and can cause glare and compromise compliance.
In this project, the light-treatment prototype tested by Figueiro’s team was developed by Topbulb.com, LLC, based on prior LRC light and health research. The device offers an alternative approach using specially designed goggles that deliver blue light spectrally tuned for optimum circadian response.
“The goal of this phase of the development project was to create a device in a smaller form factor or envelope that allowed for social inclusion and end-user mobility, while still delivering the required dose of light,” said Topbulb.com Senior Developer Philip H. Bonello, Ph.D.
The device was worn by eleven subjects between the ages of 51 and 80 years of age. Each subject was exposed to two levels of blue light (about 50 lux and 10 lux) from the personal light-treatment device for 90 minutes on two separate nights. Blood and saliva samples were collected at prescribed times to assess levels of nocturnal melatonin, a hormone used as a marker for the circadian clock, with high levels at night when a person is in a dark environment and low levels during the day.
After only one hour of light exposure, the light-induced nocturnal melatonin suppression level was about 35 percent for the low light level and about 60 percent for the high light level. In addition, the higher level of blue light suppressed nocturnal melatonin more quickly, to a greater extent over the course of the 90-minute exposure period, and was maintained after 60 minutes.
Having demonstrated its stimulation effect on the circadian system, the researchers believe the device could be subsequently used to increase sleep consolidation and efficiency in older subjects when worn for a prescribed duration at an appropriate time.
“The study suggests that the light goggles might be a practical, comfortable, and effective way to deliver light treatment to those suffering from circadian sleep disorders. The next steps are to conduct field studies where we will be testing the effectiveness of this personal light-treatment device on those suffering from circadian-related sleep disorders, while also verifying the acceptance of the device among the test groups,” said Figueiro.
http://www.sciencedaily.com/releases/2009/05/090529112605.htm
Use of Bright Lighting May Improve Dementia Symptoms for Elderly Persons
June 11, 2008
Science Daily/JAMA and Archives Journals
The use of daytime bright lighting to improve the circadian rhythm of elderly persons was associated with modest improvement in symptoms of dementia, and the addition of the use of melatonin resulted in improved sleep, according to a new study.
"In elderly patients with dementia, cognitive decline is frequently accompanied by disturbances of mood, behavior, sleep, and activities of daily living, which increase caregiver burden and the risk of institutionalization," the author write. These symptoms have been associated with disturbances of the circadian rhythm (the regular recurrence, in cycles of about 24 hours, of biological processes or activities).
"The circadian timing system is highly sensitive to environmental light and the hormone melatonin and may not function optimally in the absence of their synchronizing effects. In elderly patients with dementia, synchronization may be [diminished] if light exposure and melatonin production are reduced."
Melatonin reduced the time to fall asleep by a relative 19 percent and increased total sleep duration by 6 percent, but adversely affected caregiver ratings of withdrawn behavior and mood expressions. The addition of bright light improved the adverse effect on mood. In combination with bright light, melatonin reduced aggressive behavior by a relative 9 percent.
"In conclusion, the simple measure of increasing the illumination level in group care facilities [improved] symptoms of disturbed cognition, mood, behavior, functional abilities, and sleep. Melatonin improved sleep, but its long-term use by elderly individuals can only be recommended in combination with light to suppress adverse effects on mood.
The long-term application of whole-day bright light did not have adverse effects, on the contrary, and could be considered for use in care facilities for elderly individuals with dementia," the authors write.
http://www.sciencedaily.com/releases/2008/06/080610161247.htm
Insomnia May Perpetuate Depression in Some Elderly Patients
April 4, 2008
Science Daily/American Academy of Sleep Medicine
In addition to being a risk factor for a depressive episode, persistent insomnia may perpetuate the illness in some elderly patients, and especially in those receiving standard care for depression in primary care settings, according to a new study.
According to the results, patients with persistent insomnia were 1.8 to 3.5 times more likely to remain depressed, compared with patients with no insomnia. The findings were more robust in patients receiving usual care for depression than in patients receiving enhanced care. The findings were also stronger in subjects who had major depressive disorder as opposed to those with dysthymia alone.
"Even when depression was identified and treated in the primary care setting, the older adults in this study were more likely to remain depressed if they also exhibited persistent insomnia.
The finding that this risk was higher in the usual-care group suggests that enhanced depression care may partially mitigate the perpetuating effects of insomnia on depression," said Dr. Pigeon.
"While the findings make intuitive sense, until relatively recently insomnia was often considered a symptom that dissipated without active intervention once a primary condition like depression was treated, instead of being considered a distinct clinical entity that might affect a primary disorder. This study has several limitations, not the least of which are that it is not a causal study nor does it unequivocally answer the question of whether insomnia that presents with depression is a symptom or a co-morbid disorder. What seems most likely is that insomnia is indeed simply a symptom in some cases, but clearly a disorder requiring its own treatment focus in other cases."
Not sleeping well can lead to a number of problems. Older adults who have poor nighttime sleep are more likely to have a depressed mood, attention and memory problems, excessive daytime sleepiness, more nighttime falls and use more over-the-counter or prescription sleep aids. In addition, recent studies associate lack of sleep with serious health problems such as an increased risk of obesity, cardiovascular disease and diabetes.
http://www.sciencedaily.com/releases/2008/04/080401081930.htm
Daytime Dozing Linked to Increased Stroke Risk In Elderly
February 22, 2008
Science Daily/American Heart Association
Regular daytime dozing forewarns of a significantly increased risk of stroke in older Americans, researchers reported at the American Stroke Association's International Stroke Conference 2008.
Among 2,153 participants in a prospective study with an average follow-up of 2.3 years, the risk of stroke was 2.6 times greater for those classified as doing "some dozing" compared to those with "no dozing." Those in the "significant dozing" group had a 4.5 times higher risk.
After controlling for several stroke risk factors -- age, race-ethnicity, sex, education, blood pressure, diabetes, obesity and physical activity -- they found unexpectedly high stroke risks for the "some dozing" and "significant dozing" groups compared to "no dozing."
The risk of a heart attack or vascular death was higher -- 1.6 percent for the moderate dozers and 2.6 percent for the significant dozers. The findings were similar for all ethnicities and both genders.
"Given what's known now, it's worth assessing patients for sleep problems," Boden-Albala said. "And the initial assessment can be something as simple as the Epworth scale. If patients are moderately or significantly dozing, physicians need to think about sending them for further evaluation."
http://www.sciencedaily.com/releases/2008/02/080221153730.htm